Chiang Mai Journal of Science

 Anopheles stephensi mosquitoes are the leading vector of malaria in Indian subcontinent, parts of Asia and the Middle East. Mosquito control is facing a threat due to the emergence of resistance to synthetic insecticides. Plants may be alternative sources of mosquito control agents. The present study assessed the role of larvicidal activities of methanolic leaf and inflorescence extract of Anisomeles malabarica (L.) against malarial vector Anopheles stephensi Liston (Insecta: Diptera : Culicidae). The larvicidal activity was assayed against the mosquito species at various concentrations ranging from (20 to 100 ppm) under the laboratory conditions. The LC₅₀ and LC₉₀ value of the methanolic leaf and inflorescence extract of Anisomeles malabarica (L.) was determined by Probit analysis. The percentage of mortality of Anopheles stephensi after the treatment of Anisomeles malabarica on I to IV instar larvae from 20,40,60,80 to100 ppm. The LC₅₀ and LC₉₀ values were represented as follows: LC₅₀ value of I instar was 50.24%, II instar was 54.70%, III instar was 59.03% and IV instar was 64.33%, respectively. LC₉₀ value of I instar 106.99%, II instar was 113.33%, III instar was 118.04% and IV instar was 119.94%, respectively. The present results suggest that the effective Anisomeles malabarica leaf and inflorescence crude extracts have potential to be used as an ideal eco-friendly approach for the control of mosquito vectors.