38th Annual Meeting of the Society for Invertebrate Pathology

Spodoptera cosmioides has occurred at increasingly higher numbers in cotton fields, causing significant damage. Frequent broad spectrum insecticide applications are required to control this pest. Due to the direct and indirect effects of agrochemicals on human health and on the environment, new pest control strategies have been developed. Hence, the objective of this work was to evaluate the pathogenicity of Bacillus thuringiensis strains on 2nd instar Spodoptera cosmioides. Anticarsia gemmatalis artificial diet cubes (1 cm²) were dipped into a bacterial solution at the concentration of 108 spores per mL and offered to caterpillars placed in 20-well cell plates. Forty caterpillars were used in each treatment. The experiment was conducted in B.O.D. chambers at 25±2ºC, 60±10% RH, and a 14h photophase. Mortality assessment was performed after 72h. The mortality of caterpillars exposed to strains Br36, Br37, Br45, Br7, Br10, and Br9 was 66%, 95%, 86%, 87%, 73%, and 100% respectively, demonstrating a high efficacy against this pest. This study is part of a larger project aimed at evaluating the biological activity of Bacillus thuringiensis against the species Spodoptera eridania, Spodoptera frugiperda, and Spodoptera cosmioides, which cause serious problems in cotton in Brazil.