Studies of Nicotine as an Insect Fumigant

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Abstract
The resistance to nicotine of 37 different insects varied widely. 13 spp. of aphids and thrips and 6 other spp. were killed by concs. of 0.003-0.025 mg. per liter in 30-min. or shorter exposure at 25[degree] C in the laboratory. The resistance of Myzus persicae varied greatly depending on 3 different host plants. Comparisons of resistance are preferably made at the 95% rather that the 50% kill conc. because of its greater practical value. Nearly mature larvae of Prodenia eridania and Heliothis armigera were much more resistant than young larvae, but there was little difference with Bombyx mori larvae. Nicotine acts rapidly against some insects, giving complete kill in a 1-min. fumigation. Short exposures to high concs. were more effective than proportionately long exposures to low cones. Gas conc. had a greater weight in affecting efficiency than exposure time. This relationship appeared fairly constant for each of the 4 insects tested over a limited range of exposures. Nicotine appeared much more toxic in the laboratory than HCN to several insects on the basis of a comparison with published results with the latter gas.