Metabólitos secundários de plantas nativas e exóticas, com potencial inseticida, ao polífago, Spodoptera frugiperda (Lepidoptera, Noctuidae)

Abstract

Spodoptera frugiperda, a polyphagous Lepidoptera that causes large reductions in the productivity of rice and maize monocultures. Faced with fewer losses, agricultural producers look for different control methods, such as biological, genetic and cultural control, in addition to conventional tactics, such as periodic applications of chemical insecticides. The growing increase in losses due to pest attacks is accompanied by a decrease in the efficiency of chemical products. The search for control measures that cause less environmental impact and are of primary importance, which has been stimulating the resurgence of the use of insecticide plants as a promising tool in insect control. In this context, the present research had as general objective to carry out a selection regarding the insecticidal potential, evaluating 27 native and exotic plants regarding their insecticidal potential. From the results obtained, 3 plants were selected for better evaluation of the lethal, sublethal and histopathological effects of their secondary metabolites, when extracted by 4 different processes. With the aqueous, infusion and polypeptide extracts of Euphorbia pulcherrima, Rhododendron simsii and Maytenus ilicifolia it was not possible to have a LC50, as they did not cause 100% mortality of exposed caterpillars for 7 days. Therefore, bioassays were carried out to evaluate the sublethal effects of these extracts. The E. pulcherrima polypeptide extract caused a decrease in the larval development time of this lepidopteran. The supercritical extract of E. pulcherrima and R. simsii caused corrected mortality of 51% and 73%, respectively. The corrected mortality of S. frugiperda, when exposed to the superior extract via supercritical extraction of M. ilicifolia was 100%, enabling them to perform bioassays to define the LC50, which was specified as 0.104 mg extract / ml acetone. The supercritical extracts of E. pulcherrima and R. simsii caused damage to the gastrointestinal epithelium of exposed caterpillars.