The green bottle fly, Lucilia sericata, is of critical importance in the field of forensic entomology since it is one of the first insects to arrive at a freshly deceased carcass. These flies use a highly tuned and selective olfactory system to identify and locate the carcass; response to the decomposition odor usually occurs within minutes. Male flies use the carcass for a small protein meal and for locating females while females use the carcass for feeding (unmated) and egg-laying (mated). This divergence in behavior to a common odor cue is the subject of this thesis proposal: do unmated (feeding) females respond to the same odor cues as mated (egg-laying) females? The presence of two behaviors indicates that there may be an associated up or down regulation of gene expression of odor binding proteins during the two different stages of female sexual development. Olfactory response to selected decomposition odors in unmated versus mated females was determined using the electroantennogram (EAG) which measures the neuronal depolarization in antennae when an odor triggers a response. Fly heads were mounted on the EAG probes and exposed selected volatiles. Response was measured as the resultant change in voltage (a depolarization). Flies were also subjected to an odor choice behavioral assay. The results show a divergence in antennal response to VOC and choice of VOC at day 4 between the mated and unmated female flies. These results indicate that there are underlying molecular, biochemical, and physiological processes associated with fly response to odors
