Impacto de Extratos Botânicos Aquosos em Plutella xylostella L. (1758): Estudos de Antibiose e Antixenose

Abstract

Over the last four decades, the phytosanitary market has undergone major changes. Synthetic chemical insecticides, which used to be the main way of controlling harmful insects, have been losing ground, mainly due to popular pressure, which has increasingly put the issue of sustainability on the agenda. In this context, new tools and old methods for pest control have resurfaced. This is the case with botanical insecticides, a natural and alternative control method that is gaining market acceptance. This study aims to provide data on the insecticidal potential of aqueous extracts of the leaves of Tapirira guianensis (EATg), Coussarea hydrangeifolia (EACh), Duguetia furfuracea (EADf) and Anemopaegma arvense (EAAa) on Plutella xylostella. This work conducted experiments on oral toxicity; topical toxicity on the embryonic, larval and adult stages; as well as feeding preference in the larval stage. Finally, the chemical characterization of the major compounds present in the extracts was carried out. Ingestion of EAAa, EADf and EATg resulted in larval mortality and a reduction in the number of eggs laid by P. xylostella females, which may be indicative of physiological stress. The EACh extract did not cause significant mortality, despite being one of the extracts with the highest amount of secondary metabolites. Only EATg caused significant mortality in eggs and larvae under topical application, suggesting that the main mode of action of the extracts is via ingestion. In addition, all the treatments were classified as phagodeterrent, with EATg and EACh significantly reducing the leaf area consumed by the larvae. The results of this study show that the botanical extracts tested have significant potential for controlling P. xylostella, mainly due to their oral toxicity and sublethal effects on the insect's reproduction. However, for these solutions to be widely adopted, it is essential that future research explores the stability of the extracts over time, the feasibility of their application to different agricultural crops and the potential effects on non-target organisms.