Differential colonization of ephemeral resources by sarcosaprophagous Diptera in the Brazilian Caatinga and its implications for forensic entomology in arid environments

Abstract

Surveys of forensically important insects usually rely on sampling adults on baits – which may not represent the colonizing assemblage on a carcass or cadaver. We investigated the diversity of dipterans (Calliphoridae, Sarcophagidae, Muscidae, Fanniidae) in the Brazilian dry forest, an area exposed to high rates of homicide, under an integrated approach of ecology and forensic entomology. Specifically, we compared the species’ ability to colonize different substrates, related to their potential as early carrion colonizers. We used suspended traps baited with fish, feces and bovine spleen to collect adults (visitors) and eggs/larvae on baits (colonizers) and reared immatures in the laboratory until the emergence of adults. Over 30,000 adult flies belonging to at least 30 species were collected on baits, but only 10 species successfully colonized the substrates. Our data corroborate the high diversity of species in the area, especially those with previous record as cadaver colonizers – such as Chrysomya albiceps, Synthesiomyia nudiseta and Tricharaea (Sarcophagula) occidua. Minimum developmental time of the species varied from 9 to 23 days post bait colonization in the field. Blaesoxipha (Gigantotheca) stallengi (Sarcophagidae) was the most efficient colonizer of ephemeral resources in dry forests, and we discuss its potential in forensic entomology.