Larvicidal Efficacy of Aqueous Extracts of Citrus grandis (Grapefruit) against Culex Larvae

Mosquitoes serve as vector for various tropical and subtropical diseases which cause destructive effects to humans. Development of resistance to insecticides and wide spread environmental pollution necessitate a continued search for alternative pest control as well as vector control strategies. The present study was undertaken to evaluate the larvicidal activity of various extracts of boiled and unboiled leaves of Citrus grandis against Culex quinquefasciatus. Various concentrations (20 mg/200ml, 40 mg/200ml and 60 mg/200ml) of the Citrus grandis extracts were tested against fourth instar larvae of Culex quinquefasciatus. The larval mortality was observed after each 24 h of exposure. All the extracts showed significant larvicidal activity against Culex mosquito at 0.05 level of significance (p<0.05) however, the highest larval mortality was found in 30% boiled extract of leaves as it took least time (5 days) to give 97% mortality. The results indicated that the aqueous leaf extract of Citrus grandis is effective against Culex quinquefasciatus mosquito larvae and need to be explored for its possible use in the control of mosquito population