Larvicidal activity of Murraya koenigii (L.) Spreng (Rutaceae) hexane leaf extract isolated fractions against Aedes aegypti Linnaeus, Anopheles stephensi Liston and Culex quinquefasciatus Say (Diptera: Culicidae)

Mosquitoes are significant public health pests and act as a vector of several diseases viz ., malaria, filariasis, Japanese encephalitis, dengue fever and chikungunya, which are transmitted by the three genera of mosquitoes, viz ., Anopheles, Culex and Aedes . Mosquito control strategies have depended primarily on the use of synthetic chemical insecticides but resulted in rebounding vectorial capacity, environmental and human health concerns. Plants may be a source of alternative agents to replace the synthetic insecticides for mosquito control. In the present study, the isolated fractions of Murraya koenigii hexane leaf extracts were evaluated for larvicidal activity against vector mosquitoes viz., Aedes aegypti , Anopheles stephensi and Culex quinquefasciatus . Six fractions viz., A, B, C, D, E and F were obtained from the residue of hexane extract by column chromatography. Standard WHO protocol with minor modifications was adopted for the larvicidal bioassay. Larvicidal activity was evaluated against the isolated fractions at concentrations of 25, 50, 75 and 100 ppm. Larval mortality was observed 24 hours post exposure. Amongst the isolated fractions tested, fraction ‘D’ showed 100.0, 97.6 and 99.2% mortality against third instar larvae of Aedes aegypti , Culex quinquefasciatus and Anopheles stephensi at 100 ppm, respectively and LC50 values were 35.06, 27.20 and 42.51 ppm respectively. Further investigations are needed to explore the larvicidal activity of the isolated fraction ‘D’ of hexane leaf extract of this plant and also the active principle(s) responsible for larvicidal activity.