| dc.description.abstract | Biotic and abiotic factors that affect insect colonization of a carrion resource have been vastly studied. Such information is used to inform the time of colonization or post-colonization interval, which is crucial for determining the time since death (i.e., postmortem interval [PMI]). However, little is known about the period in which insects detect, locate, and assess the carrion resource (pre-colonization interval [pre-CI]). A key factor suspected to play a crucial role in regulating such responses during the pre-CI, but also relatively under-studied, is the microbiome of the host at the time of death. Microbes are known to produce volatile organic compounds (VOCs), which flies use as cues to locate these resources. Deciphering the factors regulating insect attraction and colonization could provide valuable data leading to accurate determination of the true PMI. A dual-choice cube olfactometer was tested for use with adult Cochliomyia macellaria as a study species which provided optimal parameters to use during future experiments related to adjustment time, trial length, sugar and water presence or absence, and mesh type used in the olfactometer. To investigate the impact of the carrion microbiome on insect attraction, responses of adult male, gravid and non-gravid Cochliomyia macellaria to xenic (i.e., with a microbiome) and axenic (i.e., without a microbiome) mice were determined. Adults significantly preferred the xenic, rather than the axenic, mouse by an overall average of 15% with the largest difference on day 4 (40% difference). In conjunction with the behavioral assessment of the blow fly, VOC profiles were also assessed to determine which compounds were produced by each mouse treatment. Each treatment produced a distinct VOC profile, and seven indicator compounds were identified for the xenic mouse with six being microbially derived. In addition to these findings, an oviposition assay was conducted with the treatments resulting in a ~90% reduction in oviposition without microbial presence on the carrion resource. Results indicate microbial presence on a carrion resource is an important factor for blow fly attraction and acceptance of a carrion resource for reproduction. Data provide an important foundation for further research on insect-microbe interactions in decomposition related to the pre-CI. | |
