Toxicity of selected insecticides applied to western spruce budworm

Abstract

The contact toxlaty of 100 insecticides to last stage larvae of Choristoneura occidentalis Freeman was tested by topical application in a 10-yr series of screening experiments. Pyrethroids were generally the most toxic group of chemicals tested. Compounds more toxic than the standard, mexacarbate, at LD₉₀ were: bioethanomethrin, (+) cis-resmethrin, (+) trans-resmethrin, (+) cis-phenothrill. ENT 29l17 (5-benzyl-3-furylmethyl (IR,3S,E) 2,2-dimethyl-3- (2-oxo-3-tetrahydrothiophenylidenmethyl) cyclopropanecarboxylate), resmethrin, and NRDC 143 (3-phenoxybenzyl (±) -3- (2,2-dichlorovinyl-2,2-dimethylcyclopropanecarboxylate). Mexacarbate spray was tested on the western spruce budworm at selected developmental stages. First instal's were least susceptible at both LD₅₀ and LD₉₀; instars 3-5 and 6th instars weighing less than 110 mg were most susceptible. Since long-term laboratory rearing of insects did not change their responses to 3 representative chemicals periodically tested during this series of experiments, the results represented a valid estimate of relative toxicity.

Citation

Robertson, Jacqueline E.; Gillette, Nancy L.; Lucas, Barbara A.; Lyon, Robert L. 1976. Toxicity of selected insecticides applied to western spruce budworm. Journal of Economic Entomology.69(1):99-104.