Husam A. Darwazeh

Impact of selected synthetic pyrethroids and organophosphorous pesticides on the tadpole shrimp, Triops longicaudatus (Le Conte) (Notostraca: Triopsidae).

Predation by the omnivorous tadpole shrimp, Triops lonqicaudatus (LeConte) (Notostraca: Triopsidae), reduces larval populations of the mosquito Culex tarsalis Coquillett in experimental ponds in the Coachella Valley of southern California and has made field evaluation of other larval control agents very d i f f i cu l t . ! . lonqicaudatus is also a pest in rice fields where its digging and feeding activit ies uproot young seedlings, may retard seedling growth, and damage seeds (Anonymous 1983, Grigarick et al. 1985). In rice fields, this crustacean is controlled primarily by applying copper sulfate (Grigarick et al. 1985). Holck and Meek (1987) found that another crustacean rice field pest, the red swamp crawfish, Procambarus clarkii Girard (Decapoda: Cambaridae), was most susceptible to resmethrin + piperonyl butoxide (PBO) (LCsN: 0.00082 mg/L) as compared to several other pesticides used com66nly for mosquito control. Our objectives were to identify a material that would control tadpole shrimp but would not exhibit residual activity that would l imit mosquito populations and interfere with field tests of larval control agents. Here, we report the results of field tests and laboratory bioassays with two synthetic pyrethroids and two organophosphorous pesticides against tadpole shrimp.