Abstract

Brazil is the second largest producer of soybeans in the world, with the state of Mato Grosso having the highest production in the country. The soybean crop faces major phytosanitary difficulties throughout its cultivation, as is the case of pest incidence, especially the defoliating caterpillars that can cause intense defoliation of soybean and affect its productivity. Thus, the objective of this work was to evaluate the effect of different insecticides when applied in soybean seed treatment, on leaf consumption and survival of Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae) caterpillars. For this purpose, two trials were installed in the field, one in the Juscimeira Municipality/MT and the other in the Municipality of Itiquira/MT. The soybean seeds were treated with the insecticides (in g a.i./ha): chlorantraniliprole (62.5), imidacloprid + thiodicarb (75.0 + 25.0), fipronil (50.0), thiamethoxam (70.0) and cyantraniliprole + thiamethoxam (60.0 + 70.0) and a control treatment (without insecticide). Soybean leaflets were collected at different times after plant emergence and were offered to A. gemmatalis and C. includens caterpillars in the laboratory to evaluate leaf consumption and mortality. Cyantraniliprole + thiamethoxam (60.0 + 70.0) and chlorantraniliprole (62.5) treatments were found to reduce leaf consumption of A. gemmatalis and C. includens caterpillars. The highest mortality values of A. gemmatalis and C. includens were observed in the treatment cyantraniliprole + thiamethoxam (60.0 + 70.0), followed by chlorantraniliprole (62.5) when compared to the control treatment. The results showed that the treatment of soybean seeds with insecticides can protect the crop against defoliation and provide control of defoliating caterpillars, these effects being more pronounced in sandy soils than in clay soils.

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