Dissertations / Theses on the topic 'Biological control, and natural enemy'

La intensificació agrícola va impulsar la producció d'aliments durant la Revolució Verda del segle passat però també va causar una pèrdua de biodiversitat. Actualment, s'espera que la demanda d'aliments augmenti un 15% en els pròxims 10 anys, per tant l'agricultura enfronta el repte de produir més, i d'una manera sostenible. En aquest context, l'objectiu d'aquesta tesi és el d'aportar nous coneixements sobre diversos aspectes relacionats amb el manteniment i promoció de serveis ecosistèmics (pol·linització i control biològic) en cultius fructícoles mediterranis. La primera part de la tesi avalua els efectes del reg i la consegüent intensificació agrícola en abelles silvestres i sírfids. Per això, vam analitzar les comunitats d'aquests pol·linitzadors a l'àrea fructícola de Lleida. Els nostres resultats van demostrar que la transformació de secà a regadiu provoca més abundància de flors, diferent composició floral i reducció en la cobertura d'habitats seminaturals en les àrees regades. Aquests canvis ambientals comporten una transformació dràstica de les comunitats d'abelles silvestres: augmenta la presència d'abelles socials però disminueix la d'altres abelles solitàries, i es redueix, en conseqüència, la diversitat global d'espècies (Capítol 1). La segona part de la tesi se centra específicament en l'avaluació d'estratègies de maneig d'hàbitat per a la promoció de fauna auxiliar. Primer vam estudiar l'atracció d'un marge floral a enemics naturals de pugons de la pomera (Dysaphis plantaginea i Eriosoma lanigerum), després vam caracteritzar els enemics naturals presents a les colònies de pugó i finalment, vam avaluar la contribució d'aquest marge al control biològic de pugons. Els nostres resultats subratllen la importància dels parasitoides presents als voltants de les finques de fruiters en el parasitisme de les colònies de D. plantaginea (Capítol 2). La tercera part de la tesi estudia l'atracció dels sírfids a diferents característiques florals per tal d'entendre millor el seu comportament de recerca d'aliment. Vam observar que la forma, el nombre i el color de les flors provoquen diversos comportaments en els sírfids: preferien poms de flors circulars i planes, amb combinacions de groc i blanc per sobre d'aquelles que contenien blau. A més, vam observar que femelles aparellades i no aparellades es comportaven diferent (Capítol 3). L'última part de la tesi aborda el potencial i les dificultats d'utilitzar sírfids com a proveïdors de serveis ecosistèmics en els sistemes agrícoles. Per a tal efecte, vam fer una revisió de la literatura existent relacionada amb aquests insectes beneficiosos, amb especial èmfasi en els aspectes clau de la seva ecologia que poden maximitzar el seu potencial com a pol·linitzadors i depredadors (Capítol 4).
La intensificación agrícola impulsó la producción de alimentos durante la Revolución Verde del siglo pasado pero también causó la pérdida de biodiversidad. Además, se espera que la demanda de alimento aumente un 15% en los próximos 10 años, por lo que el reto actual de la agricultura es el de proveer más, y de un modo más sostenible. En este contexto, el objetivo de esta tesis es el de aportar nuevos conocimientos sobre diversos aspectos relacionados con el mantenimiento y promoción de servicios ecosistémicos (polinización y control biológico) en cultivos frutícolas mediterráneos. La primera parte de la tesis evalúa los efectos del riego y la consecuente intensificación agrícola en abejas silvestres y sírfidos. Con esta finalidad, analizamos las comunidades de polinizadores en el área frutícola de Lleida. Nuestros resultados demostraron que la transformación de secano a regadío provoca una mayor abundancia de flores, una distinta composición floral y una reducción de la cobertura de hábitats seminaturales en las áreas regadas. Estos cambios ambientales resultan en una transformación drástica de la comunidad de abejas silvestres: aumenta la presencia de abejas sociales, pero disminuye la de abejas solitarias, reduciendo, consecuentemente, la diversidad global de especies (Capítulo 1). La segunda parte de la tesis se centra específicamente en la evaluación de estrategias de manejo del hábitat para la promoción de fauna auxiliar. Primero estudiamos la atracción de un margen floral a enemigos naturales de pulgones del manzano (Dysaphis plantaginea y Eriosoma lanigerum), luego caracterizamos los enemigos naturales presentes en las colonias de pulgón y finalmente, evaluamos la contribución de este margen al control biológico de pulgones. Nuestros resultados destacan la importancia de los parasitoides presentes en los alrededores de las fincas de frutales en el parasitismo de colonias de D. plantaginea (Capítulo 2). La tercera parte de la tesis, estudia la atracción de distintas características florales a sírfidos con la finalidad de entender mejor su comportamiento de búsqueda de alimento. Observamos que la forma, el número y el color de las flores suscitan diversos comportamientos en los sírfidos: preferían ramos de flores circulares y planas, y combinaciones de amarillo y blanco eran preferidas ante combinaciones con azul. Además, observamos que hembras apareadas y no apareadas se comportaban de modo distinto (Capítulo 3). La última parte aborda el potencial y las dificultades de utilizar sírfidos como proveedores de servicios ecosistémicos en los sistemas agrícolas. Para tal efecto, hicimos una revisión de la literatura existente relacionada con estos insectos beneficiosos, con especial énfasis en los aspectos clave de su ecología que pueden maximizar su potencial como polinizadores y depredadores (Capítulo 4).
Agricultural intensification boosted food production during the Green Revolution of the last century but it also caused loss of biodiversity. Nowadays the demand for food is expected to raise by a 15% in the next 10 years, so agriculture must face the challenge of providing more food in a sustainable way. In this context, the aim of this thesis was to give further insight in several aspects of the maintenance and promotion of ecosystem services (pollination and biological control) in Mediterranean fruit orchards. The first part of the thesis evaluates the effects of irrigation and the consequent agricultural intensification on two of the main groups of pollinators: wild bees and hoverflies. For that, we assessed these pollinator communities in the fruit-tree growing area of Lleida. Our results showed that the transformation of dryland into irrigation caused a higher flower abundance, different flower composition and reduced cover of semi-natural habitats in the irrigated areas. These environmental changes resulted in a drastic transformation of the wild bee communities: in the irrigated areas the presence of social bees increased but the presence of other solitary species was hindered, reducing overall wild bee species diversity (Chapter 1). The second part of the thesis specifically focuses on the evaluation of habitat management strategies to promote beneficials. First, we assessed the attractiveness of a specific flower margin to natural enemies of apple aphids (Dysaphis plantaginea and Eriosoma lanigerum), then we characterized the natural enemies present in the aphid colonies and finally, we evaluated the contribution of this margin to aphid biological control. Our results highlight the importance of parasitoids present in the surroundings of the orchards on the parasitism of D. plantaginea colonies (Chapter 2). The third part of the thesis studies the attractiveness of different flower traits to hoverflies to better understand the foraging behavior of these insects. We observed that flower shape, number and color elicit diverse behaviors in hoverflies: they showed a predilection for flat circle-shaped flowers bouquets and, that combinations with yellow and white are preferred to those that contain blue. In addition, we found behavioral differences between mated and unmated females with regard to their flower foraging (Chapter 3). The last part of the thesis addresses the potential and difficulties of using hoverflies as providers of ecosystem services in agricultural systems. For that purpose, we reviewed the existing literature related to these beneficials, with an emphasis on the key aspects of their ecology that can maximize their potential as pollinators and predators (Chapter 4).

1. Plant quality (bottom-up effects) and natural enemies (top-down effects) affect herbivore performance. Furthermore, plant quality can also influence the impact of natural enemies. 2. Lower plant quality through reduced irrigation increased the abundance of the cryptic species from the Bemisia tabaci complex [hereafter B. tabaci Middle East Asia Minor 1 (MEAM1)], but not its natural enemies on cotton. It was therefore predicted that lower plant quality would diminish the impact of natural enemies in regulating this herbivore. 3. Over three cotton seasons, plant quality was manipulated via differential irrigation and natural enemy abundance with insecticides. Life tables were used to evaluate the impact of these factors on mortality of immature B. tabaci (MEAM1) over nine generations. 4. Mortality of B. tabaci (MEAM1) was consistently affected by natural enemies but not by plant quality. This pattern was driven by high levels of sucking predation, which was the primary (key) factor associated with changes in immature mortality across all irrigation and natural enemy treatments. Dislodgement (chewing predation and weather) and parasitism contributed as key factors in some cases. Analyses also showed that elimination of sucking predation and dislodgement would have the greatest effect on overall mortality. 5. The top-down effects of natural enemies had dominant effects on populations of B. tabaci (MEAM1) relative to the bottom-up effects of plant quality. Effects were primarily due to native generalist arthropod predators and not more host-specific aphelinid parasitoids. The findings of this study demonstrate the important role of arthropod predators in population suppression and validate the importance of conservation biological control in this system for effective pest control.

This work covers stages one through seven (of nine stages) of a classical biological control program for Mediterranean fruit fly (=medfly), Ceratitis capitata (Wiedemann). Major research objectives concentrate on stage five (exploration and collection of natural enemies), and stage seven (testing and selecting natural enemies for additional work). Coffee was collected monthly from three locations in Kenya from November 1997 through July 1999. Four species of tephritid flies and ten parasitoid species were recovered. Four guilds of parasitoids were recorded, and two egg-prepupal endoparasitoids, Fopius caudatus (Szépligeti) and F. ceratitivorus (Wharton), were discovered. The oviposition behavior of these two species is contrasted. Domination of this tropical parasitoid assemblage by koinobionts is discussed relative to the dominance of temperate fruit-infesting tephritid systems by idiobionts. Fruit handling procedures were examined for impact on overall percent emergence and specifically percent emergence of flies versus parasitoids. It was determined that stirring samples had a significant positive effect on overall emergence, however daily misting of fruit did not. The only treatment without a significant bias in fly emergence over parasitoids was the stirred/dry treatment. Effects of these results on rearing procedures are discussed. Host specificity and host suitability of parasitoids reared from coffee were examined via: (1) association of parasitoids with host flies based on characteristics of the fly puparia from which parasitoids emerged, (2) rearing of cucurbit infesting tephritids and their parasitoids in Kenya, (3) rearing of flowerhead infesting tephritids and their parasitoids in Kenya and Hawaii, and (4) host range testing of Psyttalia species in Kenya and Hawaii. These results are discussed in terms of their utility for predicting nontarget effects. Psyttalia concolor (Szépligeti) was shipped to Hawaii and tested against the nontarget gall forming tephritid Procecidochares utilis Stone introduced to control the weed Ageretina adenophora (Maui pamakani). Psyttalia concolor failed to attack the gall-forming P. utilis both in choice and no-choice tests, but readily attacked tephritid larvae offered in fruit in choice tests. Recommendations for further testing and release of the parasitoids from Kenya are discussed for Hawaii and Latin America.

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O gênero Eucalyptus (Myrtaceae) é originário da Austrália e hospeda várias espécies de insetos da família Psyllidae. Dentre elas, o psilídeo-de-concha Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), que é considerada uma das principais pragas introduzidas desta cultura no Brasil e em outros países. O parasitóide Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) é indicado como principal agente no controle biológico desta praga. Devido a sua importância econômica, esse trabalho objetivou estudar as populações de G. brimblecombei e de P. bliteus em floresta de Eucalyptus camaldulensis para determinação de sua distribuição espacial, flutuação populacional, a relação com fatores meteorológicos (temperatura e precipitação), e determinar o índice de parasitismo pós liberação de P. bliteus em campo. O estudo da dinâmica populacional do psilídeo-de-concha e do seu parasitóide foi realizado através da utilização de 53 armadilhas amarelas e da coleta de 53 ramos/avaliação em um talhão de 19 ha com E. camaldulensis em Luiz Antônio, SP, com 42 avaliações, entre janeiro de 2006 a janeiro de 2008. Concluiu-se que as populações de ambas espécies apresentaram distribuição espacial agregada, possuem correlação inversamente proporcional à temperatura, e a precipitação pluviométrica; ocorreu aumento no índice de parasitismo em todos os pontos de liberação de P. bliteus. no período avaliado
The genus Eucalyptus is originally from Australia and hosts several species of insects of the family Psylidae. Among them, the red gum lerp psyllid is considered one of the main pests of this crop introduced in Brazil and other countries. However, for the control of phytophagous hemiptera, the treatment with insecticides proved to be expensive and unsustainable. The psylllid specific parasitic wasp Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) is indicated as the main biological control agent of this pest. Due to its economic importance, this study aimed to evaluate G. brimblecombei and P. bliteus population in Eucalyptus camaldulensis plantations to determine their spatial distribution, population fluctuation with weather interactions (temperature and rainfall), and also to determine parasitism rates in the field after release of P. bliteus. The study of population dynamic of red gum lerp psyllid and its parasitoid (53 traps sampled and 53 branches sampled per sampling dates) was carried out on E. camaldulensis plantations in 19 ha area in Luiz Antônio municipality (SP, Brazil), from January 2006 to January 2008 (42 sampling dates). This research indicated that population of both species noticed especial aggregated distribution, inversely proportional subject to temperature. Besides, was found correlation between both species and rainfall. There was also at measured period an increase in the parasitism rate at all release points of P. bliteus

Current agroecosystem management practices have a negative effect on natural enemies and their ability to control insect pests. Conservation biological control through the addition of flowering resources can manage food resources for natural enemies. These floral resources can also provide multiple ecosystem services. Study goals were to determine if perennial Thymus vulgaris L. was attractive to natural enemies and if so, could it be a dual use resource encouraging pest management and providing harvestable product. In 2018 plots in three locations were used to examine the effect of habitat throughout the growing season on the attractiveness of T. vulgaris. Large numbers of Thysanoptera and Hemiptera were collected in all locations, represented by phytophagous Aphididae and Thripidae, and predatory Anthocoridae. Location influenced other families to varying degrees. Seasonal specimen counts were influenced by vegetation density, floral phenology, and predator/prey relationships. In 2019 replicated plots of three treatments were used to examine if harvesting plant material affected the attractiveness of T. vulgaris to natural enemies. Total specimens in 2019 were not significantly different among treatments, indicating removal of blooms did not significantly affect the attractiveness of T. vulgaris. Significant numbers of Thysanoptera and Hemiptera were again collected in all treatments, represented by phytophagous Aphididae and Thripidae. Greater numbers of Diptera and Hymenoptera were also collected. Significant numbers of Thripidae, Aphididae, Mymaridae, and Platygastridae were found in the Family level analyses. Results from both years indicate T. vulgaris was attractive to natural enemy and phytophagous Families. Data from 2018 suggest natural enemy families were attracted to alternative prey and hosts utilizing the foliage rather than flowers but the use of nectar and pollen cannot be ruled out. Data from 2019 suggest the presence of flowers played an important role in the attractiveness of T. vulgaris to micro-hymenopteran parasitoids, Syrphidae, and native Apidae. In conclusion, Thymus vulgaris has the potential to be a dual use floral resource that benefits growers through supporting native enemy populations and pollination services, as well as provide income from the harvest of foliage. It could also be used as a beneficial, harvestable floral resource in urban gardens to encourage pollinator conservation and natural pest control.

Orientador: Carlos Frederico Wilcken
Banca: Edson Luiz Lopes Baldin
Banca: Nádia Cristina de Oliveira
Banca: Luiz Alexandre Nogueira de Sá
Banca: Leonardo Rodrigues Barbosa
Resumo: O gênero Eucalyptus (Myrtaceae) é originário da Austrália e hospeda várias espécies de insetos da família Psyllidae. Dentre elas, o psilídeo-de-concha Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), que é considerada uma das principais pragas introduzidas desta cultura no Brasil e em outros países. O parasitóide Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) é indicado como principal agente no controle biológico desta praga. Devido a sua importância econômica, esse trabalho objetivou estudar as populações de G. brimblecombei e de P. bliteus em floresta de Eucalyptus camaldulensis para determinação de sua distribuição espacial, flutuação populacional, a relação com fatores meteorológicos (temperatura e precipitação), e determinar o índice de parasitismo pós liberação de P. bliteus em campo. O estudo da dinâmica populacional do psilídeo-de-concha e do seu parasitóide foi realizado através da utilização de 53 armadilhas amarelas e da coleta de 53 ramos/avaliação em um talhão de 19 ha com E. camaldulensis em Luiz Antônio, SP, com 42 avaliações, entre janeiro de 2006 a janeiro de 2008. Concluiu-se que as populações de ambas espécies apresentaram distribuição espacial agregada, possuem correlação inversamente proporcional à temperatura, e a precipitação pluviométrica; ocorreu aumento no índice de parasitismo em todos os pontos de liberação de P. bliteus. no período avaliado
Abstract: The genus Eucalyptus is originally from Australia and hosts several species of insects of the family Psylidae. Among them, the red gum lerp psyllid is considered one of the main pests of this crop introduced in Brazil and other countries. However, for the control of phytophagous hemiptera, the treatment with insecticides proved to be expensive and unsustainable. The psylllid specific parasitic wasp Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) is indicated as the main biological control agent of this pest. Due to its economic importance, this study aimed to evaluate G. brimblecombei and P. bliteus population in Eucalyptus camaldulensis plantations to determine their spatial distribution, population fluctuation with weather interactions (temperature and rainfall), and also to determine parasitism rates in the field after release of P. bliteus. The study of population dynamic of red gum lerp psyllid and its parasitoid (53 traps sampled and 53 branches sampled per sampling dates) was carried out on E. camaldulensis plantations in 19 ha area in Luiz Antônio municipality (SP, Brazil), from January 2006 to January 2008 (42 sampling dates). This research indicated that population of both species noticed especial aggregated distribution, inversely proportional subject to temperature. Besides, was found correlation between both species and rainfall. There was also at measured period an increase in the parasitism rate at all release points of P. bliteus
Doutor

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The selectivity of 64 pesticides registered to the culture were assessed to Trichogramma pretiosum Riley , 1879...................
Avalio-se a seletividade de 64 agrotoxicos registrados para a cultura do milho a Trichogramma pretiosum , 1879.............

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Os psilídeos são um grupo de pragas amplamente distribuídas, causando perdas consideráveis em sistemas agrícolas e florestais. A recente descoberta da ocorrência do psilídeo-de-concha Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), no Brasil tornou-se um problema de grande importância, por ser específico de Eucalyptus. O parasitóide Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) é indicado como principal agente no controle biológico desta praga. Portanto, para o monitoramento adequado de ambas espécies é necessário um método eficiente de amostragem. Devido a sua importância econômica, esse trabalho objetivou estudar as populações de G. brimblecombei e de P. bliteus em floresta de Eucalyptus camaldulensis por dois métodos de amostragem, utilizando armadilhas amarelas e coleta de folhas para determinação de sua distribuição espacial, flutuação populacional, a relação com fatores meteorológicos (temperatura e precipitação), proporção sexual, e correlacionar os métodos de amostragem com ambas populações. A determinação da distribuição espacial, flutuação populacional, proporção sexual e correlação dos métodos de amostragem (53 armadilhas amarelas e 53 ramos/avaliação) foi realizada em um talhão de 19 ha com E. camaldulensis em Luiz Antônio, SP, com 10 avaliações, entre janeiro e junho de 2005. Concluiu-se que as populações de ambas espécies apresentaram distribuição espacial agregada, possue correlação inversamente proporcional à temperatura, independente do método de amostragem; não foi constatado correlação entre ambas espécies e a precipitação pluviométrica, as armadilhas adesivas amarelas são viáveis como método de amostragem e a proporção sexual (macho : fêmea) foi baixa para populações de G. brimblecombei e alta para populações de P. bliteus, sendo coletados mais fêmeas que machos para ambas espécies, no período avaliado.
Psyllids are a widespread group of pests, causing severe damage on agricultural and forestry systems. The recent discovery about occurrence of red gum lerp psyllid Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), in Brazil is nowadays a great problem in Eucalyptus forests, mainly in E. camaldulensis. The psyllid specific parasitic wasp Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) is this pest main biological control agent. Thus, the adequate monitoring of both species by a efficient sampling method would facilitate a future decision making. Due to its economic importance, this study aimed to evaluate G. brimblecombei and P. bliteus populations in Eucalyptus camaldulensis plantation by two sampling methods, using yellow traps and foliage samples to determinate their spatial distribution, population fluctuation with weather interactions (temperature and rainfall) and sexual rate and to correlate sampling methods with both populations. The study of the populational fluctuation, the sexual rate, the spatial distribution and correlation sampling methods (53 traps sampled and 53 branches sampled per sampling dates) was carried out on E. camaldulensis plantations in a 19 ha area in Luiz Antônio municipality (SP, Brazil), between January and June, 2005 (10 sampling dates). This research indicated that population of both species noticed special aggregated distribution, inversely proportional correlation subject to temperature. However between sampling methods, there was no correlation between both species with the rainfall, yellow stick traps were useful as sampling methods, sexual rate (male:female) is low to G. brimblecombei populations and high to P. bliteus populations, have been collected more female than male to both species in the evaluated period.

Cirsium arvense (L.) Scop. (Californian, Canada, or creeping thistle) is an exotic perennial herb indigenous to Eurasia that successfully established in New Zealand (NZ) approximately 130 years ago. Presently, C. arvense is considered one of the worst invasive weeds in NZ arable and pastoral productions systems. The mechanism most commonly invoked to explain the apparent increased vigour of introduced weeds is release from natural enemies. The enemy release hypothesis (ERH) predicts that plants in an introduced range should experience reduced herbivory, particularly from specialists, and that release from this natural enemy pressure facilitates increased plant performance in the introduced range. In 2007 broad surveys were carried out in NZ and central Europe in order to quantify and compare growth characteristics of C. arvense in its native vs. introduced range. Additionally, permanent field plots were established in NZ and Europe where natural enemies were excluded with the use of insecticide and fungicide applications, and compared with controls (ambient natural enemy pressure). The impact of the specialist leaf-feeding beetle, Cassida rubiginosa Müller, which was recently released in NZ as a biological control agent against thistles, was also assessed. From the field surveys, significantly more endophagous herbivory was present in the native range compared to the introduced range, as predicted by the ERH. Endophagous herbivory in NZ was solely from the capitulum-feeding weevil, Rhinocyllus conicus (Frölich), and was only found in the North Island surveys. No stem mining attack was found anywhere in NZ. The proportion of shoots attacked by the specialised rust pathogen, Puccinia punctiformis (Str.) Röhl., was similar in both the native and introduced ranges. Interestingly, this has casted doubt on the idea that stem-mining vectors, such as Ceratapion onopordi Kirby, are important for transmission of the rust pathogen. Contrary to the ERH, there were no significant difference in plant performance between the native and introduced ranges, or differences could be explained by simple climatic factors. Climate tended to be more favourable for growth of C. arvense in NZ. In the permanent field plots in the native range, population growth of C. arvense was significantly greater where natural enemies were excluded, suggesting that insect herbivores and pathogens might have a regulating influence on the population growth of this plant. Furthermore, the probability of shoots transitioning to the reproductive growth stage was enhanced when insect herbivores were excluded, indicating that natural enemies might influence plant development. The biological control agent C. rubiginosa reduced the growth of C. arvense, although the impact of this herbivore was minimal in comparison to interspecific plant competition. Thus, although there is reduced specialist natural enemy pressure in NZ, the growth of C. arvense is not significantly different from in its native range. Nevertheless, there is some evidence that natural enemies in the native range might have a regulating influence on the population dynamics of the plant, and that the specialist herbivore, C. rubiginosa, can impact the plant in certain conditions.

Orientador: Carlos Frederico Wilcken
Banca: Wilson Badiali Crocomo
Banca: Luiz Alexandre Nogueira de Sá
Resumo: Os psilídeos são um grupo de pragas amplamente distribuídas, causando perdas consideráveis em sistemas agrícolas e florestais. A recente descoberta da ocorrência do psilídeo-de-concha Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), no Brasil tornou-se um problema de grande importância, por ser específico de Eucalyptus. O parasitóide Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) é indicado como principal agente no controle biológico desta praga. Portanto, para o monitoramento adequado de ambas espécies é necessário um método eficiente de amostragem. Devido a sua importância econômica, esse trabalho objetivou estudar as populações de G. brimblecombei e de P. bliteus em floresta de Eucalyptus camaldulensis por dois métodos de amostragem, utilizando armadilhas amarelas e coleta de folhas para determinação de sua distribuição espacial, flutuação populacional, a relação com fatores meteorológicos (temperatura e precipitação), proporção sexual, e correlacionar os métodos de amostragem com ambas populações. A determinação da distribuição espacial, flutuação populacional, proporção sexual e correlação dos métodos de amostragem (53 armadilhas amarelas e 53 ramos/avaliação) foi realizada em um talhão de 19 ha com E. camaldulensis em Luiz Antônio, SP, com 10 avaliações, entre janeiro e junho de 2005. Concluiu-se que as populações de ambas espécies apresentaram distribuição espacial agregada, possue correlação inversamente proporcional à temperatura, independente do método de amostragem; não foi constatado correlação entre ambas espécies e a precipitação pluviométrica, as armadilhas adesivas amarelas são viáveis como método de amostragem e a proporção sexual (macho : fêmea) foi baixa para populações de G. brimblecombei e alta para populações de P. bliteus, sendo coletados mais fêmeas que machos para ambas espécies, no período avaliado.
Abstract: Psyllids are a widespread group of pests, causing severe damage on agricultural and forestry systems. The recent discovery about occurrence of red gum lerp psyllid Glycaspis brimblecombei Moore (Hemiptera: Psyllidae), in Brazil is nowadays a great problem in Eucalyptus forests, mainly in E. camaldulensis. The psyllid specific parasitic wasp Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) is this pest main biological control agent. Thus, the adequate monitoring of both species by a efficient sampling method would facilitate a future decision making. Due to its economic importance, this study aimed to evaluate G. brimblecombei and P. bliteus populations in Eucalyptus camaldulensis plantation by two sampling methods, using yellow traps and foliage samples to determinate their spatial distribution, population fluctuation with weather interactions (temperature and rainfall) and sexual rate and to correlate sampling methods with both populations. The study of the populational fluctuation, the sexual rate, the spatial distribution and correlation sampling methods (53 traps sampled and 53 branches sampled per sampling dates) was carried out on E. camaldulensis plantations in a 19 ha area in Luiz Antônio municipality (SP, Brazil), between January and June, 2005 (10 sampling dates). This research indicated that population of both species noticed special aggregated distribution, inversely proportional correlation subject to temperature. However between sampling methods, there was no correlation between both species with the rainfall, yellow stick traps were useful as sampling methods, sexual rate (male:female) is low to G. brimblecombei populations and high to P. bliteus populations, have been collected more female than male to both species in the evaluated period.
Mestre

Dans le contexte politique (réduction 50% de l'utilisation des pesticides à échéance de 2018 -Plan Ecophyto) et social actuel (mise en place de modes de production plus respectueux pour l'environnement), la sévérité des dommages causés par le puceron cendré du pommier, Dysaphis plantaginea Passerini (Hemiptera : Aphididae), surtout en agriculture biologique, rend nécessaire la mise au point de solutions alternatives s'appuyant sur le rôle des ennemis naturels. Nous avons donc essayé d'apporter des éléments nouveaux sur la connaissance des relations entre le puceron cendré et ses ennemis naturels et sur les conditions à même de favoriser leur action. Des suivis hebdomadaires des arthropodes présents sur les rameaux infestés par D. plantaginea, ont mis en évidence l'effet négatif des auxiliaires sur les populations de D. plantaginea, sans pour autant atteindre une véritable régulation à même d'éviter les dégâts économiques. Nous avons également montré l'action favorisante des fourmis sur la dynamique du puceron cendré et négative sur celle des auxiliaires. Nous avons pu identifier trois groupes d'auxiliaires dominants avec une arrivée séquentielle marquée : les syrphes, dont l'installation coïncide avec le début de l'infestation de D. plantaginea, puis les coccinelles et les forficules qui arrivent plus tardivement. Pour que les auxiliaires jouent un rôle plus important contre D. plantaginea, il faut d'autres pratiques permettant d'abaisser significativement le nombre de traitements pesticides. Une innovation très récente permet la réduction drastique des traitements insecticides : les filets Alt'Carpo. Malgré son influence négative sur l'abondance et la richesse du cortège des auxiliaires présents dans les colonies de D. plantaginea, surtout les coccinelles, cette technique freine le développement des populations de D. plantaginea à l'échelle du rameau ou de l'arbre lorsque les filets sont fermés après la floraison (en conformité avec les préconisations contre le carpocapse). Cependant, la réduction des populations de D. plantaginea sous les filets requiert la présence d'au moins un stade actif d'auxiliaire par rameau, ce qui interroge sur la réalité de la régulation de ce ravageur par le simple usage des filets. Sur la base de leur précocité, pour Episyrphus balteatus De Geer (Diptera : Syrphidae) et de leur abondance dans les colonies de D. plantaginea, pour Forficula auricularia Linnaeus (Dermaptera : Forficulidae) et E. balteatus, ces deux espèces apparaissent comme de bons candidats pour la régulation de D. plantaginea. Nos études en conditions contrôlées ont démontré leur potentiel régulateur sur D. plantaginea, en particulier aux stades les plus âgés. L'efficacité optimale intervient à 20°C pour les deux prédateurs, pour lesquels nous n'observons par ailleurs pas d'interaction négative lorsqu'ils sont associés en présence de fortes densités de D. plantaginea. Sur la base de ces résultats de laboratoire nous avons analysé les possibilités de lâchers printaniers de ces deux prédateurs sur de jeunes colonies de D. plantaginea. Dans nos conditions expérimentales en vergers de pommiers, des lâchers précoces de larves du 3ème stade de F. auricularia n'ont pas permis de limiter les populations de D. plantaginea, confirmant la difficulté des lâchers de prédateurs en cultures de plein champ. De la même manière, des lâchers précoces d'E. balteatus pourtant réalisés sous filets Alt'Carpo restent sans effet sur l'infestation par D. plantaginea. Cette thèse, en s'appuyant sur des essais en conditions contrôlées, semi contrôlées et de plein champ, constitue une étape dans un processus d'élaboration d'un modèle dynamique du développement de D. plantaginea à l'échelle du rameau, prenant en compte le rôle des fourmis et des auxiliaires et l'influence des pratiques de protection (par exemple, les filets Alt'Carpo et les lâchers d'auxiliaires). Elle confirme, si besoin en était, la complexité des phénomènes de régulation, des pucerons en particulier, et la nécessité d'études complémentaires pour définir les conditions d'application de la lutte biologique contre D. plantaginea

Chromophoric Dissolved Organic Matter (CDOM) is a substance produced by the planktonic community that naturally blocks biologically damaging, ultraviolet radiation (UV; wavelengths = 280 to 400 nm). While a variety of planktonic species produce CDOM, investigations into the quality and quantity of their CDOM production are few. The purpose of this study was to investigate the properties of CDOM produced by phytoplankton versus zooplankton. Typically, UV radiation breaks down CDOM. However, marine organisms sometimes produce CDOM that, when exposed to sunlight, increases its absorbance of UV radiation. The reasons for this anomaly and the source of this unusual CDOM are unclear. To test for distinctions among sources, filtered water samples from cultures of two marine phytoplankton, Gymnodinium sp. and Dunaliella sp., and a marine copepod, Tigriopus californicus were exposed to sunlight for intervals of 0, 0.5, 1, 2, and 4 hours. The maximal UVB radiation (wavelengths; λ = 280 to 320 nm) was 0.1699 J cm-2. Before and after sunlight exposures, CDOM sources were assessed by comparing absorbance spectra from 184 to 730 nm with detailed comparisons at wavelengths of 254, 305, 320, and 350 nm. Results are expressed as "absorption", which is the raw absorbance converted to the natural log. Before exposure to sunlight, CDOM from algal species had 5- to 8-times higher average absorption values across UV wavelengths than CDOM produced by Tigriopus. CDOM samples produced by phytoplankton were more susceptible to photochemical change than CDOM from Tigriopus. In response to sunlight, CDOM from Gymnodinium varied greatly, increasing in UV absorption in 2 out of 5 replicates but decreasing in absorption in the other replicates. In contrast, peak absorption at λ = 260 nm of CDOM from Dunaliella decreased directionally by an average of 76% in absorption and 75% in specific absorption, and this decrease in absorption was significant (p = 0.03). CDOM from Tigriopus significantly decreased in both absorption (all UV wavelengths, p < 0.01) and "specific absorption", which is absorption standardized per mg of dissolved organic carbon (λ = 320 nm; p < 0.03), but the magnitude of change was only 17%. Thus, photochemical responses of CDOM from the three planktonic sources demonstrated more, consistently less, and unchanged UV absorption. Phytoplankton biomass, which is greater than that of copepods at the next trophic level, likely produce more CDOM but because of greater variability in CDOM absorbance of UV both within and between algal sources, copepods may offer a more stable source of UV protection depending on sunlight exposure and their relative abundance. Definitive conclusions depend on future laboratory studies expanded to more planktonic organisms as well as in situ studies during oceanographic cruises to test the relative contributions of planktonic species.

Emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Buprestidae), is an aggressive invader from Asia that has killed millions of trees in North America. Recently EAB has been documented developing in a novel host, white fringetree, Chionanthus virginicus. I evaluated larval performance in two common ash species and white fringetree by infesting excised bolts with emerald ash borer eggs. In addition I evaluated several plant characteristics to determine which most influence larval development. I also conducted choice and no choice assays using the classical biological control agent, Tetrastichus planipennisi (Hymenoptera: Eulophidae), to assess its ability to locate larval EAB in the different host plants. I found significantly lower survival rates of EAB larvae in white fringetree compared to white ash, F. americana. Larval phloem consumption and larval growth were lower in fringetree than in both ash tested. In choice and no choice assays T. planipennisi failed to parasitize larvae in fringetree. Failure of T. planipennisi to parasitize larvae within fringetree has implications for the efficacy of this classical biological control agent. Coupled with the use of white fringetree as a reservoir host, the enemy free space provided to EAB through use of this alternate host may have repercussions for EAB invasion dynamics.

Peach and nectarine tree belongs to the species Prunus persica and is the third most produced fruit species in the world. Within Europe, Spain is a leading producer. Most of the crops are located in Catalonia (northeastern Spain). Peach tree is the primary host of Myzus persicae, which is one of the most damaging pests of the crop. To date, its management has mainly based on insecticides, but the risk they pose to the human health and the environment, requires a reduction in their usage. Biological control could be a good tool to improve its control because of the wide array of natural enemies. Among the different strategies, conservation of already natural enemies present in the agroecosystem seems the more promising. Therefore, the present thesis was undertaken to determine the possibility of implementing conservation biological control against M. persicae in peach orchards in the Mediterranean area. The identification of the key natural enemies has to be the first step to start a conservation biological control program. The inclusion of floral resources close to the orchards might help to enhance the control by providing natural enemies with food sources, therefore improving aphid biological control. The first two chapters of this thesis, are dedicated to identify the key natural enemies of M. persicae in the Segrià area (Catalonia) and to evaluate in field conditions, the potential contribution of insectary plants to enhance aphid natural enemy populations. Sentinel plants, were used to recruit the natural enemies, and molecular and morphological methods were used to identify them. Then, their attraction to Achillea millefolium, Lobularia maritima, Moricandia arvensis, and Sinapis alba was evaluated. Results showed that, the most abundant natural enemies were parasitoids with the species Aphidius matricariae the most prevalent. Regarding predators, Aphidoletes aphidimyza and Episyrphus balteatus were the most prevalent, followed by Orius majusculus. Insectary plants were highly attractive to hoverflies and parasitoids, and none of the plants was a reservoir of damaging aphids for peach crops. Lobularia maritima was one of the more suitable plants. However, the proximity of these plants did not increase the abundance of natural enemies, probably due to the size of the orchards. To effectively contribute to natural enemy fitness, flowering insectary plants have to provide profitable food. The third chapter focused on assess whether the insectary plant L. maritima is a potential food source for Aphidius ervi and A. aphidimyza. Results showed that L. maritima, with and without flowers, attracted both natural enemies. However, this attractiveness was disrupted when compared with peach shoots infested with aphids. L. maritima flowers did not improved the fitness of A. aphidimyza, since the floral morphology prevented females to feed on the nectar. Nevertheless, flowers increased the longevity of A. ervi. The high diversity of natural enemies increases the probability of intraguild predation, additionally the presence of natural enemies in an aphid colony can also produce behavioral changes in aphids. The last chapter had the aim to evaluate the interactions among predators and parasitoids, and how these interactions may influence the biological control of the aphid. The contribution of E. balteatus, A. aphidimyza and O. majusculus was determined. The changes in the aphid’s behavior mediated by the aphid cornicle exudate and the interaction of these predators with the parasitoid A. matricariae were also evaluated. The most voracious predator was E. balteatus. O. majusculus did not reduce pest population. The cornicle exudate triggers fecundity compensation A. aphidimyza and O. majusculus preferred to kill nonparasitized aphids, and avoid to feed on mummies. The results of this thesis, suggest that the conservation biological control can be a useful tool to improve M. persicae control in peach and nectarine crops.
El melocotero y la nectarina pertenecen a la especie Prunus persica (L.) Batsch y es el tercer cultivo frutal con mayor producción a nivel mundial. En Europa, España es uno de los mayores países productores representando más del 30% del total de la producción. La mayoría de las plantaciones de melocotoneros y nectarinas están localizados en Cataluña, al noreste de España. Prunus persica es el huésped primario de Myzus persicae (Sulzer) (Hemiptera: Aphididae), comúnmente conocido como el pulgón verde del melocotonero, que es una de las plagas más dañinas para el cultivo. Hasta la fecha el control de este pulgón se ha basado en la utilización de insecticidas pero, debido al riesgo que representan tanto para la salud humana como para el medio ambiente, se requiere reducir el uso de estos productos. El control biológico puede ser una buena herramienta para mejorar el control de la plaga en este cultivo debido a que los pulgones tienen un amplio rango de enemigos naturales que podrían contribuir a su control. Dentro de las diferentes estrategias de control biológico que se han utilizado contra los pulgones, la conservación de los enemigos naturales ya existentes en el agroecosistema parece ser la más prometedora para los cultivos frutales. Con estos antecedentes, la presente tesis se llevó a cabo para determinar la posibilidad de implementar el control biológico por conservación contra M. persicae en cultivos de melocotón y nectarina en el área del Mediterráneo. El control biológico por conservación, se basa en preservar a los enemigos naturales presentes en la zona e implementar estrategias para mejorar sus poblaciones. Por lo tanto, la identificación de los enemigos naturales clave involucrados en el control de M. persicae, debe ser el primer paso para comenzar un programa de control biológico por conservación. La inclusión de recursos florales cerca del cultivo, podría ayudar a mejorar el control al ofrecer a los enemigos naturales recursos alimenticios como néctar y polen, contribuyendo así a aumentar sus poblaciones en el momento adecuado para controlar eficazmente la plaga. Los dos primeros capítulos de esta tesis, están dedicados a identificar los depredadores y parasitoides clave de M. persicae en la comarca del Segrià (Cataluña), y a evaluar, en condiciones de campo, el potencial de ciertas plantas insectarias para mejorar sus poblaciones. Para recolectar a los enemigos naturales de M. persicae, se utilizaron plantas centinela, es decir plantones de melocotonero expresamente infestados con M. persicae, y para identificar a las especies más abundantes se utilizaron métodos moleculares y morfológicos. Posteriormente se evaluó la atracción de los enemigos naturales hacia manchas florales que incluían las siguientes especies: Achillea millefolium L. (Compositae), Lobularia maritima L. (Brassicaceae), Moricandia arvensis L. (Brassicaceae) y Sinapis alba L. (Brassicaceae). Los resultados mostraron que los enemigos naturales más abundantes de M. persicae fueron parasitoides. A pesar de que existió un amplio rango de especies, Aphidius matricariae Haliday (Hymenoptera: Braconidae: Aphidiinae) fue con mucho la más abundante. De los pulgones parasitados se identificaron, así mismo, diez especies de hiperparasitoides. Sin embargo, la ausencia de hiperparasitoides a principio de la temporada, cuando las poblaciones de M. persicae son elevadas, sugiere que el control biológico de este pulgón no se vería afectado negativamente. En cuanto a los depredadores, Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) y Episyrphus balteatus DeGeer (Diptera: Syrphidae) fueron los más abundantes, seguidos de Orius majusculus Reuter (Hemiptera: Anthocoridae). Los experimentos de campo realizados en esta tesis, mostraron que la presencia de manchas florales fue atractiva para los sírfidos y para los parasitoides y ninguna de las plantas evaluadas fue reservorio de pulgones dañinos para los cultivos de melocotón y nectarina. Entre las cuatro plantas insectarias evaluadas, L. marítima fue uno de los mejores para los enemigos naturales. Sin embargo, la proximidad de las plantas insectarias al cultivo no incrementó la abundancia de las poblaciones de enemigos naturales en las plantas centinela, probablemente a causa del tamaño de las parcelas. Para poder contribuir de manera positiva al estado físico (fitness en inglés) de los enemigos naturales, y por lo tanto al control biológico de M. persicae, las flores de las plantas insectarias deben proporcionar a los parasitoides y depredadores un alimento que puedan aprovechar, tanto en términos de calidad como de accesibilidad. En base a ello, el tercer capítulo de esta tesis se centró en evaluar si la planta insectaria L. marítima es una fuente de alimento adecuada para el parasitoide Aphidius ervi (Haliday) (Hymenoptera: Braconidae: Aphidiinae) y el depredador A. aphidimyza. Con este objetivo, se realizaron experimentos de laboratorio para investigar si ambos enemigos naturales eran atraídos hacia L. marítima en presencia y ausencia de flores. También se evaluaron los efectos de las flores en cuanto a la longevidad y el potencial reproductivo de estos insectos. Los resultados de los experimentos llevados a cabo en el olfactómetro mostraron que los compuestos volátiles producidos por L. maritima, con y sin flores, atraían a ambos enemigos naturales. Sin embargo, esta atracción se vio afectada cuando se comparó la L. marítima con brotes de melocotón infestados con M. persicae. Aunque A. aphidimyza se benefició de una alimentación rica en azúcar, la disponibilidad de L. marítima no mejoró ni la longevidad ni la reproducción del depredador, ya que la morfología floral de esta especie impidió que las hembras se alimentaran del néctar. En cambio, las flores de L. maritima incrementaron la longevidad de las hembras de A. ervi en ausencia de pulgones. Por lo tanto, la provisión de otros recursos azucarados, como nectarios extraflorales o flores con nectarios expuestos, pueden ser un recurso alimenticio viable para los enemigos naturales y por lo tanto ayudarían a mejorar el control biológico de M. persicae. Debido a la gran diversidad de enemigos naturales que atacan a M. persicae en el área de estudio, existe una alta probabilidad de que ocurra depredación intragremial porque estos enemigos naturales no solo compiten por el mismo recurso alimenticio, sino que también pueden depredarse entre sí. Además, dado que el desarrollo de las larvas de los parasitoides ocurre dentro del pulgón, los depredadores pueden comérselos al alimentarse del pulgón. Por otro lado, la presencia de enemigos naturales en una colonia de pulgones también puede producirles cambios en su comportamiento. El último capítulo de esta tesis tuvo como objetivo evaluar las interacciones entre depredadores y parasitoides, y estudiar cómo estas interacciones pueden influir en el control biológico de M. persicae. En ensayos de laboratorio, se determinó la contribución de E. balteatus, A. aphidimyza y O. majusculus al control de M. persicae. También se evaluaron los cambios en el comportamiento del pulgón asociados por las secreciones de los cornículos o sifones, y la interacción de estos depredadores con el parasitoide A. matricariae. Los resultados mostraron que el depredador más voraz fue E. balteatus, seguido de A. aphidimyza. Orius majusculus no redujo la población de M. persicae. La secreción de los cornículos de M. persicae desencadenó una compensación de la fecundidad, es decir, un aumento de la descendencia. Aunque, A. aphidimyza y O. majusculus prefirieron matar los pulgones no parasitados, ambos depredadores fueron capaces de matar a los individuos de M. persicae parasitados pero aún no momificados. Su preferencia por matar pulgones no parasitados indica que la coexistencia de parasitoides y depredadores no sería negativa para el control biológico de M. persicae. Los resultados de esta tesis, sugieren que el control biológico por conservación puede ser una herramienta útil para mejorar el control de M. persicae en cultivos de melocotón y nectarina.
Els préssecs i les nectarines Prunus persicae (L.) Batsch és el tercer conreu fruiter amb més producció a escala mundial. Dins d'Europa, Espanya és un dels majors productors amb el 30% del total de la producció europea. La majoria de camps de presseguer i nectarina estan localitzats a Catalunya, al nord-est d'Espanya. Prunus persicae és l'hoste primari del pugó verd del préssec, Myzus persicae (Sulzer) (Hemiptera: Aphididae) que és una de les plagues més nocives per al cultiu. Fins a la data actual, el control d'aquest pugó s'ha basat en l'ús d'insecticides, però el risc que representen tant per a la salut humana com per al medi ambient, fa necessari reduir-ne l’ús. El control biològic pot ser una bona eina per millorar el control d’aquesta plaga en els camps de cultiu, ja que els pugons tenen un ampli rang d'enemics naturals que podrien contribuir al seu control. Dins de les diferents estratègies de control biològic que s'han utilitzat contra els pugons, la conservació dels enemics naturals ja existents en l'agroecosistema sembla ser la més prometedora pels cultius de fruiters. Amb aquests antecedents, la present tesi es va dur a terme amb l'objectiu de determinar la possibilitat d'implementar el control biològic per conservació contra M. persicae en cultius de préssec i nectarina en l'àrea del Mediterrani. El control biològic per conservació es basa en preservar als enemics naturals presents a la zona i en la implementació d'estratègies per millorar les seves poblacions en l'agroecosistema. Per tant, la identificació dels enemics naturals clau involucrats en el control de M. persicae ha de ser el primer pas per a començar un programa de control biològic per conservació. La implementació de recursos florals prop dels camps, podria ajudar a millorar el control, ja que ofereixen als enemics naturals recursos alimentaris com nèctar i pol·len, contribuint així a augmentar les seves poblacions en el moment adient per a controlar eficaçment la plaga. Els dos primers capítols d'aquesta tesi, estan dedicats a identificar els depredadors i parasitoides clau de M. persicae en la comarca del Segrià (Catalunya), així com a avaluar, en condicions de camp, el potencial de certes plantes insectàries per incrementar les poblacions d’enemics naturals. Per a determinar els enemics naturals de M. persicae es van utilitzar plantes sentinella, plançons de presseguer expressament infestats amb M. persicae. Per identificar les espècies més abundants es van utilitzar mètodes moleculars i morfològics. Posteriorment es va avaluar l'atracció dels enemics naturals clau cap a marges florals que incloïen les següents espècies: Achillea millefolium L. (Compositae), Lobularia maritima L. (Brassicaceae), Moricandia arvensis L. (Brassicaceae) i Sinapis alba L. (Brassicaceae). Els resultats van mostrar que els enemics naturals predominants de M. persicae eren els parasitoides. Tot i l’ampli rang d'espècies, Aphidius matricariae Haliday (Hymenoptera: Braconidae: Aphidiinae) va ser amb diferència la més abundant. Dels pugons parasitats es van identificar també deu espècies d'hiperparasitoides. Amb tot, l'absència d'hiperparasitoides a principi de la temporada, quan les poblacions de M. persicae són elevades, suggereix que el control biològic d'aquest pugó no es veuria afectat negativament. Pel que fa als depredadors, Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) i Episyrphus balteatus DeGeer (Diptera: Syrphidae) van ser els més abundants, seguits de Orius majusculus Reuter (Hemiptera: Anthocoridae). Els experiments de camp realitzats en aquesta tesi, mostren que la presència de taques florals va ser atractiva per als sírfids i per als parasitoides, i cap de les plantes avaluades va ser reservori de pugons nocius per al cultiu. Entre les quatre plantes insectari avaluades, L. marítima va ser un bon recurs per als enemics naturals. No obstant això, la proximitat de les plantes insectàries no va incrementar l'abundància de les poblacions d'enemics naturals en les plantes sentinella, probablement degut a la mida de les parcel·les. Per a poder contribuir de manera positiva al estat físic (fitness en anglès) dels enemics naturals, i per tant al control biològic de M. persicae, les flors de les plantes insectàries han de proporcionar als parasitoides i depredadors aliment que puguin aprofitar tant pel que fa a la qualitat com a l’accessibilitat. Basat en l'anterior, el tercer capítol d'aquesta tesi es va centrar en avaluar si la planta insectària L. marítima és una font d'aliment adequada per al parasitoide Aphidius ervi (Haliday) (Hymenoptera: Braconidae: Aphidiinae) i el depredador A. aphidimyza. Amb aquest objectiu, es van realitzar experiments de laboratori per investigar si tots dos enemics naturals eren atrets cap a L. marítima en presència i absència de flors. També es van avaluar els efectes de les flors pel que fa a la longevitat i el potencial reproductiu. Els resultats dels experiments duts a terme en l'olfactòmetre van mostrar que els compostos volàtils produïts per L. maritima, amb i sense flors, atreien tots dos enemics naturals. Amb tot aquesta atracció es veia afectada quan L. marítima es van comparar amb brots de presseguer infestats amb M. persicae. Tot i que A. aphidimyza es va beneficiar d'una alimentació rica en sucre, la disponibilitat de L. maritima no va millorar ni la longevitat ni la reproducció d’aquest depredador, ja que la morfologia floral d'aquesta espècie va impedir que les femelles s'alimentessin del nèctar. D'altra banda, la disponibilitat de flors de L. maritima va incrementar la longevitat de les femelles d’ A. ervi en absència de pugons. Per tant, la provisió d'altres recursos rics en sucre, com nectaris extraflorals i flors amb nectaris exposats poden ser una opció per millorar el control biològic de M. persicae. A causa de la gran diversitat d'enemics naturals que ataquen a M. persicae en l'àrea d'estudi, existeix una alta probabilitat que hi hagi depredació intragremial, ja que aquests enemics naturals no només competeixen pel mateix recurs alimentari, sinó que també poden depredar-se entre ells. A més, degut al desenvolupament de les larves dels parasitoides dins del pugó, els depredadors se’ls poden menjar en alimentar-se de pugó. D’altra banda, la presència d'enemics naturals en una colònia de pugons també pot produir-los-hi canvis de comportament. L'últim capítol d'aquesta tesi va tenir com a objectiu avaluar les interaccions entre depredadors i parasitoides, i com aquestes interaccions poden influir en el control biològic de M. persicae. Es va determinar la contribució d’E. balteatus, A. aphidimyza i O. majusculus al control de M. persicae. També es van avaluar els canvis en el comportament del pugó derivats de el líquid secretat per les cornícules o sifons i la interacció d'aquests depredadors amb el parasitoide A. matricariae. Els resultats van mostrar que el depredador més voraç va ser E. balteatus, seguit d’ A. aphidimyza. Orius majusculus no va reduir la població de M. persicae. El líquid secretat per les cornícules de M. persicae va desencadenar una compensació de fecunditat, és a dir, un augment en la descendència. Tot i que, A. aphidimyza i O. majusculus van preferir matar pugons no parasitats, els dos depredadors van ser capaços de matar als individus de M. persicae parasitats que encara no estaven momificats. La seva preferència per matar pugons no parasitats suggereix que la coexistència de parasitoides i depredadors no seria negativa pel control biològic de M. persicae. Els resultats d'aquesta tesi, suggereixen que el control biològic per conservació, pot ser una eina útil per millorar el control de M. persicae en cultius de préssec i nectarina.

The floating aquatic weeds common salvinia (Salvinia minima Baker) and giant salvinia (Salvinia molesta Mitchell) degrade aquatic systems through fast, mat forming growth. The Salvinia specialist weevil Cyrtobagous salviniae Calder and Sands has been used to reduce the severity of giant salvinia infestations and associated with reduced severity of common salvinia infestations. Genetically, morphologically and biologically distinct strains of C. salviniae exist, but their relative potential for success as biological control agents of Salvinia species has not been evaluated. This thesis (1) describes a recirculating water system designed for conducting such studies and (2) reports the results of C. salviniae strain comparisons. A recirculating water system with a high degree of replication and minimal variation in water flow, temperature and light intensity was used for laboratory experiments using sixty-day temperature profiles averaging 31.4, 26.5 and 8.0ºC derived from surface water temperatures measured at lakes in expected range of Salvinia species in the North America. Larval and adult population numbers of two C. salviniae strains (Australia and Florida) were determined for each temperature profile along with feeding induced plant necrosis on both Salvinia species. Australia C. salviniae had lower survivorship rates to adulthood on common salvinia than did Florida C. salviniae at the 31.4 and 26.5ºC temperature profiles. Neither strain reproduced, and no significant between-strain differences in plant necrosis were detected at the 8.0ºC temperature profile. At 31.4ºC there were no significant differences in adult counts, larval counts or plant damage between the two strains on giant salvinia. At 26.5ºC, however, significantly fewer larvae were collected from initially released adults and significantly less plant necrosis was associated with weevil feeding by Florida strain compared to Australia strain weevils. These results may have arisen from comparing Australia weevils from a growing colony to Florida weevils from a declining colony. Overall, the results indicate that only Florida C. salviniae should be released against common salvinia. Florida C. salviniae may be equally suitable to Australia C. salviniae for releases against giant salvinia, but further study is needed to fully assess the potential for using Florida C. salviniae against giant salvinia.

Differences in plant structure and host abundance, distribution and density within and between plants may affect host finding success of searching parasitoids. The main objective of this research consisted in developing and validating a model that can predict parasitism by Trichogramma evanescens on various plant structures. Also, we evaluated the effect of both artificial and natural plant structures on host encountering success and on searching behavior of two species of Trichogramma.
Size (S), heterogeneity (H) and connectivity (C) define plant structure. The development of the model of parasitism was based on laboratory experiments using three dimensional artificial plants of different combinations of S, H and C. The model was then validated with experiments, within greenhouse, using natural cruciferous plants of different structures. Significant regressions of observed values of parasitism as a function of those predicted by the model were obtained.
The effect of plant structure on two species of Trichogramma was studied by using three species of Lepidoptera and three structurally different but closely related crucifers. Also the distribution pattern of parasitized eggs according to leaf side and plant height was characterized. A repeated measure ANOVA in time where plant ages defined the repeated measures showed that all three main effects (plant, host, parasitoid) had significant effect on parasitism and only the parasitoid x plant structure interaction was significant. Mean percent of parasitism was higher on cabbage, intermediate on broccoli and lower on Brussels sprouts whereas cabbage appeared to be intermediate in plant structure, broccoli appeared to be the most simple and Brussels sprouts the most complex plant structure. On simple plant structure, both wasp species performed well on the three varieties of plant but T. evanescens outperformed T. pretiosum more often on the various plant structures. A doubly repeated measures ANOVA in space revealed significant effects of leaf side and plant height on parasitism, being greatest under leaf surface and at the base of the plant. The interaction between those two variables was not significant.
The effect of plant structure on searching behavior of T. evanescens was determined by direct observation of individual females searching on simple and complex plant structures during 1 hour. Time, frequence and sequence associated to activities and plant parts explored were obtained and analyzed. Plant structure had significant effect on time budget associated to activities (walking, resting, flying) and plant parts explored.
This study demonstrates that plant structure mediates ecological interactions by affecting host finding success and this may have important implications in population dynamics, evolution of hosts and parasitoids but also in biological control programs.

Arthropod natural enemies play a key role in controlling potentially damaging pest populations in agroecosystems. An abundant and diverse natural enemy community is associated with higher yields in a variety of crops. Certain aspects of soybean production can make a field more or less amenable to a robust natural enemy community. For instance, commonly used broad-spectrum insecticides which are highly toxic to most arthropods can decrease natural enemy densities and allow for secondary pest outbreaks. Selective insecticides that have less impact on natural enemy populations allow for pest control while preserving important predators. Another production decision that could alter natural enemy communities is the choice of cropping system, specifically planting early (full season) or late, after small grain harvest (double crop). My research objectives were to examine how 1) selective insecticides and 2) cropping system affect the density and diversity of natural enemies in Virginia soybean. To address the first objective I compared the natural enemy community in soybean plots that were exposed to selective insecticides, broad-spectrum insecticides or no insecticide. I sampled insects using three different techniques and found that the two selective insecticides I tested, both from a new class called diamides, did not reduce the natural enemy community compared to controls. To examine how cropping system affects the natural enemy community I sampled full season and double crop fields during the growing season for two years. In 2014 ground-dwelling spider diversity was higher in full season soybean. In both years, double crop soybeans had higher abundance of spiders and insect natural enemies on the ground and in the foliage compared with full season soybean. This was unexpected, since double crop soybeans are planted later than full season and arthropod populations would have less time to colonize and grow. When I compared diversity of a family of predatory beetles I found higher diversity in full season soybean. The similarity in spider and insect natural enemy diversity and abundance trends suggests that a greater number of species can co-exist in full season soybean, while in double crop soybeans a few dominant natural enemies thrive.
Ph. D.

Thesis (MSc)--Stellenbosch University, 1992.
One copy microfiche.
ENGLISH ABSTRACT: The effects of synthetic pyrethroids on the spider mite, Tetranychus urticae Koch, and its natural enemies was investigated. The pyrethroid cyfluthrin, sprayed for the control of fruit weevil Phlyctinus callosus, did not cause mite outbreaks and was not harmful to the predators when sprayed before they appeared on the apple trees. This spray also gave good control of thrips, bollworm (Heliothis armigera) and fruit weevil (P. callosus). A late season spray of deltamethrin against codling moth, caused an increase in the phytophagous mite population. This was assosiated with a temporary reduction in the population level of the predatory beetle, Oligota fageli. The plants found on the orchard floor were examined. The plant diversity was low and plants that acted as hosts of phytophagous mites during the winter were scarce. However, Solanum nigum carried high mite populations and infected the adjacent apple trees. The plants were too few to have an effect on the whole orchard. Eight synthetic pyrethroids were tested for repellency in a leafdisk dip and spray bioassay using T. urticae. Deltamethrin and fenvalerate caused no walk-off. Cyfluthrin and fluvalinate caused moderate walk-off and bifenthrin, cyhalothrin and lambda-cyhalothrin caused high walk-off.
AFRIKAANSE OPSOMMING: Die invloed van sintetiese piretroIedes op die rooispinmyt, Tetranychus urticae Koch en hul natuurlike vyande is ondersoek. Die piretroIed, cyfluthrin, gespuit vir die beheer van snuitkewer, P4ctinus callosus, het the mytuitbrake veroorsaak the en was ook the skadelik vir predatore nadat dit vroeg in die seisoen, voordat myte in die appelbome verskyn het, gespuit is the. Die bespuiting het ook goeie beheer van blaaspootjies, bolwurm (Heliothis amdgera) en P. callosus gegee. Deltametrien wat later in die seisoen toegedien is vir die beheer van kodlingmot, Cydia pomonella, het 'n mytuitbraak veroorsaak. Dit word geassossieer met die tydelike onderdrukking van die populasievlak van die predatoriese kewer, Oligota fageli. Die plante in die dekgewas is ondersoek. Die plant-verskeidenheid was laag en plante wat kon dien as oorwinterings gashere vir fitofage myte kon dien was skaars. Solanum nigrum het egter groot bevolkings myte gedra wat die appelbome naaste aan hulle eerste besmet het. Daar was egter te min van hierdie plante om 'n invloed op die hele boord te he. Agt piretroIedes is vir afwering van T. urticae in 'n blaarskyf doop en spuit bioessal getoets. Deltamethrin en fenvalerate het geen afwering getoon the. Cyfluthrin en fluvalinate het 'n redelike afwering, terwyl bifenthrin, cyhalothrin en lamda-cyhalothrin het 'n hod mate van afwering getoon

The work reported in this thesis is divided into 3 main sections as follows. Section 1. The external morphology of byssus threads produced by Mytilus edulis and Modiolus modiolus was studied by scanning electron microscopy. Section 2. Several laboratory experiments were performed to determine how sediment with stones at different layers and of different particle size ranges affects byssus thread production. These experiments were: (i) An initial experiment to determine the rate of byssus thread production. (ii) The response of single animals and groups of animals to different particle size ranges of sediment. (iii) The response of single animals and groups of animals to experimental sediments (particle size range < 2.0cm) with stones present or not present at different depths. Section 3. Experiments were performed to determine the effects of single animals and groups of animals on sediment stability. All experiments were performed under controlled conditions in an experimental sea water flume. These experiments were: (i) the effects of single animals on sediment stability in different particle size ranges of sediment. (ii) the effects of groups of animals on sediment stability in different particle size ranges of sediment. (iii) the effects of groups of animals on sediment stability in sediment of particle size < 2.00mm, with stones present or not present at different depths.

>Magister Scientiae - MSc
The sustainable use of natural resources is of utmost importance for every community. In particular, it is important for every given generation to plan in such a way that proper provision is made for future generations. The scientific understanding of resources use and appreciation for its life-supporting capacity is therefore essential. Mathematical modeling has proved useful to inform the planning and management of strategies for sustainable use of natural resources. Some specific topics in resource management has been studied intensively through many decades. In particular, mining, fisheries, forestry and water resources are among these. Instead of presenting a study of the latter topics, this dissertation presents a variety of cases of mathematical modeling in resource management. The aim is to improve the general understanding of the relevant problems. We expand on existing literature, papers of other authors, and add to such studies by focusing on specific items in the work, illuminating it with further explanations and graphs, or by modifying the models through the introduction of stochastic perturbations. In particular this dissertation makes contributions by giving more explanation, on the so-called environmental Fisher information or EFI for brevity (Section 2.4 and Chapter 6), and by introducing stochasticity into a pest control model (Chapter 4) and into a savanna vegetation model (Chapter 5). In Chapter 3 we present a model from the literature pertaining to the problem of shifting cultivation, i.e, the use of forest land when used for subsistence level agricultural purposes, until the land is so degraded that the occupants abandon it and move on to a new stand. The model used to study the shifting period is similar to the forest rotation problem. A model, already in the literature, for biological control of a pest is studied in Chapter 4. Onto the deterministic model we impose a stochastic perturii bation, so that we obtain a stochastic differential equation model. We prove stochastic stability of the disease-free state, when the basic reproduction number of the pest is below unity. We have performed simulations of solutions of the stochastic system. In Chapter 5 we review an existing ordinary differential equation model for the competition between trees and grass in savanna environment. The competition between them is for soil water, fed by annual rainfall. On the other hand, trees and grass are perturbed by fire, and some other environmental forcings such as herbivores. For this ODE model, we introduce stochastic perturbations. The stochastic perturbations are in the form of three mutually independent Brownian motions. Simulations to illustrate the effect of the stochasticity are shown. We present a three-tiered predator-prey model and consider its stability in terms of Fisher information. This appears as Chapter 6. The Fisher information is defined on the basis of the so-called sustainable measures hypotheses. The model is already in the literature and in the dissertation we present several computations to show the influence of carrying capacity of prey and of mortality rate on EFI. Another problem that we consider, in Chapter 7, is that of lake eutrophication caused by excessive phosphorus inflow. The computation illustrates the management of the runoff nutrients into or out of the lake. Necessary and the sufficient conditions for an optimal utility management are obtained using standard optimal control theory. The results of this dissertation demonstrate the modeling techniques in the sustainable use of natural resources. Sustainability is the quest for equal opportunities over all generations. The manner in which this sustainability is quantified in models is being debated and improved all the time. The discourse on sustainability is especially important in view of a growing world population, and with forcings such as climate change. The most important original contribution in this dissertation is the stochastic analysis on the pest control model and the savanna model.

[EN] Ants constitute an important component of the citrus agroecosystem fauna acting simultaneously as predators and as hemipteran mutualists. Thus, ants in citrus are in the center of a complex food web affecting the composition and the population dynamics of a wide arthropod community including honeydew and non-honeydew producing herbivores as well as their natural enemies. In eastern Spain the most abundant and widespread ant species are the natives Lasius grandis Forel and Pheidole pallidula (Nylander), whereas the invasive Linepithema humile (Mayr) is also present but not widespread. We have conducted ant-exclusion experiments in three commercial citrus orchards, each one dominated by one ant species (Pheidole pallidula, Lasius grandis or Linepithema humile) with the aim to disentangle the ecological interactions with honeydew and non-honeydew producing pests and with natural enemies at the community-level. We quantified the effect of the ant-exclusion on the infestation levels and parasitism of three of the most important citrus pests in the area, the honeydew producer Aleurothrixus floccosus (Maskell) and the non-honeydew producers Aonidiella aurantii (Maskell) and Phyllocnistis citrella (Stainton). California red scale densities on fruits were significantly lower in the two seasons and in the three orchards in the ant-excluded treatment. Similarly, the percentage of shoots occupied by A. floccosus was significantly lower in the ant-excluded plots in the orchards dominated by P. pallidula and L. humile. Interestingly, no significant differences were found in the percent parasitism between ant-allowed and ant-excluded treatments. These results suggest that factors other than parasitoid disruption might explain the increased pest populations observed in the presence of ants. Thus, in the same orchards we compared the abundance, species richness, diversity and community structure of predators and parasitoids between the ant-allowed and ant excluded treatments. A total of 176,000 arthropods belonging to 81 taxa were captured and identified. Regarding abundance, the response of natural enemies to ant-exclusion was species specific. When examining functional groups, parasitoids showed higher abundances in the ant-allowed treatment whereas most generalist predators were less abundant. Similarly, the species richness and the Shannon diversity index of parasitoids were higher in the ant-allowed treatment, whereas the species richness of predators was significantly lower. The community structure of predators and parasitoids was not significantly different between treatments. Thus, ants were not associated with a dramatic and/or general decrease in natural enemy abundance or biodiversity. On the other hand, the negative impact of ants on generalist predators may have important implications for the regulation of pest populations. Finally we tested a novel hypothesis examining the potential competition between ants and natural enemies for honeydew produced by Hemiptera. Through the use of high performance liquid chromatography (HPLC) we related the level of ant activity with the energy reserves and feeding history of individual specimens collected in the field. A significant negative correlation between ant activity and the total sugar content and honeydew feeding incidence by A. chrysomphali was found in summer, when ant activity peaked. Ant activity was negatively correlated with the sugar feeding incidence by C. carnea in spring. This is a previously undocumented indirect interaction in food webs in which ants interfere with the physiological state of the natural enemies. Given that the absence of sugar feeding is detrimental for the fitness of many species of predators and parasitoids, this interaction may have important consequences for the arthropod community composition and practical implications for biological control.
[ES] Las hormigas constituyen un elemento importante del agroecosistema de los cítricos, en el que actúan simultáneamente como insectos depredadores y como mutualistas de hemípteros. Como consecuencia, las hormigas pueden afectar a la composición y a la dinámica poblacional de un amplio grupo de artrópodos, en los que se incluye herbívoros productores y no productores de melaza, así como a sus enemigos naturales. Se han llevado a cabo estudios de exclusión de hormigas en tres parcelas comerciales de cítricos en las que, en cada una de ellas, predominaba una especie de hormiga (Lasius grandis Forel, Pheidole pallidula (Nylander) y Linepithema humile (Mayr)). El principal objetivo ha sido el de esclarecer las interacciones ecológicas existentes entre las hormigas y los artrópodos productores y no productores de melaza, así como con los enemigos naturales a nivel de comunidad. Se ha cuantificado el efecto de la exclusión de hormigas sobre los niveles de infestación y el parasitismo de tres de las plagas más importantes de los cítricos de la zona, la plaga productora de melaza Aleurothrixus floccosus (Maskell) y las plagas que no producen melaza Aonidiella aurantii (Maskell) y Phyllocnistis citrella (Stainton). Las densidades poblacionales de A. aurantii en frutos i de A. floccosus fueron significativamente menores en el tratamiento de exclusión de hormigas. Curiosamente, no se encontraron diferencias en el porcentaje de parasitismo entre los dos tratamientos. Estos resultados sugieren que otros factores, más allá de la interferencia con los parasitoides, podrían explicar los incrementos poblacionales de plagas observados en presencia de hormigas. Por ello, se comparó la abundancia, riqueza de especies, diversidad y estructura de la comunidad de depredadores y parasitoides entre los tratamientos de exclusión y presencia de hormigas. Se capturaron e identificaron un total de 176,000 artrópodos pertenecientes a 81 taxones distintos. En cuanto a la abundancia, la respuesta de los enemigos naturales a la exclusión de hormigas fue específica para cada especie. Los parasitoides mostraron mayores abundancias en presencia de hormigas, mientras que la mayoría de los depredadores generalistas fueron menos abundantes. De igual modo, la riqueza de especies y el Índice de diversidad de Shannon de los parasitoides fueron mayores en presencia de hormigas, mientras que la riqueza de especies de los depredadores fue menor. La estructura de la comunidad de depredadores y parasitoides no difirió entre tratamientos. El impacto negativo de las hormigas sobre los depredadores generalistas puede tener importantes implicaciones sobre la regulación de las poblaciones de plagas. Finalmente, se estudió una novedosa hipótesis en la que se planteó la existencia de competencia por la melaza que producen los hemípteros, entre las hormigas y los enemigos naturales. Mediante el uso de cromatografía líquida de alta resolución (HPLC) se relacionó la actividad de las hormigas con las reservas energéticas y las fuentes alimenticias utilizadas por especímenes de enemigos naturales colectados en el campo. Se encontró una correlación significativamente negativa entre la actividad de las hormigas y el contenido total de azúcares y la alimentación a base de melaza del parasitoide Aphytis chrysomphali (Mercet) en verano. La actividad de las hormigas se correlacionó negativamente con la alimentación a base de azúcares del depredador Chrysoperla carnea s.l en primavera. Esta interacción indirecta en la que las hormigas interfieren con el estado fisiológico de los enemigos naturales no ha sido documentada previamente. Dado que la ausencia de azúcares en la alimentación de muchas especies de depredadores y parasitoides es perjudicial para su estado físico, esta interacción puede tener importantes consecuencias para la composición de la comunidad de artrópodos e implicaciones prácticas sobre el control biológico de plagas.
[CAT] Les formigues són un element important de l'agroecosistema dels cítrics, en el que poden actuar simultàniament com a insectes depredadors i com a mutualistes d'hemípters. Com a conseqüència, poden afectar a la composició i la dinàmica poblacional d'un ampli grup d'artròpodes, incloent herbívors productors i no productors de melassa així com els seus enemics naturals. Les espècies de formigues més abundants i esteses als cítrics de l'est de la Península Ibèrica són les espècies natives Lasius grandis Forel i Pheidole pallidula (Nylander) mentre que l'espècie invasora Linepithema humile (Mayr) es troba també present però no de forma estesa. S'han dut a terme estudis d'exclusió de formigues en tres parcel·les comercials de cítrics en les que, en cada una d'elles, predominava una de les tres espècies de formigues. El principal objectiu ha estat el d'esclarir les interaccions ecològiques existents entre les formigues i els artròpodes productors i no productors de melassa així com els enemics naturals a nivell de comunitat. S'ha quantificat l'efecte de l'exclusió de formigues sobre els nivells d'infestació i el parasitisme de tres de les plagues més importants dels cítrics de la zona, la plaga productora de melassa Aleurothrixus floccosus (Maskell) i les plagues no productores de melassa Aonidiella aurantii (Maskell) i Phyllocnistis citrella (Stainton). Les densitats poblacionals d' A. aurantii en fruits i d'A. floccosus foren significativament menors en el tractament d'exclusió de formigues. Curiosament, no es trobaren diferències en el percentatge de parasitisme entre els dos tractaments per a ninguna de les plagues estudiades. Aquests resultats suggereixen que altres factors, més enllà de la interferència amb els parasitoides, podrien explicar els increments poblacionals de plagues observats en presència de formigues. Davant aquests resultats, es va comparar l'abundància, riquesa d'espècies, diversitat i estructura de la comunitat de depredadors i parasitoides entre els tractaments d'exclusió i presència de formigues. Es capturaren i identificaren un total de 176,000 artròpodes pertanyents a 81 taxons distints. En quant a l'abundància, la resposta dels enemics naturals a l'exclusió de formigues fou específica per a cada espècie. Els parasitoides mostraren majors abundàncies en presència de formigues mentre que la majoria de depredadors generalistes foren menys abundants. La riquesa d'espècies i l'Índex de diversitat de Shannon dels parasitoides foren majors en presència de formigues mentre que la riquesa d'espècies dels depredadors fou menor. L'estructura de la comunitat de depredadors i parasitoides fou similar entre tractaments. L'impacte negatiu de les formigues sobre els depredadors generalistes pot tenir importants implicacions per a la regulació de les poblacions de plagues. Finalment s'estudià una novedosa hipòtesi en la que es va plantejar l'existència de competència per la melassa que produeixen els hemípters entre les formigues i els enemics naturals. Mitjançant l'ús de cromatografia líquida d'alta resolució (HPLC) es va relacionar l'activitat de les formigues amb les reserves energètiques i les fonts alimentàries utilitzades per espècimens d'enemics naturals recol·lectats al camp. Es va trobar una correlació significativament negativa entre l'activitat de les formigues i el contingut total de sucres i l'alimentació a base de melassa del parasitoide Aphytis chrysomphali (Mercet) en estiu. L'activitat de les formigues es va correlacionar negativament amb l'alimentació a base de sucres del depredador Chrysoperla carnea s.l. en primavera. Aquesta interacció indirecta en la que les formigues interfereixen en l'estat fisiològic dels enemics naturals no ha sigut documentada prèviament. Donat que l'absència de sucres en l'alimentació de moltes espècies de depredadors i parasitoides és perjudicial per al seu estat físic, aquesta interacció pot ten
Calabuig Gomar, A. (2015). Ants, pests and natural enemies in Mediterranean citrus. Ecological interactions and practical implications for biological control [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54122
TESIS

Bibliography: leaves 165-188. This research examines biological and behavioural interactions among the diamond-back moth, Plutella xylostella L. (Lepidoptera: Plutellidae), Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) and the microbial insecticide, Bacillus thuringiensis Berliner. A deterministic simulation model is developed describing the influence of C. plutellae on the evolution of resistance to Bt in a diamond-back moth poulation.

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The leafminer Liriomyza trifolii is nowadays the main pest of melon orchards in the region of Chapada do Apodi, Northeast of Brazil. In order of the high infestation level of this insect, the control based only in pesticides has not been plenty satisfactory. However, considerable parasitism levels occasioned by Opius sp. have been found in field, mainly in the beginning of the production. Because of this fact, the first studies with this parasitoid are been developed in the Entomology Laboratory of UFERSA. The present study had the objective of adapting a rearing technique to the parasitoid Opius sp. in laboratory conditions, and study the aspects of it s parasitism, aiming the future utilization of this parasitoid in the leafminer integrated management programs, in the Semi-Arid conditions of Rio Grande do Norte State. Initially, infested melon leaves with L. trifolii larvae were collected in field to obtain the parasitoids. From the first parasitoids obtained from field, a technique to multiply them in L. trifolii on melon plants was developed. In the observations of the parasitism aspects of Opius sp., was perceived that it prefer to oviposite in 2nd and 3rd instar larvae. In addition, was observed that females present the highest levels of parasitism in the first two days of life
A mosca-minadora Liriomyza trifolii (Diptera: Agromyzidae), é atualmente a principal praga do meloeiro Cucumis melo L., na região da Chapada do Apodi, nordeste brasileiro. Devido às altas infestações deste inseto, o controle baseado exclusivamente no uso de inseticidas não tem sido plenamente satisfatório. Por outro lado, índices consideráveis de parasitismo, ocasionados pelo parasitóide Opius sp. (Hymenoptera: Braconidae), têm sido constatado em campo, principalmente no início da safra. Em função deste fato, estudos básicos com este parasitóide estão sendo realizados no Laboratório de Entomologia da UFERSA, Mossoró, RN. Dessa forma, o presente trabalho objetivou descrever uma técnica para criação de Opius sp., em condições de laboratório, e estudar aspectos de seu parasitismo, visando sua utilização em futuros programas de manejo integrado da mosca-minadora do meloeiro, nas condições do semi-árido do Rio Grande do Norte. Inicialmente, folhas de meloeiro infestadas com larvas da mosca-minadora foram coletadas em campo para obtenção dos parasitóides. A partir dos primeiros parasitóides obtidos foi adaptada uma técnica para multiplicação destes sobre L. trifolii em plantas de meloeiro. Nas observações sobre os aspectos do parasitismo do Opius sp., constatou-se que estes preferem ovipositar em larvas de 2º e 3º ínstar. Além disso, foi observado que as fêmeas do Opius sp. apresentam maiores índices de parasitismo nos primeiros dois dias de vida

Typhlodromips montdorensis is a non-native predatory mite used for control of red spider mite and thrips, but is not yet licensed for use in the UK. Current legislation requires that non-native glasshouse biological control agents may not be introduced into the UK without a risk assessment of establishment potential outside of the glasshouse environment. This work focuses on the application of a recently developed protocol to assess the establishment potential of T. montdorensis in the UK. Further, the use of alternative prey outside the glasshouse by, Macrolophus caliginosus is examined, and interactions between Neoseiulus californicus, Typhlodromus pyri and T. montdorensis are investigated. Laboratory results demonstrate that T. montdorensis has a developmental threshold of 10.7°C, lacks cold tolerance and is unable to enter diapause when tested under two different regimes. Field studies indicate that no reproduction occurs within the field in winter (November to March) and 100% mortality of eggs, larvae and adults occurs within two weeks of release during this period. It is suggested that T. montdorensis would be a ‘safe candidate’ for introduction as a glasshouse biological control agent in the UK as outdoor establishment is unlikely to occur. Macrolophus caliginosus is able to feed and reproduce on Trialeurodes vaporariorum, Myzus persicae and Aleyrodes proletella although performance (lower fecundity and longevity) is reduced on the latter prey source. Both N. californicus and T. pyri were able to feed on larval stages of each other but when given a mixed diet, showed a preference for Tetranychus urticae over their phytoseiid prey. Neoseiulus californicus showed a preference for T. urticae over T. montdorensis, whereas the latter species showed no preference between T. urticae and N. californicus. This work has identified a robust experimental protocol for predicting the establishment potential of non-native biological control agents outside the glasshouse and has begun to develop a further experimental system for assessing the possibility of non-native biological control agents feeding on alternate hosts outside the glasshouse.

This thesis was designed to address three seldom studied aspects of the relationship between herbivores and vegetational diversity. 1. Interactions between vegetational diversity and herbivore mortality due to predation were assessed by experimentally manipulating both the species diversity of plants and the densities of a common generalist predator, the spider Enoplagnatha ovata. 2. The importance of plant size to herbivore densities was examined by quantifying plant size (measured as plant height, width, leaf area and growth rates) and adjusting for it through covariate analysis. 3. Differences in population responses of several species of herbivores to both vegetational diversity and a predator, were compared by concurrently studying four lepidopterans. The main experiment used a two factor design, with two planting treatments and two predator treatments. The planting treatments consisted of plots planted with monocultures of brussels sprouts (Brassica oleraceae) and dicultures of brussels sprouts intercropped with peppermint (Mentha piperita). The natural enemy treatments involved augmentations of E ovata in some plots and untreated controls. Two of the herbivores studied, Plutella xylostella and Pieris rapae are monophagous lepidopterans, specializing on crucifers, while the others, Autographa californica and Mamestra configurata are polyphagous. For two species, P. xylostella and M. configurata responses to augmentations of the spider, E. ovata. were different in monocultures and dicultures. Reduced densities of these two species were found in monoculture plots with added spiders; in dicultures increased densities were found in plots with added spiders. This interaction effect points out that generalist predators can be effective in monocultures. I suggest that the importance of natural enemies in monocultures is often overlooked because only the initial colonization phase is being studied. By augmenting predator populations I was able to simulate densities equivalent to those in more established cropping systems. The increased herbivore densities in dicultures with added spiders might be explained by possible predation by E. ovata on other natural enemies of P. xylostella and M. configurata in dicultures but not in monocultures. Supporting evidence for this interpretation lies in the fact that percent parasitism of P. xylostella by the ichneumonid, Diadegma insulare was lower in plots with added spiders than in control plots. Furthermore, parasitism of P. xylostella by D. insulare increased with host density in diculture plots, but not in monoculture plots. Mamestra configurata was not subject to parasitism in this study, precluding assessment of a similar relationship. No A. californica larvae were found in plots with additional spiders. In contrast, P. rapae larvae were not affected by the experimental treatments. Plant size was a crucial determinant of both herbivore populations and percent parasitism of those herbivores. Most importantly, had plant size not been accounted for, the importance of vegetational diversity to both herbivore densities and percent parasitism would have been overestimated. For example, the incorrect conclusion, that vegetational diversity alone was important in determining the abundance of both of the generalist feeders would have been reached. The greater densities of A. californica in monocultures and M. configurata in dicultures were accounted for by plant size. Without plant size adjustments, percent parasitism of P. xylostella by D. insulare would have been misinterpeted as being greater in monocultures than dicultures. With plant size adjustments, the importance of E. ovata augmentations on lowering percent parasitismwas unmasked. All important interaction effects were discovered only after adjustments for plant size had been made. Despite the low densities of all herbivore species, significant responses to experimental treatments were found in three of the four species studied. Only P.l rapae was unaffected by any of the treatments. However, conclusions based on the feeding ng habits of the herbivores could not be made. The polyphagous feeders were affected by generalist predation as much as the crucifer specialist. Parasitism was found in only two of the species, P. xylostella and A. californica. Of these two species parasitism of the specialist, P. xylostella was affected by both vegetational diversity and generalist predation, whereas parasitism of A. californica was not. My study emphasizes multifaceted interactions between the size and diversity of a primary resource and several trophic levels of consumers. Multifactor models, involving several aspects of a cropping system, are required to uncover the important mechanisms behind variable herbivore responses to vegetational diversity.
Land and Food Systems, Faculty of
Graduate

Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia - UL
The olive tree (Olea europaea L.) has been shaping and characterizing landscape and culture in the Mediterranean basin. This tree is attacked by pest that can cause significant losses. This thesis was focused on the conservation biological control of one of its most damaging pests: the olive moth, Prays oleae (Bernard). Naturally, a large number of parasitoid and predator species are associated to this pest, and in order to satisfy their needs they make use of ecological infrastructures occurring in the olive grove agroecosystem. However, how these ecological infrastructures can be used to enhance the olive moth conservation biological control needs to be disentangled. For that, two approaches were followed. First, the influence of ecological infrastructures on P. oleae and its natural enemies was analyzed through field surveys. Then, different food resources were evaluated as potential foods for P. oleae and its natural enemies, i.e., the parasitoid Elasmus flabellatus (Fonscolombe) and the predator Chrysoperla carnea s. l. (Stephens). In the first approach, P. oleae was found to disperse throughout non-crop patches, although the implications for the pest population are unknown. The heterogeneous landscapes composed by herbaceous and woody vegetation around the olive groves were exploited by syrphids as food sources. Finally, ground covers within the olive groves favored the parasitoid Ageniaspis fuscicollis (Dalman) while the herbicide application diminished it. In the second approach, insects’ honeydews [Saissetia oleae (Olivier) and Euphyllura olivina (Costa)] and the flowers of Malva sylvestris L. favored the survival and/ or reproduction of P. oleae, C. carnea and E. flabellatus. Several plant species such as Daucus carota L., Veronica persica Poir, and Lamium purpureum L. showed to be potential food resources for the studied natural enemies. From the results obtained in this research various applications for managing the olive grove agroecosystem are proposed

Eastern and Carolina hemlock in the eastern United States are experiencing high mortality due to the invasive non-native hemlock woolly adelgid (HWA). The most promising means of control of HWA is the importation of natural enemies from the native range of HWA for classical biological control. Prior to release, natural enemies must be tested for suitability as a control agent, including the ability to locate the target prey. Coleopteran predators, including Scymnus coniferarum and Laricobius osakensis are under consideration as a means of biological control of HWA. Laricobius nigrinus was released in hemlock forests in 2003. It was recently discovered to hybridize with the native Laricobius rubidus. Behavioral responses of these predators to HWA and host tree foliage were observed using a 4-chambered olfactometer, and genetic analysis was used to differentiate responses of L. nigrinus, L. rubidus, and hybrids. In the olfactometer, insects are allowed to amble about the arena and respond to volatile cues from each treatment. Host foliage with and without HWA was tested, as were various comparisons of eastern versus western foliage, host versus non-host foliage, and foliage containing HWA and a congeneric feeding beetle. Olfactometer bioassays demonstrated that foliage from hosts where prey is commonly found is preferable to foliage where prey is seldom found, and that the presence of HWA-induced volatile cues is the strongest driver of behavior, and trumps the presence of a competitor. There is evidence in the study that supports the reliability-detectability phenomenon common in parasitoid biological control agents. Hybrid individuals were found to behave similarly to released L. nigrinus, although in some cases intermediate behavioral traits were evident, with respect to the parental species. This study and others support the continued need for strict testing of potential biological control agents prior to release, as well as a strong impetus for the inclusion and implementation of genetic analysis as a standard component of agent evaluation.

Mediante as modificações ambientais realizadas por ações antrópicas, os sistemas ecológicos vêm sendo cada vez mais afetados pela perda de organismos, resultando em simplificações nas interações tróficas, que acarretam em desequilíbrio entre espécies, principalmente em sistema agrícolas e florestais. Assim, compreender a atuação dos inimigos naturais é fundamental para sua implementação em programas de manejo integrado. Neste estudo, investigou-se as interações predador presa de duas espécies da subordem Heteroptera, Podisus nigrispinus e Graptocleptes bicolor, para compreender suas dinâmicas e respostas funcionais com algumas presas da ordem Lepidoptera.
Because of the environmental modifications made by anthropic actions, the ecological systems have been losing their organisms, resulting in simplification of trophic interactions, which bring out species instability, especially at agricultural and forest systems. Thus, to understand the performance of natural enemies it is primordial to their usage at integrated pest management programs. In this study, the predator prey interactions of two species from the suborder Heteroptera, Podisus nigrispinus and Graptocleptes bicolorwere investigated, to understand their dynamics and functional responses, with some preys from the Lepidoptera order.

O equilíbrio entre insetos-praga e inimigos naturais existentes na cultura da soja, pode ser influenciado pelo manejo do solo, produtos fitossanitários e cultivares de soja. O presente estudo avaliou a diversidade de lepidópteros associados à cultura da soja, no continente Americano, e a abundância específica destes insetos e seus inimigos naturais (parasitóides e fungos entomopatogênicos), em soja convencional e transgênica RR, com aplicação de herbicidas seletivos (Amplo® e Aramo®) e uma formulação de glifosato (Gliz®), sendo o cultivo da soja BRS 133-convencional e BRS Charrua RR-transgênico realizado em Vacaria, RS, sob manejo de solo convencional, em três lotes de um hectare cada. Nas amostragens semanais, os lepidópteros foram coletados com pano-de-batida, mantidos em criação laboratorial até a obtenção dos adultos, dos parasitóides ou dos fungos entomopatogênicos. Também realizaram-se amostragens de solo para isolamento de fungos entomopatogênicos. Elaborou-se uma listagem dos lepidópteros associados à cultura da soja no continente Americano, relacionando-se 71 espécies cujas formas larvais já foram referidas alimentando-se de soja. No presente estudo foram coletadas 1634 larvas de lepidópteros identificados em 22 táxons, destacando-se Anticarsia gemmatalis, Pseudoplusia includens e Rachiplusia nu como as mais representativas (83,05% das larvas coletadas). A aplicação da formulação de glifosato afetou negativamente o número médio de lagartas em relação aos demais lotes tratados com herbicidas seletivos. Os himenópteros, dípteros e strepsípteros foram responsáveis pelo parasitismo de 34,52% das lagartas. Entretanto com relação ao parasitismo específico, observou-se que entre as lagartas parasitadas, 93,05% pertenciam às três espécies mais freqüentes, destacando-se os plusiíneos que foram mais parasitados que A. gemmatalis. N. rileyi foi o único fungo entomopatogênico isolado a partir de lagartas, sendo responsável por 1,41% da mortalidade das três espécies mais abundantes. Os números de unidades formadoras de colônias de Beauveria, Metarhizium e Paecilomyces, isolados das amostras de solo não diferiram estatisticamente entre os lotes.
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In soybean plantations, the equilibrium between insect pests and their natural enemies can be influenced by various factors such as soil management, use of phytosanitary products and soybean cultivar. This study evaluated the diversity of Lepidoptera associated with soybean crops in the Americas, and the specific abundance of these organisms and their natural enemies (parasitoids and entomopathogenic fungi) on conventional and transgenic RR soybean, treated with selective herbicides and glyphosate formulations. The experiment was carried out in Vacaria, Rio Grande do Sul state. Conventional BRS 133 and transgenic RR soy were each planted on three, one-hectare plots and treated with either selective herbicides or a glyphosate formulation. During weekly sampling, Lepidoptera were collected using the drop cloth method and maintained in the laboratory until adults and associated parasitoids and fungi could be obtained. Entomopathogenic fungi were isolated from soil samples. Based on literature data one list of 71 species of Lepidoptera that had been previously reported as feeding on soybean crop was prepared. In the present study, 1634 Lepidoptera larvae were identified in 22 taxa, including the following well-represented species: A. gemmatalis, P. includens e R. nu (83.05% of the larvae collected). The glyphosate treatments reduced the mean number of larvae when compared with the selective herbicide treatments. Hymenopterans, dipterans and strepsipterans were responsible for 34.52% of the total caterpillar parasitism. A large percentage of the larvae parasitized (93.05%) belong to the three most common species of Lepidoptera in our sampling, particularly to the Plusiinae, which were more heavily parasitized than A. gemmatalis. The entomopathogenic fungus N. rileyi was the only species isolated from the caterpillars and was responsible for 1.41% of the deaths amongst the three most common species. The numbers of colony-forming unities of Beauveria, Metarhizium and Paecilomyces, isolated from soil samples, did not differ among the plots.

Conservation of natural habitats and planting wildflower plots are two commonly promoted tactics to enhance pollination services and biological control of crop pests, which are ecosystem services that can improve agricultural outputs. There are several programs at various levels of government in the United States that landowners can use to defray the costs of implementing these conservation strategies. Studies of European Agricultural Environmental Schemes have shown these tactics to have positive outcomes for crop production. However, real-world applications of cost-sharing programs have not been evaluated in the United States on pollination services and biological control. Furthermore, these tactics may inadvertently perform ecosystem disservices, like increasing crop pests or creating habitat for disease vectors. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, sentinel egg predation, crop damage, seed pollination, biomass production, marketable crop yield, sampled the bee community, and recorded tick abundance in wildflower plots. Many of the measures of biological control and pollination services had idiosyncratic results in regards to the wildflower plots and natural habit in the landscape. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks.
Doctor of Philosophy
Conservation of natural habitats and planting wildflower plots are two strategies to enhance pollination services and biological control of crop pests. These two ecosystem services are of needed to improve agricultural production without further damaging the environment. There are several programs at various levels of government in the United States that landowners can use to subsidize the costs of implementing these strategies. European studies have shown these government programs to be successful. However, these programs have not been evaluated in the United States on their ability to enhance pollination services and biological control. Furthermore, studies investigating potential ecosystem disservices these strategies. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, egg predation, crop damage, seed pollination, and yield. We also sampled the bee community, and recorded tick abundance in wildflower plots. There were no consistent trends for many measures of biological control and pollination services in response to the wildflower plots and natural habit. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks.

Conservation of natural habitats and planting wildflower plots are two commonly promoted tactics to enhance pollination services and biological control of crop pests, which are ecosystem services that can improve agricultural outputs. There are several programs at various levels of government in the United States that landowners can use to defray the costs of implementing these conservation strategies. Studies of European Agricultural Environmental Schemes have shown these tactics to have positive outcomes for crop production. However, real-world applications of cost-sharing programs have not been evaluated in the United States on pollination services and biological control. Furthermore, these tactics may inadvertently perform ecosystem disservices, like increasing crop pests or creating habitat for disease vectors. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, sentinel egg predation, crop damage, seed pollination, biomass production, marketable crop yield, sampled the bee community, and recorded tick abundance in wildflower plots. Many of the measures of biological control and pollination services had idiosyncratic results in regards to the wildflower plots and natural habit in the landscape. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks.
Doctor of Philosophy
Conservation of natural habitats and planting wildflower plots are two strategies to enhance pollination services and biological control of crop pests. These two ecosystem services are of needed to improve agricultural production without further damaging the environment. There are several programs at various levels of government in the United States that landowners can use to subsidize the costs of implementing these strategies. European studies have shown these government programs to be successful. However, these programs have not been evaluated in the United States on their ability to enhance pollination services and biological control. Furthermore, studies investigating potential ecosystem disservices these strategies. In this study, we evaluated the effects of natural habit and wildflower plots on biological control, pollination services, bee communities, and tick populations in Eastern Virginia and Maryland. This research was conducted on 22 farms. 10 of these farms had wildflower plots that were designed by Natural Resource Conservation Service personnel, and implemented by cooperating farmers. Collards, strawberries, tomatoes, and squash were used as model systems. We measured pest density, egg predation, crop damage, seed pollination, and yield. We also sampled the bee community, and recorded tick abundance in wildflower plots. There were no consistent trends for many measures of biological control and pollination services in response to the wildflower plots and natural habit. However, the proportion of high quality yield for all four crops increased with increasing natural habitat in the landscape. Bee communities between sites with and without wildflower plots were not different. Bee abundance did increase at wildflower sites when natural habitat comprised a certain proportion of the habitat around the site. Ticks were sampled from wildflower plantings, but not in greater abundance compared to field margins. In this study, the effects of wildflower plots were overshadowed by the landscape effects of natural habitat. Government personnel that oversee these programs may need to consider the surrounding landscape when helping implement on-farm conservation measure like wildflower plots. Such measures, do not perform an ecosystem disservice in regards to ticks.

The pine bark adelgid, Pineus strobi (Hemiptera: Adelgidae) is a native herbivore of eastern white pine, Pinus strobus (Pinales: Pinaceae), in eastern North America. It is a sessile insect that settles on P. strobus and inserts its stylet bundle to feed on the tree’s phloem. Although P. strobi is not considered a serious pest, it shares its range with the invasive hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae). Predators introduced as biological control agents of A. tsugae interact with P. strobi and its native predators, including Laricobius rubidus LeConte (Coleoptera: Derodontidae). Prior to this study, little work had been done to document the phenology or predators of P. strobi, particularly in its southern range. In the present study, the phenology of P. strobi is reported in southwestern Virginia. Patterns in overwintering population dynamics varied notably from those described from this species’ northern range. The number of annual generations could not be measured due to overlap following two distinct spring generations. Adult body size varied seasonally and was greatest in the spring. Variation between observations from the northern and southern ranges of P. strobi indicate phenological plasticity that informs biological control efforts and offers insight into implication of climatic effects on population dynamics of this and related species. Arthropod predators associated with P. strobi in forests of southwest Virginia were collected during a two-year survey. Morphology and DNA barcoding were used for identification. Species of predators found included: Laricobius rubidus (Coleoptera: Derodontidae), a native adelgid specialist, and two species from the dipteran family Chamaemyiidae, Leucopis piniperda Malloch and L. argenticollis Zetterstedt, which are adelgid specialists. Members of the families Cecidomyiidae, Coccinellidae, Chrysopidae, Hemerobiidae, and Syrphidae were also recovered. Most diverse were the Cecidomyiidae, with 15 different species inferred from their DNA barcodes. Additional work was performed to quantify supercooling points of L. rubidus collected from November – December 2016. These will be compared to those of other Laricobius species in a parallel study. Knowledge of this predator complex is beneficial to describing P. strobi ecology, and also with regard to potential biological control of invasive adelgids in the same region.
Ph. D.

Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xvi, 166 p.; also includes graphics (some col.). Includes bibliographical references. Available online via OhioLINK's ETD Center.

In Quebec, the swede midge (Contarinia nasturtii), a newly invasive pest, was found for the first time in 2003. During a two year study (2004-2005) I studied the seasonal development of the swede midge, the presence of natural enemies and tested entomopathogenic nematodes for its control. Results showed that the overwintering generation of the swede midge emerged during the second half of June. Based on adult captures and abundance of larvae in the field, there were three to four overlapping generations. Late transplants were more heavily attacked by the swede midge and broccoli and cauliflower were the most susceptible crops. No parasitoids were found in the experimental sites during either year of the study and two polyphagous coccinellid predators (Harmonia axyridis and Coccinella septempunctata) were field-collected for further evaluation under laboratory conditions. Although these two coccinellid species fed on swede midge larvae in plastic containers, further experiments demonstrated that H. axyridis was not able to prey on swede midge larvae on infested broccoli plants. The susceptibility of swede midge larvae to three species of entomopathogenic nematodes (Steinernema feltiae, S. carpocapsae, and Heterorhabditis bacteriophora) was also evaluated in laboratory assays. Heterorhabditis bacteriophora was the only species that caused significant mortality to swede midge larvae and, at a concentration of 1000 IJs/larva, caused 90-100% mortality in loam, sandy loam, clay and muck soil. This is the first study describing the seasonal development of the swede midge in Quebec. In addition, the potential use of entomopathogenic nematodes as biological control agents against the swede midge is demonstrated.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O conhecimento do comportamento de infestação dos insetos em sistemas agrícolas facilita as amostragens, economiza tempo sem perder a confiabilidade para a tomada de decisões no sistema de manejo de pragas. Assim o objetivo foi estudar a distribuição vertical e temporal de ovos de Alabama argillacea e de Heliothis virescens, e o parasitismo de ovos por Trichogramma pretiosum em cultivares de algodoeiro. O delineamento experimental foi em blocos ao acaso, com cinco tratamentos (cultivares DeltaOPAL, FMX-933, FMT-701, FMX-910 e NuOPAL), com oito repetições. As avaliações foram semanais, a partir da emergência das plantas. Para a distribuição vertical, as plantas foram avaliadas nas partes superior, média e inferior, anotando-se o número de ovos. Os ovos de A. argillacea e de H. virescens foram parasitados por Trichogramma pretiosum. Não houve preferência para oviposição por A. argillacea e por H. virescens durante os estágios fenológicos das plantas, tal como o grau de parasitismo por T. pretiosum também não foi influenciado. Quanto à distribuição vertical dos ovos, o terço superior e o médio das plantas foram os mais preferidos para oviposição por A. argillacea nas cultivares NuOPAL, DeltaOPAL e FMX-910, enquanto que H. virescens preferiu ovipositar no terço superior das plantas. T. pretiosum preferiu ovipositar em ovos de A. argillacea presentes no terço superior e médio das plantas, sendo que ovos de H. virescens presentes no terço superior das plantas foram mais parasitados por T. pretiosum
The knowledge of a pest infestation behavior on agricultural areas help the sampling and reduce time without lose confidence on decisions in integrated pest management. This work aimed to study the vertical and temporal distribution of Alabama argillacea and Heliothis virescens eggs, as well as parasitism of its eggs by Trichogramma pretiosum in cotton cultivars. The experimental design was randomized blocks with five treatments with five treatments (cultivars DeltaOPAL, FMX-933, FMT-701 and FMX-910 and NuOPAL) and with eight replicates. Evaluations were performed weekly since plant emergence. For the vertical distribution, plants were divided into three parts, upper, middle and bottom. The number of eggs present in plants was recorded. A. argillacea and H. virescens eggs were parasitized by Trichogramma pretiosum. There was no preference for oviposition by A. argillacea and H. virescens during the plants phenological stages, as well as T. pretiosum parasitism. Concerning the vertical distribution of eggs, the upper and middle parts of the plants were the most preferred for oviposition by A. argillacea on cultivars NuOPAL, DeltaOPAL and FMX-910, and H. virescens preferred to oviposit in the upper part of the plants. T. pretiosum preferred to oviposit in A. argillacea eggs on the upper and middle parts of the plants, and in H. virescens on the upper part of the plants

Paropsis atomaria Olivier (Coleoptera: Chrysomelidae: Paropsini), is a major pest of commercially grown eucalypts in South-East Queensland. Current management of paropsine beetles involves regular inspection and the application of chemical sprays if defoliation is severe. However, non-chemical control of plantation pests is highly desirable given the requirement to certify forest practices for sustainability, and community concerns over the use of pesticides. One way of reducing pesticide use is through conservation biological control, which requires detailed knowledge of the life history of the pest and its natural enemies. This thesis documents aspects of P. atomaria phenology, including life tables, sex ratios and damage estimates; identifies the predators, parasites, and egg and larval parasitoids of P. atomaria; and examines the ecology of the most promising natural enemy, Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) in South-East Queensland. P. atomaria adults are active from September until April and can complete up to four generations in a season. Field mortality between egg and fourth instar larvae is approximately 94%. A large proportion of this mortality can be attributed to natural enemies. The most abundant predators in eucalypt plantations were spiders, comprising 88% of all predators encountered. Egg parasitoids exerted the greatest influence on P. atomaria populations, emerging from around 50% of all egg batches, and were responsible for mortality of almost one third of all eggs in the field. Only about one percent of larvae were parasitised in the field, in contrast to paropsine pests in temperate Australia, where egg parasitism rates are low and larval parasitism rates high. Neopolycystus sp. was the only primary parasitoid reared from P. atomaria eggs, along with three hyperparasitoid species; Baeoanusia albifunicle Girault (Encyrtidae), Neblatticida sp. (Encyrtidae) and Aphaneromella sp. (Platygasteridae). This is the first record of B. albifunicle hyperparasitising Neopolycystus spp. B. albifunicle emerged from one-third of all parasitised egg batches and could pose a potential problem to the efficacy of Neopolycystus sp. as a biological control agent. However, within egg batches, hyperparasitoids rarely killed all Neopolycystus sp. with only 9% of hyperparasitised egg batches failing to produce any primary parasitoids. Total field mortality of P. atomaria through direct and indirect effects of parasitism by Neopolycystus sp. was 28%. The proportion of egg batches parasitised increased with exposure time in the field, but within-batch parasitism rate did not. In general, there was no significant correlation between parasitism rates and distance from landscape features (viz. water sources and native forest).

Paropsis atomaria Olivier (Coleoptera: Chrysomelidae: Paropsini), is a major pest of commercially grown eucalypts in South-East Queensland. Current management of paropsine beetles involves regular inspection and the application of chemical sprays if defoliation is severe. However, non-chemical control of plantation pests is highly desirable given the requirement to certify forest practices for sustainability, and community concerns over the use of pesticides. One way of reducing pesticide use is through conservation biological control, which requires detailed knowledge of the life history of the pest and its natural enemies. This thesis documents aspects of P. atomaria phenology, including life tables, sex ratios and damage estimates; identifies the predators, parasites, and egg and larval parasitoids of P. atomaria; and examines the ecology of the most promising natural enemy, Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) in South-East Queensland. P. atomaria adults are active from September until April and can complete up to four generations in a season. Field mortality between egg and fourth instar larvae is approximately 94%. A large proportion of this mortality can be attributed to natural enemies. The most abundant predators in eucalypt plantations were spiders, comprising 88% of all predators encountered. Egg parasitoids exerted the greatest influence on P. atomaria populations, emerging from around 50% of all egg batches, and were responsible for mortality of almost one third of all eggs in the field. Only about one percent of larvae were parasitised in the field, in contrast to paropsine pests in temperate Australia, where egg parasitism rates are low and larval parasitism rates high. Neopolycystus sp. was the only primary parasitoid reared from P. atomaria eggs, along with three hyperparasitoid species; Baeoanusia albifunicle Girault (Encyrtidae), Neblatticida sp. (Encyrtidae) and Aphaneromella sp. (Platygasteridae). This is the first record of B. albifunicle hyperparasitising Neopolycystus spp. B. albifunicle emerged from one-third of all parasitised egg batches and could pose a potential problem to the efficacy of Neopolycystus sp. as a biological control agent. However, within egg batches, hyperparasitoids rarely killed all Neopolycystus sp. with only 9% of hyperparasitised egg batches failing to produce any primary parasitoids. Total field mortality of P. atomaria through direct and indirect effects of parasitism by Neopolycystus sp. was 28%. The proportion of egg batches parasitised increased with exposure time in the field, but within-batch parasitism rate did not. In general, there was no significant correlation between parasitism rates and distance from landscape features (viz. water sources and native forest).

Orientador: Antonio Carlos Busoli
Banca: Marcos Gino Fernandes
Banca: Nilza Maria Martinelli
Resumo: O conhecimento do comportamento de infestação dos insetos em sistemas agrícolas facilita as amostragens, economiza tempo sem perder a confiabilidade para a tomada de decisões no sistema de manejo de pragas. Assim o objetivo foi estudar a distribuição vertical e temporal de ovos de Alabama argillacea e de Heliothis virescens, e o parasitismo de ovos por Trichogramma pretiosum em cultivares de algodoeiro. O delineamento experimental foi em blocos ao acaso, com cinco tratamentos (cultivares DeltaOPAL, FMX-933, FMT-701, FMX-910 e NuOPAL), com oito repetições. As avaliações foram semanais, a partir da emergência das plantas. Para a distribuição vertical, as plantas foram avaliadas nas partes superior, média e inferior, anotando-se o número de ovos. Os ovos de A. argillacea e de H. virescens foram parasitados por Trichogramma pretiosum. Não houve preferência para oviposição por A. argillacea e por H. virescens durante os estágios fenológicos das plantas, tal como o grau de parasitismo por T. pretiosum também não foi influenciado. Quanto à distribuição vertical dos ovos, o terço superior e o médio das plantas foram os mais preferidos para oviposição por A. argillacea nas cultivares NuOPAL, DeltaOPAL e FMX-910, enquanto que H. virescens preferiu ovipositar no terço superior das plantas. T. pretiosum preferiu ovipositar em ovos de A. argillacea presentes no terço superior e médio das plantas, sendo que ovos de H. virescens presentes no terço superior das plantas foram mais parasitados por T. pretiosum
Abstract: The knowledge of a pest infestation behavior on agricultural areas help the sampling and reduce time without lose confidence on decisions in integrated pest management. This work aimed to study the vertical and temporal distribution of Alabama argillacea and Heliothis virescens eggs, as well as parasitism of its eggs by Trichogramma pretiosum in cotton cultivars. The experimental design was randomized blocks with five treatments with five treatments (cultivars DeltaOPAL, FMX-933, FMT-701 and FMX-910 and NuOPAL) and with eight replicates. Evaluations were performed weekly since plant emergence. For the vertical distribution, plants were divided into three parts, upper, middle and bottom. The number of eggs present in plants was recorded. A. argillacea and H. virescens eggs were parasitized by Trichogramma pretiosum. There was no preference for oviposition by A. argillacea and H. virescens during the plants phenological stages, as well as T. pretiosum parasitism. Concerning the vertical distribution of eggs, the upper and middle parts of the plants were the most preferred for oviposition by A. argillacea on cultivars NuOPAL, DeltaOPAL and FMX-910, and H. virescens preferred to oviposit in the upper part of the plants. T. pretiosum preferred to oviposit in A. argillacea eggs on the upper and middle parts of the plants, and in H. virescens on the upper part of the plants
Mestre

Bibliography: leaves 73-76.
A form of the southern African plant Asparagus asparagoides (Asparagaceae), is a serious environmental week in Australia, where it is known as bridal creeper. Bridal creeper has an extensive underground tuber system and can invade native vegetation, two factors that make chemical and/or mechanical control difficult. The fruit is bird dispersed which facilitates colonisation of new sites. Surveys for potential biological control agents for use against bridal creeper in Australia were initiated in South Africa during 1989. This dissertation describes the identification, distribution and phenology of A. asparagoides in South Africa, as well as the natural enemies associated with the plant and their potential for use as biological control agents in Australia. Potential biological control agents that attack vegetative growth of bridal creeper included an undescribed Zygina sp. (Cicadellidae), two undescribed Crioceris species (Chrysomelidae - Criocerinae) and the rust fungus, Puccinia myrsiphlli DC. (Uredinales). The seeds of bridal creeper are attacked by an undescribed Eurytoma sp. (Eurytomidae) and the fruits by Zalaca snelleni (Wallengren) (Noctuidae). An organism directly attacking the tuber mass of bridal creeper was not found. Experimental results illustrated that herbivore damage to the above ground parts of the plant resulted in reduced tuber mass and also impacted negatively on fruit production.