| dc.description.abstract | Insect succession on carrion is highly variable and can be affected by a multitude of biotic and abiotic factors, including, but not limited to, temperature, carcass type, species interactions, genetics, and scavenging. The functional utilization of carrion by various insects has not been extensively investigated, since the majority of carrion associated insects are assumed to be feeding on the carcass, thus investigation into the functional groups present on carrion has not yet been clarified. The study presented here was conducted to evaluate the drivers of oviposition on carrion resources, and clarify the utility of arthropod succession on carrion to estimate the time of colonization (TOC) estimates for insects present at vertebrate remains. The present study aimed at identifying the volatile organic compounds (VOC) emitted from variably aged carrion resources, as well as colonized and uncolonized rat carcasses by inter- and intraspecific species, and evaluating the responses of two carrion-associated flies to these resources.
The secondary screwworm, Cochliomyia macellaria (specialist), and black soldier fly, Hermetia illucens (generalist), were selected for investigation in this study. Both species were exposed to fresh and aged (5 d) rat carcasses, colonized by C. macellaria or not, and oviposition responses at each carcass type documented. H. illucens was also provided with a grain-based diet (control) for oviposition, to account for their wider dietary breadth. There was a significant difference in the VOC profiles obtained through headspace analysis from the different treatments, with indicator compounds all being of microbial origin. Both species exhibited a significantly greater preference to oviposition on the aged rat carcasses than at fresh carcasses, regardless of colonization status. However, when a grain-based diet was included, H. illucens exhibited a significantly higher response to this treatment. The results of this study allowed for a quantification of compounds emitted during vertebrate decomposition under various treatments, and provided insight into the drivers governing arthropod succession in the two species examined. C. macellaria can colonize fresh or aged carrion, suggesting general conclusions about this species as solely colonizing carrion soon after death are not always accurate. Furthermore, H. illucens, while known to colonize carrion, is potentially responding to VOCs associated with decaying plant matter (i.e., control) rather than those associated with the carrion resource. Successional patterns in carrion-associated Diptera are highly variable, and should be reevaluated for use in TOC estimates for criminal investigations. Caution should also be exercised when assuming that all species associated with carrion are feeding on the carcass to meet their developmental requirements. | en |
