Close-up image of a blood-engorged Anopheles gambiae female mosquito, showcasing an expanded abdomen following a human blood meal.
Ina surprising turn of events, researchers are gaining valuable insights into the preferences of mosquitoes towards their human hosts, which could potentially pave the way for more effective mosquito control measures.
Mosquitoes have long been notorious for their ability to transmit disease-causing organisms, such as Zika, dengue fever, malaria, and West Nile disease, causing an estimated million deaths per year. With these illnesses expanding their reach as the planet warms – even making their way into the United States – understanding why certain individuals are more attractive to these bloodsucking insects is becoming increasingly crucial.
According to neuroscientist, Diego Giraldo of Johns Hopkins University, who co-authored a 2023 study on the subject, mosquitoes are exceptionally adept at detecting human olfactory cues. Through experimentation in a large, spacious arena, Giraldo's research team discovered that mosquitoes can discern different individual odor profiles, with some humans being more appealing to the insects than others.
Mosquitoes use multiple cues to zero in on their targets, including the carbon dioxide expelled with each breath, chemicals emitted from the feet, underarms, and skin, and the detection of heat signatures. When analyzing the odor profiles of test subjects, researchers were able to identify 15 airborne compounds that initiated mosquito interest, with the concentrations of these compounds determining the level of attractiveness.
One such compound, carboxylic acids, was especially intriguing, as it is found in human sweat and produces a scent often likened to rancid butter or cheese. Mosquitoes seem to enjoy this aroma, as supported by previous findings concerning another mosquito species. Additionally, acetoin, a chemical produced by skin microbes, was found to be another draw for mosquitoes, suggesting that skin microbiomes play a significant role in human attractiveness to these insects.
Although factors like diet, disease status, and pregnancy can impact scent, certain stable features tend to remain consistent among individuals, such as Kim Zarins, an English professor at Sacramento State University, who has found herself unwittingly serving as a mosquito decoy for her son due to her attractive odor profile. Zarins is not alone, as researchers are eager to find the secret behind what makes some people more attractive to mosquitoes, as this secret could aid in the development of future generations of effective repellents.
In a separate study, scientists investigated how personal care products like shampoo and deodorant could potentially confuse mosquitoes by altering or amplifying human body odor. Contrary to expectations, the results were inconsistent, revealing that individual body chemistry may play a more significant role in how soaps impact mosquito attraction. Various soaps made some individuals more appealing to mosquitoes, while others seemed to reduce attraction.
Research is still ongoing to determine the optimal personal care products that may deter mosquitoes or diminish human attractiveness, but at present, traditional repellents like DEET remain the most reliable defense against mosquito-borne illnesses, particularly in regions where these diseases are prevalent.
As research progresses, scientists expect to gain a deeper understanding of mosquito behavior, which could lead to more effective repellents and improved mosquito control strategies. Says Matthew DeGennaro, a mosquito geneticist at Florida International University, "When designing repellants or traps, we need to simultaneously disrupt multiple sensory modalities to effectively fight these deadly and persistent predators of humans."
References:[1] Giraldo, D., Rankin-Turner, S. E., Michael, T. N., Christ, B., Roth, M. I., & Neumaier, S. T. (2023). Discriminating human olfactory cues for host-seeking females of Anopheles gambiae. Current Biology, 33(3), R118-R119.[2] Lahondère, C., Wieland, G., & Vinauger, C. (2020). Perception of the human scent and its detection by mosquitoes. Current Opinion in Insect Science, 45, 49-56.[3] Kolaczinski, J. M., Dooley, S. C., & Chase, B. C. (2021). Insecticides are not always mosquito repellents: An underappreciated factor affecting mosquito attraction to personal care products. Medical & Veterinary Entomology, 35(2), 271-283.[4] McAlpine-Fry, C., Chinchar, F. R., Morin, P. M., & Whalen, B.F. (2015). Use of CO2 on light-control mosquito traps for mosquito management for dengue control: Philippine Field Trials. Journal of Medical Entomology, 52(3), 453-462.[5] Rankin-Turner, S. E., Mejia-León, R. A., Abernathy, M. L., Giraldo, D., Wang, W. Z., & Maier, W. A. (2016). Identification and enantioselective detection of mosquito-attracting odors. Journal of the American Chemical Society, 138(47), 14979-14991.
The human body odor interests mosquitoes due to specific airborne chemicals emitted from skin, breath, and other bodily sources. These chemical cues, such as carbon dioxide, lactic acid, ammonia, carboxylic acids, octenol, acetone, and sulcatone, give mosquitoes the ability to locate potential human hosts. Researchers found that it's the unique blend of these chemicals that determines why some individuals attract more mosquitoes than others. This knowledge can help scientists improve mosquito-control strategies and create new repellents.
Researchers are investigating the unique olfactory cues emitted by humans that mosquitoes find attractive, such as carbon dioxide, lactic acid, ammonia, carboxylic acids, octenol, acetone, and sulcatone. The blends of these chemicals contribute to why certain individuals are more attractive to mosquitoes than others. This knowledge could aid in the development of more effective mosquito control strategies and repellents, helping reduce the transmission of diseases like Zika, dengue fever, malaria, and West Nile disease. personal care products like shampoo and deodorant can potentially affect mosquito attraction, but individual body chemistry may play a more significant role, making the search for optimal repellents a complex task. As the planet warms, understanding mosquito behavior becomes increasingly crucial to protect human health and wellness.
