Studies on the Toxicity of Acetone, Acrolein and Carbon Dioxide on Stored-Product Insects and Wheat Seed

Abstract

In laboratory experiments toxicity of acetone, acrolein and carbon dioxide were investigated against 4 species of stored-product insects. In all experiments, acrolein was the most toxic compound to the tested insects. In empty-space trials, estimated LD50 values of acrolein for adults of Tribolium castaneum (Herbst) (Tenebrionidae), Rhizopertha dominica (F.) (Bostrychidae), Sitophilus oryzae L. (Curculionidae) and Oryzaephilus surinamensis L. (Silvanidae) were 7.26, 6.09, 6.37 and 5.65 microl L(-1), respectively. Penetration tests revealed that acetone and acrolein vapors could penetrate into the wheat mass and kill concealed insects in interkernel spaces. Comparison of LD50 values of acrolein between empty-space tests and penetration experiments indicated that the increase in penetration toxicity was 4.96, 4.54, 3.64 and 3.43-fold for T. castaneum, R. dominica, S. oryzae and O. surinamensis, respectively. The effect of carbon dioxide on the toxicity of acrolein and acetone was synergistic. In the hidden infestation trials, the acrolein vapors destroyed the developmental stages of S. oryzae concealed inside the wheat kernels and resulted in a complete control with concentration of 80 microl L(-1) for 24 h and subsequently observed during 8 weeks after the exposure. Wheat germination and plumule length was reduced following exposure to all doses of acrolein. Acetone and carbon dioxide were harmless to wheat seed viability. The mixture of carbon dioxide with acrolein can be considered as a potential fumigant for replacing methyl bromide or phosphine under ambient storage conditions specifically in empty-space fumigations.