THE ACTION OF FUMIGANTS ON INSECTS: IV. THE EFFECTS OF OXYGEN ON THE TOXICITY OF FUMIGANTS TO INSECTS

Abstract

Oxygen at and below 1 atmosphere pressure was found to enhance the toxicity of seven different fumigants to two species of insects. Although oxygen produced no obvious effects on untreated insects, it enhanced the effect of the poisons within the first 24–30 hours after treatment. In pure oxygen, cyanide-poisoned insects recovered the ability to consume oxygen more rapidly than in air but this did not enable them to overcome the effects of the cyanide; instead more of the insects died. Catalase was inhibited to varying degrees by different fumigants but this inhibition did not bear any obvious relationship to enhancement of toxicity by oxygen. Exclusion of oxygen from insects prior to fumigation increased their susceptibility to cyanide by a factor of 20.