Kairomones produced by humans provide female anthropophilic mosquitoes with vital cues used in host-seeking for a blood meal. These chemicals are emanated primarily by the skin and provide the mosquitoes a means to orient themselves to humans at a relatively close range. Chemical studies of these emanations have provided new ideas for the formulation of attractant blends. We report mosquito attraction responses for three binary blends and their separate components. The blends are comprised of L-lactic acid plus either acetone, dichloromethane, or dimethyl disulfide. At the emission rates used in our bioassays, these blends synergistically attract laboratory-reared female Aedes aegypti. Carbon dioxide is not a necessary component to yield high levels of attraction with these blends. It is postulated that at least one of these synergistic blends (L-lactic acid and acetone) produces mosquito attraction behavior similar to L-lactic acid and CO2.

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.

A triple cage olfactometer for evaluating mosquito attraction responses is described. The olfactometer is designed for easy access for interior cleaning, has a mechanism that allows synchronous operation of the port doors on each cage, and requires 0.8 m2 of floor space. It is constructed of clear acrylic, contains 3 test chambers in a tiered configuration, has paired removable sleeves and mosquito traps on each cage, and is equipped with a filtered external air supply system that has temperature and relative humidity control.