Toxicity of phosphine to five species of stored‐product insects in atmospheres of air and nitrogen

Abstract

AbstractThe responses of five species of adult stored‐product insects [Tribolium castaneum (Herbst), T. confusum (DuVal), Rhyzopertha dominica (F.), Sitophilus oryzae (L.) and S. granarius (L.)] to various doses of phosphine in atmospheres of air or nitrogen were determined. A few S. oryzae and S. granarius survived phosphine concentrations up to 80 mg litre−1 for 24 h in normal (air) or nitrogen atmospheres. By contrast, T. castaneum, T. confusum and R. dominica could not tolerate more than 0.2 mg phosphine litre−1 in air for 12 h. However, they could tolerate up to 10 mg phosphine litre−1 in nitrogen for that period. Increasing the phosphine concentration resulted in increased mortalities of the last three species. The possible mechanism underlying this response is discussed. The reproductive potential of insects surviving phosphine exposure in a nitrogen atmosphere was unaffected.