Social insect species need to work together to survive, and that includes finding food. They aren’t able to shout about it when they find some, of course, which means they have to come up with rather inventive ways to wave their hands at each other. Honey bees do a waggle dance to indicate the presence of resources; some ant species leave pheromone trails.
As it turns out, some wasps engage in a bit of drumming. Specifically, they drum their bellies – well, their abdomens, technically known as their gasters – against different parts of the nest. This so-called gastral drumming is performed by worker wasps, and these idiosyncratic sounds communicate the presence of availability of food.
As explained in a new study, published in The Science of Nature, this new revelation overturns an alternate hypothesis about this well-documented drumming behavior that’s persisted for five decades. It was thought, without much substantial evidence, that gastral drumming (GD) occurred because the wasps were letting each other know they were hungry.
Instead, it appears that the team have provided the first evidence that wasps have complex communication behavior with regards to dinnertime, much like their other eusocial insect compatriots. It’s a form of recruitment, a way of saying to each other “hey, I’ve found something to chow down on!” and to get help foraging for it.
In order to come to this conclusion, the pair of researchers – from the University of Wisconsin-Madison and LaGuardia Community College/CUNY – focused on Vespula germanica, a yellowjacket wasp species. Regular wasp nests are notoriously difficult to peer inside, so instead, the team created artificial wasps nests on the fifth floor of a laboratory building, complete with see-through roofs and floors.
After letting the workers and queen chill out overnight in a refrigerator during the transfer, they were released into their new homes. Then, the wasps were put in two situations: one in which small dishes containing just water were given to the wasps (the “starvation” experiment variant), and one in which a sugary solution was bequeathed (the “food-supplementation” experiment variant). Sometimes, the wasps were allowed to forage outdoors, and sometimes they weren’t.
The idea was that GD bouts – recorded by specialized equipment – should pick up during the supplementation phases, and decrease during the starvation phases. Indeed, that’s precisely what happened, which clearly supports the idea that wasps drum to signal the presence of food and to recruit others to forage for it.
The team even managed to play some of their hit tracks back to the wasps, which caused them to move around a lot more and trigger worker departures from the nest, again suggesting that it was a way to recruit workers into food foraging.
They even increasingly engaged in trophallaxis – exchanging regurgitated liquids – when GD playback occurred, which allows them to share digestive and scent-based information about the type of resources coming into the nest.
Is there anything else hidden within their sick beats? Could slight differences in drumming indicate the quality and quantity of the food too, as is observed in other species of insects, and even birds and mammals? Future experiments will hopefully enlighten us as to just how good these insectoid percussionists really are.