How mosquitoes choose whom to bite - new research
Scientists have figured out the principle by which mosquitoes attack people. In an experiment with over 450 volunteers at the Lowlands festival in August 2023, researchers found that Anopheles mosquitoes primarily detect carbon dioxide, then body heat and odor signals. Factors increasing attractiveness: recent alcohol consumption, cannabis use, lack of sunscreen, and sleeping with a partner. Diet and blood type showed no correlation.
Scientists have determined the principle by which mosquitoes attack people, analyzing insect behavior. An experiment with over 450 volunteers helped researchers identify several features that influence mosquito response and behavior. Scientists found that Anopheles mosquitoes primarily detect carbon dioxide, which a person exhales. Then they use other cues—body heat and specific odor signals. Previously, scientists speculated that a person's attractiveness to mosquitoes might be linked to skin microbiome composition or genetic traits. Studies on blood type influence gave mixed results. The danger of these insects is that they can transmit malaria, dengue, Zika virus, and other infections. To find out why mosquitoes prefer some people over others, a research team including biologist Sarah Lynn Blanken and biophysicist Felix Hall from Radboud University Medical Center in the Netherlands organized an unusual experiment. The study was conducted during the three-day Lowlands festival in August 2023. On the festival grounds, scientists set up a temporary laboratory in shipping containers and recruited over 450 volunteers. They filled out questionnaires about sleep patterns, skin care, diet, blood type, and substance use. Participants also had their alcohol levels measured with breathalyzers and had skin surface samples taken. Each person then placed their forearm next to a special cage with a mosquito. Between the skin and the insect was a thin plastic mesh through which a female Anopheles stephensi could detect the person's scent. Mosquito reactions were recorded by video cameras. The study identified several factors that increase mosquito interest. Insects more often chose people who had recently consumed alcohol, used cannabis, had not applied sunscreen, or had slept with a partner. Additionally, attractiveness could depend on skin microbiome: higher levels of Streptococcus bacteria were associated with more active mosquito response. Diet and blood type showed no significant correlation with attractiveness. Researcher Wendy O'Meara noted that determining a single cause for victim selection is difficult, and results from one experiment cannot automatically be applied to regions with prevalent mosquito-borne diseases. Special attention was given to alcohol: beer drinkers more often attracted mosquitoes. Scientists hypothesize this may be due to increased body temperature, enhanced carbon dioxide emission, or altered scent from sweating and physical activity. However, the exact mechanism remains unconfirmed. Moreover, the experiment only involved a specific type of mosquito, so conclusions cannot be automatically extended to other species that may choose humans differently.