Mosquitoes are attracted to carbon-dioxide and body odors.
Are you the one that always seems to be the sweet target of mosquito terror? Do you wake up from a night out camping to find your ankles and wrists completely covered with mosquito bites, while your tent mates are untouched? In the peak of mosquito season, some outdoor venturers are lucky, while others get relentlessly assaulted by these bloodsucking creatures. Have you ever wondered why? Scientists at the University of California (Riverside) have identified that mosquitoes are attracted to people that exhale more carbon-dioxide and release skin odors.
Olfactory receptor neurons
Mosquitoes transmit deadly diseases such as malaria and dengue. It is therefore important to find the reason for their selective attractiveness towards some people. Earlier studies found that female mosquitoes detect exhaled CO2 using a class of olfactory receptor neurons (ORNs) known as cpA. These cpA neurons are located in maxillary palps (sensory organs) and express the CO2 receptors. The identity of olfactory receptor neurons required for attraction to skin odor remained a mystery, until now. The recent report links both CO2 as skin odor detection to the same receptor neurons.
Foot odor
Researchers developed a novel chemical based strategy to selectively stop the activity of cpA in dengue spreading mosquito (Aedes aegypti) to check the levels of skin odor responses. The role of this neuron was checked to see the mosquito’s behavior on human foot odor which was found to be substantially reduced.
This new information leads to possibilities for practical solutions to prevent mosquito bites. About 0.5 million compounds were screened to identify several CO2 receptor ligands, including an antagonist, ethyl pyruvate, that reduces attraction to skin and an agonist, cyclopentanone, that lures mosquitoes to traps as effectively as CO2. Several of these compounds were safe, pleasant-smelling and affordable enough to use in new generation of mosquito control strategies worldwide.
New strategies
Current findings have wide-reaching implications for control of mosquito-borne disease. Present mosquito control strategies use CO2 traps, but they are costly, as generation of CO2 requires energy input. The new alternatives are affordable to use in surveillance and control traps in countries affected most by mosquito-borne diseases. These approaches will protect large areas and might present an economical and environmentally friendly way to control deadly mosquitoes.
Reference:
Tauxe GM, Macwilliam D, Boyle SM, Guda T, & Ray A (2013). Targeting a Dual Detector of Skin and CO2 to Modify Mosquito Host Seeking. Cell, 155 (6), 1365-79 PMID: 24315103
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