Field evaluation of toxicity of plant extracts against vector of filariasis Culex quinquefasciatus Say, 1823 (Diptera: Culicidae)

Abstract

Mosquito control has been facing backlashes due to the emergence of resistant varieties against synthetic insecticides. The bioactivity of five plant extracts viz., Poncirus trifoliate, Murraya paniculata, Citrus bergamia, Aegle marmelos and Limonia acidissima was studied against the filarial vector of Culex quinquefasciatus Say, 1823. Larvicidal assays were conducted under laboratory condition to evaluate the 24 h LC50 and LC90 of the selected plants against 3rd instar larvae of Cx. quinquefasciatus. The lethal concentration (LC50 and LC90) values ranged from 76.26 to 208.32 mg/L and 191.85 to 477.16 mg/L, respectively. The result of larvicidal test suggests that the larvicidal activity of the L. acidissima and P. trifoliate extracts were highly influenced. Test results showed that the flavonoid compounds exhibited larvicidal activity against 3rd instar Cx. quinquefasciatus mosquitoes. Percent reduction was recorded with an LC50 concentration of L. acidissima and P. trifoliate. A field study was carried out to evaluate larvicidal activity on 24 h, 48 h and 78 h period and percentage of larval and pupal reduction due to L. acidissima and P. trifoliate extracts in the unused cement tank and mini water pool in Puthanampatti, Tiruchirappalli district. The field tested plant extracts proved to have various activities against different life stages of Cx. spp. Therefore, flavonoid compounds from L. acidissima and P. trifoliate plant can be a potential candidate for use in the development of commercial mosquito larvicidal products that may be an alternative to conventional synthetic chemicals, particularly in integrated vector control applications.