Acute toxicity of newer insecticides to red swamp crayfish, Procambarus clarkii in small plot rice field experiment

Rice-crawfish rotation practiced in south-west Louisiana is the major source of the both commodities in the state. The rice water weevil is a major pest of rice for which insecticides are applied. Small plot field evaluations were conducted in drill-seeded rice using a randomized complete block design to evaluate the acute toxicity of different insecticides to red swamp crawfish. Plots were stocked twice with crawfish representing different stages (mature and immature) of both sexes (male and female) in cages at permanent flood and one or two weeks later. The treatments were seed treatments (Dermacor X-100™ & Nipsitt™), a granular insecticide (dinotefuran), two foliar insecticides (Belay™ & Karate™) and an untreated control. Crawfish treated with Karate showed 100% mortality within 2 days of stocking. Second stocking of crawfish done 10 days after permanent flood did not result any significant kill in crawfish although elevated levels of percent mortality were noticed. Parallel bioassays conducted in the lab using field collected water in plastic containers provided with individual crawfish yielded similar results during I stocking.