A novel association between a beetle and a snake: Parasitism of Elaphe obsoleta by Nicrophorus pustulatus

While studying the nesting ecology of black rat snakes (Elaphe obsoleta [Sa y]; Serpentes: Colubridae) in eastern Ontario, we discovered that their egg s regularly contained larvae of the burying beetle Nicrophorus pustulatus ( Herschel) (Coleoptera: Silphidae). The beetle appears to be a parasitoid of the snakes, which may make this thr first documented case in which a verte brate is the host of a parasitoid. Up to 100% of snake eggs in a nest were destroyed by beetles, indicating that N. pustulatus may be a significant, a nd heretofore unrecognized source of egg mortality for oviparous snakes. Ev idence suggests that the association between these two species is well esta blished, and that the beetle may also attack other species of oviparous sna kes. identification of snake eggs as the substrate for reproduction by N. p ustulatus solves the mystery of where this species breeds. Also, the large amount of available biomass in communal black rat snake nests may explain w hy N. pustulatus is so fecund relative to its congeners.