Investigation of reduced agent and area treatments for soybean aphid management and its effects on key predators

Soybeans are an abundant and valued agricultural crop in Nebraska and other parts of the world. Significant soybean aphid, Aphis glycines Matsumura, mortality has been observed in research plots adjacent to soybean treated with chlorpyrifos in late July through August. The objectives of our study were to determine the efficacy of the chlorpyrifos vapor effect on soybean aphids in adjacent untreated areas and assess the impact of the vapor effect on key biological control agents. Observation of soybean aphid populations and sweeps of other arthropod species, including Oruis insidiosus, began weekly in mid to late July. When aphid levels reached economic thresholds, chlorpyrifos pesticide was applied to designated spray areas. Weekly assessments continued to monitor populations both in the spray areas and at set distances from the spray areas. Results from the 2013 field season suggest an area of eight to sixteen rows may be left in the untreated zones. Results from 2014 field season to be presented.