In a group of people enjoying the outdoors during the summer months, there is often one person who feels unfairly favored by mosquitoes. This leads to the folk belief that some people have “sweeter blood” than others, making them the ultimate mosquito magnets.
A new study published in iScience suggests that there may not be a universal mosquito attractor. Rather, different mosquito species might have different preferences, which could include sex, the absence of common fragrances some people apply, and even the microbial composition of the skin.
By testing how some of the world’s most dangerous mosquitoes react to the body chemistry of more than 100 human volunteers, researchers from Florida International University (FIU) hope to develop species-specific repellents.
"Isolating the components of human odor that attract or repel mosquitoes could lead to novel strategies to combat vector-borne diseases," said study lead Matthew DeGennaro, a neurogeneticist and director of the Biomolecular Sciences Institute at FIU, in a press release.
How Do Mosquitoes Track Their Hosts?
Female mosquitoes transmit diseases that cause over one million deaths globally each year; males feed only on nectar and other plant juices, according to the American Mosquito Control Association.
The first-of-its-kind experiment examined three of the four deadliest mosquito species and compared how each reacted to the same people. When infected, Aedes aegypti (yellow fever mosquito) and Aedes albopictus (Asian tiger mosquito) can transmit viruses that cause dengue and Zika. Ae. aegypti can also transmit yellow fever virus, while Culex quinquefasciatus (southern house mosquito) can transmit West Nile virus.
Experts already know that mosquitoes use a combination of signals, including carbon dioxide released through breathing, humidity, heat, and body odor, to find a host.
However, human scent consists of more than 1,000 volatile organic compounds, some of which haven’t yet been characterized, making it highly individual. This has led scientists to hypothesize that humans may not be equally attractive to mosquitoes, leaving some people more vulnerable to vector-borne diseases than others.
Read More: Garlic May Stop Mosquitoes and Fruit Flies From Mating, and Could Inspire New Pest Controls
Not All Mosquito Species Prefer the Same Scents
The experiment involving 119 adults showed that the three mosquito species couldn’t collectively agree on which human was most attractive. Instead, each species responded to a distinct scent profile.
For example, Ae. aegypti was the only species with a slight preference for male participants versus female participants. Both Ae. aegypti and Cx. quinquefasciatus favored the absence of compounds such as cyclic alcohols and monoterpenes, compounds typically found in perfumes and many essential oils. Ae. albopictus showed a preference for ketones and plant-like volatile organic compounds secreted by the skin.
Another interesting finding was that the composition of the skin microbiome seems to matter, too. For instance, the researchers associated certain bacterial families with attraction in Cx. quinquefasciatus and others with aversion.
"It is clear to me now that our skin microbiomes define our human odor signature,” said DeGennaro. “Each species found its own way to decode that signature."
Developing Species-Specific Repellents
As the climate changes, these mosquito species are expanding their ranges across the Americas. The U.S. recently recorded a 22-year high in West Nile virus cases, according to UC Berkeley.
In much of the U.S., mosquitoes spread disease mainly during the summer. However, as warm weather arrives earlier and lingers later in the year, they have more time to spread disease.
In their study, the FIU team created detailed profiles of human odors and their microbiomes to further analyze which compounds, and at what concentrations, trigger responses in mosquitoes. They hope to map species-specific chemical cues to refine repellents and inform public health strategies based on which mosquitoes are most common in certain regions.
Read More: Like Jurassic Park, Mosquitoes Can Capture an Entire Ecosystem in Their Blood Meals
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in iScience:Individual humans are more attractive to certain mosquito species
- This article references information from the American Mosquito Control Association: Vector-borne Diseases
- This article references information from UC Berkeley: How worried should you be about West Nile virus?