Pacific Southwest

Title: Toxicity of selected insecticides applied to western spruce budworm

Author: Robertson, Jacqueline L.; Gillette, Nancy L.; Look, Melvin; Lucas, Barbara A.; Lyon, Robert L.

Date: 1975

Source: Pacific Southwest Forest and Range Experiment Station, Forest Service, USDA, Berkeley, CA 94701

Description: The contact toxicity 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 Ld₅₀ were: bioethanomethrin, (+) cis-resmethrin, (+) trans-resmethrin, (+) cis-phenothrin. ENT 29117 (5-benzly-3-furylmethyl (IR,3S,E) 2,2-dimethyl-3- (2-oxo-3-tetrahydrothiophenylidenmethly) cyclopropanecarboxylate), resethrin, and NRDC 143 (3-phenoxybenzly(±) -3-(2,2-dichlorovinyl-2,2-dimethylcyclopropanecarboxylate). Mexacarbate spray was tested on the western spruce budworm at selected developmental stages. First instars 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.

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Citation

Robertson, Jacqueline L.; Gillette, Nancy L.; Look, Melvin; Lucas, Barbara A.; Lyon, Robert L.  1975.  Toxicity of selected insecticides applied to western spruce budworm.   Pacific Southwest Forest and Range Experiment Station, Forest Service, USDA, Berkeley, CA 94701.