Adulticidal potentials of dichloromethane extracts of some selected plant leaves against <i>Culex</i> mosquitoes

Abstract

Culex mosquitoes are vectors of Lymphatic filariasis and Japanese encephalitis diseases and the control of these diseases using synthetic chemical insecticides such as Pyrethroids results in development of resistance by the mosquitoes and polluting the ecosystem. This research was aim at evaluating the adulticidal potentials of dichloromethane extracts of some selected plant leaves against Culex mosquitoes. The results of the phytochemical screening analysis of the dichloromethane extracts shows that, Cymbopogon citratus, Mentha piperita and Ocimum citriodorum contained the highest number of phytochemicals four (4) each, followed by Lamium pupureum and Zingiber officinale having three (3) the last extracts having the least phytochemicals is Senna occidantalis which contains only two (2). The results of the adulticidal bioassay of the extracts shows that Cymbopogon citratus exhibited the highest adulticidal activities against the Culex mosquitoes tested at the LC₅₀ 5.721mg/ml and LC₉₀ 211.703mg/ml. The percentage mortality was recorded highest at the highest concentration 20mg/ml (87%), followed by 10mg/ml (74%) and 5mg/ml (43%). The mean average mortality and standard error were also recorded at 21.7±0.47, 18.5±3.01 and 10.7±1.37 respectively. From these results, it can be concluded that, the adulticidal activity of an extract depends on the solvent used in the extraction. Cymbopogon citratus extract was an excellent potentials for controlling Culex mosquitoes. Therefore we recommend that it should be used to control Culex mosquito in the affected areas.

Keywords: Adulticidal, Culex mosquito, Dichloromethane, Extracts, Phytochemicals