Bioassays with diamide insecticides in the Mid-South

The diamide insecticides have recently become an invaluable asset in caterpillar control in multiple crops throughout the Mid-South. These insecticides can be characterized as having high levels of acute toxicity to most caterpillar pests. Additionally, these insecticides provide excellent residual control against target pests. The high levels of acute toxicity and long residual life make this class of chemistry especially vulnerable to the development of resistance by one or more species in a relatively short period of time. It is important to have a thorough understanding of the impact of selection pressure on the development of resistance. Additionally, an understanding of the mechanisms of resistance to this class of chemistry is needed to evaluate the risk of resistance development, predict levels of control that can be expected if or when resistance develops, to design management plans to control resistant populations, and to develop an effective resistance management plan to delay and/or prevent resistance.  Baseline susceptibility to the diamides is necessary for future resistance monitoring efforts for caterpillar pests. Bioassays were conducted in the summer of 2013 to determine the best method for conducting concentration mortality bioassay to establish baseline susceptibility levels for multiple caterpillar pests in Mississippi to the diamides.