Burying the flies: Fly control by carrion feeding beetles

The nutrients contained in a vertebrate carcass are used by many organisms including vertebrate scavengers, bacteria and fungi, and a large number of invertebrates including flies and beetles.  Carrion beetles in the family Silphidae usually arrive at a carcass soon after death to feed and to use the carcass for reproduction.  The subfamily Silphinae feed on maggots while the subfamily Nicrophoridae bury carcasses and form a brood ball on which they rear their larvae.  In addition to Silphidae, dung beetles, Scarabaeidae, also visit carcasses.   The effects of beetle activity on flies able to complete their life cycle on a small carcass has not been examined.  We allowed flies to oviposit on a series of mouse carcasses and then compared the number of flies produced from control carcasses to those that were also exposed to beetles.  We tested two burying beetle species, Nicrophorus orbicollis and Nicrophorus tomentosus, two members of the Silphinae, Necrophila americana, and Necrodes surinamensis and the dung beetle, Canthon pilularius. Burying beetles significantly reduced the number of flies compared to all other beetles tested.  Approximately 200 calliphorid flies were produced per mouse carcass except when the carcass was utilized by Nicrophorus.  In trials with N. orbicollis, a mean (± 1 S.E.) of 26.3 ± 11 flies were produced and in trials with N. tomentosus, and 9.0 ± 3 flies were produced.These results indicate the genus Nicrophorus reduces fly breeding on small carcasses and may benefit humans and livestock by reducing fly-vectored diseases.