Mosquitoes are a common presence, often raising questions about what draws them to certain individuals. This article explores the scientific insights into mosquito attraction, clarifying common beliefs and providing accurate information.
The Sweet Smell Myth
A common perception suggests mosquitoes are drawn to sweet scents from perfumes, lotions, or sugary drinks. This is largely a misconception, as “sweetness” itself is not their primary attractant. While some floral or fruity scents in personal care products might increase a person’s attractiveness, this is often due to specific chemical compounds within these fragrances that appeal to mosquitoes, not the general perception of sweetness. Mosquitoes do not seek sugar from humans for a blood meal; instead, they are primarily interested in cues indicating a potential blood source.
Primary Attractants for Mosquitoes
Mosquitoes use various sensory inputs to locate hosts. A primary long-range attractant is carbon dioxide (CO2), exhaled by humans and other animals. Mosquitoes detect CO2 plumes from considerable distances, using it as a signal for a potential blood meal. The amount of CO2 emitted varies with metabolic rate, making exercising or pregnant individuals more noticeable.
Beyond CO2, human body odor offers a rich mix of chemical cues. This odor comes from compounds released directly from the skin and those produced by skin microbes. Key chemicals include lactic acid, a byproduct of human metabolism, along with other fatty acids, uric acid, and ammonia. Recent research also highlights carboxylic acids in body odor as strong attractants.
Mosquitoes are also sensitive to heat radiated by warm-blooded hosts. They detect body temperature as a close-range cue to pinpoint a target, helping them find areas with accessible blood vessels. Visual cues also contribute, especially at closer distances. Mosquitoes are drawn to movement and favor dark clothing, such as black, navy blue, or red, which stands out against lighter backgrounds.
How Mosquitoes Sense Their Targets
Mosquitoes have specialized sensory organs to detect host attractants. Their antennae are equipped with olfactory and thermoreceptors, crucial for sensing odors and temperature changes. These appendages pick up airborne chemical signals and thermal variations.
The maxillary palps, located near the mosquito’s mouthparts, are highly sensitive to carbon dioxide. These palps contain receptor neurons that respond to small CO2 increments, enabling mosquitoes to track exhaled breath. Different receptor types, including odorant (ORs), ionotropic (IRs), and gustatory (GRs) receptors, process chemical signals within these organs.
For thermal detection, a protein called TRPA1 in the antennae senses infrared radiation from warm bodies, extending heat detection range. Mosquitoes also use their compound eyes for visual navigation. While their vision is not as sharp as human vision, they detect movement and contrast to locate hosts. This combination of chemical, thermal, and visual sensing allows mosquitoes to effectively identify and approach potential blood meal sources.