Project Summary/Abstract
The long-term goal of the proposed research is to develop effective, alternative chemical repellents that
counter mosquito host-seeking and blood-feeding behaviors by disrupting the mosquito’s human odor-
detection mechanism. The information gained in this proposal will inform the development of chemical
repellents that by-pass known mechanisms of insecticide resistance in order to reduce the incidence of
mosquito-borne diseases and to protect public health.
When seeking blood meals, mosquitoes rely on their olfactory system to detect chemical odorants
emitted by their
human hosts [8]; these human odorants assist in the
t
ransmission of mosquito-related
diseases to humans. Using chemical repellents that disrupt the odor-detection mechanisms in mosquitoes may
be a viable alternative strategy to current insecticides, such as DEET (Section A.3), for desensitizing the
mosquito’s ability to smell humans. A better understanding is needed of the mechanisms governing the
interactions among chemical repellents, host odorants, and the response of olfactory receptors of mosquitoes
to enable the development of new repellent alternatives that will desensitize the mosquito to humans, thus
interfering with the mosquito recognizing its human host.
In preliminary studies, we investigated the interactions of 48 repellent chemicals with the olfactory
receptor neurons (ORNs) of the Aedes aegypti mosquito, and identified several terpene/terpenoid compounds
that exhibit inhibitory effects on mosquito ORNs [40]. We have further characterized the responses of the ORN
to 103 compounds and discovered that certain human odorants elicit decreased responses after blood feeding,
suggesting these human odorants are involved in Aedes aegypti host-seeking behaviors [21]. We hypothesize
that chemical repellents exhibiting inhibitory effects (inhibitory chemical repellents) may interact with human
odorants, resulting in the disruption of the mosqutoes’ olfactory recognition of human hosts and in diminished
responses to them when mosquitoes are seeking feeding hosts.
The proposed research objective is to determine the chemical repellents that affect a mosquito’s
olfactory sense in order to prevent it from finding a human target or host. The proposed aims are to: 1)
characterize the responses of Ae. aegypti ORs to inhibitory chemical repellents and to human odorants that
may be involved in Ae. aegypti host-seeking and blood-feeding and 2) determine the competition effects of
inhibitory chemical repellents and human odorants on Ae. aegypti ORs.
