Mosquitoes that spread Zika, dengue, and yellow fever rely heavily on human skin odors. The precise chemical mix behind this scent has only recently been pinpointed.
A study led by researchers at the University of California, Riverside (USA) identifies a specific odor produced when carbon dioxide combines with two skin chemicals, 2-ketoglutaric acid and lactic acid. This scent signature helps mosquitoes locate a human host and settle on the skin for a blood meal. The same blend appears to drive females of the species toward people, enhancing biting behavior and contact with the skin.
The resulting odor profile is linked to Aedes aegypti, the mosquito vector for Zika, chikungunya, dengue, and yellow fever. This species originated in Africa and is now found in tropical and subtropical regions around the world, including North America and the United States.
The discovery appeared in Scientific Reports. The researchers note that while many compounds have been shown to attract mosquitoes, this combination has a rapid and pronounced effect, making it a standout attractant. This finding was highlighted by an entomologist from UCR as a breakthrough in understanding host-seeking behavior.
Smell plays a dominant role in host location
Mosquitoes use a variety of cues to find humans, including carbon dioxide, visual signals, temperature, and humidity. New findings indicate that skin odors may be more influential than previously thought in guiding mosquitoes to human targets.
An example of the species that bites humans is depicted in related imagery.
Researchers observed that when mosquitoes encountered visually ambiguous targets infused with the two scents, they still landed, even in the absence of heat or humidity. This suggests skin odor is the primary driver in this context.
With scent proving so crucial to successful blood feeding, scientists sought to identify the exact chemosensory components that make human odor so potent for insects. Lactic acid has been recognized as a key element of the fragrance profile since the late 1960s.
Beyond lactic acid, other studies have shown that carbon dioxide together with ammonia and other human-derived chemicals can attract mosquitoes. Yet the strongest attractants observed in this work were the combined action of carbon dioxide with 2-ketoglutaric acid and lactic acid, according to the team leader who has studied these insects for decades.
The team explains that traditional analytical methods may miss certain acids. Gas chromatography, for example, does not reliably isolate 2-ketoglutaric acid due to its unique properties. The researchers credit collaboration with a chemist who specializes in extracting compounds from human sweat and who devised novel methods to identify the potent mix.
That collaboration involved extracting compounds from sweat collected in socks worn during a walking trial. Compounds were isolated from beads in the socks as mosquitoes observed stronger responses to the resulting scent profile. The culmination of this process was the discovery that the strongest attractant combination consists of 2-ketoglutaric acid and lactic acid.
The researchers plan further work to determine if this same mixture attracts other mosquito species and to explore why individual attractiveness to mosquitoes varies. The team notes that some people are more prone to bites, but the reasons remain unclear.
Although the study does not propose new repellents, it opens the door to methods for luring, trapping, and possibly reducing disease-spreading mosquito populations. The researchers expressed satisfaction at the moment of discovery and acknowledged the challenges involved in uncovering the chemistry of human odors.
Reference work: Nature Scientific Reports. Attribution to the authors and the publication is noted in the source record.
Note: This article excludes direct contact details and external links. All information is presented with proper attribution to the original scientific work.