Mosquitoes use their sense of smell to find hosts to bite. The chemical cues that attract mosquitoes are emitted from sources like the carbon dioxide in a person’s breath, certain scents produced by the skin, and aromatic compounds released by plants. Mosquitoes are drawn to different scents depending on the species, sex, age, and whether or not the mosquito is hungry. While there is no single scent that is universally the most attractive to all mosquitoes, decades of research have revealed some of the key scents that mosquitoes use to locate hosts.
Carbon Dioxide
One of the most important scent cues for mosquitoes is carbon dioxide. Mosquitoes can detect carbon dioxide exhaled by animals from up to 50 meters away. They use the scent of carbon dioxide to orient themselves toward potential hosts. Carbon dioxide is the primary attractant that causes mosquitoes to fly toward people. Higher concentrations of carbon dioxide are more attractive to mosquitoes. Adults tend to exhale more carbon dioxide than children, making adults more attractive targets for mosquitoes.
Lactic Acid
Lactic acid is another significant mosquito attractant. It is emitted from human sweat. Mosquitoes sense lactic acid from distances of up to 15 meters. The amount of lactic acid produced depends on factors like a person’s sex, diet, and level of physical activity. Mosquitoes are especially drawn to lactic acid when combined with carbon dioxide. The synergistic effects of lactic acid and carbon dioxide result in increased mosquito activity compared to either compound alone.
1-Octen-3-ol
1-Octen-3-ol is a chemical produced by human skin that attracts some mosquito species. It is present in human breath and sweat. 1-Octen-3-ol activates mosquito odorant receptors that detect chemical cues associated with hosts. Different species show different sensitivity to 1-octen-3-ol. For example, the yellow fever mosquito Aedes aegypti and the malaria vector Anopheles gambiae are highly attracted to 1-octen-3-ol.
Nonanal
Nonanal is an aldehyde component of human odor that triggers host-seeking behavior in the malaria mosquito Anopheles gambiae. Nonanal is released from human skin. Research shows that Anopheles gambiae is far more sensitive to nonanal than another major malaria vector Anopheles quadriannulatus. Nonanal may play an important role in enabling some Anopheles mosquito species to preferentially target humans.
Ammonia
Ammonia emitted in human breath and sweat helps attract mosquitoes like Aedes aegypti. Ammonia intensifies the attractiveness of lactic acid to Aedes aegypti. The combination of ammonia and lactic acid is about three times more attractive to these mosquitoes than lactic acid alone. Ammonia concentrations vary between individuals based on diet and metabolism. People with higher ammonia emissions tend to be more attractive to ammonia-sensitive mosquito species.
Floral Scents
Certain floral scents are attractive to mosquitoes. For example, Aedes aegypti is drawn to the scent of Bergamot mint flowers. Anopheles gambiae is lured by fragrant Lantana camara flowers. Mosquitoes that typically bite birds and other animals will also nectar on flowers for energy. They locate the flowers by the scents they produce. Some compounds from flowers that mosquitoes detect and respond to are benzaldehyde, caryophyllene, linalool, and phenethyl propionate.
Conclusion
In summary, there are a variety of scents that attract mosquitoes to potential hosts. Carbon dioxide, lactic acid, 1-octen-3-ol, nonanal, and ammonia are some of the most significant human-derived chemical attractants. Different compounds and blends elicit variable response between mosquito species. While single compounds can lure some mosquitoes, a synergistic combination of scents like CO2 and lactic acid is often most effective. Although no scent appeals universally to all mosquitoes, understanding the key attractants provides insight into mosquito sensory biology and opportunities to improve surveillance, control, and bite prevention.
| Scent | Source | Mosquito Species Attracted |
|---|---|---|
| Carbon dioxide | Exhaled breath | Most species |
| Lactic acid | Sweat | Aedes, Anopheles |
| 1-Octen-3-ol | Breath, sweat | Aedes, Anopheles |
| Nonanal | Skin | Anopheles gambiae |
| Ammonia | Breath, sweat | Aedes aegypti |
| Floral scents | Flowers | Aedes, Anopheles |
