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Tesi sul tema "Insect pests"
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1
Stacey, David Andrew. "Insect pests in a changing climate". Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271618.
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2
Prosdocimi, E. M. "GUT-BACTERIA SYMBIOSIS IN INSECT PESTS". Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/252503.
Testo completoAbstract (sommario):
Insects are one of the most fascinating taxa on Earth: their diversity, diffusion, colonization of different niches are unparalleled in the animal kingdom. Besides, they have a remarkable impact on human life: they are parasites for people, animals and crops, vectors of diseases, pollinators, and even breeding animals (e.g. honeybees, silkworms). This extraordinary evolutionary success and diversification is partially due to the symbiotic relationships that insects have with a wide range of bacteria. These symbionts can be divided into primary, secondary symbionts and gut bacteria. Primary symbionts are found in very specialized cells (the bacteriocytes), strictly maternally transmitted and not cultivable. They are essential for their host, and vice-versa: they can actually be considered part of a single organism called “holobiont”. Secondary symbionts are not necessary for the host survival, although often beneficial, and they can inhabit various organs and tissues. In this category fall also reproductive parasites, as Wolbachia, which spreads in the population by maternal transmission, manipulating the reproduction of the host to favour the birth of infected daughters. Finally, gut bacteria are a more vague category, comprising organisms that live in the insect intestine because they are ingested with the diet, but also symbionts that establish a close relationship with the host, being essential for its survival and development. The roles of all these microorganisms are, to different extents, important for the insect physiology. Primary symbionts are generally essential to complement unbalanced diets and secondary ones contribute to the host fitness, while reproduction parasites deeply affect the reproduction mode of their hosts. Even commensals have been demonstrated to influence the development, mating choice and immune responses in Drosophila flies. For these reasons, the understanding of the biology of an insect can not do without the characterisation of its microbiota.
In the second chapter of my PhD thesis, a review on the microbial ecology techniques applied to the study of insect microbial communities gives an overview on the methods that can be applied to this purpose. On one hand, molecular analyses based on the 16S gene sequencing, such as 16S rRNA barcoding (pyrotag) and Denaturing Gradient Gel Electrophoresis (DGGE) are the most powerful methods to get a complete picture of the microbial community composition and structure. Microscopic localisation of symbionts can be also achieved by Fluorescent In Situ Hybridisation. On the other hand, the isolation of bacteria allows to deeply characterize the cultivable fraction, verifying through direct in vitro tests the activities of the strains. Taking advantage of a strain collection isolated from the target insect, the symbiotic relationship can be investigated through in vivo experiments. The more common ones involve i) the labeling of the strains with fluorescent proteins and the recolonization of the insects, to evaluate their localisation and colonisation ability, ii) the assessment of the detrimental effects of symbionts deprivation on the hosts, and iii) the comparison of insects monoassociated with different strains to check the effects on host fitness. To further analyse the interaction between bacteria and their hosts from a genetic point of view, advanced techniques, such as Signature Tagged Mutagenesis or In Vivo Expression Technology, can be performed. Many of these techniques have been applied in the case studies here presented, in which the microbial communities associated to three insect pests have been characterised.
In the third chapter is presented a study on the spotted-wing fly Drosophila suzukii. Unlike its relative D. melanogaster, which feeds on rotten fruit, this fly feeds and lays eggs on healthy fruits. The most damaged crops are members of the Drupaceae family (e.g. cherries) and berries (strawberries, raspberries, blueberries). The bacterial community associated to this pest have been characterised with a focus on acetic acid bacteria (AAB), important symbionts of many sugar-feeding insects. According to our findings, D. suzukii harbours a diverse community of AAB, detected both in the isolate collection and in culture-independent screenings (pyrotag, DGGE). They are primarily localised in the gut, attached to the peritrophic matrix, as showed by FISH micrographs. The ability of three AAB species (Gluconobacter oxydans, Acetobacter tropicalis and Acetobacter indonesiensis) to colonise the gut has been proved by recolonization experiments of the insect using GFP-marked strains.
In the fourth chapter, the bacterial community of the wood-feeding beetle Rhynchophorus ferrugineus has been analysed. Commonly named Red Palm Weevil (RPW), this insect is an important pest for palm trees. The plants are damaged mainly by the larvae, which dig tunnels in the trunks until pupation. Bacteria associated to the red palm weevil have been studied primarily by molecular means (pyrotag). Our results outline that the bacteria hosted by R. ferrugineus are mainly acquired from the environment while feeding. Indeed, a sharp difference has been registered between field-caught and bred specimens. While field caught RPW harbour more bacterial taxa which are in common with their feeding plants, the animals fed on apple in the laboratory show a higher prevalence of lactic acid and acetic acid bacteria, which presumably grow on the rotten fruit. The latter result is further confirmed by the bacterial isolations performed on apple-fed specimens. Besides, the DNA sequence of a primary symbiont, Candidatus Nardonella, has been detected. This bacterium has been shown to inhabit a wide range of insects of the same family of the RPW, Curculionidae.
The fifth chapter is about the gut bacterial community of Psacothea hilaris hilaris. Native of Japan and east China, this longicorn beetle (family: Cerambicidae) arrived in Italy as a consequence of the wood trade, and settled as a stable population in a small area in Como province. Its larvae dig tunnels in the trunks of the trees of the Moraceae family, while the adults feed on leaves. The most damaged by its feeding habits are mulberry and fig trees. This beetle hosts a variegate gut microbiota, that, as shown by DGGE, greatly changes according to the diet and to the gut tract examined. The cultivable fraction of this microbiota has been tested for several activities that proved the capability of the community as a whole to exploit the food sources in the insect gut (primarily, sugars from plant cell walls) and to assist their host in carbon and nitrogen absorption. Thus, even if acquired from the environment, these bacteria seem to be adapted to a symbiotic lifestyle.
From the comparison among these three studies, some conclusions can be drawn. All three case studies outline the importance of the diet in shaping the insect microbial community. In detail, wild insects always show higher diversity and individual variability in their associated microbiota. Reared insects appear, on the contrary, dominated by the species that can rapidly grow on laboratory diets, such as Lactobacillales and Enterobacteriales. Secondly, these studies depict a more accurate image of the commensal bacteria, which are not merely acquired by chance through feeding, but are capable to actively colonize insect guts, and to efficiently exploit this niche to multiply and spread in the environment. Finally, the research data point out that the origin and the function of many of the organisms detected in insects are yet poorly understood. For this reason, these studies can be considered a basis to for future research, aimed to a more in-depth understanding of the roles of these bacteria and their interactions with the hosts.
3
Jensen, Mari N. "Designer Toxins Kill Bt- Resistant Insect Pests". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2007. http://hdl.handle.net/10150/622102.
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4
Huggett, David Alan John. "Potential insect pests of the biomass crop Miscanthus". Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/7180.
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5
Farr, Ian John. "Automated bioacoustic identification of statutory quarantined insect pests". Thesis, University of York, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437593.
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6
Smith, Ethan A. "Is everything connected? following the predators, pests, and plants within a no-till, western Montana agroecosystem /". CONNECT TO THIS TITLE ONLINE, 2006. http://etd.lib.umt.edu/theses/available/etd-12212006-142245/.
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7
Schirocki, Anke Gabriele. "The effect of temperature on invasion and pathogencity of entomopathogenic nematodes (nematoda: Rhabditida) to larvae of Galleria mellonella and Otiorhynchus sulcatus". Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308061.
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8
Williams, Elizabeth Catherine. "Entomopathogenic nematodes as control agents of statutory insect pests". Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265978.
Testo completo
9
Powell, Kevin Steven. "Antimetabolic effects of plant proteins on homopteran insect pests". Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5757/.
Testo completoAbstract (sommario):
Homopteran insect pests can cause severe economical damage to crop plants by both direct physical means and as vectors of plant viral diseases. They are notoriously difficult insects to control by conventional methods, primarily due to their ability to evolve resistance-breaking biotypes within a relatively short time period. The production of genetically modified crop plants, expressing insecticidal genes, offers a novel method of control for a wide range of insect species. Once suitable gene products, such as plant- derived proteins, have been identified as having insecticidal effect against specific insects in vitro, their effect can be determined in vivo by expressing the relevant gene in transgenic plants. Insect feeding trials were carried out to determine the effects of incorporating a range of plant-derived proteins into artificial diets fed to planthopper, leafliopper and aphid pests and to aphids in planta. The lectins Galanthus nivalis agglutinin (GNA) and wheat germ agglutinin (WGA), and the enzyme soybean lipoxygenase (LPO) were shown to exhibit significant antimetabolic effects towards first and third instar nymphs of rice brown planthopper (Nilaparvata lugens Stal) when incorporated into artificial diet at 0 1% {w/v}, 0-1% (w/v) and 0 08% {w/v} levels respectively. The lectin GNA was also shown to exhibit a significant antimetabolic effect towards third instar nymphs of the rice green leafhopper (Nephottetix cinciteps Uhler) and the peach potato aphid {Myzus persicae Sulzer). A number of inert proteins, lectins, protein inhibitors and enzymes also tested showed relatively little or no effect towards both insects. The mechanism of action of all three effective proteins was examined using BPH as a model insect. As judged by honeydew production, the proteins all had a deterrent effect on insect feeding. However, subsequent toxic effects are also indicated. When fed sub-optimal concentrations of effective proteins in combination no synergistic or additive effects were observed, indicating that pyramiding the genes of these effective proteins would be of no advantage in protecting the crop against BPH.
10
Malek, Robert Nehme. "Novel Monitoring and Biological Control of Invasive Insect Pests". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/257781.
Testo completoAbstract (sommario):
Invasive species are alien to the ecosystem under consideration and cause economic or environmental damage or harm to human health. Two alien insects that fit this description are the brown marmorated stink bug, Halyomorpha halys and the spotted lanternfly, Lycorma delicatula. Both invaders are polyphagous pests that feed on a myriad of plant species and inflict severe crop losses. As sustainable control methods depend on the accurate monitoring of species’ invasion and involve the use of natural enemies, we addressed these two facets by exploring novel monitoring techniques and deciphering host-parasitoid interactions for improved integrated pest management. Thus, we adopted ‘BugMap’, a citizen science initiative that enables students, farmers and everyday citizens to report sightings of H. halys from Italy, with emphasis on Trentino-Alto Adige. Aside from fostering citizen participation in scientific endeavors and the enhanced literacy that ensues, BugMap helped uncover the invasion dynamics of H. halys and forecast its potential distribution in Trentino, all while coordinating technical monitoring and informing management strategies. The most promising agent currently under study for the classical biological control of H. halys is the Asian egg parasitoid Trissolcus japonicus. To assess the wasp’s potential non-target impacts, we investigated its foraging behavior in response to chemical traces ‘footprints’ deposited by its main host H. halys and by a suboptimal predatory species, the spined soldier bug, Podisus maculiventris. Wasps exhibited a ‘motivated searching’ when in contact with footprints originating from both species. However, T. japonicus arrestment was significantly stronger in response to H. halys footprints, compared with P. maculiventris, implying the presence of underlying chemical cues that shape its natural preferences. A series of GC-MS chemical analyses revealed that n-tridecane and (E)-2-decenal were more abundant in H. halys footprints and are probably the key components utilized by the wasp for short range host location. The function of the aforementioned compounds was studied, n-tridecane acted as an arrestant, prolonging T. japonicus residence time, whereas (E)-2-decenal fulfilled its presumed defensive role and repelled the wasp. These results shed new light on the chemical ecology of T. japonicus and help expand the understanding of parasitoid foraging and its implications for classical biological control. Moving to the other invader L. delicatula, an egg parasitoid Anastatus orientalis was reported attacking it at high rates in its native range in Eastern Asia and may play a key role in reducing its populations there. A series of bioassays revealed that wasps responded to footprints deposited by L. delicatula gravid females by initiating a strong searching behavior. Moreover, A. orientalis preferred to oviposit in egg masses with intact oothecae, suggesting that the host’s egg covering functions as a trigger for A. orientalis probing and oviposition. Thus, A. orientalis not only overcomes, but also reverses an important line of host structural defense for its own fitness gains. This dissertation discusses the benefits of combining citizen science with traditional monitoring, and the usefulness of decoding host-parasitoid interactions to design more efficacious management strategies of invasive insect pests.
11
Malek, Robert Nehme. "Novel Monitoring and Biological Control of Invasive Insect Pests". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/257781.
Testo completoAbstract (sommario):
Invasive species are alien to the ecosystem under consideration and cause economic or environmental damage or harm to human health. Two alien insects that fit this description are the brown marmorated stink bug, Halyomorpha halys and the spotted lanternfly, Lycorma delicatula. Both invaders are polyphagous pests that feed on a myriad of plant species and inflict severe crop losses. As sustainable control methods depend on the accurate monitoring of species’ invasion and involve the use of natural enemies, we addressed these two facets by exploring novel monitoring techniques and deciphering host-parasitoid interactions for improved integrated pest management. Thus, we adopted ‘BugMap’, a citizen science initiative that enables students, farmers and everyday citizens to report sightings of H. halys from Italy, with emphasis on Trentino-Alto Adige. Aside from fostering citizen participation in scientific endeavors and the enhanced literacy that ensues, BugMap helped uncover the invasion dynamics of H. halys and forecast its potential distribution in Trentino, all while coordinating technical monitoring and informing management strategies. The most promising agent currently under study for the classical biological control of H. halys is the Asian egg parasitoid Trissolcus japonicus. To assess the wasp’s potential non-target impacts, we investigated its foraging behavior in response to chemical traces ‘footprints’ deposited by its main host H. halys and by a suboptimal predatory species, the spined soldier bug, Podisus maculiventris. Wasps exhibited a ‘motivated searching’ when in contact with footprints originating from both species. However, T. japonicus arrestment was significantly stronger in response to H. halys footprints, compared with P. maculiventris, implying the presence of underlying chemical cues that shape its natural preferences. A series of GC-MS chemical analyses revealed that n-tridecane and (E)-2-decenal were more abundant in H. halys footprints and are probably the key components utilized by the wasp for short range host location. The function of the aforementioned compounds was studied, n-tridecane acted as an arrestant, prolonging T. japonicus residence time, whereas (E)-2-decenal fulfilled its presumed defensive role and repelled the wasp. These results shed new light on the chemical ecology of T. japonicus and help expand the understanding of parasitoid foraging and its implications for classical biological control. Moving to the other invader L. delicatula, an egg parasitoid Anastatus orientalis was reported attacking it at high rates in its native range in Eastern Asia and may play a key role in reducing its populations there. A series of bioassays revealed that wasps responded to footprints deposited by L. delicatula gravid females by initiating a strong searching behavior. Moreover, A. orientalis preferred to oviposit in egg masses with intact oothecae, suggesting that the host’s egg covering functions as a trigger for A. orientalis probing and oviposition. Thus, A. orientalis not only overcomes, but also reverses an important line of host structural defense for its own fitness gains. This dissertation discusses the benefits of combining citizen science with traditional monitoring, and the usefulness of decoding host-parasitoid interactions to design more efficacious management strategies of invasive insect pests.
12
Weaver, David K. (David Keith). "The role of selected frass chemicals and cuticular lipid components in the orientation of certain larval Tenebrionidae /". Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74340.
Testo completoAbstract (sommario):
The larvae of Tenebrio molitor Linne and Alphitobius diaperinus (Panzer) both aggregated upon substrates treated with aqueous extracts of conspecific larval frass. Lactic acid is a pheromone in the frass of both species. Alphitobius larvae were attracted to lactic acid, while lactic acid caused Tenebrio larvae to arrest.Propionic acid is a repellent pheromone present in Tenebrio frass, but the lactic acid-induced response is dominant. The role of these chemical factors in population orientation of the larvae of these mealworm species is discussed.
The cuticular lipids of the larvae of both species contained close-range attractants that had a role in aggregate formation. The Tenebrio cuticular lipid pheromone is predominately 8,9-pentacosanediol. The Alphitobius cuticular pheromone is a mixture of at least two compounds.
The ecological preferences of these larvae suggested that these aggregation pheromones increased the density of individuals per unit volume. This increased density had varying effects on the physiological development of Tenebrio individuals.
13
Zhou, Yanmin. "Insect adhesion on rough surfaces and properties of insect repellent surfaces". Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709055.
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14
Perera, Mallawa Thanthrie Mudiyanselage D. Renuka. "Response of pests of brassicae and their parasitoids to synthetic and natural feeding deterrents". Thesis, University of Aberdeen, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.287701.
Testo completoAbstract (sommario):
Antifeedants and growth regulators have potential as alternatives to conventional methods of insect pest control. As with conventional chemicals it is important to consider their effects on natural enemies of the pests. The aim of this project was to determine whether the bitter-tasting synthetic chemical denatonium benzoate as an antifeedant and compare with neem derivatives. Other aims were to investigate their effect on parasitoids and the field infestation of cabbage pests. Denatonium benzoate is systemic and had no contact effect but acted as an antifeedant on a generalist sap feeder Myzus persicae and reduced the survival, fecundity, and lifespan. Neem derivatives, Azatin EC and Pestistat R were more effective of which Azatin EC was the most effective. Antifeedants further reduced the fecundity and survival when parasitized with its parasitoid, Aphidius matricariae and neem derivatives had adverse effects on both aphid and the parasitoid. Denatonium benzoate and Pestistat R with a specialist leaf feeder, Pieris brassicae and all antifeedants with Plutella xylostella (generalist leaf feeder) and Chrysodeixis eriosoma (specialist brassica leaf feeder) reduced the leaf area consumed and it was inversely proportional to the concentration. The highest leaf area consumption was in denatonium benzoate and the lowest in Pestistat R. Higher azadirachtin concentrations were detrimental but denatonium benzoate was safer to the larval parasitoid, Cotesia plutellae. Denatonium benzoate and Azatin EC reduced field infestation of M. persicae, P. xylostella and C. eriosoma in Peradeniya, Sri Lanka and Azatin EC was the most effective. Denatonium benzoate acts as an antifeedant against cabbage pests and safer towards parasitoids hence can be used in integrated pest management programmes. Neem derivatives are comparatively more effective on pests but harmful to parasitoids. Denatonium benzoate and Azatin EC effectively reduced the pest infestation under field conditions.
15
Kadango, Tendayi Lovemore. "Farmers' perceptions of insect pests in the Eastern Cape maize-based cropping systems and the effects of crop residue management on insect pest populations". Thesis, University of Fort Hare, 2018. http://hdl.handle.net/10353/6202.
Testo completoAbstract (sommario):
Maize (Zea mays L.) is one of the most important crops in South Africa that is cultivated for food, feed and as a cash crop. Maize in the Eastern Cape is typically grown for consumption and the Province is one of the least producers owing to small landholdings, poor production conditions and pests. This study investigated: (i) the different maize cropping systems smallholder farmers practice in the Eastern Cape (EC), (ii) the major maize insect pests within the identified cropping systems, (iii) the perceptions of Eastern Cape smallholder maize farmers on the effects of insect pests, and (iv) the effects of crop residues on insect pests’ population dynamics. Four major cropping systems namely: maize sole cropping without rotations by government sponsored farmers (GCP) (94 percent), maize intercropping without rotations by independent farmers (IF) (79 percent), maize sole cropping without rotations by IF (67 percent) and maize intercropping without rotations by GCP (61 percent) were identified. The choice of a cropping system by the smallholder farmers was significantly influenced by source of sponsorship, the difference in their district localities, tenure system, availability of inputs and farming equipment, percentage of farmland farmers allocate to maize, maize varieties, farming experience, fallow operations and access to irrigation facilities. The major constraints faced by the farmers in maize production are the attack by insect pests, weeds competition, drought, the lack of fencing around the fields and destruction by mammals. The major insect pests identified were stalk borers (Busseola fusca, Chilo partellus), cutworms (Agrotis spp.), aphids (Rhopalosiphum maidis), bollworms (Helicoverpa armigera) and weevils (Sitophylus spp.). The most popular control measures employed were the use of GM maize and pesticides. Results from the field trial showed that field crickets were the major ground dwelling insect pests observed followed by bollworms and cutworms. However, there were no significant influence of residue retention on the insects’ diversity indices, richness, and evenness. Above ground insects sampling revealed the domination by four major insects namely, cutworms, maize stalk borer, bollworms, and spotted stalk borer. Residue management significantly influenced the infestation by spotted stalk borer only on maize plots. However, the general trend was that there was less infestation by the insects in plots where residues were retained than the ones with residue removed. Results from the study indicate that government sponsorship is significantly influencing the maize cropping systems of the smallholder farmers of the Eastern Cape.
16
Zanga, Daniela. "High carotenoid corn: agronomic evaluation and interactions with insect pests". Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/400802.
Testo completoAbstract (sommario):
El meu projecte de recerca està centrat en la caracterització molecular, bioquímica i agronòmica, d’una línea transgènica de panís amb un elevat contingut en carotenoides, denominada, CarolightR en condicions ambientals diferents. És important analitzar el comportament d’una varietat nova de planta en condicions de camp amb la finalitat d’avaluar l’impacte dels múltiples estressos biòtics i abiòtics als que estarà sotmesa. Amb les anàlisis que he dut a terme, he determinat que tant el contingut en carotenoides totals, com la seva composició en l’endosperma, en l’etapa de maduresa, van ser molt similars entre las plantes cultivades a l’hiverncle i les cultivades al camp. El rendiment agronòmic general i les característiques específiques dels components del rendiment de CarolightR i la seva línia isogénica, M37W, van ser indistingibles. En experiments posteriors vaig dur a terme la introgressió dels transgens Btcry1Ac (anomenat 4Bt) amb activitat insecticida a CarolightR. La línea obtinguda 4BtxHC era tòxica a les larves del barrinador Ostrinia nubilalis. No obstant, l’ activitat insecticida en les llavors 4BtxHC era inferior en un 17% a la línia original 4Bt. Finalment he analitzat la propietat intel•lectual rellevant en la producció i comercialització de CarolightR.Mi proyecto de investigación está centrado en la caracterización molecular, bioquímica y agronómica, de una línea transgénica de maíz con elevado contenido en carotenoides, denominada, CarolightR bajo diferentes condiciones ambientales. Es importante evaluar el comportamiento de una nueva variedad de planta en condiciones de campo con el fin de determinar el impacto de múltiples estreses bióticos y abióticos a los que estara sometida la planta. Con los análisis que he realizado, he determinado que tanto el contenido de carotenoides totales y como su composición en el endospermo en madurez fisiológica fueron muy similares entre las plantas cultivadas en el invernadero y las cultivadas en el campo. El rendimiento y sus componentes de CarolightR y su línea isogénica, M37W, fueron similares. En experimentos posteriores, realice la introgresión de los transgenes Btcry1Ac (llamado 4Bt) con actividad insecticida a CarolightR. La línea obtenida 4BtxHC era toxica a las larvas del taladro Ostrinia nubilalis. No obstante la actividad insecticida en las semillas 4BtxHC era inferior en un 17% a la línea original 4Bt. Finalmente, he analizado la propiedad intelectual relevante a la producción y comercialización de CarolightR.
My research project focused on the molecular, biochemical and agronomical characterization of a high carotenoid transgenic corn line, CarolightR under different environmental conditions.It is important to evaluate theperformance of a novel plant variety under field conditions in order to determine the impact of the multiple biotic and abiotic stresses to which the plant will be exposed, on its performance characteristics. I determined that the total carotenoid content and composition in the endosperm at maturity were very similar in greenhouse- and field-grown plants.The overall agronomic performance and characteristics such as yield components of CarolightR and its near isogenic line, M37W, were indistinguishable. In follow up experiments I introgressed the Bt cry1Ac insecticidal transgene (named 4Bt) into CarolightR . The new line, 4BtxHC, was toxic to larvae of the corn borer Ostrinia nubilalis. However, the insecticidal activity of 4BtxHC grains was lowered compared to the original 4Bt line by 17%. Finally I explored the intellectual property landscape relevant to the production and commercialization of CarolightR
17
Bolton, Michael. "Genetic control methods for agricultural insect pests of global importance". Thesis, University of East Anglia, 2017. https://ueaeprints.uea.ac.uk/63943/.
Testo completoAbstract (sommario):
Insect pests of agricultural significance pose substantial risks for food security in an ever-growing global population. Conventional control measures used against these pests have had varying degrees of success and examples of pesticide resistance and offtarget effects of pesticides highlight the urgent need for the development of new, environmentally benign control methods. Deployment of ‘self-limiting’ insects is a species-specific approach that can be used to combat many species, including two major agricultural insect pests, the Medfly, Ceratitis capitata, and the Diamondback moth (DBM), Plutella xylostella. In this thesis, I used transgenic ‘self-limiting’ strains of medfly and DBM to stress-test self-limiting technology in laboratory and field scenarios. In Chapter 2, I tested the effect of larval diet composition on the penetrance of a female-specific self-limiting system in the OX3864A strain of medfly under simulated control conditions. In Chapter 3 I investigated the potential for resistance to selflimiting systems, using artificial selection for survival under a low dose of the transgene antidote, in the OX3864A medfly strain. In Chapter 4 I used the OX4319L self-limiting strain of DBM and showed that its responses to an artificial pheromone source in wind tunnel flight trials were comparable to the wild type. I also described the field dispersal characteristics of a long-term, laboratory-reared wildtype DBM strain in a mark-release-recapture trial. In Chapter 5 I demonstrated that the OX4319L DBM strain had comparable field longevity, but reduced mating competitiveness, in comparison to a wild-caught DBM strain. Finally, in Chapter 6, I discuss the broader context and address the practicalities, regulatory controls and implications of transgenic technologies for insect pest control under open field conditions.
18
Ukeh, Donald A. "The identification and use of semiochemicals for the control of the maize weevil, Sitophilus zeamais (Motschulsky) in Nigeria". Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25167.
Testo completo
19
Chang, Gary C. "Ecological interaction among natural enemies and its consequences for biological control /". Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/5205.
Testo completo
20
McNamee, Peter James. "The equilibrium structure and behavior of defoliating insect systems". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27439.
Testo completoAbstract (sommario):
Defoliating insect systems, defined for the purposes of this thesis as being composed of insects which defoliate forest trees and the species with which they interact, such as their host trees and their natural enemy complexes, exhibit
a wide variety of population behaviors. Similarly, a number of theories and models have been proposed to explain these behaviors. These theories emphasize the importance of different ecological processes, often concentrate on the defoliator and overlook the importance of other components. Also, much of the current understanding of the dynamics of these systems has come from forest pest research and management
programs, tailored towards specific pest problems and often very short term in nature.
This thesis develops and begins to test a general approach for the local dynamics of defoliating insect systems.
This framework outlines the system components that are necessary to predict the behavior of defoliating insect systems. It includes ways in which the equilibrium structure
of defoliating insect systems, defined as the number of equilibria for each system component, the population levels at which the equilibria occur, and the processes creating the equilibria, might be found. The framework also includes methods of inducing the qualitative behavior of these sys- terns, defined as the periodicity of defoliator outbreaks, the length of outbreaks, and the dynamics of other important system components between, during, and in the decline of defoliator outbreaks.
The study begins with a detailed literature review of historical theories of defoliating insect system behavior and of the documented behavior patterns of these systems. Major classes of behavior are identified, as well as the various ecological processes which have been invoked to explain these behaviors. An analysis and documentation of the equilibrium structure and behavior of three defoliating defoliating insect systems, the eastern blackheaded budworm, the eastern spruce budworm, and the jack pine sawfly, are then used to develop general rules about how equilibrium structure and behavior can be explained. This analysis, coupled with the literature review, is used to develop the framework. The framework is then tested against historical defoliator population data and general syntheses of defoliating
insect system research to assess its utility and predictability.
The major results of the thesis are as follows. First, it appears that the structure and behavior of a defoliating insect system can be explained with five dynamic variables: the abundances of the defoliator; the foliage; the forest; the parasitoid; and the disease; and the effects of weather acting on the defoliator. Second, there appear to be 4 classes of defoliating insect system behavior. Third, the behavior that a defoliating insect system will exhibit seems to be determined by the magnitude of weather effects on defoliator survival and recruitment, the parasitoid numerical
response to changing defoliator densities, the disease numerical response to changing defoliator densities, and the vulnerability of the forest to defoliation. Fourth, there seem to be four equilibrium structures the defoliator can exhibit, and one each for the parasitoid, the foliage, the forest, and the disease. Finally, the framework suggests that defoliating insect system structure and behavior can be induced with a particular, well-defined set of information.
The framework is successful when applied to particular defoliating insect systems for explaining their behavior, but less successful in explaining defoliator equilibrium structure for other systems. Opportunities for more thorough testing of the framework exist if the particular types of data outlined above are gathered for defoliating insect systems. This lack of data for testing the framework make it currently difficult to clearly define those systems in which the framework is useful and those systems in which it is not. Experiments to test the framework are described and suggestions for future types of applied research on defoliating insect systems are presented.Science, Faculty of
Zoology, Department of
Graduate
21
Ramos, Olgaly. "Entomopathogenic nematodes for the biological control of stored product insect pests /". Search for this dissertation online, 2005. http://wwwlib.umi.com/cr/ksu/main.
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22
Mazahery-Laghab, Hojjatollah. "Endogenous resistance to insect pests in alfalfa : engineering for enhanced resistance". Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4695/.
Testo completoAbstract (sommario):
Alfalfa (Medicago sativa) is a valuable forage crop grown throughout the World. While the crop is resistant to attack by many insect pests, it is subject to potentially severe losses through the action of several specific pests, which are adapted to alfalfa as a host. The most economically damaging of these pests is the alfalfa weevil, Hypera postica. This thesis investigates the endogenous defences of alfalfa against insects, which are responsible for its resistance to non-pest species, and develops a strategy for increasing the resistance of alfalfa towards pest species, specifically alfalfa weevil. The role of saponins in the resistance of alfalfa towards non-pest species has been investigated by using successive insect bioassays, carried out with extracts, mixtures of compounds, and purified compounds, to identify which compounds present in alfalfa tissues are responsible for toxicity towards insects. Crude saponin extracts, in 80% methanol, from alfalfa seedling tissues were bioassayed against the cowpea seed weevil, Callosobruchus maculatus. Both extracts from shoot and root tissues caused larval mortality and delayed development when incorporated into an artificial diet at levels comparable to those found in alfalfa, but lower levels of root saponin extracts showed probiotic effects, whereas lower levels of shoot saponins were still toxic. Hydrolysis of the saponins present in these extracts decreased their toxicity. Purified saponin mixtures were prepared by butanol partition and ether precipitation, and were bioassayed against potato aphid (Aulacorthum solani) in a liquid artificial diet, which allowed quantitative effects to be accurately assayed. Shoot saponins showed a concentration-dependent toxic effect, decreasing survival over an initial 5 day period, decreasing growth, and inhibiting fecundity (measured by nymph production) in these insects. Alfalfa root saponins showed no deleterious effects below a threshold level, but caused complete mortality above this level. The alfalfa saponin mixtures were separated into fractions by chromatography on a reverse phase column. Bioassays showed that the toxicity towards potato was associated only with fractions containing saponins, and that fractions containing a component identified as soyasaponin I were more toxic to the aphids than others. Finally, two saponins purified from alfalfa, soyasaponin I and medicoside A, were assayed. These assays showed that soyasaponin was consistently more toxic in effects on mortality, growth and fecundity. It was concluded that alfalfa saponins, and in particular soyasaponin I, were major factors in the resistance of alfalfa towards potato aphid, and other insects. A saponin mixture from another species, sugar beet {Beta vulgaris) was also toxic to aphids, supporting the view that saponins have a general role in resistance to insects. Inhibition of insect digestive proteolysis by expression of a foreign protein protease inhibitor was selected as a strategy to protect transgenic alfalfa against alfalfa weevil. The major protease activity in larvae of this msect was shown to be due to cysteine proteases, which could be inhibited by cystatins. Rice cystatin was produced in large quantity using a recombinant protein expression system in E. coli for use in a "proving" experiment. Incorporation of the rice cystatin into an alfalfa weevil larvae artificial diet decreased survival, showing that this approach was feasible.
23
Sgard, Frederic. "Molecular genetic studies on nicotinic acetylcholine receptors of major insect pests". Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239499.
Testo completo
24
Green, Emily. "Development of genetic control strategies for insect pests using CRISPR/Cas9". Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAJ100.
Testo completoAbstract (sommario):
La lutte contre les insectes nuisibles reste un défi économique, environnemental et de santé important. Le forçage génétique par CRISPR/Cas9 (FG) est un nouveau system de control génétique. Ce sont des systèmes génétiques capables d’envahir rapidement une population. Ce travail de thèse présente mes efforts pour développer des FGs chez deux espèces nuisibles, Anopheles gambiae, un vecteur majeur du paludisme, et Drosophila Suzukii, un ravageur agricole d’importance mondiale. Les objectifs de ce projet étaient de développer un FG à but d'élimination chez D. Suzukii, visant à réduire la taille de la population, et un FG à but de modification chez An. gambiae, visant à rendre les moustiques incapables de transmettre le maladie. Mes efforts pour développer un FG chez D. Suzukii n’ont pas abouti, mais les techniques et protocoles présentés ici peuvent servir de base pour de futurs travaux. Chez An. gambiae, j'ai caractérisé avec succès deux lignées transgéniques, dont l'une capable de bloquer significativement la transmission chez un modèle rongeur. Enfin, je présente mes avancées dans la mise au point d’une nouvelle stratégie, le forçage génétique indirectInsect pest control remains an important economic, environmental, and public health challenge. CRISPR/Cas9 gene drive (GD) is a novel genetic control strategy. GDs are genetic systems that can rapidly invade a population. This manuscript presents my efforts to develop gene drives in two important pest species, Anopheles gambiae, a major vector of malaria, and Drosophila suzukii, a global crop pest. The goals of this project were to develop a suppression gene drive in D. suzukii, to reduce population size, and a modification drive in An. gambiae, to reduce malaria transmission. While I was unable to produce a functional gene drive in D. suzukii, the efforts and protocols presented here can serve as a baseline for future work in this economically important crop pest. In An. gambiae, I successfully characterized two transgenic lines, one of which significantly blocks malaria transmission to a rodent model. Finally, I present my efforts to engineer a new modification gene drive strategy, indirect gene drive
25
Dong, Xue. "Response of stored grain insect pests and barley to ozone treatment". Thesis, Dong, Xue ORCID: 0000-0002-2647-5747 (2022) Response of stored grain insect pests and barley to ozone treatment. PhD thesis, Murdoch University, 2022. https://researchrepository.murdoch.edu.au/id/eprint/64871/.
Testo completoAbstract (sommario):
Ozone (O3) has distinct advantages over other stored grain pest treatments, such a toxicity to a broad range of organisms and rapid auto-decomposition to oxygen without leaving residues, making it a promising fumigant to protect stored grains.
This research project focused on understanding how stored grain insects and barley respond to ozone. Several studies have assessed the efficacy of O3 against pests in stored maize and wheat grain, but little is known about the toxicity of O3 on stored grain pests in barley and its effects on barley quality and germination. My results indicated that more than 2 days of ozone treatment should be considered as the endpoint to evaluate insect mortality rate due to delayed toxicity of O3. C×t product 36 mg h/L (700ppm × 24 h) offered complete mortality for all stages of the two species tested insects R. dominica and T. castaneum, without affecting barley commercial quality.
As barley is to be used for malting purposes, it is important to understand that effect of ozone on barley germination, whether positive or negative. Relevant short period treatment (20 min) with ozone at 700ppm can facilitate barley germination, but it was adversely impacted for longer O3 exposure times, such as 24 h.
Ozone treated barley seed released a greater number and quantity of volatile organic compounds (VOCs). However, alcohols and hydrocarbons gradually decreased, whereas aldehydes and organic acids markedly increased with increasing time of ozone treatment. Acetic acid was identified as a potential ozone stress-specific marker. Furthermore, the dosage-dependent function of acetic acid on barley germination was verified and results indicated that low dosage (0.05 - 0.5 mg/g of barley) of acetic acid could lead to increasing germination rate.
Potential chemical biomarkers from barley seeds during germination were identified using gas chromatography mass spectrometry (GC/MS). Statistical assessment of the data via principal component analysis demonstrated that the metabolic changes during germination were reflected by time-dependent shifts. Alcohols, fatty acids and ketones were the major contributors to the time-driven changes during germination. In addition, ozone induced an increase in fatty acids at the early stage of barley germination and probably enhanced germination by supplying carbon skeletons and energy for germination via the TCA cycle.
My results indicate that ozone could be utilized to improve the quality of malting barley on enhancing germination rate. The key finding is that acetic acid could be used as a regulator to control germination. Moreover, this PhD study is the first-time explored effect of O3 on metabolite profiles of barley germination, which could lead to identifying the factors might impact barley germination or malt quality.
26
Salloum, Gregory Stewart. "Insect growth inhibitors from asteraceous plant extracts". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26529.
Testo completoAbstract (sommario):
Petrol and ethanolic extracts of six asteraceous weeds were added to artificial diet and screened for inhibition of larval growth on variegated cutworm, Peridroma saucia (Hbn.). Petrol and ethanolic extracts of Artemisia tridentata and Chamomilla suaveolens and ethanolic extracts of Chrysothamnus nauseosus and Centaurea diffusa were highly inhibitory at five times the naturally occurring concentrations. The two C. suaveolens extracts and the ethanol extract of A. tridentata were active at the natural concentration (100%) and were further examined at 20, 40, 60, and 80% of this level. Inhibition of larval growth was directly related to concentration for each of the three extracts tested. EC₅₀'S (effective concentration to inhibit growth by 50% relative to controls) for the three extracts were 36-42% of the naturally occurring level in the plants.
Nutritional indices were calculated for second instar P. saucia feeding on the active ethanolic A. tridentata extract and the petrol extract from C. suaveolens. The relative growth rate (RGR) of P. saucia larvae fed the ethanolic extract of A. tridentata in artificial diet was significantly lower than that in larvae fed diet with the petrol extract of C. suaveolens and larvae on control diet. Dietary utilization was significantly lower for larvae fed the A. tridentata extract. Results of a field trial indicated that a single treatment of A. tridentata extract at the equivalent of 0.2 g/ml could protect cabbage significantly better than the carrier solvent (30% aq ethanol) or distilled water as measured by a visual damage estimate. An insecticide standard, deltamethrin (17.9 µg/1 with 0.4% Superspred TM ), suppressed pest damage significantly better than the A. tridentata-extract treatment.
A residual oviposition deterrency to Pieris rapae was found in the field results. Caged experiments in the laboratory confirmed the contact oviposition deterrency of the A. tridentata extract at 0.2 g/ml. Offspring of field-collected P. saucia larvae grew 2.5-fold heavier than larvae from the laboratory colony. However, diet with the A. tridentata extract inhibited both field-collected and laboratory reared saucia larvae equally when compared to their respective controls fed untreated diet. In summary, these results indicate the potential benefit of using specific unrefined plant extracts for growth inhibitors and oviposition deterrents against insect pests. The contribution of individual phytochemicals in the A. tridentata ethanolic extract to growth inhibition or oviposition deterrency is currently speculative.Land and Food Systems, Faculty of
Graduate
27
Miah, Mohammed Ismail. "The phylogeny and taxonomy of the parasitic wasp subfamily campopleginae (hymenoptera, ichneumonidae)". Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286298.
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28
Finn, Erin. "Developing integrated pest management (IPM) techniques for managing key insect pests of blueberries in the Southeastern United States". [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001370.
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29
Jacquemai, Ivo. "Acoustic wireless sensing for environmental monitoring". Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2011. https://ro.ecu.edu.au/theses/395.
Testo completoAbstract (sommario):
The European House Borer (EHB) is a timber pest which attacks dead timber. This pest can cause large scale damage to wooden structures and has already spread throughout many parts of the world. The larvae usually remains undetected for many years while it busily inflicts irrevocable and substantial harm to the timber. Since the pest was first discovered in Western Australia in 2004 the Government has endeavoured to extinguish its existence. In this research, an electronic sensor has been developed in order to detect the presence of EHB larvae in timber. Only an accurate detection can allow for selective treatment, which is required in order to eliminate the pest. In the past no reliable detection methods were available. However, with the developed acoustic sensing device, non-destructive and reliable detection of EHB is now possible. The developed handheld device is capable of analysing the acoustic emissions from a timber structure which allows for determining whether or not EHB is present in its vicinity. Depending on the level of the infestation, the detection can take as little as a few seconds. The tests, which have been carried out on infested timber beams in a secured laboratory, show a reliable detection of the larvae over a distance of several metres. The research discusses the challenges encountered throughout the development of the acoustic sensor and the limitations of the technology. Also presented are other potential applications for the device and areas which require further research in order to improve the efficiency of the sensor.
30
Garratt, Michael P. D. "Crops, Insect Pests and Natural Enemies : Effects of Organic and Conventional Fertilisers". Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4672.
Testo completoAbstract (sommario):
Agricultural intensification can have negative impacts on the environment and there isincreasing interest in the use of low intensity or organic agricultural methods toimprove sustainability. Fertiliser is an important component of all agriculturalsystems and can affect the performance of crop pests and their natural enemies. Thisthesis presents the results from a quantitative review of the literature on both farmingsystem and organic and conventional fertiliser effects on pests and natural enemies. Results from a series of laboratory and field experiments investigating the effectsorganic and conventional fertiliser on cereal aphids and their natural enemies arereported. The review demonstrates that crop pests and their natural enemies benefit fromorganic or low intensity methods and this is evident for natural enemies in farm scaleexperiments. The effect of organic and conventional fertilisers on arthropod pests isvariable although the influence of manures is consistently negative while the effect ofplant composts is positive. More studies investigating organic and conventionalfertilisers and the response of natural enemies are needed. Field and laboratory experiments show that conventional fertilisers can benefit cerealaphids but the mechanism behind this response is species specific. Rhopalosiphumpadi is sensitive to temporal nutrients availability and is influenced by the timing offertiliser application, while Metopolophium dirhodum is responsive to plantmorphology with aphids performing better on plants with a high proportion ofvegetative matter. The implications of pest performance on fertiliser managementstrategies are discussed. Parasitoid abundance in the field was not found to beinfluenced by fertiliser treatment although in the laboratory, indirect effects offertiliser, mediated through its aphid host, were found to affect parasitoid fitness withlarger parasitoids emerging from larger aphids. A positive influence of conventionalfertiliser on syrphid oviposition in the field was also apparent.
31
Littlefield, Joanne. "Western Flower Thrips on Salad Vegetables: Fighting Insect Pests in Southwestern Arizona". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2006. http://hdl.handle.net/10150/622144.
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32
Palumbo, John C. "Insect Pests in Yuma Winter Vegetables: Review of the 2003-2004 Season". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2004. http://hdl.handle.net/10150/215231.
Testo completoAbstract (sommario):
Insect pest populations seemed to be exceptionally abundant on our desert vegetable crops this past growing season. It is difficult to explain why some insect populations occurred in larger numbers this year, but the weather we experienced may have had a significant role. Hot, dry weather in the early fall and spring, coupled with moderate winter temperatures provided ideal conditions for some insect pests.
33
Åsman, Karolina. "Vegetational diversity as a strategy for reducing pest oviposition in field vegetables /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5813-7.pdf.
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34
Greenfield, Bethany Patricia Jane. "Metarhizium pathogenesis of mosquito larvae". Thesis, Swansea University, 2014. https://cronfa.swan.ac.uk/Record/cronfa42819.
Testo completo
35
Fakude, Moelo Patience. "Eradication of storage insect pests in maize using microwave energy and the effects of the latter on grain quality". Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-01292009-131525.
Testo completo
36
Cozens, Russel David. "Insect and disease risk factors in established interior spruce plantations". Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/24426.
Testo completoAbstract (sommario):
Forest insects and diseases active in immature interior spruce stands in the central interior of British Columbia and their possible implications in forest management practices have been surveyed. Collection records, spanning the period 1949 to 1982, from the Forest Insect and Disease Survey of the Canadian Forestry Service were reviewed for the Prince George Timber Supply Area and the pest incidence in immature interior spruce stands summarized.
Twenty-two plantations, established between 1963 and 1973, were surveyed to determine the relative incidence of the major insect and pathogen pests of immature spruce in Supply Block 'G' of the Prince George Timber Supply Area. A bud midge, likely Rhabdophaga swainei Felt (Diptera: Cecidomyiidae), and a terminal weevil, Pissodes strobi Peck (Coleoptera: Curculionidae), were found to consistently infest and damage a significant number of immature interior spruce trees.
A spruce stand stocking profile was developed as a basis for discussion of management practices in plantations and immature stands. The stocking profile can be used in the determination of not only pest management policy decisions but in stand management decisions affecting stand density and, ultimately, merchantable yield at harvest.
The findings confirmed that forest management must be actively practiced throughout the life of a forest stand. To be successful, however, stand management guidelines and merchantable yield projections are required. These guidelines and projections must include the influences of insects and diseases upon the forest crop in their development model. This information is particularly important in the development of complete Timber Supply Area plans and for the flagging of pest hazard periods during the development of spruce forests.Forestry, Faculty of
Graduate
37
Rust, Nico. "The development of a commercial production process for p-menthane-3,8-diol". Thesis, Nelson Mandela Metropolitan University, 2009. http://hdl.handle.net/10948/d1018273.
Testo completoAbstract (sommario):
The synthesis of p-menthane-3,8-diol via the acid-catalyzed cyclization of citronellal in a dilute aqueous sulphuric acid medium was investigated using conventional batch and continuous systems in order to develop a commercial production process for said p-menthane-3,8-diol (PMD). The batch studies conducted during the first part of this study showed that the formation of PMD from citronellal occurs via an intra-molecular Prins reaction that results in the formation of both the desired PMD product, as well as the partially hydrated isopulegol. It was shown that the formationof the by- product, PMD-acetal, results from the reaction between an intermediate, 5-methyl-2- isopropylcyclohexanol, and the citronellal starting material, and not from the reaction between PMD and citronellal as previously reported. Kinetic studies confirmed the existence of a complicated kinetic model. The formation of PMD from citronellal displayed typical pseudo first order kinetics up to conversions of 70 after which the kinetic model becomes complicated as the result of the establishment of quasi equilibrium reactions between PMD and isopulegol (dehydration of PMD and hydration of isopulegol) and between PMD the PMD-acetal, both systems being acid catalysed. The PMD-acetal formation reaction appears to be second order with respect to PMD. Scale-up studies of the batch process to 30L and 50L scales showed that it would be extremely difficult to limit the level of PMD-acetal formation below the desired level of 1 percent, even if citronellal conversions are restricted to about 50 percent. During studies conducted on a commercially availablemicro-structured organic synthesis plant (OSP) it was shown that it is possible to perform the PMD reaction as a continuous process. The results obtained showed that the use of a micro-mixer such as the caterpillar micro-mixer did not provide enough residence time in order for desirable conversions (- 40 percent) to be obtained. By combining themicro-mixer with delay-loops of different thicknesses and lengths, and using increasing reaction temperatures, it was shown that the conversion of citronellal could be improved to some extent, but compared poorly to the expected conversions for a well-stirred batch reactor. By packing selected delay loops with inert SiC particles, improved mass transfer was observed between the organic and aqueous phases as reflected in the increased conversion of citronellal. Using the observations that were made during the use of the OSP, a continuous-flow, tubular reactor system was designed and constructed. Advanced statistical techniques were used to investigate the effect of variables such as temperature, acid concentration, reactor length, flow rate and the organic to aqueous ratio on the rate and selectivity of the reaction. Mathematical models were derived for citronellal conversion, yield of PMD and yield of PMD- acetals, and used to predict the concentrations of citronellal, PMD and PMD-acetals at set experimental conditions. The results obtained showed that it was possible to obtain a product which approached desired specifications.Downstream processing of the PMD reaction mixture as it exits the reactor requires phase separation and neutralization of the acid catalyst solution, followed by further work-up to recover unreacted starting material and intermediates for recycle back to the synthesis reactor, followed by purification of crude PMD to the desired specification. The study showed that neutralization, prior or after phase separation, does not affect the selectivity of the PMD to such a great extent, but does influence the relative conversion due to extended contact of the catalyst with the organic phase after the reaction is terminated. Recovery of unreacted citronellal and isopulegol could be achieved by a simple vacuum evaporation step, which may either be carried out in a batch manner using traditional distillation equipment, or in a continuous process using wiped-film (short path) techniques. It was also shown that selective crystallization of PMD from the crude product mixture by addition of a solvent, such as heptanes or hexane proved to be the best way of achieving the desired product specification.
38
Nugaliyadde, Lionel. "Factors associated with the resistance of rice (Oryza sativa L.) to Nilaparvata lugens (StaÌŠl)". Thesis, University of Newcastle Upon Tyne, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387408.
Testo completo
39
Adedipe, Folukemi Ebunoluwa. "Investigation of ecological behavior of two Coccinellidae beetle adults for biological control". Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10491.
Testo completoAbstract (sommario):
Thesis (M.S.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains vii, 60 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
40
Kerns, David L., e John C. Palumbo. "Confirm and Success: New Tools for Insect Management in Cole Crops and Leafy Green Vegetables in Arizona". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1997. http://hdl.handle.net/10150/146759.
Testo completo
41
Netshifhefhe, Shandukani Rudolf. "The compilation of indigenous knowledge regarding insect pests in small-scale farming communities in North Eastern South Africa". Pretoria: [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-06302005-113354.
Testo completo
42
Rogers, Richard E. L. "Insect and mite monitoring in commercial apple orchards in Nova Scotia (1979-1985)". Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=65368.
Testo completo
43
Njoroge, Anastasia Wanjiru [Verfasser]. "Acoustic detection of insect pests of stored grains in Kenya / Anastasia Wanjiru Njoroge". Kassel : Universitätsbibliothek Kassel, 2017. http://d-nb.info/1151463493/34.
Testo completo
44
Turner, David Edward. "Reduced dose rate insecticide use in cereals : effects on insect pests and predators". Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296165.
Testo completo
45
Hinchliffe, Gareth. "Novel biopesticides based on recombinant avidin for protection of crops against insect pests". Thesis, Durham University, 2012. http://etheses.dur.ac.uk/6907/.
Testo completoAbstract (sommario):
Farmers are required to increase their food productivity to meet the demand from a continually enlarging population. A major constraint on meeting this requirement is the damage created by insect pests. Agricultural pests and associated diseases destroy 30%-40% of the world’s crop produce. The withdrawal of broad-spectrum chemical insecticides, the threat of the development of resistance in insect pests to remaining compounds and the possibility of new pest species spreading into the UK as a result of environmental change have prompted research into alternative pesticides. Protein-based insecticides offer the possibility of producing compounds that are specific to pest species and environmentally benign. The production of orally active insecticidal fusion proteins, containing toxins from Segestria florentina (tube-web spider) or Mesobuthus tamulus (Indian red scorpion) fused to a ‘carrier’ protein (snowdrop lectin; Galanthus nivalis agglutinin; GNA) which transports them across the insect gut epithelium, has shown that recombinant protein expression systems and protein engineering techniques can be used to produce novel insecticidal proteins. The main aim of the work described in this thesis is to extend this technology. Avidin, a biotin-binding protein known to be insecticidal, was evaluated as a possible ‘carrier’ protein. Recombinant avidin was produced in high yields using Pichia pastoris and was compared to the native egg white protein. Recombinant avidin has insecticidal activity towards hemipteran plant pests. It was highly toxic to Acyrthosiphon pisum (pea aphid) when fed in liquid artificial diet, causing 100% mortality after four days when present at concentrations ≥0.25mg/ml (250ppm). The toxicity towards A. pisum was prevented by biotin supplementation of the diet. In contrast, recombinant avidin had no significant effects on the survival of Sitobion avenae (cereal aphid) at concentrations up to 2mg/ml (2000ppm) in liquid diet. Analysis of genomic DNA showed that symbionts from both aphid species lack the ability to synthesise biotin de novo. Cereal aphids appear to be less sensitive to sub-optimal levels of biotin and possess a more effective system for scavenging biotin from recombinant avidin in the diet. Avidin is readily transported to the haemolymph of lepidopteran larvae after feeding, which suggested that it might replace GNA in synthetic insecticidal fusion proteins. Numerous attempts were made to produce a fully functional insecticidal avidin-based fusion protein containing scorpion or spider toxins by expression as recombinant proteins in P. pastoris but, following tests against Mamestra brassicae (cabbage moth) larvae, the fusion proteins were found to be non-toxic. The lack of toxicity was most likely due to incorrect folding of the toxin component of the fusion, since the avidin component was functional. Avidin fed to A. pisum was found to bind to the stomach region of the gut after ingestion and was retained for at least 72 hours. Feeding conjugates of avidin with fluorescently labelled biotin, or a fluorescently labelled, biotinylated peptide, showed that the conjugated compound was also retained in the aphid gut after feeding. A conjugate between avidin and biotinylated leucomyosuppressin (LMS), a myoinhibitory peptide hormone that affects gut contractions in insects, was prepared and fed to aphids. The avidin : biotin-LMS conjugate had insecticidal activity towards A. pisum when fed in diet at levels which neither of the components (avidin or biotin-LMS) caused significant mortality. It was hypothesised that binding to the gut, through the avidin moiety, was responsible for the observed oral toxicity of the avidin : biotin-LMS conjugate. The same principle was applied to lepidopteran larvae. A conjugate between avidin and biotinylated allatostatin was prepared and fed to M. brassicae larvae. The avidin : biotin-allatostatin was non-toxic, most likely due to cleavage between the biotin molecule and allatostatin as a result of the high levels of gut proteolysis in lepidoptera. Avidin conjugates of peptides that have little or no oral toxicity to insects, as a result of restricted access to sites of action, could have the potential to form a novel class of insecticidal compounds.
46
Crespo-Pérez, Maria Veronica. "Global changes and distribution modeling of invasive insect pests in the Tropical Andes". Paris 6, 2012. http://www.theses.fr/2012PA066013.
Testo completoAbstract (sommario):
La physiologie, le comportement et la distribution des insectes sont grandement influencés par la température. La compréhension de la réponse des insectes à la température permet de développer de modèles capables de simuler leurs dynamiques spatio-temporelles. De tels modèles représentent des outils intéressants afin d’améliorer le contrôle intégré des ravageurs car ils permettent d’identifier les risques liés a ces espèces. La présente étude a pour objectif de développer plusieurs stratégies de modélisation de la distribution et propagation de ravageurs invasifs de la pomme de terre dans la région Nord andine. D’abord, nous avons développé un automate cellulaire simulant la dynamique d’invasion des ravageurs en prenant en compte l’influence de l’activité anthropique sur la propagation. Ensuite, nous avons développé des modèles capables de simuler l’influence de l’hétérogénéité thermique et de simuler les dynamiques en présence de jeux de données limités. Enfin, nous avons construit un modèle individu centré permettant de simuler les dynamiques en réponse à la température. Ce modèle nous a permis de réaliser des cartes de risque présent et futur d’invasion à l’échelle de la région Nord-andine. Ce travail montre l’importance de l’hétérogénéité environnementale et sociale sur la propagation des ravageurs. Les modèles développés dans cette thèse pourront être appliqués dans des programmes de contrôle intégré des ravageurs afin de présenter aux agriculteurs de la région les risques d’évolution de l’infestation en relation avec leurs pratiques culturales et les changements globaux.
47
Hamilton, Amanda Jane. "Discovery and development of new phylloplane bio control agents to control insect pests". Thesis, University of Reading, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.701806.
Testo completoAbstract (sommario):
Aphids cause considerable harm to a variety of crops each year due to damage from feeding and the transmission of viruses. Effective, conventional pesticides that are authorised for use are in continuous decline; simultaneously many of the current biological pesticides fail to meet required efficiency. Increasing demands for improved food security mean that a solution for this problem is needed. Plant surfaces are well known to provide a niche for many bacteria. Some species of bacteria possess pathogenic qualities and are known to kill or incapacitate insects. Therefore there is the potential for the discovery of a direct bacterial application, or the opportunity to manipulate the crop environment in order to encourage the colonisation of these beneficial bacteria. In this project we aim to identify bacteria from plants and screen them for toxicity against aphids and their relatives. Investigations will be carried out into their host specificity, methods of pathogenicity, and potential application methods, with the hope of identifying suitable bacteria for use as a pesticide.
48
Rabin, Daniel. "Using Computer Imaging to Assess Visual Impacts of Forest Insect and Disease Pests". DigitalCommons@USU, 1989. https://digitalcommons.usu.edu/etd/6446.
Testo completoAbstract (sommario):
Forest insect and disease pests alter the appearance of trees, thereby impacting visual resources. Because of the complexity of most forest landscapes, the degree of visual impact of pest-infested forest stands is difficult to quantify.
This paper describes a method of measuring visual impacts of pest-infested forest stands. Photographs of healthy Ponderosa pine trees were entered into a computer video-image-processing system. Using this system, images of trees were altered to simulate different degrees of infestation by limb rust, a forest pathogen.
The altered and unaltered images were shown to groups of observers who rated the scenes in terms of "scenic beauty." The great majority of individuals were able to detect a change in the appearance of trees infected with limb rust disease even when only small sections of a tree were altered. There was also general agreement within the groups of observers that the presence of limb rust disease had a detrimental effect on the visual quality of the forest scenes. The tests also suggested that the location of infestation in the tree crown, the amount of crown mortality, and the number of infected Ponderosa pine in a stand influenced the degree to which visual quality was impacted.
49
Chavan, S. B. "Biocontrol of insect pests in agriculture using chitinolytic enzyme complex of myrothecium verrucaria". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2009. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2734.
Testo completo
50
Scholtz, Anna J. "Evaluation of the large-scale trapping of blowflies (Lucilia spp.) for an integrated pest management program : the lucitrap". Thesis, Port Elizabeth Technikon, 2003. http://hdl.handle.net/10948/126.
Testo completoAbstract (sommario):
The results presented in this dissertation have been partially presented at scientific meetings. Chapter 2 is an exact copy of the technical contents of a paper submitted to a scientific journal. The format of this paper however has been changed to comply with the format used in this dissertation. The results of this paper were partially presented at the 36th National Congress of the South African Society of Animal Science, 5 – 8 April 1998 held in Stellenbosch. In this chapter errors occurred in the execution of the trial, but these were corrected in the follow-up trial after consulting with the manufacturers. It is discussed in the paper. Results of chapter 3 were partially presented at the 5th International Sheep Veterinary Congress 21 – 25 January 2001 held in Stellenbosch and at an International Congress (The FLICS (Flystrike & Lice IPM Control Strategies) Conference, 25 – 27 June 2001, Launceston) in Tasmania by Mr. S.W.P. Cloete in 2001. The updated results are given in this chapter. The results of chapter 4 were presented at a combined congress between the Grasslands and the Animal Production Societies of South Africa (The GSSA/SASAS Joint Congress 2002. 13 – 16 May) in Christiana in 2002. The results in this chapter represent the same experimental period as was reported upon at that congress, but additional statistical analyses were executed on the same data set. Copies of the abstracts of the contributions to these meetings are attached in chapter 6. The major objective of this study initially was to evaluate the Lucitrap® system under South African conditions. During the experimental period I had an opportunity to visit Australia and meet many role players. It came under my attention that the control of the blowfly is a rather complex problem with many facets. A current issue worldwide on the use of chemicals as a control method against insects and its hazardous influence on the environment is forcing producers to minimize chemical residues in textiles and other agricultural products. An Integrated Pest Management (IPM) approach seems to be the only option. This study has been executed to try and understand some aspects of the blowfly problem for future application in such a blowfly control program.