Repellence of Aedes aegypti with oils from Citrus sinensis and Citrus paradisi fruit peelsi from Nsukka
Aedes aegypti spread yellow fever, dengue fever, Zika virus and Chikungunya that can be prevented through vector control. Chemical insecticides are resisted by vectors, harm humans and the ecosystem thereby making their use opprobrious. Plants essential oils are safer alternatives. Oils of Citrus sinensis and Citrus paradisi fruit peels are readily available in Nsukka but their effect on Aedes aegypti remain uncertain so it became imperative to verify the effect of these oil extracts on them. The cold maceration method was used to extract essential oils from their peels. They were used singly and in various formulations to evaluate the behaviour of starved Ae. aegypti adults. WHO protocols were applied in obtaining the effective doses and complete protection time. Data collected were analysed using SPSS version 23.0. Various formulations repelled mosquitoes in the magnitude of 100 % > 75 % > 50% > 25% and significant differences (p < 0.05) noted between formulations. Formulations B and H showed highest repellence effects with 0 – 3 number of mosquito landings during the three minutes of test period. Probit analysis showed that 1.14 ml of formulation G was required to achieve 99% repellence. Formulation B demonstrated synergism of the oils attaining the highest complete protection time of 150 minutes. This study showed that oil extracts of C. sinensis and C. paradisi would prevent female Aedes aegypti adults from landing on or feeding from skins smeared with each of the oil or their combinations. The oils exhibited synergism when combined hence could be used to control this mosquito.
Ugwu Francis Stephen Ogbonna and Chime Chidiebere Divine