Reproductive Competition between the Burying Beetle Nicrophorus quadripunctatus without Phoretic Mites and the Blow Fly Chrysomya pinguis

The competition between the burying beetle Nicrophorus quadripunctatus and the blow fly Chrysomya pinguis for carcasses as a reproductive resource was examined with mouse carcasses in the laboratory after removing all phoretic mites from beetles. Adult pairs of N. quadripunctatus succeeded in reproduction with carcasses containing fly eggs or larvae. When flies were in the egg stage or first larval instar, beetles killed or removed them completely from the carcasses. When flies had already reached the third larval instar when beetles were introduced, however, a few larvae escaped from being killed by the beetles and became puparia in some cases. Therefore, the phoretic mites of N. quadripunctatus are not indispensable to removal of fly eggs or larvae from the carcass for reproduction of the beetle. N. quadripunctatus shows remarkably successful reproduction in competition with flies as compared to other Nicrophorus species that show no or low levels of reproductive success in carcasses containing fly larvae.