leave the carcass jack, and don’t you come back…no more, no more

Beetles in the genus Nicrophorus (Coleoptera: Staphylinoidea: Silphidae) are commonly known as burying beetles or carrion beetles.  Why?  Because they locate small animal carcasses and feed upon them, of course.  They also bury the carcass and use it as a food source for their young.  The particular genus Nicrophorus is a special rarity within the beetles because the species exhibit bi-parental care.  Beetles tend not to be such loving and caring parents.  But in the case of these burying beetles, both mom and dad stay to help ward off the competition for the carcass and rear the young.  The males are most important at the early stages of reproduction because it’s the time when the carcass is most seductive to outsiders that may want to steal it away.  As the larvae mature and consume the carcass, this becomes less of an issue.  Come on, who would honestly want a half-eaten mouse carcass?  These beetles have their standards!  In some species, like Nicrophorus vespilloides, males often leave their offspring 2-5 days before the females leave resulting in single beetle mothers rearing their offspring for the last few days.

Researchers recently tested the hypothesis that females are actually adapted for brood desertion by their mates.  Surprisingly, the experiments showed that females actually benefit from their male partners deserting them – “Get off my damn carcass and don’t come back!”.  The explanation appears to be that females feed on the carcass once their offspring start to feed themselves.  Since the males are gone, females don’t need to share the resource and thus they benefit.  When males are around, they may prevent females from eating as much of the carcass – “Hey honey, maybe you should lay off that rotting carcass meat so you can fit into those skinny jeans”.  So in the case of these beetles, as long as you predict that your man is going to leave, you’ll be better off without him.

One of my favorite aspects of this research are the laboratory set-ups.  The researchers keep a colony of burying beetles at Cambridge University and for the breeding experiments they “placed pairs into plastic boxes filled with soil, provided them with a freshly thawed mouse carcass and kept them in the dark”.  And people think my lab is odd…

Boncoraglio G & Kilner RM (2012) Female burying beetles benefit from male desertion: sexual conflict and counter-adaptation over parental investment. PlosOne, 7(2): e31713.

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