UC Riverside

Mosquitoes that are human-feeding specialists vector several pathogens responsible for hundreds of thousands of deaths each year. Mosquitoes use odor to locate humans and to tell them apart from other potential hosts. By understanding how mosquitoes follow odor plumes, and which odor components they use, we may be able to improve traps used for vector surveillance. First, to examine host finding in female Aedes aegypti, a diurnal biting mosquito, we used a small source of skin odor that was visually indistinguishable from its surroundings. Despite being thought of as a visually guided mosquito, we found Ae. aegypti landed on a visually indistinguishable patch of odor. A blend of lactic and ketoglutaric acids elicits landings in a cage assay. We found, in a wind tunnel assay, that this blend elicits takeoff, upwind flight, and landing of Ae. aegypti, even without the addition of CO2. This property makes the blend of lactic and ketoglutaric acids a candidate for use in mosquito traps because suppling CO2 to traps in the field is logistically challenging. Finally, we tested the landing response of wild type Ae. aegypti and two genotypes lacking Ir8a or orco receptors. Aedes aegypti lacking the Ir8a coreceptor, required for lactic acid detection, landed on the blend of lactic and ketoglutaric acid at half of the rate of wild type mosquitoes. This shows that a receptor other than Ir8a is responsible for the detection of ketoglutaric acid. Future studies will be able to determine how Ae. aegypti detect ketoglutaric acid.