Dissertations / Theses on the topic 'Insects as biological pest control agents'

Includes bibliographical references (leaves 168-198) The horehound plume moth (Wheeleria spilodactylus Curits), an agent introduced to control the invasive weed horehound (Murrubium vulgare L.), was used as a model system to investigate factors believed to influence the successful establishment of an introduced natural enemy. Retrospectively tests the use of generic population viability analysis and decision making tools for determining optimal release strategies for the horehound plume moth in South Australia and to compare outcomes with the emprical data collected during the course of this project

Includes bibliographical references (leaves 102-114) The highly successful biological control of the citrophilous mealybug Pseudococcus calceolarie (Maskell) (CM) by the parasitic wasp Coccophagus gurneyi Compere in several countries led to the release of this parasitoid in the Riverland of South Australia as part of an integrated pest management program. However CM has not been successfully controlled in this region. The results of this study may help to explain the lack of effective biological control of CM in Riverland citrus.

Orientador: Sergio Antonio De Bortoli
Banca: Roberto Marchi Goulart
Banca: Raphael de Campos Castilho
Resumo: O objetivo desta pesquisa foi adequar uma metodologia de criação para o predador Xylocoris afer e avaliar, bem como aspectos biológicos e o custo de produção predando ovos de Corcyra cephalonica ou Plutella xylostella. Visando otimizar e adequar uma metodologia para multiplicação de X. afer em condições de laboratório, foi estabelecida uma colônia do predador utilizando como referência, a metodologia de criação de outra espécie de Anthocoridae, Orius insidiosus. Porém, nos recipientes de criação onde os insetos foram criados, não foram utilizadas inflorescências de picão preto (Bidens pilosa), comumente empregada como substrato de oviposição, mas pequenos rolos de algodão, eliminando a dependência de um substrato vegetal. O experimento visando obter informações sobre os aspectos biológicos de X. afer, foi conduzido inicialmente com ninfas de 12-24h de idade, uma por placa, num total de 60 ninfas (60 repetições). Em cada placa foram colocados, diariamente, ovos de P. xylostella ou ovos de C. cephalonica e um chumaço de algodão umedecido com água destilada. As avaliações foram realizadas a cada 24 horas. Os adultos foram separados por sexo, acasalados e mantidos também em placas de Petri para a verificação das características reprodutivas e longevidade. Foram avaliados os seguintes parâmetros: duração, viabilidade e consumo dos estádios ninfais e da fase ninfal; consumo e longevidade de machos e fêmeas; ovos por fêmea e fertilidade dos ovos. Os dados biológicos também foram uti... (Resumo completo, clicar acesso eletrônico abaixo)
Mestre

Yellow toadflax, Linaria vulgaris (L.) Mill. (Plantaginaceae), is a non-native invasive plant. Rhinusa pilosa Germar (Coleoptera: Curculionidae) is a proposed biocontrol agent. Gall development by R. pilosa was described using histological methods and compared between plant populations from native and introduced ranges. Key stages of oviposition were isolated histologically to determine their importance in gall induction. Rhinusa pilosa galled and developed on four geographically distinct Canadian populations in a pre-release quarantine study. Low agent densities only negatively affected one population. High densities of R. pilosa reduced potential reproductive output and plant biomass. Conducting detailed investigations into the biology, impact, and development of R. pilosa on populations from invasive and native ranges may help predict the efficacy of R. pilosa in the field if approved for release and.goes beyond current pre-release testing requirements.
ix, 168 leaves : ill. (chiefly col.) ; 29 cm

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2002.
Thesis documentation sheet inserted. Appendix reprints five published papers and manuscripts, three co-authored with others. Includes bibliographical references. Also available electronically via World Wide Web in PDF format; online version lacks appendix.

The biology of key citrus pests Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae), Ceratitis capitata Wiedemann (Diptera: Tephritidae) and Ceratitis rosa Karsch (Diptera: Tephritidae) includes their dropping from host plants to pupate in the soil below citrus trees. Since most EP fungi are soil-borne microorganisms, the development and formulation of alternative control strategies using these fungi as subterranean control agents, targeted at larvae and pupae in the soil, can potentially benefit existing IPM management of citrus in South Africa. Thus, a survey of occurrence of entomopathogenic fungi was undertaken on soils from citrus orchards and natural vegetation (refugia) on conventionally and organically managed farms in the Eastern Cape Province in South Africa. A method for baiting soil samples with citrus pest T. leucotreta and C. capitata larvae, as well as with the standard bait insect, Galleria mellonella Linnaeus (Lepidoptera: Pyralidae), was implemented. Sixty-two potentially useful entomopathogenic fungal isolates belonging to four genera were collected from 288 soil samples, an occurrence frequency of 21.53%. The most frequently isolated entomopathogenic fungal species was Beauveria bassiana (Balsamo) Vuillemin (15.63%), followed by Metarhizium anisopliae var. anisopliae (Metschnikoff) Sorokin (3.82%). Galleria mellonella was the most effective insect used to isolate fungal species (χ2=40.13, df=2, P≤ 0.005), with a total of 45 isolates obtained, followed by C. capitata with 11 isolates, and T. leucotreta with six isolates recovered. There was a significantly (χ2=11.65, df=1, P≤ 0.005) higher occurrence of entomopathogenic fungi in soil samples taken from refugia compared to cultivated orchards of both organically and conventionally managed farms. No significant differences were observed in the recovery of fungal isolates when soil samples from both farming systems were compared. The physiological effects and host range of 21 indigenous fungal isolates obtained in the Eastern Cape were investigated in the laboratory to establish whether these isolates could be effectively used as biological control agents against the subterranean life stages of C. rosa, C. capitata and T. leucotreta. When these pests were treated with a fungal concentration of 1 x 10⁷ conidia ml⁻¹, the percentage of T. leucotreta adults which emerged in fungal treated sand ranged from 5 to 60% (F=33.295; df=21; P=0.0001) depending on fungal isolate and the percentage of pupae with visible signs of mycosis ranged from 21 to 93% (F= 96.436; df=21; P=0.0001). Based on fungal isolates, the percentage adult survival in C. rosa and C. capitata ranged from 30 to 90% and 55 to 86% respectively. The percentage of C. rosa and C. capitata puparia with visible signs of mycosis ranged from 1 to 14% and 1 to 11% respectively. Deferred mortality due to mycosis in C. rosa and C. capitata adult flies ranged from 1 to 58% and 1 to 33% respectively, depending on fungal isolate. Entomopathogenic fungal isolates had a significantly greater effect on the adults of C. rosa and C. capitata than they did on the puparia of these two fruit fly species. Further, C. rosa and C. capitata did not differ significantly in their response to entomopathogenic fungi when adult survival or adult and pupal mycosis were considered. The relative potency of the four most virulent Beauveria isolates as well as the commercially available Beauveria bassiana product, Bb Plus® (Biological Control Products, South Africa), were compared against one another as log-probit regressions of mortality against C. rosa, C. capitata and T. leucotreta which all exhibited a dose-dependent response. Against fruit flies the estimated LC50 values of all five Beauveria isolates ranged from 5.5 x 10¹¹ to 2.8 x 10¹² conidia/ml⁻¹. There were no significant differences between the relative potencies of these five fungal isolates. When T. leucotreta was considered, isolates: G Moss R10 and G 14 2 B5 and Bb Plus® were significantly more pathogenic than G B Ar 23 B3 and FCM 10 13 L1. The estimated LC₅₀ values of the three most pathogenic isolates ranged from 6.8 x 10⁵ to 2.1 x 10⁶ conidia/ml⁻¹, while those of the least pathogenic ranged from 1.6 x 10⁷ to 3.7 x 10⁷ conidia/ml⁻¹. Thaumatotibia leucotreta final instar larvae were exposed to two conidial concentrations, at four different exposure times (12, 48, 72 and 96 hrs) and showed an exposure time-dependant relationship (F=5.43; df=3; P=0.001). At 1 x 10⁷conidia/ml⁻¹ two Beauveria isolates: G Moss R10 and G 14 2 B5 were able to elicit a response in 50% of test insects at 72 hrs (3 days) exposure. Although a limited amount of mycosis was observed in the puparia of both fruit fly species, deferred adult mortality due to mycosis was high. The increased incidence of adult mortality suggests that post emergence mycosis in adult fruit flies may play a more significant role in field suppression than the control of fruit flies at the pupal stage. The increased incidence of pupal mortality, as well as the relatively low concentrations of conidia required to elicit meaningful responses in T. leucotreta pupae may suggest that pre-emergent control of false codling moth will play a more significant role in field suppression than the control of adult life stages using indigenous isolates of entomopathogenic fungi. Various entomopathogenic fungal application techniques targeted at key insect pests within integrated pest management (IPM) systems of citrus are discussed.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
RESUMO – A família Pseudococcidae é a segunda maior da Infraordem Coccomorpha, com cerca de 2000 espécies descritas. No Brasil, conhecidas popularmente como cochonilhas-farinhentas, compreendem a terceira maior família, com 77 espécies registradas, distribuídas em 22 gêneros. Destas, 32 espécies são conhecidas para o estado de São Paulo, sendo 30% polífagas e de origem exótica, infestando plantas de importância agrícola. O controle biológico é uma alternativa, e dentre os inimigos naturais os himenópteros parasitoides vêm sendo muito utilizados. O objetivo deste trabalho foi inventariar os micro-himenópteros parasitoides de 11 espécies de pseudococcídeos pragas, primarias ou secundarias, de várias culturas e plantas ornamentais no estado de São Paulo, como café, citros, pinha, goiabeira, entre outros, relacionando estes com seu hospedeiro, origem e distribuição geográfica. Os levantamentos dos himenópteros parasitoides foram realizados entre agosto de 2016 e agosto de 2017, de forma aleatória, em áreas rural e urbana de cinco municípios do estado São Paulo: Jales, Ribeirão Preto, Jaboticabal, São Carlos e Campinas. As espécies de pseudococcídeos amostrados para obtenção dos parasitoides foram: Dysmicoccus brevipes (Cockerell, 1893), Ferrisia virgata (Cockerell, 1893), Leptococcus capixaba Kondo, 2005, Leptococcus minutus (Hempel, 1932), Maconelicoccus hirsutus (Green, 1908), Nipaecoccus nipae (Maskell, 1893), Phenacoccus solenopsis Tinsley, 1898, Planococcus citri (Risso, 1813), Planococcus minor (Maskell, 1897), Pseudococcus cryptus (Hempel, 1918) e Pseudococcus longispinus (Targioni Tozzetti, 1867). Obtiveram-se 628 exemplares de himenópteros parasitoides, distribuídos em 27 espécies. Registra-se aqui, pela primeira vez, Bothriocraera bicolor Compere & Zinna, 1955, Gyranusoidea deionae Noyes, 2000 e Allotropa merrilli Muesebeck, 1954 no Brasil; e, Anagyrus fusciventris (Girault, 1915), Gyranusoidea pseudococci (Bréthes, 1924) e Tetracnemoidea peregrina (Compere, 1939) para o estado de São Paulo; e 26 novas associações entre cochonilha/parasitoide. Os gêneros que apresentaram o maior número de espécies associadas aos pseudococcídeos foram: Gyranusoidea, Anagyrus e Aprostocetus.
ABSTRACT– The Pseudococcidae family is the second largest from the Coccomorpha Infraorder, with about 2000 described species. In Brazil, popularly known as mealybugs, it comprised the third largest family, with 77 species registered, distributed in 22 genera. From these, 32 species are known to the state of São Paulo, being 30% polyphagous from exotic origin, infesting plants of agricultural importance. Biological control is an alternative and among natural enemies, parasitoid Hymenoptera are being widely used. The objective of this work was to inventory the parasitoid microhymenoptera from 11 mealybug pest species, primary or secondary, from various crops and ornamental plants in the state of São Paulo, such as coffee, citrus, sugar-apple, guavas and others, relating these to their host, origin and geographical distribution. The parasitoid hymenopteran surveys were carried out between August 2016 and August 2017, in a random way, in rural and urban areas from five municipalities in the state of São Paulo: Jales, Ribeirão Preto, Jaboticabal, São Carlos and Campinas. The Pseudococcidae species sampled to obtain parasitoids were: Dysmicoccus brevipes (Cockerell, 1893), Ferrisia virgata (Cockerell, 1893), Leptococcus capixaba Kondo, 2005, Leptococcus minutus (Hempel, 1932), Maconelicoccus hirsutus (Green, 1908), Nipaecoccus nipae (Maskell, 1893), Phenacoccus solenopsis Tinsley, 1898, Planococcus citri (Risso, 1813), Planococcus minor (Maskell, 1897), Pseudococcus cryptus (Hempel, 1918) and Pseudococcus longispinus (Targioni Tozzetti, 1867). There were 628 specimens of parasitoid Hymenoptera distributed in 27 different species. It is recorded here, for the first time, Bothriocraera bicolor Compere & Zinna, 1955, Gyranusoidea deionae Noyes, 2000 and Allotropa merrilli Muesebeck, 1954 for Brazil; and, Anagyrus fusciventris (Girault, 1915), Gyranusoidea pseudococci (Bréthes, 1924), e Tetracnemoidea peregrina (Compere, 1939) for the state of São Paulo; and 26 new associations between mealybugs x parasitoids. The genera that presented the greatest number of species associated to the Pseudococcidae were: Gyranusoidea, Anagyrus e Aprostocetus.
134767/2016-0

The life-history and infection parameters of the entomopathogenic nematodes Steinernema feltiae (Filipjev)(Nematoda:Rhabditida) and Heterorhahditis megidis (Poinar, Jackson & Klein)(Nematoda:Rhabditida) were examined to provide specific details for the construction of mathematical SI models for biological control of soil insect pests. Laboratory experiments using the Greater Waxmoth, Galleria mellonella as the model host were undertaken to specifically examine the transmission behaviour of infective juvenile nematodes. The proportion of infective juveniles of S. feltiae which infected hosts was dependent on time. Previous studies declared that the proportion of infective juveniles which can infect is static, however, over a period of 5 days most of the infective juveniles infected hosts, demonstrating that the proportion infecting is dynamic. Infection of hosts by both species of nematode was compared using two mathematical representations of the transmission rate. Whereas the most parsimonious form of transmission for H. megidis was the linear Mass Action function, it was evident that, when measured at the individual nematode scale, S. feltiae transmission was non-linear. I postulated that this functional difference is due to the biology of the two species of nematodes. The subsequent effect of including the non-linear response on model predictions were investigated and it was demonstrated that the dynamics of the host nematode interaction became less stable. Spatial models of S. feltiae infection were parameterised from laboratory experiments, and control prediction of these models examined. The horizontal rate of dispersal through sand columns was determined in the presence and absence of hosts. Infective juveniles were found to disperse preferentially towards hosts. The predicted dynamics of pest control using the spatial moqel were highly dependent on the degree of nematode dispersal, host dispersal and the attraction of nematode infective juveniles towards hosts. The overall findings of this thesis have been placed in the context of epidemiological models created elsewhere, and predict that entomopathogenic nematodes may be targeted to specific pest systems with a high degree of success. An understanding of the infection biology of these nematode species is crucial in determining how and when pests may be controlled, and equally importantly, which systems successful control is not predicted.

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Os besouros Carabidae (Coleoptera) apresentam grande importância para a agricultura como inimigos naturais de insetos pragas. No entanto, pouco se conhece sobre hábitos alimentares desses besouros. O presente trabalho visou verificar a ocorrência e o hábito alimentar de espécies de carabídeos associadas a plantas herbáceas floríferas nos diferentes Períodos fenológicos do algodoeiro colorido. O conteúdo alimentar foi avaliado em espécies presentes em cultura de algodoeiro colorido, Gossypium hirsutum L. raça latifolium Hutch., cultivar BRS verde, herbáceo, adjacente de plantas espontâneas e das plantas herbáceas floríferas (PHF) Lobularia maritima (L.) (Brassicaceae), Tagetes erecta L. (Asteraceae), Fagopyrum esculentum Moench (Polygonaceae). Algumas espécies de carabídeos ocorreram em diferentes Períodos fenológicos do algodoeiro e o número mais elevado de indivíduos verificou-se no período reprodutivo do algodoeiro. Os resultados obtidos no aparelho digestivo das espécies de carabídeos mostram que esses insetos podem se alimentar de vários tipos de conteúdo alimentar, relacionados com artrópodes e vegetais associados aos canteiros de PHF, nos diferentes períodos fenológicos do algodoeiro, podendo ser considerados predadores polífagos, e a morfologia do aparelho digestivo das nove espécies de carabídeos mostraram padrões de estruturas adaptadas para o tipo de dieta consumida por essas espécies
The Carabidae beetles (Coleoptera) have great importance to agriculture as natural enemies of insect pests. However, little is known about the content of these beetles feed. This study aimed to assess the occurrence and feeding habits of Carabid species associated with herbaceous plants (PHF) in different growth periods of coloured cotton. The food contents was evaluated in species that occurred in coloured cotton, Gossypium hirsutum L. latifolium Hutch., variety BRS green, herbaceous cotton, adjacent weeds and PHF Lobularia maritima (L.), Tagetes erecta L., Fagopyrum esculentum Moench. Some species of Carabid beetles occurred at different cotton growth periods and the highest number of individuals was found in the cotton reproductive stage. The results showed many types of feed contents ingested by the Carabidae beetles gut tract, like arthropods and vegetable associated with PHF in different growth periods of cotton and can be considered polyphagous predators. The gut tract morphology showed that nine species of Carabid beetles showed standards structures adapted to the type of diet ingested

Orientador: Francisco Jorge Cividanes
Banca: Antonio Carlos Busoli
Banca: Sergio Ide
Resumo: Os besouros Carabidae (Coleoptera) apresentam grande importância para a agricultura como inimigos naturais de insetos pragas. No entanto, pouco se conhece sobre hábitos alimentares desses besouros. O presente trabalho visou verificar a ocorrência e o hábito alimentar de espécies de carabídeos associadas a plantas herbáceas floríferas nos diferentes Períodos fenológicos do algodoeiro colorido. O conteúdo alimentar foi avaliado em espécies presentes em cultura de algodoeiro colorido, Gossypium hirsutum L. raça latifolium Hutch., cultivar BRS verde, herbáceo, adjacente de plantas espontâneas e das plantas herbáceas floríferas (PHF) Lobularia maritima (L.) (Brassicaceae), Tagetes erecta L. (Asteraceae), Fagopyrum esculentum Moench (Polygonaceae). Algumas espécies de carabídeos ocorreram em diferentes Períodos fenológicos do algodoeiro e o número mais elevado de indivíduos verificou-se no período reprodutivo do algodoeiro. Os resultados obtidos no aparelho digestivo das espécies de carabídeos mostram que esses insetos podem se alimentar de vários tipos de conteúdo alimentar, relacionados com artrópodes e vegetais associados aos canteiros de PHF, nos diferentes períodos fenológicos do algodoeiro, podendo ser considerados predadores polífagos, e a morfologia do aparelho digestivo das nove espécies de carabídeos mostraram padrões de estruturas adaptadas para o tipo de dieta consumida por essas espécies
Abstract: The Carabidae beetles (Coleoptera) have great importance to agriculture as natural enemies of insect pests. However, little is known about the content of these beetles feed. This study aimed to assess the occurrence and feeding habits of Carabid species associated with herbaceous plants (PHF) in different growth periods of coloured cotton. The food contents was evaluated in species that occurred in coloured cotton, Gossypium hirsutum L. latifolium Hutch., variety BRS green, herbaceous cotton, adjacent weeds and PHF Lobularia maritima (L.), Tagetes erecta L., Fagopyrum esculentum Moench. Some species of Carabid beetles occurred at different cotton growth periods and the highest number of individuals was found in the cotton reproductive stage. The results showed many types of feed contents ingested by the Carabidae beetles gut tract, like arthropods and vegetable associated with PHF in different growth periods of cotton and can be considered polyphagous predators. The gut tract morphology showed that nine species of Carabid beetles showed standards structures adapted to the type of diet ingested
Mestre

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo foi investigar a influência da sinigrina no comportamento de busca e seleção do predador Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae) pela presa Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae). Foi avaliado o desenvolvimento, reprodução e preferência de O. insidiosus predando lagartas de P. xylostella alimentadas com sinigrina. Foi possível observar que os predadores que consumiram lagartas alimentadas com folhas de couve pulverizadas com sinigrina na concentração de 1,6 mg/mL apresentaram período ninfal mais curto, menor consumo de presas e também menor viabilidade ninfal. Os predadores adultos consumiram maior número de presas que ingeriram sinigrina e a exposição à substância proporcionou maior fertilidade de ovos. Quando os predadores entraram em contato com a sinigrina por meio da superfície pulverizada, a substância estimulou o consumo na fase ninfal, não apresentando influência negativa em outros aspectos biológicos da fase adulta. No segundo ínstar e na fase adulta, os predadores preferiram presa que ingeriram sinigrina; no terceiro e no quarto ínstar ocorreu preferência por lagartas que não ingeriram a substância e no quinto não ocorreu preferência. A seleção pelos predadores que tiveram experiência prévia com presas que ingeriram singrina, em geral, não foi influenciada pela substância. Em casa telada, a longevidade dos adultos e o consumo de presas foram menores quando os predadores foram alimentados com lagartas criadas com folhas pulverizadas com sinigrina. Com base nestes resultados é possível concluir que a sinigrina tem influência sob a preferência e o consumo de presas pelo predador em laboratório, no entanto, em casa telada, a sinigrina tem efeitos não favoráveis ao predador O. inisidiosus
The aim was to investigate the influence of sinigrin in search behavior and prey selection of predator Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae) by Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae). We evaluated the development, reproduction and preference of O. insidiosus preying P. xylostella caterpillars fed on kale leaves treated with sinigrin. It was observed that the predators that consumed caterpillars fed on kale leaves sprayed with sinigrin at concentration of 1.6 mg / mL, showed nymphal period shorter, smaller prey consumption and also lower nymphal survival. When the predators contacted the sinigrin throught the sprayed surface, it was stimulated the consumption of prey to the nymphal stage, moreover, showed no negative influence on the biological aspects of adults. In the second larvae instar and adult, predators preferred prey fed on leaves treated with sinigrin, on the third and fourth instar occurred preference by larvae that not ingesting the substance and fifth instar there was no preference. Predators that had previous experience with prey fed on kale leaves treated with sinigrin, in general, were not affected in the process of selection prey. Under greenhouse conditions, the longevity of adults and prey consumption were lower when predators were fed caterpillars reared on leaves sprayed with sinigrin. Based on these results we conclude that the sinigrin has influence on the preference and prey consumption by the predator in the laboratory. However, under greenhouse conditions sinigrin has not unfavorable effects to the predator O. insidiosus

Orientador: Sérgio Antônio De Bortoli
Banca: Odair Aparecido Fernandes
Banca: Laila Herta Mihsfeldt
Resumo: O objetivo foi investigar a influência da sinigrina no comportamento de busca e seleção do predador Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae) pela presa Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae). Foi avaliado o desenvolvimento, reprodução e preferência de O. insidiosus predando lagartas de P. xylostella alimentadas com sinigrina. Foi possível observar que os predadores que consumiram lagartas alimentadas com folhas de couve pulverizadas com sinigrina na concentração de 1,6 mg/mL apresentaram período ninfal mais curto, menor consumo de presas e também menor viabilidade ninfal. Os predadores adultos consumiram maior número de presas que ingeriram sinigrina e a exposição à substância proporcionou maior fertilidade de ovos. Quando os predadores entraram em contato com a sinigrina por meio da superfície pulverizada, a substância estimulou o consumo na fase ninfal, não apresentando influência negativa em outros aspectos biológicos da fase adulta. No segundo ínstar e na fase adulta, os predadores preferiram presa que ingeriram sinigrina; no terceiro e no quarto ínstar ocorreu preferência por lagartas que não ingeriram a substância e no quinto não ocorreu preferência. A seleção pelos predadores que tiveram experiência prévia com presas que ingeriram singrina, em geral, não foi influenciada pela substância. Em casa telada, a longevidade dos adultos e o consumo de presas foram menores quando os predadores foram alimentados com lagartas criadas com folhas pulverizadas com sinigrina. Com base nestes resultados é possível concluir que a sinigrina tem influência sob a preferência e o consumo de presas pelo predador em laboratório, no entanto, em casa telada, a sinigrina tem efeitos não favoráveis ao predador O. inisidiosus
Abstract: The aim was to investigate the influence of sinigrin in search behavior and prey selection of predator Orius insidiosus (Say, 1832) (Hemiptera: Anthocoridae) by Plutella xylostella (L., 1758) (Lepidoptera: Plutellidae). We evaluated the development, reproduction and preference of O. insidiosus preying P. xylostella caterpillars fed on kale leaves treated with sinigrin. It was observed that the predators that consumed caterpillars fed on kale leaves sprayed with sinigrin at concentration of 1.6 mg / mL, showed nymphal period shorter, smaller prey consumption and also lower nymphal survival. When the predators contacted the sinigrin throught the sprayed surface, it was stimulated the consumption of prey to the nymphal stage, moreover, showed no negative influence on the biological aspects of adults. In the second larvae instar and adult, predators preferred prey fed on leaves treated with sinigrin, on the third and fourth instar occurred preference by larvae that not ingesting the substance and fifth instar there was no preference. Predators that had previous experience with prey fed on kale leaves treated with sinigrin, in general, were not affected in the process of selection prey. Under greenhouse conditions, the longevity of adults and prey consumption were lower when predators were fed caterpillars reared on leaves sprayed with sinigrin. Based on these results we conclude that the sinigrin has influence on the preference and prey consumption by the predator in the laboratory. However, under greenhouse conditions sinigrin has not unfavorable effects to the predator O. insidiosus
Mestre

Professional paper (M.S.)--Montana State University--Bozeman, 2005.
Title from PDF t.p. (viewed on July 4, 2006). Chairperson, Graduate Committee: Theodore Weaver. Includes bibliographical references (leaves 54-57).

Orientador: Mohamed Ezz El-Din Moustafa Habib
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: No presente estudo registraram-se dados biológicos e morfológicos de Migdolus .fryanus (Westwood, 1863) (Coleoptera: Vesperidae), praga da cultura da cana-de-açúcar. Machos e fêmeas, imediatamente após o acasalamento eram coletados em campo, trazidos ao laboratório (temp. 26 :1:2 °C umidade relativa U.R. 70:1: 10 % e fotofase de 12 h), onde se procederam as observações. Fêmeas foram individualizadas em baldes de plástico (20 L). Observou-se o número de ovos colocados, o tamanho, a viabilidade o desenvolvimento embrionário e o tamanho das larvas ao eclodirem. As medições foram obtidas com um micrômetro ocular de escala de 0,05 mm. Machos foram conduzidos em cilindros de vidros (12 cm alto X 12 cm 0), fechados com placas de Petri (15 cm de 0) e definida a longevidade. Utilizando-se 50 larvas estudou-se uma dieta artificial modificada, sendo acrescida em sua receita 50 g de cana-de-açúcar "in natura" moída. Para os estudos morfológicos, os adultos foram coletados em cultivo de cana-de-açúcar, pastagens e cafezal abandonado, sendo os caracteres observados com microscópio estereoscópico. As macromedições foram tomadas com um paquímetro, de escala de 1 mm. As fêmeas depositaram 19 a 38 ovos/fêmea (X = 29,4 :I: 5,5), com viabilidade de 65 a 98 % (X = 84,9 :I: 11,6) e desenvolvimento embrionário de 17 a 25 dias (X = 20,6 :I: 0,9). Os ovos têm formato oval e mediram 3 a 5 mm (X = 4,5 :I: 1,8). A longevidade das fêmeas variou de 28 a 38 dias (X = 32,5 :I: 3,5) e de machos de 3 a 9 dias (X = 5,8 :I: 1,9). As larvas ao eclodirem mediram entre 4 a 6 mm. Na dieta as larvas foram mantidas por 2 anos, passando por 6 e 7 ecdise, mas não completando o ciclo ovo-adulto. Embora os adultos tenham apresentado grandes variações morfológicas, em dimensões e coloração, apenas a espécie M .fryanus foi constatada, nos municípios estudados. Em outra pesquisa estudou-se o comportamento de revoada, na ocasião do acasalamento, em canaviais de 4 municípios de São Paulo (Olímpia, Catanduva, Promissão e Teodoro Sampaio), entre os meses de outubro de 2001 e março de 2003, realizando-se 3 observações por município em cada ano. Em Catanduva/SP foi estudada a flutuação de larvas por intermédio de abertura de trincheiras no solo (50 cm X 50 cm X 40 cm de profundidade), entre os meses de março de 2002 e fevereiró de 2004. Além disso, no mês de setembro de 2003 foi comparado entre três municípios (Olímpia, Catanduva e Teodoro Sampaio) o índice de infestação de larvas por touceira de cana, em reboleira atacadas. As revoadas ocorreram sempre após chuvas, algumas duraram até 7 dias e aconteceram entre os meses de outubro e março. Fêmeas se posicionaram de forma bem sincronizada entre 8:00 e 10:00 h da manhã e permaneceram no solo até o aparecimento dos machos. Os machos foram freqüentes o dia todo, aparecendo primeiro que as fêmeas. A cópula demorou entre 5 a 30 segundos. As larvas foram mais freqüentes entre março e setembro e estiveram em maior número no período de baixa pluviosidade julho a setembro). O maior índice por touceira ocorreu em Teodoro Sampaio, (X= 3,96 larvas) e Olímpia, (X= 3,88 larvas) que diferiram significativamente de Catanduva, (X= 1,6 larvas). Com relação as reboleiras estudadas ocorreu diferença significativa do número de larvas por touceira no município de OIímpia. A patogenicidade de nematóides entomopatogênicos, nativos, Steinernema glaseri (Steiner,1929)(Rhabditida: Steinemematidae) e Heterorhabditis indica Poinar, Karunakai & David, 1992 (Rhabditida: Heterorhabditidae) (IBCB-n5) foi avaliada contra ovos e larvas de M fryanus, em condições de laboratório. No experimento I, ovos do inseto foram expostos a uma suspensão de Juvenis Infectivos (Jls) de H indica, em 2 concentrações, 60 e 600 JIs/ovo. Foram considerados 3 tratamentos com 3 repetições, cada uma com 5 ovos. Não ocorreu diferença significativa entre os tratamentos. Porém, constatou-se a penetração do nematóide e redução da viabilidade. No experimento 2 avaliou-se S. glaseri e H indica (600 Jls/larva) contra larvas recém-ecIodidas de M fryanus. O experimento constou de 3 tratamentos com 4 repetições, cada uma com 5 larvas. S. glaseri causou 100 % de mortalidade e H indica 80 %, diferindo significativamente da testemunha. No último ensaio estudou-se S. glaseri e H indica em 2 concentrações (400 e 800 Jls/lnseto) contra larvas de 3 a 4 cm de tamanho. Consideraram-se 7 repetições por tratamento, cada uma contendo 3 larvas. Não ocorreu diferença significativa entre as concentrações dos nematóides. Já a patogenicidade de H indica, nas 2 concentrações, destacou-se significativamente da testemunha e de S. glaseri, proporcionando mortalidade larval de 76,43 e 71,57 % respectivamente. Os resultados demonstraram que esses nematóides têm potencial para serem utilizados como agentes de controle biológico de M fryanus em cultivos de cana-de-açúcar, no Estado de São Paulo. Em uma pesquisa de campo, comparou-se a eficiência de 3 agentes de controle, em 2 situações (cana-planta e cana-soca) contra insetos de solo. O fungo Metarhizium anisopliae (Metsch.) Sorok. (Deuteromycotina, Hyphomycetes, Moniliaceae) (IBCB-348), e o nematóide H indica, foram os agentes biológicos escolhidos, junto com o inseticida químico fipronil, (Regent 800 WG). H indica, foi usado em 2 concentrações, 5 X 108 e 5 X 109 (JIs)/ha, o inseticida Fipronil 800 WG, na dosagem de 500g/ha, e o fungo M anisopliae 30 kg/ha, contendo 5 X 108 de esporos/g, mais a testemunha. Consideraram-se 5 repetições por tratamento, cada uma formada por parcelas de 7 sulcos de 5,00 m de comprimento e espaçamento de 1,40 m entre linhas. Os produtos foram aplicados, com um pulverizador costal com bico tipo leque. Foram efetuadas duas avaliações, aos 40 e 360 dias após o plantio da cana, mediante a abertura de 2 trincheiras (50 cm X 50 cm X 40 cm de profundidade) em cada parcela. Já a produção foi avaliada em agosto de 2004, 1 ° corte e setembro de 2005, 2° corte. Em outra pesquisa, em um canavial de 4° corte (cana-soca), estudou-se H. indica na concentração de 5 X 108 Jls/ha, Fipronil 800 WG, 300 g/ha e a testemunha. Consideraram-se cinco repetições por tratamento, cada qual formada por parcela de 6 sulcos com 10m de comprimento e espaçamento de 1,40 m entre linhas. As aplicações foram efetuadas, usando-se trator com um pulverizador desprovido de bico e com vazão de 1200 litros de águalha. Os produtos foram distribuídos a uma profundidade de 10 a 15 cm no solo, nos dois lados da linha de plantio. Foi efetuada uma avaliação, pelo mesmo sistema anterior, aos 20 dias após a aplicação. Em cana planta, obteve-se um incremento na produtividade 14,25 %, com M anisopliae e H indica na concentração de 5 X 109. Para H indica na concentração de 5 X 108 o aumento foi de 17,6 %. Já o produto químico resultou em apenas 5,9 % de aumento. Em cana soca, tanto o produto químico como H. indica diferiram significativamente da testemunha (F = 9,11; P = 0,004) e (F = 5,40; P = 0,02) respectivamente. H. indica promoveu uma supressão na população de M fryanus de 45, 2 % e na de Cyclocephala paraguayensis Arrow, 1903 (Coleoptera: Scarabaeidae) de 54,8 %. O inseticida promoveu um controle de 41,5 % para M fryanus e 42 % para C. paraguayensis
Abstract: During de present study biological and morphological data of Migdolus fiyanus (Westwood, 1863) (Coleoptera: V esperidae) were obtained. Males and females after mating were collected in sugar cane field and brought to the laboratory for morphological and biological investigations. Females were individualized in plastic containers ( 20 L). The dimensions were caIculated utilizing an ocular micrometer of 0,05 mm precision. Males were maintained in glass eylinders (12 em height X 12 cm 0), eovered with Petri dishes (15 cm 0) the longevity data for obtained. An artificial and modified diet was studied adding 50 g of triturated fresh sugar cane. For the morphological observations the inseets were collected in sugar cane fields, pastures and abandoned coffee erops, and the material was examined by means of an optical microseope. The measurements were taken with a 1 mm preeision paquimeter. The females deposited from 19 to 38 eggs, with an average of 29.4 ::!:: 5.5. The egg viability ranged from 65 and 98 % with an average of 84.9 ::!:: 11.6 and the egg period from 17 to 25 days, with an average of20.6::!:: 0.9. The egg length varied from 3 to 5 mm. The female longevity lasted from 28 to 38 days, with an average of 32.5 ::!:: 3.5 and the mal e from 3 to 9 days, with an average of 5.8 ::!:: 1.9. The hatehing larvae measured from 4 to 5 mm. The larvae were maintained for 2 years, undergoing 6 or 7 moults without reaching the pupal stage. The adults showed significant variation in color and dimensions, but only the speeies M fryanus was deteeted. M fiyanus normally causes high damages in sugar cane fields. The reproductive behavior should be considered important as a strategic point to reach eontrol methods. The flight behavior during mating was studied in 4 municipalities of São Paulo state, in sugar cane fields, (Olímpia, Catanduva, Promissão and Teodoro Sampaio), from October 2001 to March 2003. The fluctuation of larvae populations was studied in Catanduva/SP between March 2002 and February 2004. On September 2003, the larval infestation among sugar cane roots was compared in the municipalities of Olimpia, Catanduva and Teodoro Sampaio. The reproductive flight involves a high adult male density and oeeurred after raining, between Oetober and March. Such flights lasted up to seven days. The female comes out from soil in the moming from 8:00 to 10:00 a.m., for mating. Normally and influenced by the female sex pheromone, the male could be seen in the spots before the female emergence. The mating lasted from 5 to 30 seconds. Immediately after mating, the female returned to the soiI to start ovipositi6h. Larvae were more frequent between June and September (dry season). The highest larval infestation was observed in Teodoro Sampaio; while the lowest one occurred in Catanduva Native entomopathogenic nematodes, Steinernema glaseri (Steiner, 1929) (Rhabditida: Steinernematidae) e Heterorhabditis indica Poinar, Karunakai & David, 1992 (Rhabditida: Heterorhabditidae) (IBCB-n5) were evaluated against eggs and larvae of M fryanus under laboratory conditions. In a first experiment, eggs of the insect were exposed to suspensions of Infective Juveniles (IJs) of H indica in 2 concentrations, 60 and 600 IJs/egg. Three treatments, each one with 3 replications containing 5 eggs, were used. The nematode did not differed significatively from the control, but it penetrated the eggs and reduced the viability. In the second experiment, S. glaseri and H indica (600 IJs/larva) were evaluated against the newly hatching larvae of M fryanus. Four replications per treatment, each one with 5 larvae were used. Both nematodes caused significantly higher mortality. S. glaseri caused 100 % of mortality and H indica 80 %. There was no significative difference between the nematodes. In the last experiment, we evaluated S. glaseri and H indica in 2 concentrations (400 and 800 IJs/larva) against the last larval stage of M fryanus. Seven replications, each one with 3 larvae per treatment were used. There was no significative difference between the concentrations for both nematodes. However, H indica showed more efficiency for it caused significative difference in larvae mortality in two concentrations (76.43 and 71.57 % respectively). H indica. and S. glaseri were pathogenic to egg and larvae of M fryanus. These nematodes seem to have high potential for the control of M fryanus in sugar cane crop, in Sao Paulo State of Brazil. In the field studies the efficiency of three control agents (two biological and one chemical) was investigated in two different situations, against some sugar cane soil insects. While the first situation involves a planted sugar cane field, less than a year old, the second one was set in a 4 years . old sugar cane. The entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorok. (Deuteromycotina, Hyphomycetes, Moniliaceae) (IBCB-348) and the nematode H indica were the biological agents; while fipronil (Regent 800 WG) was the chemical insecticide. Two concentration of H indica were utilized: 5 XI08 and 5 XI09 IJs/ha. The chemical product was applied in a concentration of 300 g/ha, while M anisopliae in a concentration of 30 kg/ha. For the first situation, each treatment was divided in 5 replications with 7 rows each. Each line was 5 m in length and the spacing between rows was 1.4 m. The products were applied by using a costal spraying machine, and the treatments were evaluated 40 and 360 days after application. Two square spots per replication were examined and the insects were counted. The dimensions for each spot were 50 cm X 50 cm X 40 em depth. The productivity for each treatment was calculated through data obtained during August 2004 and September 2005. For the second situation, the applications were done by using a tractor system, with the same dosages mentioned above, diluted in 1.200 liters per ha. ln the case of H indica, only the concentration of 5 Xl08 JIs/ha was utilized. Each replication was composed of 6 rows, 10 meter long. Spacing between rows was the same mentioned above. The control agents were applied in the soil at a depth which varied from 10 to 15 cm, on both sides of the same row. The efficiency of each treatment was evaluated 20 days after application. As to the young culture (the I sI situation), M anisopliae, as well as the higher concentration of nematode treatment, resulted in 14.25 % of more productivity. The lower nematode concentration increased the productivity in 17.6 %. While the chemical insecticide increased only 5.9 % of it. For the older field (the 2st situation), the nematode as well as chemical insecticide suppressed the soil fauna more successfully than the controI
Doutorado
Doutor em Parasitologia

Pereskia aculeata Miller (Cactaceae) is an environmental weed that is damaging to natural ecosystems in South Africa. The plant is native to Central and South America and was first recorded in South Africa in a botanical garden in 1858. In this thesis, research into the biological control of P. aculeata was conducted with the intention of improving the control of the weed. A pre-release study of the relationship between P. aculeata density and native plant biodiversity indicated that P. aculeata has a negative impact on native biodiversity. The native plant biodiversity associated with different P. aculeata densities was used to determine threshold values and goals for the control of the weed. A threshold value of 50% P. aculeata density was calculated, indicating that P. aculeata density must be maintained below 50% in order to conserve native plant biodiversity. The ultimate goal of the control programme should be to maintain P. aculeata densities below 30%. At these densities there was no significant difference in native plant biodiversity from if the weed were absent from the ecosystem. The biological control agent, Phenrica guérini Bechyne (Chrysomelidae), has been released in South Africa but the potential of the agent to impact P. aculeata is not known and no post release evaluation has been conducted. Impact assessment studies indicate that P. guérini does not impact P. aculeata, even at high densities, but the results of greenhouse experiments should be interpreted with caution because of problems with extrapolation into the field. Although observations in the field suggest that P. guérini has reduced P. aculeata densities at one site, it is clear that new biological control agents are needed to reduce the weed to acceptable levels. Identifying the origin of the South African P. aculeata population was believed to be important to the biological control programme due to the disjunct native distribution and intraspecific variation of the species. Natural enemies associated with plant genotypes in different parts of the native distribution may have developed specialised relationships with certain intraspecific variants of the plant, resulting in differences in agent efficacy on certain host plant genotypes. A molecular study indicated that the closest relatives to the South African weed population found in the native distribution were in Rio de Janeiro Province, Brazil. A bioassay experiment in which fitness related traits of the biological control agent, P. guérini, were measured on various P. aculeata genotypes was conducted to determine the importance of host plant intraspecific variation. There was little variation in fitness traits between genotypes and no evidence of intraspecific host plant specialization. Although intraspecific variation had no effect on agent efficacy in the case of P. guérini, it is possible that other natural enemies may be more specialized. Genotype matching is expected to be more important when natural enemies likely to be specialised to individual genotypes are considered for biological control. Potential biological control agents were prioritized from data collected on surveys in the native distribution. The most promising of these, based on the presence of feeding, incidence, predicted host range, climatic matching, genotype matching and mode of damage, are two species of Curculionidae, the current biological control agent P. guérini and the stem boring moth, Maracayia chiorisalis Walker (Crambidae). The two curculionid species and M. chlorisalis should be considered priorities for host specificity studies. Releases of P. guérini and any new biological control agents should be made at sites where the pre-release study was conducted so that post-release evaluation data can be compared with the pre-release data and the impact of biological control can be evaluated. Retrospective analyses of biological control programmes provide important ways of improving aspects of biological control programmes, such as methods of agent selection. The evaluation of success in biological control programmes is essential for retrospective analyses because factors that have lead to successes or failures can be analysed. Retrospective analyses of biological control programmes, such as this thesis, may improve weed management, thereby contributing to the conservation of natural resources.

Thesis (MSc (Biomedical Sciences))--Cape Peninsula University of Technology, 2019
Background: Baculoviruses have great potential as alternatives to conventional chemical insecticides. The large scale adoption of such agents has however been hampered by the slow killing times exhibited by these bio-insecticides, limitation to single target insect and difficulty of large scale production of these preparations. Trichoplusia ni single nucleopolyhedrovirus (TnSNPV), initially identified in the Eastern Cape region of South Africa, has potential as a biocontrol agent as it possesses a higher speed of kill compared to other baculoviruses. Aims and methods: The main objective of this study was the identification, molecular characterisation and cloning of a structural core gene (polyhedrin) and three auxiliary genes, the inhibitor of apoptosis (iap2 and iap3) and the ecdysteroid UDP-glucosyltransferase (egt) genes, from TnSNPV in order to delineate its phylogenetic relationship to a Canadian isolate of the same virus and to other baculoviruses. In addition, the genes were expressed in an Escherichia coli (E. coli) based system as a prelude to genetic modification to increase the pesticidal property of the virus. Results: The genome size of the South African strain of TnSNPV was estimated at 160 kb and is significantly larger than the Canadian isolate of TnSNPV and may reflect genetic variation as the two strains have adapted to varying environmental conditions. Occlusion bodies of the South African strain of TnSNPV were visualised by Transmission Electron Microscopy and consisted of rod shaped single virions composed of a single enveloped nucleocapsid. Insect bioassays showed that the median lethal time (LT50) of the virus strain averaged 1.8 days which is significantly faster than other baculoviruses. The South African and Canadian strains of TnSNPV share nucleotide similarities greater than 95% for the genes analysed in this study, which indicates that they are closely related. From this analysis, the South African strain of TnSNPV identifies as a Group II NPV with the closest relatives being the Canadian strain of TnSNPV and ChchNPV. The topology of the tree for the polyhedrin protein was better resolved than that of the IAP2, IAP3 and EGT proteins and was comparable to the tree inferred from a concatenated data set consisting of complete polyhedrin/granulin, LEF8, and LEF9 proteins of 48 completely sequenced genomes. For the IAP2, IAP3 and EGT proteins, the separation of the lepidopteran and hymenopteran specific baculoviruses was not evident while the separation of Group I and II Alphabaculoviruses diverged from that observed from the baculovirus core gene polyhedrin as well as the tree inferred from complete polyhedrin/granulin, LEF8, and LEF9 proteins. Five distinct groups relating to IAP-1, 2, 3, 4 and 5 could be distinguished from the tree inferred from all IAP proteins from 48 fully sequenced baculoviruses. From this analysis, the IAP protein from the South African isolate of TnSNPV can be designated as an IAP3 due to sequence homology to other IAP3 proteins. Similarly, the IAP2 can be confirmed as an IAP2 protein as it clusters with other IAP2 proteins. RNA transcripts of the four genes were detected by RT-PCR at one hr after induction with Larabinose in BL21-A1 E. coli and persisted until four hrs post induction. Antisera directed against the C-terminal 6X His tag was able to detect the recombinant proteins at two hours after induction confirming the rapid rise in expression of the proteins which persisted at high levels until four hrs after induction. The discrepancy observed with the predicted molecular mass of the EGT protein and the migration on SDS-PAGE may be due to the absence of posttranslational modification in the E. coli expression system and the hydrophobic residues present in the N-terminal signal sequence. Conclusion: Sequence and phylogenetic analysis suggest that the two isolates of TnSNPV have been exposed to similar evolutionary pressures and evolved at similar rates and represent closely related but distinct variants of the same virus. The difference in genome size between the two strains is likely to reflect actual genetic differences as the strains have adapted to their local environments and hosts and the extent of the differences will only be apparent as more sequencing results become available. Phylogenetic analysis of the IAP and EGT proteins yields a tree that varies from the phylogenetic reconstruction observed for the polyhedrin gene as well as the concatenated data set consisting of complete polh/gran, LEF8, and LEF9 proteins and highlights the risks inherent in inferring phylogenetic relationships based on single gene sequences. The tree inferred from the concatenated data set of polh/gran, LEF8, and LEF9 proteins was a quick and reliable method of identification particularly, when whole genome data is unavailable and mirrors the accepted lineage of baculoviruses. Expression of the recombinant IAP2, IAP3, EGT and polyhedrin was confirmed by RT-PCR and immunoblot analysis and rose rapidly after induction and persisted at high levels. It is as yet unclear if the expressed proteins are functional particularly as post translation modifications are lacking in this system.

False codling moth (FCM), Thaumatotibia leucotreta is an extremely important pest of citrus in South Africa and with the shift away from the use of chemicals, alternate control options are needed. One avenue of control which has only recently been investigated against the soil-borne life stages of FCM is the use of entomopathogenic fungi (EPF). In 2009, 12 entomopathogenic fungal isolates collected from South African citrus orchards showed good control potential during laboratory conducted bioassays. The aim of this study was to further analyse the potential of these isolates through concentration-dose and exposure-time response bioassays. After initial re-screening, concentration-dose response and exposure-time response sandconidial bioassays, three isolates were identified as exhibiting the greatest control potential against FCM in soil, Metarhizium anisopliae var. anisopliae (G 11 3 L6 and FCM Ar 23 B3) and Beauveria bassiana (G Ar 17 B3). Percentage mycosis was found to be directly related to fungal concentration as well as the amount of time FCM 5th instar larvae were exposed to the fungal conidia. LC50 values for the three isolates were not greater than 1.92 x 10⁶ conidia.ml⁻ₑ and at the LC₅₀, FCM 5th instar larvae would need to be exposed to the fungus for a maximum of 13 days to ensure a high mortality level. These isolates along with two commercially available EPF products were subjected to field persistence trials whereby net bags filled with a mixture of autoclaved sand and formulated fungal product were buried in an Eastern Cape citrus orchard. The viability of each isolate was measured on a monthly basis for a period of six months. All isolates were capable of persisting in the soil for six months with the collected isolates persisting far better than the commercially used isolates. Two of the isolates, G 11 3 L6 and G Ar 17 B3, were subjected to small scale laboratory application trials. Two formulations were investigated at two concentrations. For each isolate, each formulation and each concentration, FCM 5th instar larvae were applied and allowed to burrow into the soil to pupate before fungal application or after fungal application. Contact between fungi and FCM host is essential as, in contrast to pre-larval treatments, percentage mortality in post-larval treatments was low for both formulations and both isolates. For isolate G Ar 17 B3, a conidial suspension applied as a spray at a concentration of 1 x 10⁷ conidia.ml⁻ₑ obtained the highest percentage mortality (80 %). For isolate G 11 3 L6 however, both formulations performed equally well at a high, 1 x10⁷ conidia.ml⁻ₑ concentration (conidial suspension: 60 %; granular: 65 %) The results obtained thus far are promising for the control of FCM in citrus, but if these EPFs are to successfully integrate into current FCM control practices more research, some of which is discussed, is essential

The role of interspecific competition as a regulating force in natural populations has been controversial, especially for phytophagous insect communities. A series of manipulative experiments using enclosure cages were conducted to evaluate the role of interspecific competition between a weevil and a fly, two seed feeding agents released against spotted knapweed in North America. The fly, an inferior biological control agent, was the superior competitor. Consequences of the antagonistic interaction included reduced seed destruction compared to if just the weevil was released on its own. The role of plant phenology on insect herbivore density was also assessed. The implications of phenologyinduced variation in insect density were evaluated with respect to competition between the fly and the weevil and were found to be important. Hypotheses of four plantmediated mechanisms of interspecific competition were also tested. Results support resource preemption as a competitive mechanism.
vii, 97 leaves ; 29 cm

Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.

Control of the citrus pest, false codling moth (FCM), Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae) is crucial for the South African citrus industry. The economic losses and phytosanitary status of this pest, coupled with increased consumer awareness and demands, has created a need for effective, IPM-compatible control measures for use against the soil-dwelling life stages of FCM. Promising developments in the field of microbial control through the use of entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPNs) have highlighted the need for research regarding pupation biology, behaviour and survival of FCM, as a good understanding of biology of the target organism is an important component of any biological control programme. The aim of this study was to improve the current understanding of FCM pupation habits through the manipulation of soil texture class, ground cover, shading, soil compaction, air temperature, and soil moisture in the laboratory. These findings would then be used to aid the biological control programmes using EPF and EPNs against FCM in the soil. Three soil texture classes (sandy loam, silt loam and silty clay loam) were obtained from orchards for use in the study. FCM larvae were allowed to drop into the soil of their own accord and the pupation behaviour that followed was then captured on film with pupae formed in the soil being kept in order to measure adult eclosion. In general, very few abiotic factors had a clear influence on FCM pupation. Larval wandering time and distance was short, but also variable between individuals. Distance did increase when soils were moist. Pupation depth was shallow, with pupal cocoons generally being formed on the soil surface. Depth of pupation was less than one centimetre for all abiotic conditions, with little burrowing into soil. Eclosion success was higher for sandier soils when these were dry and uncompacted, but the addition of both moisture and soil compaction increased FCM eclosion success. FCM was sensitive to desiccation when the soils were dry and temperature limits of 15 °C and 32 °C had a strongly negative impact on eclosion success. Preferences for particular abiotic conditions were limited to only certain moisture conditions when interacting with soil texture class and a preference for pupating in soil when it is available. Limited preference was found for particular soil textures despite this having a strong influence on eclosion success, but individuals did appear to pupate in close proximity to one another. Viable direct habitat manipulation for FCM control could not be identified. These results and all of the abiotic variables measured have important implications for EPF and EPN application, survival and persistence in the soil in order to improve the ability of these biological control agents to control FCM. These are discussed in each chapter.

Lantana camara L. (Verbenaceae) remains a highly invasive and ecologically damaging weed in South Africa, despite some 50 years of biological control efforts. Lack of success has been ascribed to varietal differences, climate and predation of agents but these have not been tested. In this study, the effects of ant predation were tested on populations of three biological control agents for L. camara. Colonies of two species, Crematogaster sp. 1 and 2 were investigated. Crematogaster sp. 1 colonies were offered no choice between immature stages of the agents Hypena laceratalis Walker (Lepidoptera: Noctuidae), Falconia intermedia Distant (Hemiptera: Miridae) or Teleonemia scrupulosa Stål (Hemiptera: Tingidae) on lantana shoots. Density-dependent predation on F. intermedia and T. scrupulosa nymphs on lantana shoots was tested using Crematogaster sp. 2 colonies. In choice experiments Crematogaster sp. 2 colonies were offered F. intermedia or T. scrupulosa nymphs on potted lantana plants. Preliminary food trials confirmed that colonies foraged for protein, thereby validating results of no-choice experiments. Crematogaster sp.1 foragers removed 50% of F. intermedia nymphs, followed by 45% of H. laceratalis larvae and only 9% of T. scrupulosa nymphs. Foragers recruited most actively to H. laceratalis larvae and significantly more H. laceratalis biomass was removed than either F. intermedia or T. scrupulosa. A trade-off existed in prey size selection because larger larvae provided considerably more biomass but required forager cooperation and a longer time to subdue than did smaller prey. This increases both forager energy expense and mortality risk by other predators. This study showed that all Crematogaster sp. 1 colonies removed small (≤10mm) H. laceratalis larvae more frequently than larvae larger than 10mm. Thus, of these biological control agents, predators probably prefer small H. laceratalis larvae. Significantly more F. intermedia than T. scrupulosa nymphs were removed by Crematogaster sp. 1, while Crematogaster sp. 2 colonies removed comparable numbers of both agent species. Falconia intermedia nymphs' fast movement triggered a predatory response by these ant species. In contrast, the relatively immobile behaviour of T. scrupulosa nymphs was identified as a highly effective predator avoidance strategy. Since T. scrupulosa nymphs are unable to escape predators by moving, they appear to depend on the presence of alternative prey attracting predator attention. At high agent and/or forager density, T. scrupulosa nymphs attempted escape, but foragers identified them as prey once they moved and caught them. Predation on F. intermedia was also density dependent in that at high nymph and/or forager densities, escape routes were congested and nymphs were more easily caught. Survival of F. intermedia and T. scrupulosa nymphs in particular was low on ant-accessed shrubs in choice experiments and high on ant-excluded shrubs. It is likely that ants significantly depress F. intermedia populations in the field since besides predation, ant foragers probably interrupt F. intermedia feeding and ovipositioning. The combination of parasitism and predation on early instar larvae may explain why H. laceratalis occurs across lantana's range in South Africa but populations remain low. It is unlikely that T. scrupulosa nymphs are habitually preyed on by ant species unless they attract attention by being mobile. Although biological control of L. camara is influenced by climate and physiological defence mechanisms, this study has shown that predation by two ant species severely impacts leaf-feeding agents for L. camara. Thus, it is recommended that future selection of additional agents to control lantana should exclude leaf-feeding .

A viticultura é uma atividade de grande importância econômica, destacando-se a sustentabilidade da pequena propriedade e o desenvolvimento territorial associados às atividades ligadas ao turismo. As plantas cultivadas se tornam vulneráveis a patógenos e insetos-praga e a videira apresenta diversas espécies consideradas pragas que reduzem sua produção e rentabilidade, entre estas, Spodoptera frugiperda, causando danos em diferentes partes da planta. Fungos entomopatogênicos podem oferecer uma alternativa aos pesticidas convencionais para o controle de pragas, pois produzem enzimas que degradam o exoesqueleto do inseto como quitinases e proteases facilitando o modo de infecção. Neste trabalho foi avaliado o potencial inseticida do fungo Nomurea rileyi, linhagem UCS03, contra S. frugiperda e o perfil eletroforético por SDS-PAGE das proteínas secretadas por N. rileyi em presença da cutícula do inseto em diferentes intervalos de tempo em gel unidimensional. O fungo N. rileyi apresentou virulência contra S. frugiperda, determinando um CL50 de 2 x 109conídios/mL com a linhagem UCS03 demonstrando atividade bionseticida. Na avaliação do perfil proteico do secretoma de N. rileyi em presença da cutícula do inseto, em diferentes tempos de cultivo, foi possível verificar um perfil altamente diferenciado. A maior concentração de proteína foi encontrada no 14° dia de incubação (0,3507 mg/mL) reduzindo a quantidade de proteínas após este período. Na análise por SDS-PAGE foi possível verificar diferentes proteínas de diferentes massas moleculares, nos intervalos de tempo considerados, sendo muitas inferiores a 75 kDa. Estas proteínas com diferentes massas moleculares podem estar envolvidas no metabolismo do fungo. Desta forma, estes resultados podem contribuir para a compreensão do processo de infecção de N. rileyi em S. frugiperda, oferecendo potencial para o desenvolvimento de novas pesquisas e aplicações destas em processos biotecnológicos.
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Viticulture is an activity of great economic importance with emphasis on the sustainability of small property and territorial development associated with tourism related activities. Cultivated plants become vulnerable to pathogens and insect pests and the vine has several species considered as pests that reduce their production and profitability, among them, Spodoptera frugiperda, with causes damage in different parts of the plant. Entomopathogenic fungi can provide an alternative to conventional pesticides for controlling pests, they produce enzymes that degrade the insect exoskeleton, such aschitinases and proteases facilitating the infection. In this work, the insecticide potential of the fungus Nomurea rileyi and S. frugiperda was evaluated, as well as the proteins secreted by N. rileyi in the presence of insect cuticle at different time intervals in one-dimensional gel. The fungus N. rileyi presented virulence against S. frugiperda, determining a CL50 of 2 x 109 con / mL with UCS03 strain demonstrating bionseticida activity. In assessing the protein profile of secretome N. rileyi in the presence of insect cuticle, at different times of cultivation, a highly differentiated profile was verified. The highest concentration of protein was found at day 14 of incubation (0.3507 mg / ml) reducing the amount of protein after this period. In the one-dimensional gel analysis was verified different molecular weights of proteins, in the time interval considered being many less than 75kDa. These proteins with different molecular weights may be involved in fungal metabolism. Thus, these results can contribute to the understanding of the infection process of N. rileyi in S. frugiperda, offering potential for the development of new researches and applications in biotechnological processes.

Thesis (M.S.)--University of Kentucky, 2003.
Title from document title page (viewed June 21, 2004). Document formatted into pages; contains xii, 122 p. : Ill. Includes abstract and vita. Includes bibliographical references (p. 106-121).

Cydia pomonella (Linnaeus) (Family: Tortricidae), the codling moth, is considered one of the most significant pests of apples and pears worldwide, causing up to 80% crop loss in orchards if no control measures are applied. Cydia pomonella is oligophagous feeding on a number of alternate hosts including quince, walnuts, apricots, peaches, plums and nectarines. Historically the control of this pest has been achieved with the use of various chemical control strategies which have maintained pest levels below the economic threshold at a relatively low cost to the grower. However, there are serious concerns surrounding the use of chemical insecticides including the development of resistance in insect populations, the banning of various insecticides, regulations for lowering of the maximum residue level and employee and consumer safety. For this reason, alternate measures of control are slowly being adopted by growers such as mating disruption, cultural methods and the use of baculovirus biopesticides as part of integrated pest management programmes. The reluctance of growers to accept baculovirus or other biological control products in the past has been due to questionable product quality and inconsistencies in their field performance. Moreover, the development and application of biological control products is more costly than the use of chemical alternatives. Baculoviruses are arthropod specific viruses that are highly virulent to a number of lepidopteran species. Due to the virulence and host specificity of baculoviruses, Cydia pomonella granulovirus has been extensively and successfully used as part of integrated pest management systems for the control of C. pomonella in Europe and around the world, including South Africa. Commercial formulations have been typically based on the Mexican strain of CpGV. However due to long-term multiple applications of CpGV and the reliance on CpGV in organic farming practices in Europe, resistance to the CpGV-M strain has developed in a number of field populations of C. pomonella. This study aimed to identify and characterize novel isolates of CpGV in South Africa and compare their virulence with the commercial standard CpGV-M. Secondly, since C. pomonella is difficult to culture on a large scale, an alternate method of CpGV production was investigated in order to determine if CpGV could be produced more efficiently and at a reduced cost without negatively impacting the quality of the product. Several isolates of CpGV were recovered either from field collected larvae or from a laboratory-reared C. pomonella colony. Characterisation of DNA profiles using a variety of restriction enzymes revealed that only a single isolate, CpGV-SA, was genetically different from the Mexican strain of the virus used in the commercially available CpGV based products in South Africa. In dose-response bioassays using CpGV-SA, LC₅₀ and LC₉₀ values for neonate C. pomonella larvae were 3.18 x 10³ OBs/ml and 7.33 x 10⁴ respectively. A comparison of these values with those of CpGV-M indicated no significant difference in the virulence of the two isolates under laboratory conditions. This is a first report of a genetically distinct CpGV isolate in South Africa. The biological activity and novelty of CpGV-SA makes this isolate a potentially important tool for CpGV resistance management in South Africa. In order to justify production of CpGV in an alternative host, studies on the comparative biological performance of C. pomonella and T. leucotreta based on oviposition, time to hatch, larval developmental times and rearing efficiency as well as production costs were performed. Thaumatotibia leucotreta was found to be more fecund and to have significantly shorter egg and larval developmental times. In addition, larval production per unit of artificial diet was significantly higher than for C. pomonella. This resulted in T. leucotreta being more cost effective to produce with implications for reduced insectary space, sanitation practices as well as the labour component of production. Virus yield data generated by inoculation both C. pomonella and T. leucotreta with nine concentrations of CpGV resulted in comparable virus yields, justifying the continuation of the research into production of CpGV in T. leucotreta. It was important to determine the LC and LT values required for mass production of CpGV in late instar T. leucotreta larvae. Dose- and time-response bioassays with CpGV-M were conducted on artificial diet to determine these values. Fourth instar LC₅₀ and LC₉₀ values were 5.96 x 10³ OBs/ml and 1.64 x 10⁵ OBs/ml respectively. LT50 and LT90 values were 81.10 hours and 88.58 hours respectively. Fifth instar LC₅₀ and LC₉₀ values were 6.88 x 10⁴ OBs/ml and 9.78 x 10⁶ OBs/ml respectively. LT₅₀ and LT₉₀ values were 111.56 hours and 137.57 hours respectively. Virus produced in fourth instar T. leucotreta larvae was bioassayed against C. pomonella neonate larvae and compared to CpGV-M to establish if production in the heterologous host negatively affected the virulence of the isolate. No significant difference in virulence was observed between virus produced in T. leucotreta and that produced in C. pomonella. The data generated in the bioassays was used in CpGV mass production trials to evaluate production. All production methods tested produced acceptable virus yields. To examine the quality of the virus product, genomic DNA was extracted from larval cadavers and subjected to REN analysis with HindIII. The resulting DNA profiles indicated that the virus product was contaminated with the homologous virus, CrleGV. Based on the above results, the use of T. leucotreta as an alternate host for the in vivo production of CpGV on a commercial basis is not at this stage viable and requires further investigation before this production methodology can be reliable used to produce CpGV. However, this study has shown that CpGV can be produced in a homologous host, T. leucotreta and significant strides have been made towards developing a set of quality control standards that are essential for further development of successful production methodology. Finally a novel isolate of CpGV has been identified with comparable virulence to the CpGV-M. This is an important finding as it has broad reaching implications for resistance management of CpGV products in South Africa.

In Mozambique, establishment of aquatic weeds has been enhanced through the increased enrichment of water bodies by nutrient runoffs from human and agricultural wastes that lead to an increase in nitrate and phosphate in the water. The aquatic weeds, water hyacinth (Eichhornia crassipes), red water fern ( Azolla microphylla), water lettuce (Pistia stratiotes) and salvinia (Salvinia molesta) were found in most watercourses in Mozambique and are becoming aggressive in some watercourses, especially in the Umbeluzi and Incomati rivers. Farmers and people living along the rivers are aware of the negative impact of the water weeds because the large mats of weeds cause loss of shoreline and navigability along the rivers. Other commonly perceived effects of aquatic invasive plants in Mozambique rivers include: reduced navigable surface area; difficulties for fishermen, which reduces income; increased prevalence of insects and insect-borne disease, and decreased aesthetic value. The methods currently used for the control and management of the aquatic weeds are mechanical and manual control. Both methods are costly, time consuming, and only provide a short-term solution to the problem. The study found that the weevils Neochetina eichhorniae and N. bruchi were effective biological control agents in the study area but their impact is too gradual compared to the aggressive proliferation of water hyacinth. The one year lab-experiment clearly demonstrated that the water lettuce weed had a significant impact on the recruitment of macro-invertebrates to the artificial substrates, and water lettuce contributed to the reduction of oxygen in the water and consequent reduction of macro-invertebrate abundance and diversity. The biodiversity recovered at the same time in the pools containing water lettuce controlled by N. affinis and water lettuce controlled by herbicide, but richness and diversity of macro-invertebrates was higher in the water lettuce controlled by N affinis during the first sampling occasion compared to the water lettuce in pools controlled by herbicide, where macro-invertebrates increased only when DO levels recovered after water lettuce mat decay. The number of taxa recorded in this study is an indication of the significance of macro-invertebrates in an aquatic environment. This therefore emphasizes the need for more research efforts into macrophyte and macro-invertebrate associations in the aquatic system to better understand the implications of habitat modification arising from human activities. It will also enable us to be better equipped with a more appropriate ecological understanding for aquatic resources management.

Thesis (M. Tech) --Central University of Technology, Free State, 2008
Aphids (Hemiptera: Aphididae) are amongst the most destructive insects in agricultural crop production systems. This reputation stems from their complex life cycles which are mostly linked to a parthenogenetic mode of reproduction, allowing them to reach immense population sizes within a short period of time. They are also notorious as important and efficient vectors of several plant viral diseases. Their short fecund life cycles allow them to be pests on crops with a short growth period, e.g. lettuce (Lactuca sativa L.). It is common practice to provide this crop with some degree of protection from environmental extremes on the South African Highveld. Shadehouses are popular in this regard, but aphids are small enough to find their way into these structures, and their presence on lettuce is discouraged due to phytosanitary issues. In addition, the excessive use of insecticides is criticized due to the negative influence on human health, and because aphids can rapidly develop resistance. This necessitates the use of alternative control options in order to suppress aphid numbers. Biological control is popular in this regard and the use of predatory ladybirds (Coleoptera: Coccinellidae) is a popular choice. This study investigated the aphid and coccinellid species complex encountered under varying shadehouse conditions on cultivated head lettuce in the central Free State Province (South Africa). Their seasonality was also examined, along with variations in their population size throughout a one-year period. Finally, the impact of varying aphid populations on some physical characteristics of head lettuce was examined, and recommendations for aphid control (using naturally occurring coccinellid predators) were made. Two shadehouse structures were evaluated during this study. One was fully covered with shade netting and designed to exclude the pugnacious ant, Anoplolepis custodiens (Hymenoptera: Formicidae), while the other was partially covered with shade netting (on the roof area) allowing access to the ants. Six cycles of head lettuce were planted and sampled four times during each cycle. These were scheduled to monitor the seedling, vegetative and heading stage of lettuce. Four important aphid species were recorded on the lettuce, namely Acyrthosiphon lactucae, Nasonovia ribisnigri, Myzus persicae and Macrosiphum euphorbiae. Both structures harboured similar aphid and coccinellid species, but their population dynamics differed. A. lactucae dominated in the absence of A. custodiens in the fully covered structure (whole study), while N. ribisnigri dominated in the partially covered structure in the presence of these ants during the warmer months (December – January). M. euphorbiae replaced this species as the dominant species in the absence of A. custodiens (April – September). M. persicae occured during the winter (May – August) in the fully covered structure. Promising coccinellid predators were Hippodamia variegata and Scymnus sp. 1, and to a lesser extent, Exochomus flavipes and Cheilomenes lunata. However, the fully covered structure hampered the entrance of the larger adult coccinellid species, resulting in their lower occurrence. Aphid and coccinellid activity peaked during the summer months (October – January), and the fully covered structure attained the highest aphid infestation levels and coccinellid larval numbers during this time. On the other hand, aphid numbers were higher in the partially covered structure during the cooler months of the year (April – July) and this structure also harboured more adult coccinellids. In most cases, aphid infestation levels did not affect the amount of leaves formed. However, symptomatic damage in terms of head weight reduction did occur under severe infestation levels. Specific environmental conditions within a shadehouse structure concurrently contributed to this reduction, with less favourable conditions accelerating this condition. Results from this study have shown that even though the type of shadehouse structure does not influence the insect species complex found on lettuce, it does have an influence on detrimental and beneficial insect population dynamics. Aphid species infesting lettuce have been identified, along with coccinellid predators that could potentially be used in their control. Both types of structures had advantages and disadvantages, and therefore, decisions concerning shadehouses should not be focused on which type of structure to use, but rather which type of structure to use during different seasons of the year.

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xv, 126 p.; also includes graphics (some col.). Includes bibliographical references (p. 96-107). Available online via OhioLINK's ETD Center

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Os carabídeos (Coleoptera: Carabidae) são reconhecidos mundialmente como importantes agentes de controle biológico de pragas agrícolas. Os objetivos deste trabalho foram estudar os aspectos biológicos, morfometria e técnica de criação de Abaris basistriata Chaudoir, 1873 (Harpalinae: Pterostichini) e Selenophorus seriatoporus Putzeys, 1878 (Harpalinae: Harpalini) utilizando como dieta larvas de Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae: Tenebrioninae: Tenebrionini). Os estudos foram conduzidos em câmara climatizada mantida a 26±1°C, 70±10% de umidade relativa e fotofase de 14h. Os recipientes para postura de ovos e criação de larvas, pupas e adultos foram preenchidos com os seguintes substratos esterilizados e umedecidos: (1) solo, (2) vermiculita fina e (3) guardanapo de papel. O ciclo biológico (ovo a adulto) de A. basistriata e S. seriatoporus apresentou diferença no período de duração nos substratos solo e papel. A viabilidade dos ovos e das larvas de primeiro e segundo instares foi similar nos três substratos estudados, enquanto o terceiro instar e a pupa apresentaram maior sobrevivência no solo quando comparado com a vermiculita e o papel. O substrato solo foi o mais favorável para a longevidade de A. basistriata, sendo as fêmeas mais longevas que os machos, enquanto em S. seriatoporus esse parâmetro biológico foi similar. Abaris basistriata apresentou menor período de pré-oviposição e maior período de oviposição e pós-oviposição no substrato solo. Também, a fecundidade e viabilidade de A. basistriata foram superiores quando criado em recipiente com solo em relação à vermiculita ou papel. As larvas de T. molitor foram adequadas para a criação de A. basistriata e S. seriatoporus em laboratório. A baixa umidade dos subtratos solo, vermiculita e papel diminuiram a sobrevivência das larvas dos carabídeos. O solo foi o substrato que proporcionou melhores condições para o ...
The family Carabidae (Coleoptera) is recognized worldwide as containing important species of biological control agents of agricultural pests. Our aim was to study the biology, morphometrics and rearing protocol of Abaris basistriata Chaudoir, 1873 (Harpalinae: Pterostichini) and Selenophorus seriatoporus Putzeys, 1878 (Harpalinae: Harpalini) using Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae: Tenebrioninae: Tenebrionini) larvae as the diet. The study was conducted in environmental chambers at 26±1°C, 70±10% relative humidity, under a photoperiod of 14:10h (L:D). Containers used to egg laying and rearing larvae, pupae, and adults, were filled with one of the following types of sterilized and moistened substrate: (1) soil, (2) fine vermiculite, or (3) paper napkins. The life cycle (egg to adult) of A. basistriata and S. seriatoporus showed differences in duration in soil and paper substrates. The viability of eggs and larvae of first and second instars was similar in the three substrates studied, while the third instar and pupae in the soil showed improved survival when compared with vermiculite and paper. The soil substrate was more favorable to the longevity of A. basistriata, and the females live longer than males, while in S. seriatoporus this biological parameter was similar. Abaris basistriata showed lower pre-oviposition period and higher oviposition and post-oviposition on soil. Also, fecundity and viability of A. basistriata were higher when created in the container with respect to the soil or vermiculite and paper. The T. molitor larvae were adequate to keep creating A. basistriata and S. seriatoporus in the laboratory. The moisture conditions of subtrato interfere in larval survival of carabid. The soil was the substrate that provided better conditions for the complete life cycle of A. basistriata and S. seriatoporus, however the vermiculite and paper were easy to handle substrates that made possible the ...

Orientador: Francisco Jorge Cividanes
Banca: Sérgio Ide
Banca: Amarildo Pasini
Banca: Raphael de Campos Castilho
Banca: Arlindo Leal Boiça Junior
Resumo: Os carabídeos (Coleoptera: Carabidae) são reconhecidos mundialmente como importantes agentes de controle biológico de pragas agrícolas. Os objetivos deste trabalho foram estudar os aspectos biológicos, morfometria e técnica de criação de Abaris basistriata Chaudoir, 1873 (Harpalinae: Pterostichini) e Selenophorus seriatoporus Putzeys, 1878 (Harpalinae: Harpalini) utilizando como dieta larvas de Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae: Tenebrioninae: Tenebrionini). Os estudos foram conduzidos em câmara climatizada mantida a 26±1°C, 70±10% de umidade relativa e fotofase de 14h. Os recipientes para postura de ovos e criação de larvas, pupas e adultos foram preenchidos com os seguintes substratos esterilizados e umedecidos: (1) solo, (2) vermiculita fina e (3) guardanapo de papel. O ciclo biológico (ovo a adulto) de A. basistriata e S. seriatoporus apresentou diferença no período de duração nos substratos solo e papel. A viabilidade dos ovos e das larvas de primeiro e segundo instares foi similar nos três substratos estudados, enquanto o terceiro instar e a pupa apresentaram maior sobrevivência no solo quando comparado com a vermiculita e o papel. O substrato solo foi o mais favorável para a longevidade de A. basistriata, sendo as fêmeas mais longevas que os machos, enquanto em S. seriatoporus esse parâmetro biológico foi similar. Abaris basistriata apresentou menor período de pré-oviposição e maior período de oviposição e pós-oviposição no substrato solo. Também, a fecundidade e viabilidade de A. basistriata foram superiores quando criado em recipiente com solo em relação à vermiculita ou papel. As larvas de T. molitor foram adequadas para a criação de A. basistriata e S. seriatoporus em laboratório. A baixa umidade dos subtratos solo, vermiculita e papel diminuiram a sobrevivência das larvas dos carabídeos. O solo foi o substrato que proporcionou melhores condições para o ...
Abstract: The family Carabidae (Coleoptera) is recognized worldwide as containing important species of biological control agents of agricultural pests. Our aim was to study the biology, morphometrics and rearing protocol of Abaris basistriata Chaudoir, 1873 (Harpalinae: Pterostichini) and Selenophorus seriatoporus Putzeys, 1878 (Harpalinae: Harpalini) using Tenebrio molitor Linnaeus, 1758 (Coleoptera: Tenebrionidae: Tenebrioninae: Tenebrionini) larvae as the diet. The study was conducted in environmental chambers at 26±1°C, 70±10% relative humidity, under a photoperiod of 14:10h (L:D). Containers used to egg laying and rearing larvae, pupae, and adults, were filled with one of the following types of sterilized and moistened substrate: (1) soil, (2) fine vermiculite, or (3) paper napkins. The life cycle (egg to adult) of A. basistriata and S. seriatoporus showed differences in duration in soil and paper substrates. The viability of eggs and larvae of first and second instars was similar in the three substrates studied, while the third instar and pupae in the soil showed improved survival when compared with vermiculite and paper. The soil substrate was more favorable to the longevity of A. basistriata, and the females live longer than males, while in S. seriatoporus this biological parameter was similar. Abaris basistriata showed lower pre-oviposition period and higher oviposition and post-oviposition on soil. Also, fecundity and viability of A. basistriata were higher when created in the container with respect to the soil or vermiculite and paper. The T. molitor larvae were adequate to keep creating A. basistriata and S. seriatoporus in the laboratory. The moisture conditions of subtrato interfere in larval survival of carabid. The soil was the substrate that provided better conditions for the complete life cycle of A. basistriata and S. seriatoporus, however the vermiculite and paper were easy to handle substrates that made possible the ...
Doutor

Addendum in pocket. Biblography: leaves 162-173. Phytophagous sucking insects, aphids in particular, are common pests of plants. These insects secrete salivary enzymes into their food material. One plant defence mechanism is the induction and/or accumulation of deterrent phytochemicals. In the present study, a model enzyme system was chosen to mimic the oxidative activity of insect saliva. Isolation and sructural identification of the products of plant allelochemicals was achieved for several substrates. Insects were also exposed to individual plant chemicals in feeding "choice" tests. Preliminary examinations suggest that plants containing increased levels of phenolic allelochemicals show correlated increases in resistance to attack by aphids.

Biological agents have been employed in a series of experiments to evaluate their efftcacy,in control of the citrus nematode and Liohippelates eye gnat in the Yuma mesa area. Steinernema riobravis, an entomopathological nematode, considered climatically adapted to western Arizona temperatures, was selected from commercially available sources. Three field trials and a greenhouse study utilizing the nematodes at population ratés of one and two billion juveniles per acre were each unsuccessful in reducing the nematode or insect pest. Poor viability and survival were attributed to the negative results in each of the investigations. The microbial nematicide, DiTera, which was included in two limited trials, was found to be highly effective in suppression of citrus nematode populations infecting Yuma citrus. These results have prompted Abbott Laboratories, manufactures of the product; to establish two demonstration plots in the Yuma mesa area.

Dasineura sp. is a gall forming midge that was introduced into South Africa for the biocontrol of the Australian myrtle, Leptospermum laevigatum. It causes galls on both the vegetative and reproductive buds of the plant. Although Dasineura sp. was initially regarded as a potentially successful agent, galling up to 99 percent of the buds of the host plant, it has been preyed on by native opportunistic mites, which caused a decline in the performance of the midge as a biocontrol agent of L. laevigatum. This raised a concern about whether this fly will be able to perform effectively in the presence of its new natural enemies. Therefore, the objectives of this study were to: 1) ascertain whether mite abundance has seasonal variations; 2) determine if plant density and plant size have an effect on midge predation by the mites; and 3) determine if midge predation varies in different locations. The study was conducted at three sites in the Hermanus area, Western Cape Province. Every three weeks for thirteen months, galls were collected and dissected so as to count and record the numbers of midge larvae, pupae, adults and mites that were found. Data collected showed that predation varied with season, and the mites were scarce during the flowering season. Predation also varied among the study sites and plant density had an effect on midge predation. Midges in smaller plants (saplings) were more vulnerable to predation than those in the bigger plants (plants from isolates and thickets). It was concluded that although mites have an effect on midge populations, they do not prevent their establishment on the plant. Therefore, a survey should be done in two to three years time to check if the midges are still persisting on the plant, vi and recommendations are that a new agent should be released to supplement the midges.

Insecticide resistance and on-going legislation changes on the use of insecticides are likely to reduce their availability for use in agriculture; hence there is an urgent need to develop effective biological controls against these plant pests. Aphids are major insect pests of the agricultural and horticultural sectors. Recent work screened a range of phylloplane-residing bacteria for their ability to kill aphids and used alternative insect targets to determine host specificity. Tests with five other aphid genera indicated the bacteria were also able to kill them. However, the bacteria were generally not effective against non-aphid species including Lepidoptera. I aimed to characterise potential aphid killing pathogens and investigate the killing mechanism. An artificial feeding system with a liquid diet was used to devise a high-throughput screening system to identify pathogenic bacteria against the Green Peach Aphid Myzus persicae (“wild type” insecticide susceptible clones plus insecticide resistant clones). Six bacterial strains were pathogenic to all insecticide susceptible and resistant clones although variation in susceptibility was observed. No single bacterial strain was identified that was consistently more toxic to insecticide resistance clones than susceptible clones, suggesting there was no penalty in resistant clones that makes such clones less fit to bacterial challenge. Pseudomonas poae, which was the most pathogenic to nearly all of aphid clones, was selected for further in-depth analyses. Plant colonisation assays showed that the bacterium could effectively grow and persist on three different plant species. Foliar spray of P. poae did not show any hypersensitive (HR) response and populations (log 5-6) remained stable over three weeks of infestation. Additionally, application of the bacterium to plants before aphid colonisation led to a 68 %, 57 %, 69 % reduction in aphid populations on pre-infested peppers, Arabidopsis and sugar beet plants, respectively. Olfactometer analysis showed that bacterial colonisation of leaves had a deterrent effect on aphids that was not evident for leaves or bacteria alone. Genome analysis of the bacterium revealed three different insecticidal toxins, stress response genes and other pathogenicity-related effector proteins which reflect potential toxicity towards aphids. RNA-Seq was used to examine changes in aphid and bacterial gene expression after 38 h of infection. The altered transcript profiles of the aphid revealed 193 differentially expressed genes and limited gene expression of lysosomal and detoxification genes. 1325 genes were differentially expressed in bacteria, which mainly includes iron acquisition and stress response genes, and putative toxins. Single and combinational deletion, and complementation, of different toxins was conducted. In vitro killing analysis indicated all toxins contributed to aphid killing, with a particularly strong effect seen for one, AprX. Together, these data are being used to understand the molecular basis of aphid mortality to bacterial infection with the aim of utilising them as effective biocontrol agents.

Thesis (MEng) -- Stellenbosch University, 2014.
ENGLISH ABSTRACT: As overpopulation threatens the world’s ability to feed itself, food has become an invaluable resource. Unfortunately, almost a third of the food produced for human consumption is lost annually. Pests including insects, phytopathogens and weeds are responsible for more than a third of the annual major crop losses suffered around the world. The majority of current post-harvest control strategies employ synthetic agents. These compounds, however, have been found to be detrimental to the environment as well as human health, which has led researchers to investigate alternative strategies. Biocontrol agents are environmentally compatible, have a lower toxicity and are biodegradable, making them an attractive alternative to the synthetic control agents. The lipopeptides produced by Bacillus spp. in particular, have shown great potential as biocontrol agents against various post-harvest phytopathogens. Most biocontrol strategies apply the biocontrol organism, for example Bacillus, directly, whereas this study focused on the use of the lipopeptide itself as an antifungal agent. This is advantageous as the lipopeptides are less sensitive to their surroundings, such as temperature and pH, compared to living organisms, allowing for the production of a standardized product. This study investigated the production of the Bacillus lipopeptides surfactin, fengycin and iturin under controlled batch conditions. Parameters increasing lipopeptide production were quantified, focussing on antifungal lipopeptides (iturin and fengycin), and lipopeptide production was optimized. Experiments were performed in a fully instrumented 1.3 L bench-top bioreactor and lipopeptide analyses were performed via high pressure liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS). After screening four Bacillus spp., Bacillus amyloliquefaciens DSM 23117 was found to be the best antifungal candidate. This was based on it outperforming other candidates in terms of maximum antifungals produced, Yp/x,antifungals (yield per cells), and antifungal productivity. Nitrate, in the form of NH4NO3, was critical for lipopeptide production and an optimum concentration was observed above which the CDW (cell dry weight) no longer increased significantly and both μmax (maximum specific growth rate, h-1) and lipopeptide production decreased. For μmax, the optimum NH3NO4 concentration was 10 g/L and for lipopeptides it was 8 g/L. At these respective NH4NO3 concentrations μmax = 0.58 (h-1), the maximum antifungals (fengycin and iturin) were 285.7 mAU*min and the maximum surfactin concentration was 302 mg/L. The lipopeptides produced by B. amyloliquefaciens, the antifungals (fengycin and iturin) and surfactin, are secondary metabolites, regardless of the optimization treatment, i.e. increased NH4NO3 concentrations. Using 30% enriched air extended the nitrate utilization period, suggesting that when increasing supply concentration, more oxygen was available to act as electron acceptors, allowing nitrate to be used for lipopeptide production. The number of iturin and fengycin homologues generally increased with an increase in nitrate concentration. This suggested that process conditions, such as nitrate concentration, can be used to manipulate homologue ratios, allowing for the possibility to tailor-make biocontrol-agent upstream, during the production process, and possibly increase the efficacy of the biocontrol strategy. The lipopeptides produced by B. amyloliquefaciens showed complete inhibition against Botryotinia fuckeliana and diminished the growth capabilities of Botrytis cinerea. No inhibition was observed against Penicillium digitatum. These results indicate potential of the biocontrol strategy, although scale-up and fed-batch studies are recommended, especially when considering commercial implementation. Studies regarding the lipopeptide application method, i.e. a single application or multiple applications, should also be investigated as this will influence the efficacy of the lipopeptides against the target organisms.
AFRIKKANSE OPSOMMING: Met oorbevolking wat die wêreld se vermoë om die groeiende bevolking te onderhou belemmer, het dit noodsaaklik geword om huidige voedselbronne te beskerm. Daar word beraam dat een derde van die voedsel wat wêreldwyd geproduseer word vir menslike verbruik verlore gaan elke jaar. Verder is insekte, plantpatogene en onkruide verantwoordelik vir meer as ‘n derde van die verliese rakend jaarlikse oeste. Meeste bestaande na-oes beheermetodes maak gebruik van sintetiese stowwe. Ongelukkig kan hierdie verbindings nadelig wees vir die omgewing sowel as menlike gesondheid. Navorsers het hulsef dus toespits daarop om alternatiewe beheermetodes te ondersoek. Bio-beheermetodes is omgewingsvriendelik sowel as bio-afbreekbaar, wat hulle ideale alternatiewe maak vir die sintetiese stowwe. Bacillus spp. lipopeptiede het veral hoë potensiaal getoon as bio-beheermiddels teen verskeie na-oes plantsiektes. Meeste bio-beheermetodes wend die biobeheer organisme, soos Bacillus, direk aan, waar hierdie studie op die gebruik van lipopeptiede as ‘n beheermiddel gefokus het. Die voordeel is dat lipopeptidiede minder sensitief is vir hul omgewings, soos temperatuur en pH, i.v.m. organismes en die moontlikheid bied van ‘n gestandardiseerde produk. Hierdie studie het die produksie van spesifieke Bacillus lipopeptide, naamlik surfactin, fengycin en iturin, onder beheerde lottoestande ondersoek. Parameters wat lipopeptied produksie verhoog is gekwantifiseer, spesifiek antifungiese middels (iturin en fengycin) en lipopeptied produksie is geoptimeer. Eksperimente is uitgevoer in ‘n 1.3 L bioreaktor en lipopeptiedanaliese is met behulp van hoë druk vloeistof chromatografie en vloeistofchromatografie-massa spektroskopie uitgevoer. Van die vier moontlike Bacillus spp., was Bacillus amyloliquefaciens DSM 23117 die mees belowende antifungus-produserende kandidaat. Dit het beter resultate gelewer in terme van maksimale antifungiese produksie, Yp/x,antifungies (opbrengs per sel) asook antifungiese produktiwiteit. Nitraat, in hierdie geval NH4NO3, was noodsaaklik vir lipopeptied produksie en ‘n optimale konsentrasie is waargeneem waarbo die seldigtheid nie meer beduidend toegeneem het nie en beide die μmax (maksimale spesifieke groei tempo, h-1) en lipopeptied produksie afgeneem het. Die optimale NH4NO3 konsentrasie vir μmax was 10 g/L en vir lipopeptiedproduksie was 8 g/L. By 10 g/L NH4NO3 was μmax = 0.58 (h-1) en by 8 g/L was die maksimale antifungiese produksie (fengycin en iturin) 285.7 mAU*min en die maksimale surfactin produksie 302 mg/L onderskeidelik. Die lipopeptide, die antifungiese middels (fengycin en iturin) en surfactin, geproduseer deur B. amyloliquefaciens is sekondêre metaboliete, ongeag van die optimerings-behandelinge wat toegepas word, soos ‘n verhoging in NH4NO3 konsentrasie. Die gebruik van 30% verrykte suurstof het die nitraat verbruikingsperiode verleng, wat voorgestel het dat met die verryking, meer suurstof beskikbaar was om te dien as finale elektron ontvanger en sodoende die nitraat beskikbaar te stel vir lipopeptied produksie. Iturin en fengycin homoloë, oor die algemeen, het toegeneem soos wat die nitraat konsentrasie verhoog is. Hierdie resultate dui daarop dat prosestoestande, soos nitraat konsentrasie, gebruik kan word om die verhouding waarin lipopeptied homoloë geproduseer word te manipuleer. Hierdie resultate dui op die potensiaal vir die stroomop produksie van ‘n unieke bio-beheermiddel, wat die effektiwiteit van die bio-beheermetode moontlik sal verhoog. Die geproduseerde lipopeptiede het totale inhibisie getoon teen Botryotinia fuckeliana en ook fungiese aktiwiteit belemmer met Botrytis cinerea. Geen inhibisie is getoon teen Penicillium digitatum nie. Hierdie resultate toon die potensiaal van die bio-beheermetode, maar ‘n opskalerings-studie asook ‘n voerlot studie word aanbeveel, veral met die oog op moontlike kommersiële implementering van die strategie. Verdere studies met betrekking tot die aanwendingsmetode van die lipopeptiede moet ook verder ondersoek word, m.a.w. enkel teenoor menigte aanwendigs, aangesien dit die effektiwiteit van die lipopeptiede teen die teikenorganismes sal beïnvloed.

Many candidate mycoherbicides have shown promise in the laboratory or greenhouse, but most have been ineffective in the field. Factors limiting mycoherbicide efficiency include temperature and humidity. Results from this thesis indicate that solar radiation has both a damaging effect(reduction in germination)limiting efficacy and a photomorphogenic effect(appressorium induction)increasing efficacy. The study has also shown significant interaction between temperature and solar radiation on the survival of conidia of potential mycoherbistats. Therefore, solar radiation should be considered as third major component of the environment that should be considered when trying to produce mycoherbistats. With the findings presented in this thesis and further research on disease development under different conditions, in combination with the formulation of conidia in suitable UV protectants, a computer simulation modelling the conditions leading to epidemics caused by C.orbiculare, D.avenacea and R.alismatis could be constructed. It may be possible to manipulate fungal application time in order to expose conidia to doses of solar radiation that are not harmful to conidium germination and which stimulate appressorium formation. However, additional protection may be needed.
Doctor of Philosophy (PhD)