Efficacy of different organophosphate and synthetic pyrethroid insecticides to the larvae of malaria vector Anopheles stephensi, Liston.

Evaluation of the potency of four organophosphate (OP) (Malathion, Fenthion, Fenitrothion and Temephos) and two synthetic pyrethroid (SP) compounds (cypermethrin and deltamethrin) was carried out against larvae of Anopheles stephensi, the major malaria vector in district Bikaner (Rajasthan). Different concentrations supplied by WHO were used for determining the percent mortalities. LC50 values as calculated by probit analysis were 1.2740, 0.0600, 0.0405, 0.0046, 0.0019 and 0.0016 mg/l respectively for the above six insecticides. Both SP compounds were found more toxic followed by temephos among the OP compounds. Malathion was found the least toxic while fenthion and fenitrothion were in between these two extremes.