Do foliar insecticides applied for stink bug adults impact stink bug egg eclosion and nymphal survival?

Stink bugs are economically significant insect pests of soybean (Glycine max L.).  Producers protect their crops from stink bugs by monitoring populations and applying chemical insecticides once action thresholds are met.  However, these thresholds are based on current numbers of nymphs and adults, and it is unknown if insecticides can harm developing embryos within eggs.  An experiment was conducted to determine the efficacy of foliar insecticides applied for stink bug adults on stink bug egg eclosion and nymphal survival.  Egg masses of the three most commonly occurring stink bugs; Nezara viridula, Piezodorous guildinii, and Euschistus quadator, were selected.  Insecticides selected for testing were bifenthrin, lambda-cyhalothrin, thiamethoxam, and lambda-cyhalothrin + thiamethoxam.  Five egg masses (< 24 h old) of each species were counted and dipped in insecticide solution (treatment) and water (control) for 1 s.  Egg masses were placed in petri dishes and observed daily until nymphal emergence.  The number of nymphs and their mortality were recorded.  Lambda-cyhalothrin + thiamethoxam reduced N. viridula, P. guildinii and E. quadrator ecolsion while lambda-cyhalothrin alone reduced P. guildinii and E. quadrator ecolsion.  Bifenthrin, lambda-cyhalothrin, and thiamethoxam were not effective in reducing ecolsion.  Neonate mortality of all stink bugs feeding on the egg chorion of bifenthrin, lambda-cyhalothrin, or lambda-cyhalothrin + thiamethoxam-treated eggs was 100%.  These early studies indicate insecticides applied for adult and nymphal control can further reduce populations by impacting developing embryos within eggs. Even when neonates emerge, feeding on the insecticide-treated egg chorion can further reduce survival.