EFICÁCIA DO CONTROLE DE Euschistus heros (HEMIPTERA: PENTATOMIDAE) EM FUNÇÃO DA DISTRIBUIÇÃO VERTICAL E DE PARÂMETROS DA APLICAÇÃO DE INSETICIDA NA SOJA

Abstract

Euschistus heros is one of the main pests of soybean, causing pod damage and reducing yield. The effectiveness of chemical control can be influenced by the pest’s distribution within the plant canopy, its application rate and timing, as well as using of adjuvants. This study evaluated the influence of these factors on the efficiency of thiamethoxam + lambda-cyhalothrin in controlling E. heros. Trials were conducted in soybean fields with different infestation levels of E. heros, using a randomized block design in a factorial scheme (2 × 2 × 3), testing two application rates (75 and 150 L ha-1), with and without adjuvant, at three application times (7, 13, and 17h). The vertical distribution of the pest, control efficiency (1, 3, and 7 days after application), and insecticide deposition profile within the soybean canopy were assessed. Results showed that the E. heros vertical distribution varies according to infestation level and canopy microclimate, with eggs less frequent in the middle stratum, nymphs predominating in different strata depending on infestation level, and adults concentrated in the upper and middle strata. The insecticide was more effective when applied at 75 L ha-1 during the cooler times of the day (7 and 17h), under low-infestation conditions. Insecticide deposition was higher in the upper stratum at 150 L ha-1, while the use of an adjuvant did not affect deposition or control efficiency. These findings provide practical insights to optimize application technology and develop more efficient and sustainable strategies for managing E. heros in soybeans.