Volatile organic compounds in variably aged carrion impacted by the presence of the primary colonizer, Cochliomyia macellaria (Diptera: Calliphoridae)

The attraction and colonization of vertebrate remains by carrion-associated arthropods are processes largely governed by olfaction. As remains decompose, they emit a bouquet of volatile organic compounds (VOCs), which in part originate from endogenous and exogenous microbes surrounding the carcass or from the carcass itself. The composition and concentration of VOCs are influenced by the presence and abundance of microbial species and arthropods. Blowfly species, such as Cochliomyia macellaria, play a critical role in nutrient recycling and the decomposition process of carrion. Gas chromatography-mass spectroscopy analysis was used to identify and classify volatile emissions from insect-colonized (with C. macellaria) and uncolonized rat carcasses, as well as a standard Gainesville diet, over a 10-day period. There were significant differences in composition and abundance of compounds present in each treatment, with significant effects of time, and different compound composition between treatments. Notable indicator compounds included, but were not limited to, indole, dimethyl disulfide, and dimethyl trisulfide. A high compound richness, and a low compound diversity, was detected over the 10-day period. The indicator compounds detected across all treatments were found to be of microbial origin, highlighting the importance of microbes in decomposition processes and arthropod attraction to carrion. This study also discusses the significant impact of necrophagous arthropods to the VOC profile of carrion. The results of this study provide insight into the changes in decomposition VOCs over time, with an explanation of compounds in high concentration known to be attractive to carrion-colonizing arthropods.