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

Objective: To investigate the larvicidal and pupicidal activity of spinosad against against Anopheles. stephensi Listen. Methods: Spinosad 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. Results: The 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. Conclusions: In 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.