Trials and tribulations of rearing the necrophilous predator Euspilotus assimilis (Paykull) (Coleoptera: Histeridae)

The histerid beetle, Euspilotus assimilis (Paykull), is a common predatory beetle of fly larvae associated with decaying animal remains (carrion). Furthermore, histerid beetles are among the most forensically-important coleopteran families. Euspilotus assimilis is an abundant, well-documented species that is present year-round in Louisiana. Thus, the establishment of known development rates for this species will provide valuable information for postmortem estimations of deceased humans and poached wildlife.

The two objectives of this ongoing pilot study include: 1) to establish protocols for rearing and maintaining laboratory colonies of E. assimilis; and 2) to document development rates for all life stages using an insect growth chamber. Adult beetles were field collected from swine carcasses placed in a grassland habitat in Hammond, Louisiana. Several methods were utilized in attempts to ‘demite’ the phoretic mites associated with the field collected E. assimilis prior to introduction into the laboratory colony; as well as, to control mite populations within the colony. Mating pairs of E. assimilis were placed into individual rearing containers and incubated at a constant temperature (27 °C) and relative humidity (70%) in a Caron® Insect Growth Chamber. Following oviposition, the adult beetles were removed from the containers and returned to the laboratory colony. All rearing containers were monitored simultaneously and developments rates for each life stage were documented.