Skin odor and the microbiome: What rocks love to sting

Researchers at Florida International University have discovered that different species of mosquitoes prefer distinct types of humans based on body chemistry, according to a study published in the journal iScience. The research involved exposing 119 volunteers to three of the world’s most dangerous mosquito species, Aedes aegypti, the yellow fever mosquito; Aedes albopictus, the Asian tiger mosquito; and Culex quinquefasciatus, the southern house mosquito. The findings revealed that no individual was equally attractive to all three species. Each mosquito type appears to be drawn to specific chemical signatures unique to certain individuals. The study found that attraction is largely determined by personal body chemistry. Aedes aegypti prefers individuals without artificial fragrances and shows a slight preference for men. This species is active during the day and is not present in Austria. Aedes albopictus, which has been confirmed in all Austrian states, is attracted to elevated levels of ketones and plant-like compounds naturally secreted by human skin. It is also diurnal. Culex quinquefasciatus, which is not established in Austria, bites at night and relies on the human microbiome, the microscopic ecosystem of bacteria, fungi, and microbes on the skin, for orientation. Certain bacterial families attract these mosquitoes, while others repel them. In Austria, besides the now-established Aedes albopictus, the common house mosquito (Culex pipiens) is widespread. This species is influenced by several factors, including carbon dioxide emissions, body odor, and the skin microbiome. Carbon dioxide, particularly from larger bodies or increased respiration, serves as a strong signal. Body odor, likely one of the most significant differences between individuals, consists of a mix of sebum, sweat components, and other volatile substances that can greatly influence attractiveness. The skin microbiome, which varies among individuals, affects the resulting body scent and thus the likelihood of being bitten. Body heat, sweat, and moisture levels also play roles, especially after physical activity or in hot weather. Genetic and physiological differences further contribute to variations in attractiveness. The researchers collected both olfactory and microbiome samples alongside their preference tests. Dr. Kaylee Marrero, who led the study, noted that the team did not expect the different species to prefer different people. “Now I understand that our skin microbiome determines our individual scent signature,” she explained. “Each species has its own way of decoding this signature.” Human body odor comprises over 1,000 volatile organic compounds, many of which remain unexplored. These insights could aid scientists in developing more effective, species-specific mosquito repellents tailored to the dominant mosquito species in particular regions. Matthew DeGennaro, a neurogeneticist and leader of the research team, emphasized the potential implications of the findings. “Isolating the components of human scent that attract or repel mosquitoes could lead to new strategies in combating vector-borne diseases,” he stated. The study represents the first direct comparison of how different mosquito species react to the same individuals, offering valuable data for future public health initiatives aimed at reducing disease transmission through targeted interventions.