Avaliação da suscetibilidade a inseticidas e caracterização molecular de genes associados à resistência em populações de Spodoptera frugiperda

Abstract

Spodoptera frugiperda is a pest of great agronomic relevance, responsible for significant losses in crops such as maize. Its control with insecticides and Bt technology has been compromised by the evolution of resistance associated with intensive use. In this context, the present work evaluated the susceptibility of populations of S. frugiperda from Colombia, Peru, and Brazil to insecticides of different chemical groups, complementing the analyses with molecular characterization of the populations and bioassays with synergists. The evaluations revealed that, although most populations maintain susceptibility to cyclaniliprole, thiamethoxam + lambdacyhalothrin, spinetoram, chlorpyrifos, deltamethrin, spinosad, and lambda-cyhalothrin, with average mortality above 80%, there were populations, such as RR-Casanare (resistant to Bt maize) and Peru-LB, that presented reduced susceptibility to the neonicotinoids imidacloprid and thiamethoxam, not explained by metabolic mechanisms, since the bioassays with synergists indicated low participation of these mechanisms, nor by mutations in target-site genes. A high frequency of the mutations A201S and G227A in the FAW-ace-1 gene, associated with resistance to organophosphates, was also evidenced. These results underline the urgent need to implement integrated resistance management programs that combine toxicological and molecular monitoring, allowing the design of insecticide rotation strategies and the preservation of effective technologies for the sustainable control of S. frugiperda in the region.