The combined efficacy of neem (Azardirachta indica) seed oil and orange (Citrus sinensis) peel oil cream as a mosquito repellent

Essential oils obtained from certain plants have repellent potency against insects such as mosquitoes. Most repellents on the market have the synthetic formulation of N, N-diethyl-3-methylbenzamide (DEET) as the main active ingredient. This study is an attempt to contribute to the search for an effective plant-extracted essential oil, Neem and Orange as alternative to DEET.

The oil from Citrus sinensis (sweet orange) peels was extracted by steam distillation and that for Azadirachta indica (Neem) seed by Soxhlet extraction respectively. Creams were formulated at four concentrations of 5%, 15%, 25% and 30% v/w respectively for Neem, Orange peel and combined Neem-Orange oils, after which laboratory reared mosquitoes were used to assess the efficacy of each of the concentrations. A DEET-based cream of 13% concentration was used as the standard.

Wild mosquito larvae were brought to the laboratory from which the adults female after mating were given a blood meal. Second generation mosquitoes were used for the arm in cage test (AIC).

The combined Neem and Orange-based cream at 30% was as effective as the DEET-based repellent which recorded the highest repellent time, followed by Neem cream and the Orange peel based cream recorded the least repellent time even at 30% concentration. The statistically significant difference at 30% between DEET and Orange peel, Neem, and combined Neem-Orange creams were 0.030, 0 .499 and 0.195, respectively.

This study suggests that the combined Neem and Orange Peel Oil can be used to produce repellent creams due to their synergistic potency and good smell.