Effects of lambda-cyhalothrin on mosquito larvae and predatory aquatic insects.
Agricultural insecticides can affect mosquito production in rice fields by controlling mosquitoes, disrupting biological control or contributing to selection of insecticide resistance. The duration of insecticidal activity of the pyrethroid lambda-cyhalothrin was quantified on predatory insects in rice fields and on three kinds of mosquito larva: a pyrethroid-susceptible strain of Culex tarsalis Coquillet, a pyrethroid-resistant strain of Cx pipiens L. (sensu lato) and non-resistant Cx pipiens s.l. Lambda-cyhalothrin killed most caged, susceptible mosquitoes for up to 21 days. It killed fewer resistant Cx pipiens s.l., but suppressed their survival for over a week. Lambda-cyhalothrin suppressed field populations of predatory insects through day 29. Agricultural use of lambda-cyhalothrin can provide incidental mosquito control. However, the pyrethroid persisted in sediment and gradually decreased in activity, which could contribute to selection of pyrethroid-resistant mosquitoes. Because caged mosquitoes showed good survival before predators recovered, disruption of biological control is possible. It is therefore advisable for growers and mosquito control agencies to communicate about pesticide use.
Lawler
Sharon P
SP
Department of Entomology and Center for Vector-Borne Disease Research, University of California, 1 Shields Ave., Davis, CA 95616, USA. splawler@ucdavis.edu
Dritz
Deborah A
DA
Christiansen
Julie A
JA
Cornel
Anthony J
AJ
D000818:Animals; D003465:Culex / Q000187:drug effects* / Q000254:growth & development; D004351:Drug Resistance / Q000187:drug effects; D019015:Geologic Sediments / Q000737:chemistry; D007313:Insecta / Q000502:physiology; D007306:Insecticides; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D009570:Nitriles / Q000633:toxicity*; D011235:Predatory Behavior; D011722:Pyrethrins / Q000633:toxicity*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014874:Water Pollutants, Chemical; D014867:Water; C037304:cyhalothrin