Tropical paper wasps babysit for neighbors

Wasps provide crucial support to their extended families by babysitting children in nearby nests, according to a new study by a team of biologists from the universities of Bristol, Exeter and UCL published today in Nature’s ecology and evolution.

The results suggest that animals should often seek help from relatives further away if their next of kin are less in need.

Dr Patrick Kennedy, senior author and Marie Curie researcher at the School of Biological Sciences, University of Bristol, said: “These wasps can act like wealthy family members lending a helping hand to their cousins ​​in the world. second degree. If there isn’t much else you can do to help your immediate family, you can turn your attention to the extended family. “

By closely observing twenty thousand baby wasps and their caregivers on colonies around the Panama Canal, the research team were able to determine the usefulness of workers on colonies of various sizes. They showed that workers become less useful as the number of colony members increases, due to excess aid.

Andy Radford, professor of behavioral ecology, also from Bristol and co-author, explained: “By helping more distant relatives who are most in need – those who live next door with fewer caregivers – workers can pass on more copies of their genes as a whole. believe that similar principles of diminishing returns could explain seemingly paradoxical acts of altruism in many other social animals. “

Dr Kennedy added: “The fact that these paper wasps in Central and South America are helping in other colonies is really bizarre when you consider that most wasps, ants and bees are extremely hostile to strangers. puzzling behavior, we combined mathematical modeling with our detailed field observations. “

Dr Kennedy continued, “We ended up getting stung a lot. But it was worth it, as our results show that worker wasps can become redundant in the home. A wasp on a colony with few larvae but a lot of larvae. other workers become almost useless: the best thing to do is to keep the larvae of other parents. “

Since Darwin, biologists have tried to understand how “altruism” evolves in animals. At first glance, acts of altruism to help other individuals do not appear to allow individuals to pass on their genes.

Professor Radford said: “In 1964, legendary biologist WD Hamilton discovered the cardinal rule of animal altruism. A lavish helper for your family because it shares so many of your genes. Copies of your genes will triumph in the population.”

But the tropical paper wasps the team studied baffled Hamilton in 1964. In Brazil, he was surprised to find that Polistus wasps left their close family on their nests and flew off to help neighbors, who are less close. .

Previous work by co-author Seirian ‘@WaspWoman’ Sumner, professor of behavioral ecology at University College London, has shown that more than half of workers in a Panamanian population are helping out on multiple nests. Wasps usually viciously attack strangers, so this babysitter suggested something unusual was going on.

Professor Sumner explained, “Wasps offer incredible windows into the evolution of altruism. There is so much going on in a wasp nest: power struggles, self-sacrifice, groups fighting against all odds to survive. .. If we are to understand how societies evolve, we should take a more in-depth look at wasps. ”