Submitted by (edna.saturno@ufrpe.br) on 2016-11-24T15:23:56Z No. of bitstreams: 1 Glaucilane dos Santos Cruz.pdf: 1016632 bytes, checksum: cf89201a0bacd4f7695775c34d5d1ad4 (MD5) / Made available in DSpace on 2016-11-24T15:23:56Z (GMT). No. of bitstreams: 1 Glaucilane dos Santos Cruz.pdf: 1016632 bytes, checksum: cf89201a0bacd4f7695775c34d5d1ad4 (MD5) Previous issue date: 2012-02-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A large investment is annually demanded to control the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), which is the major insect pest of corn. To contain this demand alternative methods have been developed, including the use of botanical insecticides, known as essential oils, and entomopathogenic agents such as the bacterium Bacillus thuringiensis Berliner. These alternatives are adequate to Integrated Pest Management purposes, by being selective, low toxic to mammals and present efficiency against various pest species. Thus, we tested the hypothesis that association of long pepper and cloves oils at the concentrations of 30 and 50 mg/L DMSO with Xentari® WG (B. thuringiensis subsp. aizawai - Bta) (1000 mg/L) produces an efficient control of S. frugiperda, affecting biological, immunological and reproductive parameters, and if those concentrations of these oils affect spermatogenesis, the histochemistry of the ovarioles, as well as its impact on fertility. The results demonstrated that long pepper essential oil at a concentration of 50 mg/L associated with Bta has promoted lower larval survival, and clove does not proved efficient when combined with the Bta formulated. However, both oils, associated or not to Bta, interfered on the biology and humoral immunity of S. frugiperda. All treatments showed ovicidal effect except clove oil at the two concentrations without Bta. Histological analysis showed that clove and long pepper oils at the concentrations of 30 and 50 mg/L have affected spermatogenesis and the histochemistry of the ovarioles of S. frugiperda, reflecting on their reproduction. However, the effects of long pepper oil associated or not to Bta were more expressive, proving to be a promising tool to control this pest, adapting to MIP, controlling the survival of offspring and its success in the culture. / Anualmente demanda-se um alto investimento no controle da lagarta do cartucho Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), sendo esta a principal praga da cultura do milho. Para conter esta demanda métodos alternativos tem sido desenvolvidos, incluindo a utilização de inseticidas botânicos, conhecidos como óleos essenciais, e agentes entomopatogênicos, como a bactéria Bacillus thuringiensis Berliner. Estas alternativas adéquamse aos propósitos do Manejo Integrado de Pragas, por serem seletivos, de baixa toxicidade a mamíferos e apresentarem eficiência contra várias espécies de pragas. Assim, testou-se a hipótese de que a associação dos óleos de pimenta longa e cravo da Índia nas concentrações 30 e 50 mg/L DMSO com Xentari® WG (B. thuringiensis subsp. aizawai - Bta) (1000 mg/L) produzem um controle eficiente de S. frugiperda, afetando parâmetros biológicos, imunológicos e reprodutivos, e se as concentrações destes óleos afetam a espermatogênese, a histoquímica dos ovaríolos, bem como seu impacto na fertilidade. Os resultados demonstraram que o óleo de pimenta longa na concentração 50 mg/L associado ao Bta ocasionou menor sobrevivência larval, já o cravo da Índia não mostrou-se eficiente quando associado ao Bta formulado. Porém, ambos os óleos associados ou não ao Bta interferiram na biologia e na imunidade humoral de S. frugiperda. Todos os tratamentos afetaram a viabilidade dos ovos exceto a testemunha e o cravo da Índia nas duas concentrações sem Bta. A análise histológica mostrou que os óleos de pimenta longa e cravo da Índia nas concentrações 30 e 50 mg/L afetaram a espermatogênese e histoquímica dos ovaríolos de S. frugiperda, refletindo na sua reprodução. No entanto, os efeitos do óleo de pimenta longa, associado ou não ao Bta, foram mais expressivos, demonstrando ser uma ferramenta promissora no controle desta praga, adequando-se ao MIP, controlando a sobrevivência da prole e seu sucesso na cultura.

Submitted by (edna.saturno@ufrpe.br) on 2016-11-28T11:56:50Z No. of bitstreams: 1 Lilian Maria da Solidade Ribeiro.pdf: 1291994 bytes, checksum: 217ae867676a57b323ee75ec19d87a49 (MD5) / Made available in DSpace on 2016-11-28T11:56:50Z (GMT). No. of bitstreams: 1 Lilian Maria da Solidade Ribeiro.pdf: 1291994 bytes, checksum: 217ae867676a57b323ee75ec19d87a49 (MD5) Previous issue date: 2010-02-01 / The resistance of Plutella xylostella (L.) (Lepidoptera: Plutellidae) has been attributed to many mechanisms as alterations in cell membrane receptors on midgut and the immune response to Bacillus thuringiensis Berliner toxin. The research tested the possibility that after expositions to Bt formulations, insects from a susceptible population (SP) and a resistant population (RP) presented qualitative and quantitative differentiated alterations of hemocytes and nitric oxide levels in hemolymph, histopathological and histochemical differenced alterations in midgut and that RP presented capacity of recovery midgut. SP and RP were exposed to Dipel® 1,35 mg/L (SP), 64,93mg/L (RP); XenTari® 5,17 mg/L (SP), 236,24 mg/L (RP) plus witness had hemolymph collected in intervals of 1, 6 and 12 h for total and differential counting of hemocytes and quantification of nitric oxide. The midgut was collected in the intervals: 0, 1, 6, 12 h. The regenerative cells quantification was made through the ImageLab 2000 program. In spite of RP had showed less number of hemocytes, it exhibited greater quantity of plasmatocytes, prohemocytes and spherulocytes, this can be related to resistance. Dipel® was effective in reduction of total numbers of hemocytes of SP and RP, while XenTari® changed significantly the differential counting. The nitric oxide increased in both populations and it not differed between the insecticides, indicating the no participation of it in the resistance. The insecticides induced alterations in different intensities on midgut in SP and RP, Dipel® showed to be more aggressive independently of population, taking to degeneration of epithelium. The presence of spherites covering the epithelial lamina, the hypertrophy of columnar cells and mucus abundance can be involved in midgut preservation in larvae of resistant population, however these features were not sufficient to avoid the degeneration of epithelium or induce the hyperplasia of regenerative cells. / A resistência de Plutella xylostella (L.) (Lepidoptera: Plutellidae) pode ser atribuída a vários mecanismos como alterações nos receptores de membrana celular no mesêntero e a resposta imune às toxinas do Bacillus thuringiensis Berliner. A pesquisa testou as hipóteses de que após exposição a formulações Bt: população suscetível (PS) e população resistente (PR) da traça apresentam alterações quantitativas e qualitativas diferenciadas dos hemócitos e dos níveis de óxido nítrico na hemolinfa, alterações histopatológicas e histoquímicas diferenciadas no mesêntero e de que PR apresenta capacidade de recuperação do mesêntero. PS e PR expostas ao Dipel® 1,35 mg/L (PS), 64,93mg/L (PR); XenTari® 5,17 mg/L (PS), 236,24 mg/L (PR), além da testemunha, tiveram hemolinfa coletada nos intervalos de 1, 6 e 12 h para contagem total e diferencial dos hemócitos e quantificação de óxido nítrico. O mesêntero foi coletado nosintervalos: 0, 1, 6 e 12 h. A quantificação das células regenerativas foi efetuada através do programa ImageLab 2000. Apesar de PR ter apresentado menor número de hemócitos, exibiu maior quantidade de plasmatócitos, prohemócitos e esferulócitos, podendo isto estar relacionado à resistência. Dipel® foi efetivo na redução do número total de hemócitos das PS e PR, enquanto que o XenTari® alterou significativamente a contagem diferencial. O óxido nítrico aumentou emambas as populações, não diferindo entre os inseticidas, indicando a não participação deste na resistência. Os inseticidas ocasionaram alterações, de intensidades diferentes, no mesêntero das PS e PR, Dipel® mostrou ser mais agressivo independente da população, levando a degeneração do epitélio. A presença de esferites revestindo a lâmina epitelial, a hipertrofia das células colunares e a riqueza de muco podem estar envolvidas na preservação do mesêntero em larvas da população resistente, porém essas características não foram suficientes para impedir a degeneração do epitélio ou induzir a hiperplasia das células regenerativas.

Submitted by (edna.saturno@ufrpe.br) on 2016-11-28T13:38:03Z No. of bitstreams: 1 Maria Esmeralda Cavalcante de Sousa.pdf: 1237941 bytes, checksum: 5d11b8c813aa997680f772fa30705f65 (MD5) / Made available in DSpace on 2016-11-28T13:38:03Z (GMT). No. of bitstreams: 1 Maria Esmeralda Cavalcante de Sousa.pdf: 1237941 bytes, checksum: 5d11b8c813aa997680f772fa30705f65 (MD5) Previous issue date: 2009-02-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The cotton leafworm, Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) is an important cotton pest in Brazil, occurring almost in the whole growing season and causing economic losses between 21 and 35%. Bt cotton expressing Cry1Ac protein, a toxin from the bacterium Bacillus thuringiensis (Berliner) (Bt), has recently been released in Brazil. It is resistant to the main cotton lepidopteran pests occurring in Brazil. Bt toxins must interact with a receptor to trigger a toxic effect, although other endogenous factors may account for the differential Bt toxins selectivity towards insects. Therefore, studies on the Cry1Ac interaction with the cotton pests midguts are important to understand insect responses when exposed to the Bt cotton. Then, the aim of this work was to provide an histochemical, morphological, and ultrastructural description of the midgut of A. argillacea larvae fed with the isoline cotton (AcalaDTL-90) and the Bt cotton (AcalaDTL-90B). The morphological, histochemical, and ultrastructural characteristics of the A. argillacea midgut were very similar to those previously described for most lepidopterans. However, the mitochondrial polymorphism and bifurcate microvilli suggest an ultrastructural and physiological modification, which may cause a higherabsorption and secretion in the columnar cells. Such hypothesis may account for faster toxin and/or microbial agent action, suggesting that this species may be highly susceptible to some ofthese agents. After 20 min, A. argillacea 4th-ínstar larvae feeding on Bt cotton leaves (AcalaDTL-90B) showed alterations on the midgut walls. During that time, morphological and ultrastructural alterations in the goblet and columnar cells were observed, although more prominent on the former. Also, a reduced number of regenerative cells, a deterioration of the muscle layer, and the peritrophic membrane destruction in some midgut regions were observed. The study overall conclusion is that the Cry1Ac toxin acts relatively fast in the A. argillacea midgut, causing severe and irreversible alterations. / Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) é a principal praga desfolhadora da cultura do algodão, provocando perdas entre 21 e 35%. Plantas transgênicas que expressam proteínas tóxicas de genes da bactéria Bacillus thuringiensis (Berliner) (Bt) foram recentemente liberadas no Brasil. O algodão Bt AcalaDTL-90B, que expressa a proteína Cry1Ac, é resistente às principais pragas da Ordem Lepidoptera que afetam a cultura do algodão.. Embora as toxinas de Bt interajam com pelo menos um receptor final, desencadeando o efeito tóxico, vários fatores endógenos estão associados à seletividade diferencial das toxinas Bt. Desta forma, estudos da interação da Cry1Ac com o intestino de insetos pragas do algodoeiro são de fundamental importância. Assim, esta pesquisa objetivou descrever histoquimicamente, morfologicamente e ultra-estruturalmente o mesêntero de larvas de A. argillacea alimentadas com a isolinha (AcalaDTL-90), bem como algodão-Bt (AcalaDTL-90B). As características morfológicas, histoquímicas e ultra-estruturais do mesêntero de A argillacea, de modo geral, foram semelhantes às descritas na literatura para a maioria dos insetos da Ordem Lepidoptera. No entanto, opolimorfismo mitocondrial e microvilosidades bifurcadas sugerem uma modificação ultra-estrutural e fisiológica, que pode ocasionar uma maior absorção e secreção nas células colunares. Tal hipótese pode favorecer uma ação mais rápida de toxinas e/ou agentes microbianos,sugerindo que esta espécie pode ser altamente suscetível para alguns destes agentes. Larvas de 4º ínstar após 20 min de alimentação com folhas de algodão Bt (AcalaDTL-90B) mostraram modificações na parede do mesêntero de A. argillacea. Neste tempo de alimentação, foram observadas alterações morfológicas e ultra-estruturais nas células colunares e caliciformes, sendo mais expressivas nessas últimas. Também houve uma redução no número das células regenerativas, degeneração da camada muscular e destruição da membrana peritrófica em algumas regiões do mesêntero. Assim, conclui-se que a toxina Cry1Ac age relativamente rápida no mesêntero da A. argillacea, ocasionando alterações drásticas e irreversíveis.

Submitted by (edna.saturno@ufrpe.br) on 2016-12-02T11:16:10Z No. of bitstreams: 1 Marcileyne Pessoa Leite de Lima.pdf: 517075 bytes, checksum: b7ddab703563527f0c2b8e77f710122c (MD5) / Made available in DSpace on 2016-12-02T11:16:11Z (GMT). No. of bitstreams: 1 Marcileyne Pessoa Leite de Lima.pdf: 517075 bytes, checksum: b7ddab703563527f0c2b8e77f710122c (MD5) Previous issue date: 2008-02-04 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The synthetic insecticide is the main method used to control Spodoptera frugiperda (J.E. Smith). However, the inadequate application of the insecticide has contributed to increase costs, reduction of the natural enemies, and selection of resistant populations, among other problems. Attempting to obtain alternative control of S. frugiperda more ecologically acceptable, the present work investigated the effects of neem (Azadirachta indica A. Juss) and Bacillus thuringiensis subsp. aizawai (Bta) on S. frugiperda under laboratory, greenhouse and field conditions. In the field, the commercial formulations of Natuneem® (10 mL/L in 2005 and 15 mL/L in 2006) and Neemseto® (5 and 10 mL/L in 2005, and 10 and 15 mL/L in 2006) and the biological insecticide Xentari® (10 g/L in 2005 and 2006) were applied at 15, 30 and 45 and at 15, 25 e 35 days after plant emergency in 2005 and 2006, respectively. Thee evaluations consisted of using a scale of foliar injury from 0 to 5 prior each spray. In 2005, only Neemseto® 10 mL/L was efficient at 30 days. In 2006, Neemseto® 15 mL/L and Xentari® with average score of 0.93 and 0.98, respectively, were different from the control, which produced a score of 2.38 at 35 days after plant emergency. The greenhouse assay consisted of treatment of plants 40-days old with the insecticides Natuneem®, Neemseto® and Xentari® followed by artificial infestation with newly-hatched larvae of S. frugiperda. After 10 days, it was verified that the treatment were equally efficient, differing from the control, regarding to the injury score, as well as, the number of surviving larvae. In the last bioassays, in the laboratory, 10-days old S. frugiperda larvae were fed with corn leaves treated with the insecticides Natuneem®, Neemseto® and Xentari® at 2.5; 5.0; 7.5; 10 mL or g/mL and control (water). The effect of the insecticides increased as function of increasing concentration, causing higher larval mortality, longer period and lower larval weight. In some cases, reduction of pupa weight and viability and longevity of adults were also verified. Larvae 0-24 h old were more susceptible to the insecticides, as compared with 10-days old larvae. / A utilização de inseticidas sintéticos tem sido o principal método de controle de Spodoptera frugiperda (J.E. Smith), mas o uso inadequado tem contribuindo para o aumento do custo de produção, redução de inimigos naturais, seleção de populações resistentes, entre outros problemas. Desta forma, buscando alternativas de controle mais ecológicas, estudou-se no presente trabalho os efeitos de nim (Azadirachta indica A. Juss) e Bacillus thuringiensis subsp. aizawai (Bta) sobre S. frugiperda em experimentos de laboratório, casa de vegetação e campo. Foram testadas em campo formulações comerciais de inseticidas botânicos Natuneem® (10 mL/L em 2005 e 15 mL/L em 2006) e Neemseto® (5 e 10 mL/L em 2005, e 10 e 15 mL/L em 2006) e do inseticida biológico Bta (Xentari® 10 g/L em 2005 e 2006), aplicados aos 15, 30 e 45 e aos 15, 25 e 35 dias após a emergência das plantas em 2005 e 2006, respectivamente. Antes de cada pulverização foram atribuídas notas de 0 a 5 para as injúrias foliares. Em 2005, somente Neemseto® 10 mL/L foi eficiente aos 30 dias. Em 2006, Neemseto® 15 mL/L e Bta 10 g/L, com notas médias de 0,93 e 0,98, diferiram da testemunha, com nota 2,38, na avaliação realizada aos 35 dias. Plantas de milho, com cerca de 40 dias de idade, foram pulverizadas em casa de vegetação com os inseticidas Natuneem®, Neemseto e Bta, e posteriormente infestadas,artificialmente, com lagartas de S. frugiperda recém-eclodidas. Após 10 dias verificou-se que os tratamentos foram igualmente eficientes, diferindo da testemunha, tanto em relação às notas, quando ao número de lagartas sobreviventes. Nos últimos bioensaios lagartas de S. frugiperda com 10 dias de idade foram alimentadas com folhas de milho submersas na calda inseticida nas concentrações 2,5; 5,0; 7,5; 10 mL ou g/L e testemunha (água). Os efeitos dos inseticidas dependeram da concentração utilizada, pois provocaram mortalidade crescente das lagartas, alongaram o período e reduziram o peso larval. Em alguns casos, também, reduziram o peso e a viabilidade pupal e a longevidade de adultos. Lagartas com 0-24 h de idade foram mais susceptíveis aos inseticidas, em relação às com 10 dias de idade.

No description available.

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Double-cropping of corn (Zea mays L.) for grain following the harvest of a small grain crop has been under evaluation in Virginia as an alternative cropping strategy (Brann and Pitman, 1997). To assess the potential constraints on late planted corn imposed by insects and diseases, double-cropped corn was evaluated in field experiments in Montgomery County, Virginia from 1998 to 2000. Factors included two near-isoline hybrids (NK4640 and NK4640Bt), insecticides at planting (tefluthrin in all years, 1998-2000; and imidacloprid in 1999 and 2000), and fungicide treatments (azoxystrobin or propiconazole). Response variables included yield, moisture at harvest, grain test weight, damage by European corn borer (Ostrinia nubilalis), damage by corn earworm (Heliothis zea), disease progress curves for gray leaf spot Cercospora zeae-maydis), and number of plants exhibiting virus symptoms. The Bt hybrid performed significantly better than the non-Bt hybrid for yield and test weight in double-cropped corn in 1998 and 2000, but not in 1999. A spatially referenced site suitability analysis was performed for full season and double-cropped corn in Virginia using weighted abiotic factors and constraints. Thornthwaite potential evapotranspiration (PET) and PET minus precipitation were used to identify areas of the state having a lower average moisture deficit during the silking months for double-cropped corn compared to full-season corn. It is concluded that double-cropped corn production is a viable option in Virginia where abiotic factors are not constraining, particularly growing season length and moisture availability during the sensitive stages of development. / Master of Science

Roughly 79-100% of maize in the United States (US) is treated with a neonicotinoid seed treatment (NST), and transgenic (GMO) maize, Zea mays L. (Poaceae), that produces insecticidal toxins by way of genes derived from Bacillus thuringiensis (Bt), occupies more than 75% of maize acreage. Among a variety of secondary pests targeted by NSTs, the primary soil-dwelling pest targeted by Bt maize is the western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae). Transgenic Bt technology has dramatically reduced insecticide use for WCR, and insect resistance poses the greatest threat to its utility. To delay resistance to Bt traits, in 2010 the US Environmental Protection Agency (EPA) approved a "refuge-in-a-bag" (RIB) insect resistance management (IRM) strategy, where 5% of seeds do not express Bt toxins (i.e., "refuge" maize). The RIB strategy is intended to preserve Bt trait effectiveness if mating between 'resistant' insects from Bt plants and 'susceptible' insects from refuge plants occurs at a high enough frequency. Investigations into the effectiveness of RIB for WCR have shown that beetles emerged from Bt plants tend to vastly outnumber beetles emerged from refuge plants, which contributes to low rates of mixed mating. Large proportions of Bt beetles is one of several factors that contributes to resistance development, and resistance to all currently-available WCR-Bt traits has been documented. I conducted field experiments in two regions (Indiana and Virginia) comparing refuge beetle proportions in NST-treated (NST+) and NST-untreated (NST-) 5% RIB maize, to determine whether NSTs may be limiting refuge beetle emergence. To assess advantages of combining use of Bt and NSTs, I compared stand, root injury rating, and yield between NST+, NST-, Bt and non-Bt maize in both states. I also measured neonicotinoid residues in soil, water, and stream sediment within and surrounding fields of maize, to study the off-site movement and soil residence time of these compounds. I found that 5% seed blends did not produce large populations of refuge beetles in any site-year, and that NSTs showed inconsistent effects on refuge beetle populations. Treatment comparisons showed inconsistent benefits of NSTs when combined with Bt traits. I detected neonicotinoid residues in soil matrices throughout the growing season (range: 0 – 417.42 ppb), including prior to planting, suggesting year-round presence of these compounds. My results suggest that, while the effects of NSTs on Bt IRM may be inconsistent, the benefits of universally applying NSTs to Bt maize for soil pests may not be worth the ecological costs of doing so in all cases. / Doctor of Philosophy / About 75% of maize planted in the United States is encoded with genetic traits allowing them to manufacture insecticidal proteins which are toxic to key pests. These insecticidal proteins, known as "Bt toxins," are highly specific to targeted insects, and are virtually non-toxic all other animals and non-target insects. One target insect is the western corn rootworm (WCR), which feeds on and damages maize roots. In the past, WCR was controlled by applying millions of kilograms of chemical insecticides every year, at ever-increasing rates, to compensate for reduced effectiveness due to pest resistance. "Bt" plants, were released for commercial use in the late 1990s; they reduced the need for growers to apply chemical insecticides for managing key pests. The Environmental Protection Agency established regulations aiming to maintain the effectiveness of Bt technology, which they declared have "provided substantial human health, environmental, and economic benefit." This Insect Resistance Management (IRM) strategy, also known as the "refuge" strategy, is meant to preserve Bt-susceptible insects so they can pass on their Bt-susceptible genes to successive generations. The refuge strategy works by incorporating a certain percentage of non-Bt plants per every field of Bt plants; if enough insects survive on these "refuge" plants to outnumber "resistant" insects, population-wide Bt-susceptibility may be maintained. While this strategy has been effective for other key maize pests, it is failing for WCR, evidenced by WCR populations that have developed Bt-resistance. We know current refuge configurations aren't producing enough refuge-WCR to mix sufficiently with resistant WCR, likely due to insufficient refuge sizes. I wanted to know whether the refuge strategy could be improved, if increasing refuge proportions is not an option. Considering that Bt toxins are only effective against a narrow range of insects, seed manufacturers always coat seeds with an insecticide to protect seedlings against other insects. These coatings, or neonicotinoid seed treatments (NSTs), are included on nearly all seed, including those reserved for Bt refuges. I conducted two years of field trials to investigate whether removing NSTs from refuge seeds would improve WCR-IRM by providing an insecticide-free "refuge." My results suggest that removing NSTs may increase refuge beetle proportions, however my results also show that refuge plant proportions are simply too small to support large enough refuge-WCR populations to delay resistance, regardless of whether NSTs are present or not. While NSTs may provide extra comfort to growers at little additional cost, questions regarding their necessity at current use patterns have been raised. Several studies have shown inconsistent benefits, and others have shown longer-than-expected persistence in the environment, movement into streams and groundwater, and even alterations to insect and non-insect animal communities associated with their use. I conducted research comparing their relative effectiveness against WCR and non-WCR insect pests in fields of Bt maize. Additionally, I scouted for their residues in soil collected in field margins, forests buffering streams, and in water collected from agricultural ditches and waterways neighboring fields. I found that, while NSTs produced higher plant populations, they rarely resulted in greater yields. I detected neonicotinoid residues in soil matrices throughout the growing season, including prior to planting, suggesting year-round presence of these compounds. My results suggest that, while the effects of NSTs on Bt IRM may be inconsistent, the benefits of universally applying NSTs to Bt maize for soil pests may not be worth the ecological costs of doing so in all cases.

Brinjal shoot and fruit borer (Leucinodes orbonalis Guenee) is a major limiting factor in commercial cultivation of eggplant in southeast Asia. Extensive use of pesticides as well as the conventional breeding methods have been ineffective in controlling the borer so there is a need for Integrated Pest Management (IPM) strategies for its control. Bacillus thuringiensis (Bt) is known to produce a variety of insecticidal crystal proteins toxic to lepidopteran, dipteran and coleopteran pests. The Cry2Aa protein has been found to be more toxic to brinjal shoot and fruit borer than Cry1Ab. My objective was to develop eggplant cultivars that express a codon-optimized cry2Aa gene, the sequence of which is based on that of an Indian isolate of Bt, with the eventual goal of producing fully resistant cultivars. The cry2Aa gene was modified for optimal expression in eggplant using the codon usage frequencies based on solanaceous sequences (eggplant, tomato and pepper). The GC content was increased from 34.3% in the native gene to 41.3% in the optimized gene, thus removing the AT-rich regions that are typical for Bt cry genes. Also, other mRNA destabilizing and hairpin forming structure sequences were removed. The gene was synthesized in four different parts with complementary restriction sites. A total of 152 oligonucleotides (oligos) was used to assemble the 1.9 kb gene using dual asymmetric (DA) and overlap extension (OE) PCR techniques. The individual parts were subsequently ligated using the complementary restriction sites and inserted into vector pCAMBIA 1302. Also, the transformation efficiency of 12 different eggplant cultivars was tested using plasmid pHB2892 to predict utility for transformation with the synthetic cry2Aa. / Master of Science

Depuis plus de 20 ans, l'insecticide microbien Bacillus thuringiensis var. kurstaki (Btk) est appliqué au Québec afin de réduire les impacts négatifs de la tordeuse des bourgeons de l'épinette (TBE) (Choristoneura fumiferana (Clem.)) sur la ressource ligneuse. Mais, qu'en est-il de sa rentabilité ? En période épidémique, le territoire forestier québécois ne peut être protégé en totalité en raison de sa grande superficie et de la récurrence annuelle des attaques de l'insecte ce qui impliquerait des coûts de protection cumulatifs très élevés. Dans le contexte forestier actuel et devant l'éventuel retour d'une épidémie de la tordeuse des bourgeons de l'épinette, il devient primordial d'identifier les aires à traiter sur la base des pertes anticipées en incluant les effets de l'insecte et des traitements sur la croissance. Ce questionnement est abordé dans ce projet de recherche, plus spécifiquement sur le sapin baumier, l'essence de prédilection de la tordeuse des bourgeons de l'épinette. Dans le sud-ouest du Québec, l'accroissement annuel de trois catégories (traités, non-traités et sans TBE) de peuplements mélangés de sapin baumier (Abies balsamea (L.) Mill) a été mesuré pendant une période de neuf années consécutives (1994-2002), alors qu'à différents intervalles de temps, des traitements au Btk ont été appliqués afin de réduire la défoliation causée par la tordeuse des bourgeons de l'épinette. Cette recherche démontre que les opérations de pulvérisations aériennes d'insecticide biologique s'avèrent rentables en protégeant 66% de la capacité photosynthétique. Également, grâce à ces opérations aériennes, les peuplements traités ont conservé des niveaux de croissance et de mortalité d'arbres similaires à ceux sans TBE.