Dose-mortality responses of crawfish and mosquitoes to selected pesticides.

A study was conducted to determine the toxicities (LC50S) of several pesticides on the commercially important red swamp crawfish, Procambarus clarkii, and 3 mosquito species common in Louisiana ricelands--Anopheles quadrimaculatus, Culex salinarius and Psorophora columbiae. Pesticides tested in laboratory bioassays included Bacillus sphaericus, B. thuringiensis var. israelensis, bendiocarb, glyphosate, isostearyl alcohol, malathion, propoxur, resmethrin synergized with piperonyl butoxide (PBO) and thiobencarb. Isostearyl alcohol was the least toxic compound to crawfish, with a LC50 of greater than 10,000 ppm, while resmethrin + PBO (1:3 ratio) was the most toxic with a LC50 of 0.00082 ppm. The herbicides glyphosate and thiobencarb were the least toxic compounds for the mosquito species tested, while B. t. var. israelensis and resmethrin + PBO were the most toxic.