Toxicity of Acrylonitrile, Chloroacetonitrile, Ethylene Dichloride and Other Fumigants to the Confused Flour Beetle

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Abstract
Acrylonitrile and chloroacetonitrile were the most toxic chemicals to the confused flour beetle, Tribolium conjusum, in 5-hr. exposures at 25[degree]. They were also very toxic to the bedbug, Cimex lectularius, and appear worth further study as fumigants. Other chemicals tested are listed by groups approx. in the order of decreasing toxicity to the beetle, as follows: (1) CH3Br, 1,1-dichloro-l-nitropropane, and 1,1-dichloro-l-nitroethane; (2) [beta]-methyl allyl chloride, methyl allyl bromide, and ethylene oxide; (3) CS2; and (4) ethyl bromide. Ethylene dichloride was found to have a delayed killing action, which increased mortality considerably over a period of about 20 days after fumigation. The CCl4 mixture (3:1 by volume) also showed a latent effect, but CCl4 added little to toxicity. Judging only from the mortality produced after 20 days, ethylene dichloride is not far below CH3Br in the toxicity scale. However, beetles fumigated with these low concs. of ethylene dichloride may lay viable eggs before death and dosages must be increased to prevent egg laying. Small volumes of chemicals as volatile as CS2 were conveniently measured for testing by use of a small hypodermic syringe attached to a micropipette.