Toxicity of Nicotine Administered Internally to Several Species of Insects

Abstract

Nicotine was administered in measured doses (i) by feeding leaf sandwiches containing known amts. of nicotine and measuring the areas eaten, and (ii) by injecting the nicotine directly into the pharynx or blood with a micro-syringe. Larvae which were not susceptible to nicotine, and survived doses of 0.04-9.8 mg./g. were Malacosoma americana, Hyphantria cunea, Lycophotia margaritosa saucia, Mamestra picta, Estigmene acraea, Halisidota caryae, Carpocapsa pomonella, Protoparce sexta, P. quinquemaculata, Cacoecia cerasivorana, Ascia rapae, Datana integer-rima and larvae and adults of Leptinotarsa decemlineata; Bombyx mori survived no doses of nicotine above 0.017 mg./g. A compound of Reinecke''s salt (chromium ammonium thiocyanate) with nicotine was highly toxic to adults of L. decemlineata and to larvae of B. mori, moderately toxic to larvae of the tobacco worm, but not appreciably toxic to the imported cabbage worm, hickory tussock moth, ugly-nest caterpillar, walnut caterpillar or to larvae of L. decemlineata, Euchaetias egle, Nymphalis antiopa, Cacoecia cerasivorana and Halisidota carvae were repelled by nicotine in both soluble and insol. forms. Euchaetias and Nymphalis would not eat measurable doses; the ugly-nest caterpillar ate small amts. which, although they affected the larvae rapidly, were regurgitated before death occurred; and the hickory tussock moth larvae were not affected by the small doses taken. There seemed no very significant difference between soluble and insoluble forms of nicotine, or between injected and ingested nicotine. 3d-instar larvae of the walnut caterpillar were moderately susceptible to nicotine poisoning; 5th instar larvae were not.