Evaluation of target specific larvicidal activity of the leaf extract of Typhonium trilobatum against Culex quinquefasciatus Say

To investigate the target specific larvicidal potential of an edible herb Typhonium trilobatum (T. trilobatum) (L.) Schott against mosquito Culex quinquefasciatus (Cx. quinquefasciatus) Say. Different concentrations of crude and methanol extract of T. trilobatum mature leaves were treated against Cx. quinquefasciatus larvae. LC50 concentration of crude extract on mosquito 3rd instar larvae was tested on Chironomus circumdatus and Diplonychus annulatum larvae. Preliminary phytochemical analysis was performed in search of plant's secondary metabolites. 100% mortality of 1st instar mosquito larvae was recorded at 0.4% concentration after 72 h of exposure of crude extract. At 72 h 0.5% concentration produced 100%, 89.99% and 79.99% mortality of 2nd, 3rd and 4th instar larvae respectively. 50 ppm methanol extract showed 73.67% mortality of 3rd instar mosquito larvae at 72 h. 400 ppm concentration was responsible for 100% mortality in 24 h. Application of LC50 concentration (of 3rd instar mosquito larva) against non target organisms like C. circumdatus and D. annulatum larvae produced no significant mortality among them. Secondary metabolites like terpenoids and free glycoside bound anthraquinones were found. This experimental study was a pioneer attempt to establish T. trilobatum as a valuable resource of effective target specific mosquito larvicide.