Mosquitoes Detect Carbon Dioxide

the black silhouette of a mosquito with a light yellow background

Biological Strategy

AskNature Team

Image: Erik F. Brandsborg / Flickr / CC BY - Creative Commons Attribution alone

Sense Chemicals (Odor, Taste, etc.) From the Environment

Chemicals are important for signaling and communication among living systems, either intentionally (such as when two living systems try to find one another) or unintentionally (such as when a plant emits a chemical signal that an herbivore can use to find a tasty bite). They are also important for other uses, such as navigating or finding sources for minerals. But chemical signals are often relatively weak and disperse when moving through water or gases. Therefore, detecting them requires specialized abilities, including a way to determine where they are coming from. A well known example of sensing chemicals can be seen in ants following a pheromone trail laid down by others in their colony to locate a quality and abundant food source.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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The olfactory system of malarial mosquitoes detects carbon dioxide from potential hosts via a sensory mouth appendage, called a maxillary palp.

Image: (Photo: Johns Hopkins Malaria Research Institute) / Wikimedia Commons /

Blood-sucking Anopheles gambiae mosquitoes possess a hypervariable pattern recognition receptor capable of producing thousands of possible alternative splice forms to fight infection.

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“Blood-feeding insects, including the malaria mosquito Anopheles gambiae, use highly specialized and sensitive olfactory systems to locate their hosts. This is accomplished by detecting and following plumes of volatile host emissions, which include carbon dioxide (CO₂). CO₂ is sensed by a population of olfactory sensory neurons in the maxillary palps of mosquitoes and in the antennae of the more genetically tractable fruitfly, Drosophila melanogaster.” (Jones et al. 2007:86)