Influence of Onion (Allium cepa, L.) Oil Extract on Glossina palpalis gambiensis, (V.) Landing and Probing on Human Skin

Abstract

Tsetse fly Glossina palpalis gambiensis is the chief agent of Trypanosoma brucei  gambiense parasite, and a major vector of human African trypanosomiasis in west and central Africa and it poses a big socio-economic burden. This study aimed to investigate the concentration-dependent and time-dependent effects of the oil extract of onion on G. p. gambiensis landing and probing on human  skin under laboratory conditions. Oil was extracted from fresh onion bulbs using cold maceration with n-hexane, and evaluated for its influence on the landing and probing behaviour of tsetse fly using human test volunteers under laboratory conditions. Volunteers’ forearms, treated with onion oil extract at different concentrations of 50%, 75%, 87.5% and 100%, were exposed to 48-hours starved laboratory-reared teneral G. p. gambiensis. The number of tsetse flies that landed, and probed the skin were recorded over a 5-hour period. Data generated were subjected to statistical analysis using two-way analysis of variance. All graded concentrations of onion oil extract showed significant difference (p ˂ 0.01) in their mean values in preventing tsetse flies from landing and probing on skin. The strong efficacy exhibited by onion oil underscores its potential as a complementary tool in existing integrated tsetse control tools, such as the environmentally friendly methods of integrated control of tsetse flies, being advocated by the Pan African Tsetse and  trypanosomiasis Eradication Campaign initiative of the African Union (AU) to curb the transmission of trypanosomiasis.