How Mosquitoes Locate Veins So Quickly

Two olfactory receptors expressed on a mosquito’s stylet are crucial for the accurate and efficient identification of veins for blood sucking.

AsianScientist (Oct. 30, 2015) – Researchers from Seoul National University (SNU) have demonstrated a key component in a mosquito’s olfactory system to detect veins on its victim. Their work, published in Scientific Reports, may contribute to the fight against the spread of diseases by mosquitoes.

Mosquitoes are one of the most lethal animals in the world. Last year, they killed almost a million people, according to the World Health Organization (WHO). Mosquitoes are typically a minor inconvenience to many of those in developed countries, but through the spread of fatal diseases such as malaria, yellow fever, and dengue, they are a terrifying presence in many developing regions such as Africa, South America, and Asia.

Previous studies have demonstrated that mosquitoes are attracted to humans due to their emissions of octenol (found in human breath, and sweat) and carbon dioxide as well as odors emitted by sweat (lactic acid) and feet (isovaleric acid). However, it remained a mystery how mosquitoes are able to unerringly and swiftly locate the veins of its victim and suck blood before the victim even realizes its presence. Professor Ahn Young-joon and Professor Kwon Hyung-woon from SNU’s College of Agriculture and Life Science sought to understand the mechanism that allowed mosquitoes to be so efficient.

Ahn, Kwon and the team have discovered that sensory hairs located at the tip of a mosquito’s piercing-sucking stylet, an essential apparatus for blood feeding, played a major role. These hairs housed olfactory neurons that expressed two conventional olfactory receptors, AaOr8 and AaOr49.

The team demonstrated that these receptors were activated by volatile compounds present in blood, proving that the receptors were critical in allowing mosquitoes to locate the veins. By inhibiting the gene expression of these AaOrs through RNA interference, the scientists crippled the mosquitoes’ efficiency and delayed their blood feeding. It took them to take up to fifteen minutes to feed, whereas normally, mosquitoes would feed within thirty seconds. The newly discovered olfactory systems proved to be central to a mosquito’s blood feeding.

The findings of Ahn and Kwon have provided a more thorough understanding of mosquitoes’ feeding process. Using this knowledge, genetic disruption of the newly discovered olfactory receptors may decrease mosquito bites, prevent its breeding, and thus curb the spread of mosquito-borne diseases worldwide.

The article can be found at: Jung et al. (2015) A Novel Olfactory Pathway is Essential for Fast and Efficient Blood-Feeding in Mosquitoes.


Source: Seoul National University; Photo: Shutterstock.
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