In a bid to understand why mosquitoes may be more attracted to one human than another, Johns Hopkins Medicine researchers say they have mapped specialized receptors on the insects’ nerve cells that are able to fine-tune their ability to detect particularly “welcoming” odors in human skin.
Receptors on mosquito neurons have an important role in the insects’ ability to identify people who present an attractive source of a blood meal, according to Christopher Potter, Ph.D., associate professor of neuroscience at the Johns Hopkins University School of Medicine. “Understanding the molecular biology of mosquito odor-sensing is key to developing new ways to avoid bites and the burdensome diseases they cause,” he says.
Worldwide, mosquito-borne diseases such as malaria, dengue fever, and West Nile virus afflict 700 million people and kill 750,000 each year. Although mosquito control efforts using nets and pesticides have helped reduce the toll, the development of better repellants to sabotage odorant attraction remains a priority.
Mosquitoes detect odors mostly through their antennae, and scientists have long observed that variations in odors, heat, humidity and carbon dioxide are factors in attracting mosquitos to some individuals more than others.
But, says Potter, the insects use multiple senses to find hosts. Anopheles gambiae, a family of mosquitoes that cause malaria, for example, has three types of receptors that stud the surface of neurons in their organs that sense odor: odorant, gustatory and ionotropic receptors.
Odorant receptors, says Potter, are the most well studied by scientists and are thought to help mosquitoes distinguish between animals and humans. Gustatory receptors detect carbon dioxide. Ionotropic receptors respond to acids and amines, compounds found on human skin. It is thought that different levels of particular acids on human skin might be a reason for some people to be more attractive to mosquitoes than others, says Potter.
