By Raniyan Zaman ‘22 4/2/19
Aedes aeypti, a species of mosquito (Source: Wikimedia Commons)
One of the hallmarks of summer is slapping away mosquitoes under the hot sun. Scientists have long known that female mosquitoes rely on a variety of factors, such as body odor, heat, and moisture, to pick which people to bite. New findings have revealed that the acidic components of human sweat play a significant role in attracting mosquitoes. This is due to the mosquitoes’ olfactory co-receptor Ir8a, which is a cell-surface protein that binds a molecule and can lead to certain biological processes, such as cell signaling, regulation, or growth. Mosquitoes without the Ir8a gene are significantly less likely to search for people to bite; researcher Matthew DeGennaro estimates that removing Ir8a eliminates “approximately 50 percent of host-seeking activity.”(1)
DeGennaro’s previous research with a different olfactory coreceptor Orco and Orco’s effect on mosquitoes’ behavior inspired this study’s focus on Ir8a. A in Orco weakened mosquitoes’ ability to differentiate people and animals, and it also diminished their interest in nectar(1). Furthermore, it signaled that there were more receptors left to find. Therefore, DeGennaro’s team studied a different group of ionotropic receptors, which led to their focused analysis of Ir8a, located in the antenna. DeGennaro’s team utilized the CRISPR/Cas9 gene-editing system to disrupt Ir8a in Aedes aegypti mosquitoes. A series of tests including PCR and various types of assays were used to determine the coreceptor’s contribution in human odor detection and the ways in which it interacted with other pathways involved in host-seeking behavior. The team found that mosquitoes carrying a mutant version of Ir8a had difficulty detecting acidic components of human odor and weren’t attracted to lactic acid.
These findings may lead to new ideas for mosquito repellents or attractants for traps. DeGennaro also sees important medical implications, noting that “transmission of diseases like dengue, yellow fever, Zika, and malaria can be blocked if we stop these mosquitoes from biting us.” (1) In the short-term, the team plans to begin on chemical screens, with the goal of eventually having a complete picture of the Ir8a pathway.
References:
- Cell Press. (2019, March 28). How mosquitoes smell human sweat (and new ways to stop them). ScienceDaily. Retrieved April 2, 2019 from www.sciencedaily.com/releases/2019/03/190328112541.htm