Meet the (burying) beetles

Abstract

You probably know that hard-working dung beetles keep the Serengeti Plain and cow pastures clean, but even most biologists are unaware of the efforts of another diligent group of beetles: the burying beetles of the genus Nicrophorus. Burying beetles play an important role in many ecosystems through their processing of small vertebrate carcasses. The reproductive cycle of such beetles is tied to the discovery of a recently deceased small animal (Scott, 1998; Trumbo, 1997). When beetles discover a carcass, they dig a hole beneath the body and cover it with dirt. They next remove the fur or feathers. The process is complete when the denuded corpse is covered with a layer of anal gland secretions. If more than two beetles find the carcass, males fight against males and females against females until a single pair is in control. Oviposition occurs within a day of the discovery of a carcass. The female lays her eggs in the soil; the larvae hatch about 4 days later and crawl to the carcass, which serves as nest and food source. For the first 2 days on the carcass, both parents feed the larvae regurgitated carrion and defend the carcass against other burying beetles. After this time, the larvae are able to feed themselves directly from the carcass, and the parents’ role is primarily defensive (Fetherston et al., 1990). The bout of parental behavior ends with the departure of the adult beetles from the nest: the female will remain until the larvae leave the carcass in preparation for pupation (6–8 days), while the male typically leaves a little sooner. A set of larvae can be raised successfully by a single parent as well as by a pair, with males able to compensate fully for the disappearance of the female after oviposition (Fetherston et al., 1994). Burying beetles therefore provide an uncommon example of extended, facultative biparental care in insects, of interest to entomologists, ecologists, and evolutionary biologists.