Eficácia de inseticidas em adultos de Euchistus heros (Fabricius) (Hemiptera: Pentatomidae)

Abstract

The efficiency of insect-pest control has decreased in recent growing seasons, largely due to the repeated use of insecticides with the same mode of action, which promotes the selection of resistant populations. This study aimed to evaluate the susceptibility of Euschistus heros to insecticides through tarsal contamination, topical application, and ingestion. The experimental design was completely randomized in a factorial scheme using five products (acephate, imidacloprid, thiamethoxam, thiamethoxam + lambdacyhalothrin, and imidacloprid + bifenthrin) and four doses (50%, 100%, 150%, and 200% of the label-recommended rate for soybean), with 10 replicates, each consisting of five adult stink bugs for tarsal contamination and 10 adults for the other methods. For tarsal contamination, scintillation vials coated with insecticides were used; for the other methods, the insecticides were applied to soybean plants, after which pods and leaves were collected and offered to the insects. Mortality assessments were conducted at 6, 12, 18, 24, 48, and 72 hours after insect exposure to the insecticide. Data were analyzed using Tukey’s test at a 5% significance level. In topical and tarsal contamination, significant differences were observed among the insecticides tested. Imidacloprid showed the lowest mortality rates, not reaching 25% in either method. In contrast, in tarsal contamination, acephate and thiamethoxam + lambda-cyhalothrin resulted in mortality rates exceeding 75% of the insects. For ingestion and ingestion + tarsal contamination, no significant differences were detected.