Effect of neonicotinoid seed treatments on prey-predator interactions of soybean aphid and Orius insidiosus (Hemiptera:Anthocoridae)

Pesticide seed treatments are becoming a common strategy in integrated pest management of Aphis glycines Matsumura (Hemiptera: Aphididae).  One of the benefits of this technology is the reduced exposure of non-target organisms to chemical pesticides. In North America, several predator species have been reported as important regulators of soybean aphid populations. In soybean crops, Orius insidiosus can regulate soybean aphid populations and keep them below economic thresholds. In previous studies, no correlation between seed treatments and the abundance and survivorship of O. insidiosus was observed. However, in these studies it was not addressed whether the predator is consuming prey exposed to plants with insecticide seed treatments. Chemical exposure could affect predatory behavior by direct toxicity, repellency or disorientation. Consequently, pesticide residues could affect predator’s consumption rates and its capability to control A. glycines populations. In order to understand the effect of chemical residues on the predatory behavior of O. insidiosus, laboratory reared predators were exposed to neonicotinoid seed treatments using a systemic bioassay. Cut petioles of V3 soybean plants were immersed in three different insecticide solutions. Distilled water was used for the control treatment. After exposing the petiole to the chemicals for 24 hours, one aphid density was placed on the soybean leaves. Predators were introduced 24 hours after aphids were placed on the leaves. The number of consumed aphids was counted after 24 hours of the predator introduction. Biological consequences of O. insidiosus feeding on prey exposed to neonicotinoids will be discussed.