Resistência de genótipos de soja a Helicoverpa armigera (Hübner) e simulação de danos de Helicoverpa zea (Boddie) em estruturas reprodutivas da soja
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2018-12-11
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Coelho, Mariane
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Universidade Estadual Paulista (Unesp)
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A soja, [Glycine max (L.) Merrill], é cultivada em vários países e é considerada um dos principais cultivos agrícolas em todo o mundo. Embora apresente grande potencial produtivo, muitas espécies de insetos-praga estão comumente associadas à cultura, causando danos significativos e comprometendo sua produtividade. Dentre os insetos que podem afetar negativamente o rendimento da soja, destacam-se Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) e Helicoverpa zea Boddie (Lepidoptera: Noctuidae). O uso de inseticidas sintéticos, associado às culturas geneticamente modificadas são os métodos de controle mais utilizados para a manutenção das populações dessas pragas a campo. No entanto, a adoção abusiva dessas práticas pode ocasionar prejuízos ao meio ambiente e à saúde do trabalhador, além de selecionar populações resistentes dos insetos, no campo. O uso de resistência varietal no controle de pragas pode ser uma tática valiosa para o Manejo Integrado de Pragas (MIP) da soja, podendo ser empregado em conjunto com outras táticas de controle. Ainda dentro dos preceitos do MIP, o conhecimento quanto ao potencial de danos do inseto sobre as plantas e seu impacto sobre as produtividades vem sendo periodicamente reavaliado. Dessa forma, a simulação da ação dos insetos sobre as plantas também pode auxiliar na validação e determinação dos níveis de ação (NA) e, assim, favorecer a racionalização do uso de inseticidas químicos. Com base no exposto, o presente estudo teve como objetivos caracterizar possíveis categorias de resistência (antixenose e/ou antibiose) de 22 genótipos de soja sobre H. armigera em laboratório e avaliar o impacto da remoção artificial de flores e vagens na maturação e rendimento da soja, simulando o ataque de H. zea a campo. Inicialmente, foi realizado um teste preliminar de performance, empregando-se como alimento, folhas e vagens dos genótipos, visando selecionar aqueles mais promissores quanto à resistência. Na sequência, os genótipos selecionados foram novamente avaliados por meio de ensaios de confinamento (folhas), onde além de parâmetros biológicos, avaliou-se o consumo foliar, visando distinguir antixenose e antibiose. Em ensaio a campo, avaliou-se o efeito da remoção artificial de flores e vagens, em diferentes níveis de remoção e diferentes fases fenológicas da soja, sobre a maturação e produtividade da soja nos EUA, sob condições desfavoráveis de umidade. Em laboratório, PI 227687, PI 274453, PI 274454, PI 229358, PI 171451, ‘IAC 17’ e ‘IAC 19’ expressaram resistência do tipo antibiose e/ou antixenose sobre H. armigera, apresentando-se como genótipos viáveis para programas de melhoramento genético focando em resistência de soja a lagartas desfolhadoras. A campo observou-se que as plantas de soja são capazes de compensar os danos causados por H. zea, quando as flores e/ou vagens são removidas no estádio inicial de desenvolvimento reprodutivo (R2-R4), quando em condições desfavoráveis (sem irrigação). Os dados também indicaram que a planta de soja é mais sensível à perda de estruturas reprodutiva durante a fase R5, período em que o ataque reduz significativamente a produtividade das plantas.
Soybean, [Glycine max (L.) Merrill], is cultivated around several countries and it is considered one of the major agricultural crops worldwide. Although it presents great productive potential, many pest insects are commonly associated to its crop, causing significant damages and implicating on its yield. Among the insects which interfere negatively on soybean yield, it is highlighted Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) and Helicoverpa zea (Boddie, 1850) (Lepidoptera: Noctuidae). The use of synthetic insecticide associated with genetically modified crops, are the most used control method to the maintenance of this pest population in the field. The abusive use of this practice can damage the environment and the laborer’s health, moreover, contribute to the field evolved resistance of insects. The use of varietal resistance on pest control might be a rich tool for the Integrated Pest Management (IPM) on soybean, that could be used along to other control methods. Still in the precept of IPM, the knowledge about the potential of the insect damages on the plants and their impact on the yield has been periodically re-evaluated. Thus, the simulation of the insect action on the plants might also help on the validation and on the determination of the action threshold (AT) and, support the rationalization of the chemical insecticide utilization. Based on the exposed, the present study had as objectives characterize possible resistance categories (antixenosis and/or antibiosis) of 22 soybean genotypes on H. armigera in laboratory and evaluate the impact of the artificial removal of fruiting during the soybean maturation and yield, simulating H. zea attack on it, under field conditions. Initially, a preliminary performance experiment was performed using the leaves and pods of the genotypes, in order to select the most promising ones for resistance. On the sequence, the genotypes selected were evaluated again, by the confinement test (leaves), where beyond the biological parameters, it was evaluated the foliar intake, looking forward to distinguishing antixenosis and antibiosis. In field experiment, it was tested the effects of the artificial removal of the pods and flowers, in different levels of the removal and different phenological phase of the soybean, on the maturation and the yield of the crop in the USA, under unfavorable humidity conditions. In the laboratory, the genotypes PI 227687, PI 274453, PI 274454, PI 229358, PI 171451, ‘IAC 17’ and ‘IAC 19’ expressed antibiosis and/or antioxenosis resistance against H. armigera, presenting themselves as viable in breeding programs, focusing on soybeans resistance to lepidopterans. On field, it was observed that the soybean plants can compensate the damages caused by the H. zea, when the flowers and pods are removed during the initial growth stage of the reproductive development (R2-R4), in unfavorable conditions (no irrigation). The data also showed that soybean more sensitive to the loss of the reproductive structure during the R5 growth stage, when the attack decreases significantly the productivity of the plants.
Soybean, [Glycine max (L.) Merrill], is cultivated around several countries and it is considered one of the major agricultural crops worldwide. Although it presents great productive potential, many pest insects are commonly associated to its crop, causing significant damages and implicating on its yield. Among the insects which interfere negatively on soybean yield, it is highlighted Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) and Helicoverpa zea (Boddie, 1850) (Lepidoptera: Noctuidae). The use of synthetic insecticide associated with genetically modified crops, are the most used control method to the maintenance of this pest population in the field. The abusive use of this practice can damage the environment and the laborer’s health, moreover, contribute to the field evolved resistance of insects. The use of varietal resistance on pest control might be a rich tool for the Integrated Pest Management (IPM) on soybean, that could be used along to other control methods. Still in the precept of IPM, the knowledge about the potential of the insect damages on the plants and their impact on the yield has been periodically re-evaluated. Thus, the simulation of the insect action on the plants might also help on the validation and on the determination of the action threshold (AT) and, support the rationalization of the chemical insecticide utilization. Based on the exposed, the present study had as objectives characterize possible resistance categories (antixenosis and/or antibiosis) of 22 soybean genotypes on H. armigera in laboratory and evaluate the impact of the artificial removal of fruiting during the soybean maturation and yield, simulating H. zea attack on it, under field conditions. Initially, a preliminary performance experiment was performed using the leaves and pods of the genotypes, in order to select the most promising ones for resistance. On the sequence, the genotypes selected were evaluated again, by the confinement test (leaves), where beyond the biological parameters, it was evaluated the foliar intake, looking forward to distinguishing antixenosis and antibiosis. In field experiment, it was tested the effects of the artificial removal of the pods and flowers, in different levels of the removal and different phenological phase of the soybean, on the maturation and the yield of the crop in the USA, under unfavorable humidity conditions. In the laboratory, the genotypes PI 227687, PI 274453, PI 274454, PI 229358, PI 171451, ‘IAC 17’ and ‘IAC 19’ expressed antibiosis and/or antioxenosis resistance against H. armigera, presenting themselves as viable in breeding programs, focusing on soybeans resistance to lepidopterans. On field, it was observed that the soybean plants can compensate the damages caused by the H. zea, when the flowers and pods are removed during the initial growth stage of the reproductive development (R2-R4), in unfavorable conditions (no irrigation). The data also showed that soybean more sensitive to the loss of the reproductive structure during the R5 growth stage, when the attack decreases significantly the productivity of the plants.
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Palavras-chave
Antibiose, Antixenose, Resistência de Plantas a Insetos, Noctuidae, Dano artificial