Phytotoxicological evaluation of Tagetes erectes on aquatic stages of Anopheles stephensi.

Petroleum ether (5%) in ethyl acetate fraction of Tagetes erectes showed toxic activity against second and fourth instar larvae of Anopheles stephensi below 100 ppm concentrations. The LC50 values for second and fourth instar larvae were calculated to be 43 and 58 ppm respectively. The second instar larvae were more susceptible than the fourth instar larvae. The extract did not affect the larval developmental period. The growth index of treated mosquitoes was significant in comparison with that of the control and untreated sets (p < 0.01). Treatment with the extract had a significant effect on the mortality and reduction in the adult emergence of the vector.