Repellence Activity of Cymbopogon Citratus (DC) Extracts on Anopheles Mosquitoes using Swiss Albino Rat and Human Volunteer

Insect-transmitted disease remains a major source of illness and death worldwide. Anopheles stephensi and Anopheles culicifacies are the important vectors of malaria, malaria continues to be a major public health problem in the tropical world. This study is aimed at carrying out repellence activity of Cymbopogon citratus (Lemon grass) extracts on Anopheles mosquitoes using swiss albino rat and human volunteers.

Methanol, chloroform and water were used to extract the bioactive compounds of plant leaves, qualitative and quantitative phytochemical components of plant extracts were determined, twenty-five laboratory-reared 3 day old Anopheles mosquitoes which had been starved for 5 hours were used, extracts and the commercial insecticide N, N-diethyl-3-methylbenzamide (DEET) were applied topically on the skin of uncovered portions of the hand of the human volunteers and abdomen of swiss albino rat after the abdominal hairs has been shaved and the landing rate of mosquitoes were observed to calculate percentage repellency.

The result revealed that methanol extract had the highest percentage yield of 10.3%, tannin and alkaloid were present in all extracts. DEET had 100% repellency to Anopheles mosquitoes on both human volunteers and rats for 300 minutes post application, in human volunteers, water, chloroform and methanol extracts, has percentage repellency reduced from 100% to 94% after 60 minutes, 100% to 94% after 120 minutes and 100% to 83% after 150 minutes post application respectively while in swiss albino rat, water, chloroform and methanol extracts, percentage repellency reduce from 100% to 87% after 90 minutes, 100% to 87% 150 minutes and 100% to 90% after 180 minutes post application respectively.

Methanol extracts of C. citratus leaves could be used for the development of topical cream that repels mosquitoes for effective control of malaria.