Blow flies inherently act as ecosystem monitors, surveying the biological and chemical environment as they search for resources (e.g. water, protein, egg-laying sites). Thus, flies can be utilized to efficiently assess vertebrate presence and richness in nearly any environment. The goals of this research were to use an integrative molecular and chemical approach with blow flies to survey vertebrate communities in different environments.
Spatiotemporal fly collections (N = 12) were made in three distinct environments: Indianapolis, IN (=urban), and two national parks (the Great Smoky Mountains and Yellowstone National Parks). Gut contents of adult blow fly females (N = 10) underwent vertebrate DNA sequencing (12S, 16S) and fecal metabolite screening. Boosted regression trees (BRT) and integrated nested Laplace approximation (INLA) were used to determine the most important abiotic factors influencing resource-positive flies as well as vertebrate richness detected by flies.
Results/Conclusions
In 720 min of total sampling time, 28 vertebrate species were identified, with 42% of flies containing vertebrate resources: 23% DNA, 5% feces, and 14% both. Previous work has shown that species of blow fly did not impact the richness of the biodiversity detected, however, the use of females vs. males was more fruitful. Furthermore, gravidity of the female directly influenced the detection of vertebrate DNA within the fly guts, unsurprising given how active gravid females are in searching for an appropriate resource for eggs. Environmental factors such as temperature, humidity, and wind speed were all statistically relevant in every environment in maximizing fly collections with vertebrate resources (P < 0.05). Vertebrate diversity detected from flies approximated actual vertebrate biomass of each environment sampled. One uncommon species (the Pine Marten, Martes americana) and one previously undocumented prairie dog genus (Cynomys sp.) were detected by the flies in Yellowstone.
In today’s changing world, it is crucial to have an effective and efficient diversity monitoring tool that can be used across all landscapes. In addition to making it more accessible to test basic ecological theories, the method presented here can provide the means to detect small changes in animal communities as climates change and habitats disappear. This will be integral to providing data for management and remediation efforts.