How do mosquitoes smell us? The answers could help eradicate disease

Abstract

In the coastal Rabai region of southeast Kenya, two populations of mosquitoes live within a half mile of each other but lead separate and curiously different lifestyles. Entomologists in the mid-20th century found that color distinguished the two subspecies of Aedes aegypti ( Aedes aegypti aegypti are brown and Aedes aegypti formosa are black) as well as the hosts they chose for blood meals. The “domestic” brown form frequented people’s homes, preferentially feeding on people and laying their eggs in indoor water receptacles. Meanwhile, the black-colored “forest” form roamed the nearby woods preferring to bite nonhuman animals and lay its eggs in tree trunk holes. This light sheet microscope image of an adult female Anopheles gambiae mosquito includes genetic labeling to show olfactory neurons (green). The antennae, maxillary palp, and labella on the proboscis contain many such neurons. Image courtesy of Olena Riabinina, Courtney Akitake, and Chris Potter (Johns Hopkins University School of Medicine, Baltimore). Following up on these reports some 50 years later as a postdoctoral fellow at The Rockefeller University in New York, Lindy McBride saw an opportunity to examine this natural case study with modern genetic tools. The feeding habits of Aedes aegypti aegypti make it a dangerously efficient vector for spreading yellow fever, dengue, Zika, and other diseases between humans. The other subspecies poses much less of a threat. To understand why, McBride traveled to Rabai to collect mosquito larvae and pupae from people’s homes and the nearby woods. She wanted to compare the two mosquitoes genetically and discover what changes had led the more recently evolved domestic form to hunt humans. Back at Rockefeller in the laboratory of her then-postdoctorate advisor Leslie Vosshall, McBride raised 30 strains of mosquitoes from the samples and used RNA sequencing to compare the genes expressed in their antennae (a major …