Efficacy of several larvicides in laboratory and field tests against Anopheles sundaicus in a village, North Sumatra, Indonesia

Abstract

Laboratory and field evaluation of larvicides was carried out against Anopheles sundaicus in a coastal village of North Sumatra, Indonesia in 1984 and 1985. The 4th instar larvae were highly susceptible to methoprene (IC_<50>=0.00009ppm), and susceptible to temephos (LC_<50>=0.0032ppm) and chlorpyrifos-methyl (LC_<50>=0.0037ppm). However, they seemed to be a little tolerant to fenitrothion (LC_<50>=0.015ppm) and fenthion (LC_<50>=0.025ppm). Temephos 5% wp was effective to suppress larval densities almost completely for at least 9 days at a target concentration of 1ppm. Practical efficacy of this chemical was considered to remain for at least 2 weeks, taking the developmental period of the immatures into account. Chlorpyrifos-methyl 5% wp was effective to control larval densities almost completely for 7 days, and fenitrothion 50% EC was effective for less than 5 days after 1ppm field application. Field application of methoprene 10% flowable formulation (Altosid 10F) attained more than 90% emergence inhibition against the immatures for 2 weeks in artificial ditch type ponds at 1ppm target concentration, and 100% inhibition for 4 weeks in a natural flood field at 0.062g a.j./m^2 dose.