Academic literature on the topic 'Bt soybean'

Abstract The use of GMO expressing Bt toxin in soybean production has increased significantly in the last years in Brazil in order to manage the damage caused by lepidopteran pests. In this study, we compared the richness and abundance of owlet moths (Noctuoidea) associated with Bt and non-Bt soybean. We determined the temporal variations as a function of phenology, and correlated the population variations of the most common species with meteorological variables. The research was conducted at the experimental area of Embrapa Cerrados. The collection method used was differentiated being suppressive and absolute. A total of 13 species were collected, of which eight occurred on Bt soybeans. The most representative taxa were Chrysodeixis includens (72.87%), Anticarsia gemmatalis (18.17%) and Spodoptera spp (5.22%). The number of larvae belonging to species targeted by the Bt technology was 10 times lower on Bt than on non-Bt soybeans. Utetheisa ornatrix and Elaphria deltoides were recorded on soybean for the first time, observing larvae of both species in non-Bt soybean and those of U. ornatrix also in Bt soybean. Only A. gemmatalis larvae correlated (p <0.05) negatively with precipitation. This study provided field information on the abundance and species richness of owlet moths on non-Bt soybeans, associated with the effects of Bt soybean. When considering the different levels of infestation between cultivars as a criterion, larvae monitoring is of substantial importance in order to develop the lost control program.

Spodoptera cosmioides Walk (Lepidoptera: Noctuidae) is a polyphagous species, considered a secondary pest in soybean crop. The Intacta soybean (Bt soybean) event was released in Paraguay with Bt proteins which are supposed to be toxic for caterpillars. However, the effects of these proteins in the Spodoptera cosmioides biology still uncertainty. This study evaluated the biological activity of Bt soybean in S. cosmioides that were fed on Bt and non-Bt soybean leaves under laboratory conditions. The experiment was carried out at the Laboratory of Entomology; temperature 26±2 ºC; relative humidity: 60±10%; photoperiod: 14:00 h where 150 neonate larvae were used per treatment. The period and viability of each stage, the mortality of larval, number of eggs and neonate per couple, and the period of larvae to adult were the assessed variables. Higher mortality was observed in larvae fed with intact soybeans, but without statistical differences with non-Bt soybeans. For larval survival, period, number and total period, no statistical differences were verified. Higher percentage of fertility was observed in soybeans non-Bt but no statistical differences.

This study aimed to evaluate the larval biology of Heliothis virescens in soybean MON 87701 x MON 89788 and its isogenic non-Bt. In general, the impact of soybean MON 87701 x MON 89788 on H. virescens was evidenced in all bioassays, 100% larval mortality, independent of the structure (leaf or pod) consumed by the pest. The small larvae (1st and 3rdinstar) demonstrated that they were unable to damage fresh pods of soybean, regardless of whether Bt or not Bt. The large larvae (5th instar) fed on soybean MON 87701 x MON 89788 soybeans consumed three times less compared to larvae fed on non-Bt soybeans, and resulted in reduced longevity and larval survival. When soybean plants were infested with 5th instar larvae, H. virescens caused injuries in the steams of the conventional soybean. It was recorded that the insects moves quickly to this region of the plant. However the soybean MON 87701 x MON 89788 was an effective tool in controlling H. virescens.

Transgenic lines of soybean, Glycine max (L.) Merrill, expressing a synthetic cry 1A gene from Bacillus thuringiensis Berliner (Bt), were evaluated in replicated field trials in 1999–2002 for suppression of lepidopteran pests and the resultant crop injury. Velvetbean caterpillar, Anticarsia gemmatalis Hübner, soybean looper, Pseudoplusia includens (Walker), and green cloverworm, Hypena scabra (F.), population densities were essentially absent throughout the growing season in each year of the study in each of the Bt lines evaluated compared with moderate (5–10 larvae per row-m) to heavy (15–20 larvae per row-m) populations in the isogenic and parental lines serving as soybean controls. Significant A. gemmatalis larval population reductions were observed in the Bt entries compared with the nonBt entries in each year of this study. The P. includens larval densities were significantly lower in Bt entries in the 3 yrs of this study when population densities were abundant, whereas H. scabra were lower in the Bt lines in the 2 yrs of this study when this species was present. Cumulative defoliation in nonBt soybean entries exceeded 95% in some years compared with 0.0–1.6% in the transgenic lines containing Bt. Yields of the transgenic soybean lines were equal to or higher than the non Bt lines examined in each year of this study. It appears that these Bt transgenic soybeans provide superior season-long control of the common lepidopteran pests on soybeans in the southern U.S., resulting in reduced defoliation levels and potentially higher yields compared with equivalent cultivars that lack the Bt trait.

Loopers are important defoliators in several crop species. Among the loopers attacking non-Bt soybean cultivars, Chrysodeixis includens (Walker, [1858]) was the most common. The use of trangenic Bt soybean in appromately 70% of the soybean fields in Brazil led to a decrease in the loopers in these fields. However, technical field specialists and soybean producers recently observed Plusiinae larvae damaging transgenic Bt soybean, posing a risk over the Bt technology. Therefore, the aim of this study was to identify and confirm the catterpillar species feeding on transgenic Bt soybean fields in Brazil. Larvae and soybean leaf samples were collected in 12 soybean-producing locations from four Brazillian States. Soybean leaf samples were tested to confirm whether they were transgenic Bt. Larvae were reared in artificial diet and submitted to feeding trials on non-transgenic and transgenic Bt soybean leaves. The species identification was perfomed by amplicon sequencing of the cytochrome oxidase I (COI) gene of eight larvae per local. All 12 populations fed in the transgenic Bt soybean and the sequencing analysis of COI determined that they belong to Rachiplusia nu (Guenée, 1852) with 100% similarity to the COI sequences available in NCBI for this species. These results suggest that the R. nu species is not controlled by the genetic modification event present in the tested soybean variety and highlights the need for additional looper management control strategies, such as insecticide application, for controlling this insect pest in transgenic Bt soybean.

Abstract Like conventional crops, transgenic plants expressing insecticidal toxins from Bacillus thuringiensis (Bt) are subjected to water deprivation. However, the effects of water deprivation over the insecticidal activity of Bt plants are not well understood. We submitted Bt maize and Bt soybean to water deprivation and evaluated biochemical stress markers and the insecticidal activity of plants against target insects. Bt maize (DAS-Ø15Ø7-1 × MON-89Ø34-3 × MON-ØØ6Ø3–6 × SYN-IR162-4) containing the PowerCore Ultra traits, Bt soybean (DAS-444Ø6-6 × DAS-81419-2) with the Conkesta E3 traits, and commercial non-Bt cultivars were cultivated and exposed to water deprivation in the greenhouse. Leaves were harvested for quantification of hydrogen peroxide, malondialdeyde (MDA), and total phenolics and insecticidal activity. Maize or soybean leaf disks were used to evaluate the insecticidal activity against, respectively, Spodoptera frugiperda (J.E Smith) and Chrysodeixis includens (Walker) neonates. Except for Bt soybean, water deprivation increased hydrogen peroxide and MDA contents in Bt and non-Bt plants. Both biochemical markers of water deficit were observed in lower concentrations in Bt plants than in non-Bt commercial cultivars. Water deprivation did not result in changes of phenolic contents in Bt and non-Bt maize. For Bt or non-Bt soybean, phenolic contents were similar despite plants being exposed or not to water deprivation. Water deprivation did not alter substantially insect survival in non-Bt maize or non-Bt soybean. Despite water deprivation-induced biochemical changes in plants, both Bt plants maintained their insecticidal activity (100% mortality) against the target species.

Abstract Complaints of severe damage by whiteflies in soybean fields containing genetically engineered (GE) varieties led us to investigate the role of transgenic soybean varieties expressing resistance to some insects (Cry1Ac Bt toxin) and to herbicide (glyphosate) on the population growth and feeding behavior of Bemisia tabaci (Gennadius) MEAM1 (Hemiptera: Aleyrodidae). In the laboratory, the whiteflies reared on the GE Bt soybeans had a net reproductive rate (R0) 100% higher and intrinsic rate of population increase (rm) 15% higher than those reared on non-GE soybeans. The increased demographic performance was associated with a higher lifetime fecundity. In electrical penetration graphs, the whiteflies reared on the GE soybeans had fewer probes and spent 50% less time before reaching the phloem phase from the beginning of the first successful probe, indicating a higher risk of transmission of whitefly-borne viruses. Data from Neotropical fields showed a higher population density of B. tabaci on two soybean varieties expressing glyphosate resistance and Cry1Ac Bt toxin. These results indicate that some GE soybean varieties expressing insect and herbicide resistances can be more susceptible to whiteflies than non-GE ones or those only expressing herbicide resistance. Most likely, these differences are related to varietal features that increase host-plant susceptibility to whiteflies. Appropriate pest management may be needed to deal with whiteflies in soybean fields, especially in warm regions, and breeders may want to consider the issue when developing new soybean varieties.

Two soybean varieties (an early-maturing Group V and a later-maturing Group VII) and two cotton varieties (a conventional and a transgenic Bacillus thuringiensis Berliner [Bt]) were grown in adjacent replicated large field plots at two locations for 3 growing seasons. The abundance of commonly-observed lepidopteran pests within these two crops was observed weekly throughout each growing season. The green cloverworm, Hypena scabra (F.); soybean looper, Pseudoplusia includens (Walker), and; velvetbean caterpillar, Anticarsia gemmatalis Hübner, preferred soybeans over cotton at all six test sites. The bollworm complex, Helicoverpa zea (Boddie) and Heliothis virescens (F.), preferred soybeans at one site, cotton at two sites, and no crop preference at three sites. There was no difference in the seasonal mean abundance of the pests between the two soybean maturity groups. A few varietal differences were noted on soybeans on specific sampling dates; however, they occurred when insect numbers were low. Population densities approached economic injury levels on both the early and later-maturing soybean varieties. In cotton, the bollworm complex was significantly more abundant in conventional cotton than in Bt cotton. Although soybean loopers are a pest of both crops, soybeans are preferred when they are planted adjacent to cotton. Given this behavioral response, soybeans might serve as a trap crop to attract soybean loopers into a small planting of soybeans and out of the major planting of cotton.

Lepidoptera, stink bugs, and weevils are important pests in soybean. For lepidopteran control, insecticides and seed treatments are used. As an alternative, Bt soybean was developed to control primary pests of Lepidoptera such as Rachiplusia nu (Guenée) (Noctuidae), Chrysodeixisincludens (Walker) (Noctuidae), Anticarsia gemmatalis Hübner (Erebidae), Helicoverpa gelotopoeon (Dyar) (Noctuidae), and Crocidosema aporema (Walsingham) (Tortricidae). However, the use of transgenic plants, and the resulting reduction of insecticide against target pests, may allow other pest species to become more prevalent in agricultural environments. Soybean expressing Cry1Ac against different lepidopteran nontarget and target insect pests was evaluated, and its performance was compared with non-Bt soybean with seed treatment. The treatments were Bt soybean, non-Bt soybean with seed treatment (Fortenza® diamide insecticide, Syngenta, Buenos Aires, Argentina), and non-Bt soybean without seed treatment. Larvae of H. gelotopoeon, Spodoptera albula (Walker) (Noctuidae), Spodoptera cosmiodes (Walker) (Noctuidae), Spodoptera eridania (Stoll) (Noctuidae), and Spodoptera frugiperda (J. E. Smith) (Lep.: Noctuidae) were used. The plants of each treatment were infested with larvae of each species, and the percentage of leaf damage produced by each species was recorded. The results showed that Bt soybean provided control of H. gelotopoeon and had a suppressive effect on S. frugiperda and S. albula. However, S. eridania and S. cosmiodes were not susceptible to the Cry1Ac protein in MON 87701 × MON 89788 soybean when evaluated by greenhouse infestation. Considering the performance of each species using non-Bt soybean without seed treatment, S. eridania would represent a potential risk in soybean crops.

Dichelops melacanthus was studied under controlled conditions (60 ± 10% RH and 14/10 h L/D photoperiod), and three constant temperatures (19, 25, and 31 ± 2 °C). Fresh pods of MON 87701 × MON 89788 soybeans and its near non-Bt isoline (A5547) were supplied to nymphs and adults. The biology of T. podisi was studied in the same controlled RH conditions, but only at the standard temperature of 25 ± 2 °C. Overall, the development of D. melacanthus was better at higher temperatures, which accelerated the development of the stink bug without affecting adult biological parameters. No influence of Bt-soybeans on the biology of the pest was observed in any temperature studied, which shows that D. melacanthus is not affected by this transgenic soybean. The egg parasitoid T. podisi also was not harmed when it parasitized eggs of the pest fed with MON 87701 × MON 89788 soybeans, with similar results to those obtained in non-Bt isogenic soybeans. Thus, this study demonstrates that D. melacanthus is favored at high temperatures (31 ± 2 °C), and that neither did MON 87701 × MON 89788 soybean pods affect the development of the pest nor its parasitoid T. podisi.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-12-13T15:30:36Z No. of bitstreams: 1 Silvia Martins de Salles_.pdf: 1554119 bytes, checksum: 531304cc1d1683afbc987722d8e71530 (MD5)<br>Made available in DSpace on 2017-12-13T15:30:36Z (GMT). No. of bitstreams: 1 Silvia Martins de Salles_.pdf: 1554119 bytes, checksum: 531304cc1d1683afbc987722d8e71530 (MD5) Previous issue date: 2017-07-31<br>CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>O desenvolvimento da resistência representa uma ameaça ao controle de pragas com a utilização de plantas Bt. A conservação de inimigos naturais pode contribuir para reduzir a evolução da resistência à soja Bt, e entre os insetos de interesse para uso no controle de espécies do gênero Spodoptera, os parasitoides têm sido considerados os mais importantes devido à sua eficiência e à sua especificidade em relação ao hospedeiro. Nessa perspectiva, este estudo teve como objetivo avaliar as interações de Spodoptera eridania (Lepidoptera: Noctuidae) e o endoparasitoide Dolichozele sp. (Hymenoptera: Braconidae), quando tratados com a soja Bt que sintetiza a proteína Cry1Ac. Para tanto, lagartas de S. eridania foram expostas aos seguintes tratamentos: (T1) não parasitadas e alimentadas com soja convencional, (T2) não parasitadas e alimentadas com soja Bt, (T3) parasitadas e alimentadas com soja convencional, (T4) parasitadas e alimentadas com soja Bt, e (T5) parasitadas e alimentadas com soja transgênica BRR. A biologia dos parasitoides descendentes de lagartas alimentadas com soja Bt foi avaliada através da observação da data de formação do casulo do parasitoide, a data de emergência, o sexo, a longevidade do parasitoide adulto e a sobrevivência. Na avaliação de preferência do parasitoide por lagartas alimentadas com soja Bt e soja não Bt, as lagartas receberam tempos de exposição diferentes à fêmea do parasitoide – a saber, 2h, 4h e 6h. Nos tratamentos com Dolichozele sp. isolados ou em conjunto com soja Bt, a mortalidade foi significativamente maior que o tratamento-controle (F= 63,5; gl= 4,14; p=0,001), apresentando mortalidade média de lagartas de 17,0 (T3), 20,2 (T4) e 17,5 (T5). Através dos ensaios imunoenzimáticos (ELISA), foi possível detectar a presença da proteína Cry1Ac em folhas de soja Bt, fezes de S. eridania e em larvas de Dolichozele sp. Os parasitoides emergidos de lagartas alimentadas com soja Bt e soja RR evidenciaram diferenças significativas na fase de pupa (F= 15,058; gl=2; P=0,001) nos tratamentos T4 (16,6 dias) e T5 (17,08 dias), quando comparados com o controle, T3 (18,2 dias). Parasitoides submetidos ao T4 (lagartas alimentadas com soja Bt) apresentaram menor sobrevivência em relação aos outros tratamentos (Kaplan–Meier, Log Rank, X2 =8,22, gl=2, p = 0,016; Breslow, X2 =9,58, gl=2, P = 0,008; Tarone-Ware, X2 =9,94, gl=2, p = 0,007). Observou-se correlação positiva entre o tempo de exposição e a taxa de parasitismo de Dolichozele sp. em S. eridania (Rho de Spearman = 0,758, p=0,001). Portanto, os resultados deste estudo indicam que o parasitoide tem efeito positivo no controle de S. eridania, entretanto seu desenvolvimento e sua sobrevivência podem se influenciar pela presença da toxina Bt. Dolichozele sp. revelou potencial para agir de forma eficiente em estratégias de manejo da evolução da resistência às proteínas Cry em soja Bt, pois podem ajudar a suprimir as populações de pragas alvo e não alvo.<br>The development of insect resistance poses a threat to pest control using Bt plants. The conservation of natural enemies may contribute to reduce the evolution of Bt soybean resistance. Among the insects of interest for use in the control of species of the genus Spodoptera, parasitoids have been considered the most important due to their efficiency and specificity in relation to the host. In this way, this study aimed to evaluate the interactions of Spodoptera eridania (Lepidoptera: Noctuidae) and the endoparasitoid Dolichozele sp. (Hymenoptera: Braconidae) when treated with Bt soybean that synthesizes Cry1Ac protein. For this purpose, S. eridania larvae were exposed to the following treatments: (T1) non-parasitized and fed with conventional soybean; (T2) non-parasitized and fed with Bt soybean; (T3) parasitized and fed with conventional soybean; (T4) parasitized and fed with Bt soybean; and (T5) parasitized and fed with transgenic BRR soybean. The biology of the parasitoids descendant from larvae fed with Bt soybean was evaluated by observing the date of formation of the parasitoid pupa, date of emergence, sex, adult parasitoid longevity and survival. In the evaluation of the parasitoid preference for larvae fed with Bt soybean and non-Bt soybean, larvae received different exposure times to the parasitoid female, of 2h, 4h and 6h. In the treatments using Dolichozele sp. isolated or in conjunction with Bt soybean, mortality was significantly higher than the control treatment (F = 63.5; gl = 4.14; P = 0.001), with a mean larval mortality of 17.0 (T3), 20.2 (T4) and 17.5 (T5). Through the enzyme-linked immunosorbent assay (ELISA), it was possible to detect the transfer of the Cry1Ac protein in S. eridania and Dolichozele sp.). The parasitoids emerged from larvae fed Bt soybean showed significant difference in the pupal phase (F = 15.058, gl = 2, P = 0.001) in the treatments T4 (16.6 days) and T5 (17.08 days) when compared as control T3 (18.2 days). The survival of the parasitoids that emerged from larvae fed with Bt soybean (T4) was lower (Kaplan-Meier, Log Rank, X2 = 8.22, gl = 2, p = 0.016, Breslow, X2 = 9.58, gl = 2, p = 0.008; Tarone-Ware, X2 = 9.94, gl = 2, p = 0.007). There was a positive correlation between the exposure time and the parasitism rate of Dolichozele sp. in S. eridania (Spearman's Rho = 0.758, p = 0.001). The results of this study indicate that the parasitoid has a positive effect on the control of S. eridania, however its development and survival may be influenced by the presence of the Bt toxin. Dolichozele sp. presented the potential to act positively in strategies to manage the evolution of resistance to Cry proteins in Bt soybeans, as they may help suppress pest populations.

A evolução da resistência de insetos a culturas que expressam proteínas derivadas de Bacillus thuringiensis (Bt) é o maior desafio para a manutenção dessa biotecnologia em programas de manejo integrado de pragas. Diante do risco de evolução de resistência de Helicoverpa armigera (Hübner) à soja MON87701 × MON89788 foi realizada uma análise de risco levando em consideração o conjunto de fatores que influenciam no processo de seleção. Portanto, os objetivos do presente estudo foram a de caracterizar a suscetibidade à proteína Cry1Ac em populações de H. armigera e H. zea, caracterizar a eficácia da soja MON87701 × MON89788, bem como a adequação do produto ao conceito de alta dose para H. armigera e H. zea, avaliar a frequência dos alelos que conferem resistência à proteína Cry1Ac em populações de H. armigera, identificar a preferência hospedeira de H. armigera e H. zea em diferentes culturas e paisagens agrícolas e avaliar os parâmetros biológicos e demográficos de H. armigera e H. zea em diferentes hospedeiros. A espécie H. zea foi aproximadamente 60 vezes mais tolerante à proteína Cry1Ac que H. armigera. Além disso, baixa variabilidade na suscetibilidade à Cry1Ac foi verificada em populações de H. armigera coletadas em diferentes regiões do Brasil, o que pode ser explicada pela recente introdução dessa espécie no continente americano. A soja MON87701 × MON89788 resultou em mortalidade completa de H. armigera durante todo o ciclo da cultura, enquanto que para H. zea não foi verificado 100% de mortalidade sob condições de laboratório em bioensaios de cinco dias de duração, apesar dos altos níveis de mortalidade encontrados. Uma baixa frequência (frequência estimada = 0,0011) de alelos que conferem resistência à soja MON87701 × MON89788 em populações de campo de H. armigera foi estimada pelo método de F2 screen. A avaliação da tabela de vida em laboratório demonstrou que H. armigera tem altos níveis de desenvolvimento e a reprodução nas principais culturas das regiões dos Cerrados, sendo a cultura do algodão a que resulta nos maiores valores de crescimento populacional e menor tempo entre gerações. Por outro lado, H. zea se mostrou menos polífaga, se estabelecendo até a fase adulta e gerando descendentes apenas em milho e milheto. A ocorrência das duas espécies no campo corrobora com as informações encontradas na tabela de vida, na qual H. armigera foi encontrada em grande parte as culturas da soja e algodão, e em menor frequência à cultura do milho, enquanto que H. zea apresentou comportamento funcionalmente monófago no campo, associada apenas à cultura do milho. Os parâmetros toxicológicos da soja MON87701 × MON89788 associada à alta suscetibilidade de H. armigera à proteína Cry1Ac e à baixa frequência inicial de alelos que conferem resistência se adéquam aos preceitos da estratégia de alta dose/refúgio. A manutenção das áreas de refúgio com plantas não-Bt, de acordo com as recomendações, é essencial para retardar o processo de seleção de resistência de populações de H. armigera à soja MON87701 × MON89788 no Brasil.<br>Insect resistance to crops expressing proteins derived from Bacillus thuringiensis proteins (Bt) impose the biggest challenge to maintaining the value of this biotechnology in integrated pest management programs. To support a resistance to Helicoverpa armigera (Hübner) to soybean MON87701 × MON89788 was carried out a risk analysis taking into account all factors that influence the selection process. Therefore, the objectives of this study were to characterize the suscetibidade the Cry1Ac protein in H. armigera populations and H. zea, characterize the effectiveness of soybean MON 87701 × MON 89788, as well as the suitability of the product to the concept of high dose H. armigera and H. zea, evaluate the frequency of alleles that confer resistance to Cry1Ac protein in H. armigera populations from different regions of agricultural production, understand the host preference of H. armigera and H. zea in different crops in and agricultural landscapes and evaluate the biological and demographic parameters of H. armigera and H. zea on different hosts. The species H. zea was approximately 60 times more tolerant to Cry1Ac protein than H. armigera. Low variability on susceptibility to Cry1Ac was found among field H. armigera populations, what can be explained by the recent introduction of this species into America. MON 87701 × MON 89788 soybean resulted in complete mortality of H. armigera throughout the crop cycle, while incomplete mortality was found for H. zea using leaf disc bioassays, although high levels of mortality were found. A low resistance allele frequency (estimated frequency = 0.0011) to MON 87701 × MON 89788 soybean was estimated by using the F2 screen methodology. The assessment of the Life Table parameters in laboratory demonstrated the main row crops such as cotton, soybean and maize are suitable for the development and reproduction of H. armigera, wherein cotton resulted in higher values of population growth parameter and shorter times between generations. Conversely, H. zea was less polyphagous in which only corn and millet were suitable hosts. Field occurrence of both species was consistent with laboratory studies. H. amigera was mostly found in soybean and cotton, and rarely on corn, while H. zea was found mainly on maize. Overall, toxicological aspects of MON87701 × MON89788 soybean associated with high susceptibility of H. armigera to Cry1Ac protein and low initial resistance allele frequency fit properly to the highdose/ refuge strategy to delay resistance evolution. Therefore, maintenance of compliance with the refuge recommendation is essential to delay the evolution of resistance in H. armigera to MON87701 × MON89788 soybean in Brazil.

Submitted by DANIELA DE LIMA VIANA null (danielaviana28@gmail.com) on 2018-03-12T18:58:25Z No. of bitstreams: 1 Tese_Daniela_de_Lima_Viana.pdf: 1718435 bytes, checksum: fb23294ce65ac4d0c05140ed95a1d66d (MD5)<br>Approved for entry into archive by Neli Silvia Pereira null (nelisps@fcav.unesp.br) on 2018-03-13T13:15:00Z (GMT) No. of bitstreams: 1 viana_dl_dr_jabo.pdf: 1718435 bytes, checksum: fb23294ce65ac4d0c05140ed95a1d66d (MD5)<br>Made available in DSpace on 2018-03-13T13:15:00Z (GMT). No. of bitstreams: 1 viana_dl_dr_jabo.pdf: 1718435 bytes, checksum: fb23294ce65ac4d0c05140ed95a1d66d (MD5) Previous issue date: 2018-02-16<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O cenário agrícola no Centro Oeste conta com os chamados sistemas de produção, nos quais os cultivos ocorrem de forma constante e sucessiva durante um mesmo ano agrícola. No entanto, isso tem propiciado problemas cada vez mais frequentes relacionados a alguns grupos de pragas, dentre eles os lepidópteros. Espécies como Chrysodeixis includens e o complexo de Spodoptera vem crescendo de importância, causando prejuízos, principalmente em culturas como a soja e o algodoeiro. Dentre os métodos mais utilizados para o controle de insetos-praga no Brasil, destaca-se o uso de OGM, a partir da inserção de genes da bactéria Bacillus thuringiensis (Bt), com expressão de proteínas com ações inseticidas. Entretanto, um dos grandes problemas é a seleção de populações de pragas resistentes aos cultivos Bt devido ao uso contínuo e inadequado da tecnologia. Diante disso, os objetivos do presente estudo foram avaliar os efeitos de cultivares Bt de soja e algodoeiro, que expressam proteínas inseticidas Cry, sobre os aspectos biológicos de C. includens em laboratório, como também avaliar a dinâmica populacional e a infestação natural de lagartas de C. includens e de Spodoptera spp. em condições de campo, no estado do Mato Grosso. Para o estudo dos aspectos biológicos, utilizou-se lagartas neonatas que foram alimentadas com folhas das cultivares de soja e algodoeiro não Bt e Bt de diferentes tecnologias. Os experimentos de campo foram realizados em área experimental do IMAmt na safra 2016/2017, utilizando cultivares de soja e algodoeiro não Bt e Bt com expressão de diferentes proteínas Cry. As cultivares de soja Bt, que expressam a proteína Cry1Ac, afetam os parâmetros biológicos de C. includens, controlando de maneira eficiente, tanto em laboratório quanto em campo. Em relação às lagartas de Spodoptera spp. observou-se que as cultivares de soja Bt não controlam eficientemente esses lepidópteros. A cultivar de algodoeiro que expressa a proteína Cry1Ac, causa pouco efeito sobre as lagartas de C. includens, não apresentando controle satisfatório, tanto nos aspectos biológicos observados em laboratório quanto na infestação em campo, se comportando de forma similar à cultivar de algodoeiro não Bt. As cultivares de algodoeiro Bt piramidadas, Cry1Ac+Cry1F, Cry1Ac+Cry2Ab2 e Cry1Ab+Cry2Ae, apresentaram controle de C. includens, afetando a sobrevivência de lagartas pequenas em laboratório e campo. Por outro lado, a piramidação de cultivares por si só não é suficiente, por exemplo, para as lagartas de Spodoptera spp. Nos eventos de algodão Bt em campo, verificou-se que as cultivares que expressam as proteínas Cry1Ac e Cry1Ac+Cry1F, não suprimem suas infestações, enquanto que nas cultivares piramidadas que expressam Cry1Ac+Cry2Ab2 e Cry1Ab+Cry2Ae a supressão foi considerada eficiente.<br>The agricultural scenario in the brazilian midwest counts on the socalled production systems, in which crops occur constantly and successively during the same agricultural year. However, this has caused increasingly frequent problems related to some groups of pests, among them the Lepidoptera. Species such as Chrysodeixis includens and the Spodoptera complex have been increasing in importance, causing damage, especially in crops such as soybean and cotton. Among the most used methods for the control of insect pests in Brazil, the use of GMOs, from the insertion of genes of the bacterium Bacillus thuringiensis (Bt), with expression of proteins with insecticidal actions, stands out. However, one of the major problems is the selection of populations of pests resistant to Bt crops due to the continuous and inadequate use of the technology. The objectives of the present study were to evaluate the effects of Bt cultivars of soybean and cotton, which express insecticidal Cry proteins, on the biological aspects of C. includens in the laboratory, as well as to evaluate the population dynamics and the natural infestation of caterpillars C. includens and Spodoptera spp. under field conditions, in the state of Mato Grosso. For the study of the biological aspects, we used caterpillars that were fed with leaves of the cultivars of soybean and non-Bt and Bt cotton of different technologies. Field experiments were carried out in the experimental area of the IMAmt in the 2016/2017 season, using soybean and cotton cultivars non-Bt and Bt with different Cry protein expression. Soybean Bt cultivars, which express the Cry1Ac protein, affect the biological parameters of C. includens, efficiently controlling both in the laboratory and in the field. In relation to the caterpillars of Spodoptera spp., it was observed that Bt soybean cultivars do not efficiently control these lepidoptera. The cotton cultivar that expresses the Cry1Ac protein causes little effect on the caterpillars of C. includens, not showing satisfactory control, both in the biological aspects observed in the laboratory and in the infestation in the field, behaving in a similar way to the cultivar of non-Bt cotton. Cotton Bt cultivars, Cry1Ac+Cry1F, Cry1Ac+Cry2Ab2 and Cry1Ab+Cry2Ae, showed control of C. includens, affecting the survival of small caterpillars in the laboratory and in the field. On the other hand, the pyramiding of cultivars alone is not sufficient, for example, for the caterpillars of Spodoptera spp. In the field cotton Bt events, it was found that cultivars expressing the Cry1Ac and Cry1Ac+Cry1F proteins do not suppress their infestations, whereas in pyrite cultivars expressing Cry1Ac+Cry2Ab2 and Cry1Ab+Cry2Ae suppression was considered efficient.