Eliane Carneiro

O complexo de lagartas desfolhadoras - Spodoptera cosmioides, Spodoptera frugiperda e Helicoverpa armigera, são responsáveis por uma considerável redução na produção de grãos. A aplicação de extratos botânicos consiste em uma alternativa viável e eficiente de controle, além de ser menos nociva ao meio ambiente e a saúde do homem. O objetivo foi avaliar o potencial inseticida do extrato bruto de folhas e casca de Anadenanthera macrocarpa, sobre as lagartas de S. frugiperda, S. cosmioides, H. armigera. Os insetos foram mantidos em dieta artificial em condições controladas. Foi avaliada a ação toxica dos extratos por aplicação tópica. Primeiramente foi estimada a concentração letal e em seguida foram determinados os parâmetros biológicos das três espécies de lepidópteros. Os extratos etanólicos de folhas e casca de A. macrocarpa foram eficientes no controle de H. armigera, S. frugiperda e S. cosmioides reduzindo a sobrevivência em 75, 60 e 50%, respectivamente, além de alterações nos parâmetros biológicos como, aumento do período larval, redução de peso das larvas e pupas. Os compostos químicos presentes nos extratos etanólicos de folhas e casca de A. macrocarpa, além de causar mortalidade direta dos insetos estudados, alteram o ciclo biológico de S. frugiperda, S. cosmoides e H. armigera. Palavras-chave: Angico-preto; Spodoptera cosmioides; Spodoptera frugiperda; Helicoverpa armigera; bioinseticidas. POTENTIAL INSECTICIDE OF THE ETHANOLIC EXTRACT OF Anadenanthera macrocarpa (BENTH.) IN LEPIDOPTERAN-PESTS ABSTRACT: The leafless worm complex - Spodoptera cosmioides, Spodoptera frugiperda and Helicoverpa armigera - are responsible for a considerable reduction in grain production. The application of botanical extracts is a viable and efficient alternative of control, besides being less harmful to the environment and human health. The objective was to evaluate the insecticidal potential of the raw extract of leaves and bark of Anadenanthera macrocarpa, on S. frugiperda, S. cosmioides, H. armigera. The insects were kept on artificial diet under controlled conditions. The toxic action of the extracts was evaluated by topical application. First the lethal concentration was estimated and then the biological parameters of the three lepidopteran species were determined. The extracts of leaves and bark of A. macrocarpa were efficient in the control of H. armigera, S. frugiperda and S.a cosmioides, reducing survival in 75, 60 and 50%, respectively, as well as changes in biological parameters such as larval period increase, weight reduction of larvae and pupae. The chemical compounds present in the leaves and bark extracts of A. macrocarpa, besides causing direct mortality of the studied insects, alter the biological cycle of S. frugiperda, S. cosmoides and H. armigera. Keywords: Angico-black; Spodoptera cosmioides; Spodoptera frugiperda; Helicoverpa armígera; bioinsecticides.

The toxicity of some insecticides to Helicoverpa armigera was studied through sublethal effects, evaluating the enzymatic activity of esterase and the behavioral response. The commercial formulation of insecticides selected were chlorpyrifos, spinosad, indoxacarb, chlorantraniliprole, lambda-cyhalothrin and Bacillus thuringiensis, corresponding the most used by farmers to control of H. armigera. To determine the esterase activity, the larvae were fed with soybean leaf discs dipped in insecticide solution using the lethal concentration (LC₅₀). For the behavioral response, filter paper were immersed in three concentrations of insecticides (LC₅₀, LC₉₅ and recommend dose.), then the behavior of the larvae observed in Videomex-One. The results for the enzymatic activity showed an increase in the activity of the esterase, with variation along the treatments and the time of exposure of the insects to the insecticides. With exception of spinosad, other insecticides showed an increase in EST-α activity, 6 and 24 hours after contact of caterpillars with insecticide.Different behavioral patterns of walking (walking distance, walking speed and resting time) were observed for H. armigera exposed to different insecticides. H. armigera exposed to chlorpyrifos, lambda-cyhalothrin and B. thuringiensis insecticides show greater esterase activity. Regarding walking behavior, the results confirms enzymatic activity, where H. armigera have behavioral alteration after exposure to insecticide.

Exposure of Helicoverpa armigera to sublethal concentrations of insecticides can cause physiological deficiencies manifested by reduced longevity, development, fertility and fecundity. Research on the sub-lethal effects, to identify the non-lethal negative impacts of insecticides on pests can provide practical information for integrated management. The objective of this study was to determine the lethal concentrations and sublethal effects of insecticides on larval development and reproduction of H. armigera. The insecticides were diluted in water and applied via immersion of soybean leaf discs directly in the solution for three second, subsequently provided to the larvae maintained under controlled conditions for a period of 48 h. For surviving larvae, artificial diet was provided with daily evaluation until pupation. The pupae obtained were weighed after 24 h and transferred to Petri dishes, covered with filter paper until the adult phase, to evaluate longevity and pupal viability. For the assessments related to oviposition, couples were separated in polyvinyl chloride (PVC) cages and fed with 10% honey solution; the counting of eggs was done every two days, until the end of the oviposition period. All of the insecticides tested presented lethal and sublethal effects on the parameters weight, mortality and pupal viability and reduced oviposition and can be used in pest management, representing an alternative in the product rotation for the control of the third instar of H. armigera. Key words: Management, chemical control, lethal concentration.