Abundance and diversity of beneficial arthropods after exposure to selective insecticides in Virginia soybean

More natural enemies are found in many crops treated with selective insecticides compared to those treated with broad-spectrum insecticides, but further work needs to clarify how selective insecticides alter natural enemy diversity and their population rebound after exposure. This research examines the effects of a new class of selective insecticides, diamides, on the natural enemy community immediately after exposure and population rebound in Virginia soybean. In large plots arthropods were exposed to one application of chlorantraniliprole, flubendiamide, a broad-spectrum insecticide or no insecticide. Beat cloth, sweep net and sticky card samples were taken pre- and post-treatment to determine abundance and diversity of foliar-dwelling arthropods. Total natural enemies were similar for all treatments except the broad-spectrum insecticide until three weeks after treatment. However, individual natural enemy species took different amounts of time to decrease in density in response to the broad-spectrum insecticide. For instance, spider populations were similar across treatments until two weeks after application, while Orius insidiosus densities were similar until three weeks after application. This experiment will be repeated in 2014. To further examine how crop production practices affect beneficial arthropod populations, population abundance and diversity will be compared across full-season and double-crop soybean throughout the 2014 field season.