Hematophagous insect vectors of disease locate their human targets in large part through chemosensory- driven behaviors. Development of new insect control measures will require an improved understanding of the molecular and cellular basis underlying their olfactory capabilities. Here, we propose to investigate the mechanisms underlying the ability of insects to detect ammonia, an odor released by humans and attractive to both insect vectors of human disease and non-hematophagous insects. We utilize Drosophila as a genetic model organism due to its wealth of genetic tools that allow us to dissect the fine workings of the system. Using our newly developed genetic tools, we have identified a previously unknown fourth neuron in strongly ammonia sensitive ac1 sensilla. The scientific premise of this proposal is that ammonia responses are mediated by these newly identified Rh50+ neurons and do not depend on the previously implicated IR92a odor receptors or IR92a+ neurons.
In Aim 1, we propose to characterize the odor response profile of Rh50+ neurons and determine which neuron mediates electrophysiological and behavioral responses to ammonia.
In Aim 2, we will examine whether the ammonia sensitivity of Rh50+ neurons is mediated by a novel type of odor receptor unrelated to the two previously identified odor receptor families in insects. Given the highly conserved nature of this putative receptor and its expression in the antenna of all insect species we have examined, we expect that the proposed findings regarding such ammonia-sensitive neurons and receptors in Drosophila will translate to other insect species, including vectors of human disease.
Insect vectors of disease detect hosts for blood feeding in large part through their ability to smell odors released in human sweat and breath. This study proposes to identify the molecular and cellular mechanisms that insects use to sense ammonia, a behaviorally attractive cue for many insects including mosquitoes, ticks, and lice. This research will provide a more detailed understanding of ammonia detection, including features that are likely to be evolutionarily conserved, and could eventually lead to new targets for the development of insect control agents to reduce the transmission of insect borne diseases.