Olfactometric evaluation of spatial repellents for Aedes aegypti.

The spatial repellency responses of Aedes aegypti (L.) to deet, dehydrolinalool and linalool were evaluated using a dual port olfactometer. In the absence of human attractant mixture, each of the three chemicals resulted in activation and/or orientation of mosquitoes to the chemical source. Linalool was the most attractive compound. In the presence of human attractant mixture, activation and/or orientation of mosquitoes to each of the three chemicals was reduced. We compared reductions in mosquito responses to each of the three chemicals, in the presence of human attractant mixture, to estimate spatial repellency. As expected, lowest spatial repellency (7.3%) was observed using human attractant alone. Highest spatial repellency (33.6%) was observed using a combination of linalool and dehydrolinalool. Deet did not manifest spatial repellency, whereas linalool and dehydrolinalool alone, and in combination, exhibited spatial repellency.