Efeito residual e seletividade de inseticidas sobre Telenomus podisi e associação de bioinsumos para o controle de Euschistus heros

Abstract

Soybean (Glycine max) is cultivated under different management systems and, regardless of the strategy adopted, is susceptible to insect pest attacks. Among the piercing-sucking insects, the Neotropical brown stink bug (Euschistus heros) stands out due to its high potential to cause damage, especially to marketable grains. This study aimed to evaluate the effectiveness of combining biological inputs for the control of E. heros, as well as the residual effect and selectivity of different insecticides on the egg parasitoid Telenomus podisi. Two laboratory bioassays were conducted. In the first bioassay, microbiological products and secondary metabolites of Pseudomonas chlororaphis and Chromobacterium subtsugae, applied individually and in combination with Beauveria bassiana, were evaluated against second- to fifth-instar nymphs of E. heros, with mortality assessed over eight days. In the second bioassay, soybean plants treated with different insecticides were used to evaluate the survival of adult T. podisi exposed to insecticide residues at 2, 4, 6, and 9 days after application, with evaluations performed after 24, 48, and 72 hours of exposure. Mortality was expressed as a percentage, and the data were subjected to analysis of variance (ANOVA). When significant differences were detected, means were compared using Tukey's test at the 5% probability level with the RBio software. The results showed that Thiamethoxam + Lambda-cyhalothrin caused 100% mortality of E. heros within the first 48 hours, whereas the combination of secondary metabolites from Pseudomonas chlororaphis and Chromobacterium subtsugae with Beauveria bassiana showed the best performance among the biological treatments. Regarding T. podisi, all insecticides reduced parasitoid survival. The residual effect of the insecticides decreased over time, and an interval of nine days after application was the safest period for parasitoid release. These results highlight the potential of integrating chemical and biological control strategies for the management of E.heros.