Abstract

In Brazil, the caterpillar Helicoverpa armigera (Hübner) is a key economic pest of soybean, from seedling emergence to the reproductive stage. Control of this pest has relied on foliar insecticide sprays, and the use of insect-resistant cultivars. Characterization of the efficacy of insecticides that can be used for seed treatment, as a complement or alternative control for this pest, is needed for the production sector. The study objective was to evaluate the insecticidal potential of diamides for control of H. armigera larvae, when applied to soybean seeds. The effects of seed treatment with cyantraniliprole or chlorantraniliprole on 1st- and 3rd-instar H. armigera larvae, in both conventional and in “Bt soybean” (Cry1Ac), were evaluated under laboratory conditions. Two infestations were carried out at 8, 13 and 21 days after plant emergence, to determine the leaf area consumed, and mortality of larvae. The insecticides cyantraniliprole and chlorantraniliprole, used at rate of 60 and 62.5 g a.i./100 kg seeds, respectively, have potential for the control of 1st-instar H. armigera larvae up until at 13 days after the emergence of soybeans plants. The Cry1Ac protein controlled both 1st- and 3rd-instar H. armigera larvae at least until 21 days after plants emergence.

Key words: Glycine max, pest management, insecticides.