Division of Entomology, Department of Zoology, Bharathiar University, Coimbatore - 641 046, Tamil Nadu, (India).
*Corresponding author.
1Present address: Lab. of Signal Selection, National Institute of Sericultural and Entomological Sciences, Tsukuba, Ibaraki, 305, (Japan).
Antipupational effect of neem oil and neem seed kernel extract (NSKE) was evaluated against Anopheles stephensi. As a result of treatment of water used for rearing, neem oil (5%) was more effective than NSKE, the larval mortality being 99.3% as compared to 65.9% with NSKE (5%). But 10% NSKE gave 89.8% larval mortality. The percentage of pupation and adult emergence appeared to be dose-dependent, being respectively 19.3 and 11.2% with 3% neem oil as compared to 93.7 and 89.6% obtained in control. No pupation occurred with 5% neem oil treatment. With 5% NSKE, the adult emergence was 20.7%, whereas in 3% neem oil it was reduced to 11.2%. With 2.5% NSKE, the adult emergence was 54.8%, but drastically reduced to 3.1% when 10% NSKE was used vis-a-vis control (89.6%). Evidently, the percentage of pupation and adult emergence were markedly reduced by neem oil and NSKE treatments, suggesting the growth regulatory effects and post-ingestive toxicity of neem extractives in mosquito control.
