Burying beetle
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Burying beetles (genus Nicrophorus) are the best-known genus within the family Silphidae (carrion beetles). Most of these beetles are black with red markings on the elytra (= forewings). They bury dead birds and rodents in order to lay their eggs into the carrion. Adults take care of the brood.
Species
About eighty species have been described.
Common European species:
- Nicrophorus humator
- Nicrophorus investigator
- Nicrophorus vespillo
- Nicrophorus vespilloides
- Nicrophorus vestigator
- Nicrophorus interruptus
Extinct European species:
Common North American species:
- Nicrophorus americanus
- Nicrophorus sayi
- Nicrophorus orbicollis
- Nicrophorus pustulatus
- Nicrophorus defodiens
- Nicrophorus tomentosus
- Nicrophorus vespillo
- Nicrophorus vespilloides
Reproduction
Burying beetles have large chemoreceptors at the tips of their antennae, capable of detecting a dead animal from a long way away. After finding a carcass (most likely that of a small bird or a mouse), beetles fight amongst themselves (males fighting males, females fighting females) until the winning pair remain. If a lone beetle finds a carcass, it can continue alone and await a partner.
The carcass must be buried by the beetle(s) to get it out of the way of potential competitors, which are numerous.
The prospective parents begin to dig a hole below the carcass. While doing so, the beetles cover the animal with antibacterial and antifungal oral and anal secretions, slowing the decay of the carcass and preventing the smell of rotting flesh from attracting competition. The carcass is formed into a ball and the fur or feathers stripped away, and used to line and reinforce the crypt, where the carcass will remain until it is completely consumed. The burial process can take around 8 hours.
The female burying beetle lays eggs in the soil around the crypt. The larvae hatch after a few days and move into a pit in the carcass which the parent have created. Although the larvae are able to feed themselves, both parents also feed the larvae: they digest the flesh and regurgitate liquid food for the larvae to feed on. This allows the larvae to develop faster.
At an early stage, the parents may cull their young. This infanticide functions to match the number of larvae to the size of the carcass so that there is enough food to go around. If there are too many young, they will all be underfed and will develop less quickly, reducing their chances of surviving to adulthood. If there are too few young, the resulting adult beetles will be large but the parents could have produced more of them. The most successful beetle parents will achieve a good balance between the size of offspring and the number produced.
Several pairs of beetles may cooperate to bury large carcasses and then raise their broods communally.
The adult beetles continue to protect the larvae, which take several days to mature. Many competitors make this task difficult, e.g. bluebottles and ants or burying beetles of either another or the same species.
The final stage larvae migrate into the soil and pupate, transforming from small white larvae to fully formed adult beetles.
Parental care is quite rare among insects, and burying beetles are remarkable exceptions.
- Nicrophorus Central (http://collections2.eeb.uconn.edu/nicroweb/nicrophorus.htm)de:Totengräber (Insekt)