Mosquito Repellent and Mosquitocidal Effects of Neem (Azadirachta indica) on Human Beings in Imo State, Nigeria

Abstract

This study was aimed at determining the mosquito repellent and mosquitocidal effects of volatile oil of locally acclaimed plant Neem (Azadirachta indica), using human baits. Two different formulations, 30% (v/v) and 60% (v/v) were made and used on twelve human volunteers across three sampling locations (Ihiagwa, Royce and Obinze). The volatile oil was extracted using soxhlet apparatus, with petroleum ether as solvent. Olive oil was used as base for formulation and as a control. The topical application of each lotion reduced the biting rate of mosquitoes across the three locations, with the 60% (v/v) exhibiting higher impact of 341 vs 38; 426 vs 49 and 249 vs 45. 60% (v/v) formulation also had the highest percentage repellence of 88.86% at Location A and offered a whole night protection against mosquito in location O and offered a Complete Protection Time (CPT) of 17.7, 12.3 and 14.1 respectively across all three locations. There was a significant statistical association r=0.95 (p<0.05) between concentrations of the Neem oil formulations and mean duration protection time against mosquitoes. 60% (v/v) formulation had some mosquitocidal action by causing fast immobilization or paralyzing effect on some mosquitoes that were at close range to treated volunteer’s body. The study concludes that volatile oils of Neem possess mosquito (A. gambiae and An. funestus) repellent effects, especially at higher concentrations and can be used to reduce human-mosquito contacts and hence mosquito-borne diseases and irritation caused by their bites.