[/caption]Ernest Dempsey — It is smell that attracts the mosquitoes that cause dengue and yellow fever in humans in epidemic proportions. Findings of the latest research by two entomologists in Riverside, California, tell that the dengue-causing mosquito is attracted to the smell of carbon dioxide exhaled by humans as well as to human skin order.
Science Daily reported that Aedes aegypti, the mosquito that carries the virus responsible for causing dengue fever and yellow fever in humans, traces its human subjects through the carbon dioxide exhaling from their bodies as well as their skin odor. The research conducted by entomologists Ring Cardé of the University of California and Teun Dekker of the Swedish University of Agricultural Research shows that carbon dioxide is the primary source of attraction for the dengue-causing mosquito, while in the later phase, the insect uses skin odor to settle on its human subject for a bite.
In Cardé and Dekker’s experiments, Aedes aegypti mosquitoes were left inside a wind tunnel and their flight patterns were observed. Carbon dioxide was introduced inside the tunnel through the wind currents that kept the mosquitoes floating. Curiously, it was observed that the mosquitoes showed a little upwind flight when a small whiff of the gas was released into the wind. However, the mosquitoes showed notable upwind flight when turbulent plumes of carbon dioxide were released in the wind, mimicking the patterns released by human exhalations. The experiment was repeated with odor mimicking that of human skin. Mosquitoes showed maximum upwind flight when such odorous matter was released in form of broad, uniform plumes.
The flight patterns of the mosquitoes in response to carbon dioxide plumes were faster and more vigorous than that in response to skin odor. This implies that skin odor is of secondary importance for the mosquitoes in tracing their human host. The insects quickly responded to even slight amounts of carbon dioxide in the air around them. In general terms, the dengue-causing mosquitoes go after smelly air with more carbon dioxide. Cardé and Dekker’s research findings thus give a clue about using carbon dioxide and odorous material for making tarps for the mosquitoes carrying the deadly virus causing dengue and yellow fever.
The recent research on Aedes aegypti also reveals that the sensitivity of the dengue-spreading mosquitoes to respond to skin odor increases by up to 25 percent after initially detecting carbon dioxide, which it uses to get near the host. Once near its human subject, skin odor becomes the dominant ‘tracer’ for the insect.
