The authors tested the hypothesis that vertebrate scavengers and invasive species reduce blow fly (1) ability to use carrion and (2) reproduction in human-impacted environments in central Texas, USA, with season, habitat (field and wooded landscapes), and carrion type (species of carrion and coat color) acting synergistically.
Vertebrate scavengers in this habitat, of which 75% of the documented species were mesocarnivores and obligate scavengers, consumed 100% of carrion during the winter and 62% during summer despite having low species richness (2–5 species). Of the remaining carcasses available for arthropod activity during summer, the invasive red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae), monopolized 34%, and blow flies (e.g., Lucilia eximia and Chrysomya rufifacies [Diptera: Calliphoridae]) were only able to colonize 25%. Approximately 90% of carrion that was utilized by blow flies was co-colonized by fire ants, and subsequent production of adult blow flies experienced up to a ninefold reduction in production compared with carcasses that were not scavenged by vertebrates or fire ants. These results demonstrate oviposition resources used by blow flies in environments altered by human activity are reduced significantly by vertebrate scavengers and an invasive ant species. Future research should determine whether competitive interactions between vertebrate and invasive ant competitors for access to carrion resources have population-level impacts to blow flies in human-mediated ecosystems, or whether blow flies are able to shift to other resources to maintain sustainable populations and continue providing ecosystem services, such as pollination. (Publisher abstract provided)