Larvicidal and pupicidal activity of spinosad against the malarial vector Anopheles stephensi

ObjectiveTo investigate the larvicidal and pupicidal activity of spinosad against Anopheles stephensi Listen.MethodsSpinosad from the actinomycete, Saccharopolyspora spinosa was tested against Anopheles stephensi at different concentrations (0.01, 0.02, 0.04, 0.06 and 0.08 ppm.), and against first to fourth instar larvae and pupae.ResultsThe larval mortality ranged from 36.1±1.7 in (0.01 ppm) to 79.3±1.8 (0.08 ppm) the first instar larva. The LC₅₀ and LC₉₀ values of first, second, third and fourth instar larva were 0.001, 0.031, 0.034, 0.036 and 0.0113, 0.102, 0.111, 0.113, respectively. The pupal mortality ranged from 33.0±2.0 (0.01 ppm) to 80.0±0.9 (0.08 ppm). The LC₅₀ and LC₉₀ values were 0.028 and 0.1020, respectively. The reduction percentage of Anopheles larvae was 82.7%, 91.4% and 96.0% after 24, 48, 72 hours, respectively, while more than 80% reduction was observed after 3 weeks.ConclusionsIn the present study spinosad effectively caused mortality of mosquito larvae in both the laboratory and field trial. It is predicted that spinosad is likely to be an effective larvicide for treatment of mosquito breeding sites.