Cyazypyr seed treatment to control soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae)

The soybean aphid, Aphis glycines, is one of the most limiting pests in soybean crops in North America. Cyantraniliprole (Cyazypyr) is a second generation of antranilic diamide insecticides that affect the ryanodine receptor in insects. This compound has been reported as a promising new insecticide against sucking pests in different kind of crops. In this study, we evaluated the toxicity of Cyazypyr seed treatments to soybean aphids, and its residual effect in soybean plants. Three cyazypyr treatments, a standard control treatment (thiametoxam), and an untreated control with nine replications were evaluated. Thirty apterous adults of soybean aphids were placed over the first open trifoliate on each treatment. Living aphids were counted in the first three open trifoliates after 1, 2, and 3 weeks after infestation. Cyazypyr caused a reduction in the total number of aphids at the evaluated doses. The best pest control was achieved at 37 and 44 days after planting (weeks 1 and 2 after infestation). During these days, the number of soybean aphids was maintained below the economic threshold reported in previous studies for this pest. Each treatment showed significant differences in soybean aphid densities between days. The differences in chemical properties of thiametoxam and cyazypyr may result in differences in the uptake of the compound in the plant. Evaluation of treatment doses in the plant, during different development stages, will help to understand the uptake of cynantriniliprole in soybean plants.