Screening of Local Plants for Their Repellent Activity against Mosquitoes (Diptera: Culicidae)

A preliminary screening was carried out on five plants viz., Azadirachta indica, Citrus medica, Murraya koenigii, Ocimum tenuifloreum and Ricinus communis for their repellent activity against mosquitoes. The repellent activity was studied under natural conditions in the field making use of the traditional knowledge as background. Field observations were undertaken in houses wherein dried powdered plant leaves each (250 g) burnt on glowing charcoal produced smoke act as a repellent mosquitocide. Results indicated that among the five plants utilized, Azadirachta indica, Murraya koenigii and Citrus medica provided repellence with a protection time of six hours followed by Ricinus communis and Ocimum tenuifloreum with four hours. Besides these, the incidence of mosquito bites significantly reduced after usage of plant products. It may be concluded that natural products from plants of insecticidal and medicinal values have higher efficiency in reducing mosquito menace due to their repellent toxicity. Further studies on the in-depth laboratory and field bioassays are needed as the present study indicated the scope to use local plants to control and repel mosquitoes.