Evaluation of the bio-efficacy of three brands of repellents against wild populations of anthropophilic mosquitoes.

Three commercial repellents marketed in Tanzania: Zero Bite (a blend of microcrystalline waxes, mineral oils, natural flavours, Olibanum oil, Eucalyptus oil, Geranium oil, Citronella oil and Isopropyl myristrate); X-pel (a petroleum jelly formulation containing diethyl toluamide (DEET) and dimethyl phthalate); No Bite (a spray formulation with diethyl toluamide, 2 methyl 2,4 pentondiol and pthalic ester acids) were tested and compared for their repellency effect against wild anthropophilic mosquito populations. Human forearms, feet and legs were treated with the repellent products. All repellents provided protection against wild populations of biting mosquitoes (mainly Culex quinquefasciatus and Aedes scatophagoides) with varying levels of efficacy. No Bite provided the best overall protection (98%) followed by X-pel (87%). Zero Bite gave the least protection (48%) against the two mosquito species. All products except No Bite displayed reduced efficacy after four hours of application. The results indicate that the two best products give satisfactory levels of personal protection against biting mosquitoes at least for the first five hours, following application, thus could provide complementary protection against mosquito bites particularly during the period when most people have not retired to bed where they may be protected by treated bednets.