FunNature & AnimalWasps can also be cannibals

Wasps can also be cannibals


In the world of wasps, wasp offspring are capable of cannibalizing their own brothers and sisters when food is scarce. This has been the discovery of a recent study that found that cannibalism between siblings was surprisingly common in the larvae of the species Isodontia harmandi, a type of autonomous wasp that does not live in colonies.

There are certain females that make their nests in holes in natural bushes, laying about a dozen eggs on the bodies of paralyzed insects which are then consumed by the larvae upon hatching, carrying food in the form of invertebrates to the nest and then covering the opening with moss. to keep them safe.


survival cannibalism

The problem is that, after the brood emerges and consumes the bodies of the insects that had been placed as food, the newborns have nothing else to eat and something even worse happens; a more gruesome event arrives : many begin to eat their own brothers to survive. Living with more siblings in such tight spaces creates fierce competition for food, and the new study shows that the larvae often attack each other to guarantee themselves a meal.

To see if and how these wasps were feasting on their family, the researchers placed bamboo poles in various locations in central Japan between 2010 and 2015. They waited for the females to lay their eggs inside, then carried the nests They returned to their lab and watched the larvae develop, recording the conditions of the hatchlings at various stages of growth and maturation.

In 30 of the 39 broods , the young wasps chose to eat each other. Cannibalism continued in 23 of the nests after the cocoon phase began.

“Of course, we were surprised that wasp larvae routinely cannibalized their nestmates,” say the authors publishing their study in the journal PloS One. “We were also impressed that there were no obvious aggressive interactions between cannibal and victim.” . According to experts, the larvae seemed to accept their fatal fate without a fight.

The cannibal wasp profile

They observed that the cannibal wasps were usually larger than the siblings they ate, and the victims were often newborns or very small . In one particularly gruesome example, they watched a group of larvae share an insect when one of them began to eat its brother while they were tasting the insect.

This happens because the female wasps lay too many eggs for all the larvae to survive on the insect carcasses it provides, the researchers say; something that leaves the little wasps with little choice but to eat each other to survive.

Scientists want to discover how wasp larvae are able to realize that their food supply is running low and therefore resort to cannibalism to survive. Could it be that they lay so many eggs precisely to ensure that food is always available?

“This is one of the topics for our next article,” concluded Tomoji Endo of the School of Human Sciences at Kobe College in Japan.

Referencia: Brood reduction caused by sibling cannibalism in Isodontia harmandi (Hymenoptera: Sphecidae), a solitary wasp species building communal brood cells. Yui Imasaki, Tomoji Endo Published: May 18, 2022 PLOS ONE DOI:

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