Paper wasps form an abstract concept of “same” and “different”

In a series of studies spanning more than 20 years, Elizabeth Tibbetts, an evolutionary biologist at the University of Michigan, and her colleagues demonstrated that paper wasps, despite their small brains, have an impressive ability to learn, remember and make social distinctions with others.

Researchers have shown that paper wasps recognize individuals of their species by variations in their facial markings and that they behave more aggressively towards wasps with unknown markings.

They established that paper wasps have surprisingly long memories and base their actions on what they remember from previous social interactions with other wasps. And they provided the first evidence of transitive inference – behavior that resembles logical reasoning – in a non-vertebrate animal, the lowly paper wasp.

Now, Tibbetts and his students report the first evidence that paper wasps can form abstract concepts. Surprisingly, the wasps were also able to transfer what they learned through visual training into a different sensory modality: smell.

The study used laboratory tasks to test whether paper wasps (Polistes fuscatus) could learn and apply one of the most basic abstract concepts: the idea of ​​similarity and difference.

The wasps were trained to distinguish pairs of visual or olfactory stimuli (two colored pieces of paper, two photos of wasp faces, or two chemical odors) that were the same or different. One pair of stimuli was associated with a mild but unpleasant electric shock, the other was not.

Next, the biting insects were exposed to new pairs of stimuli (same or different) and tested on their ability to avoid an electric shock by selecting the “right” pair – the one associated with safety.

The previously trained wasps made the right choice more than 80% of the time, the researchers found. The team’s findings were published online July 20 in the journal Proceedings of the Royal Society B.

“Our results show that the wasps learned the general concept of similarity and difference and applied it to new samples and new types of stimuli,” said Tibbetts, a professor in the Department of Ecology and Evolutionary Biology at the UM.

“Abstract concepts are thought to be associated with high levels of cognitive sophistication, so there has been a lot of interest in which species can form and use them. This is the first time anyone has shown that wasps can form abstract concepts.”

Historically, only primates were thought to be able to learn the same and different concepts. But later research found evidence for the same concepts in many animals, including crows, pigeons, parrots, dolphins, ducklings and bees.

Now UM researchers are adding paper wasps to the list. The first author of the Proceedings of the Royal Society B study is Chloe Weise, a former UM Masters student who graduated this spring.

“Concept learning is the cornerstone of difficult tasks like language, analogy, and awareness,” Weise said. “Our findings add to a growing body of evidence that miniature insect nervous systems do not limit sophisticated behaviors.”

For the study, female paper wasps were collected from their nests in the vicinity of Ann Arbor, Michigan. The wasps and their nests were housed in the lab and given water, sugar, and waxworms as food.

During training and testing, individual wasps were placed in a small balsa wood and plexiglass chamber to determine if they could learn and apply the same and different concepts.

The Wasps were trained and tested using a method called the Simultaneous Two-Equal-Different-Item Task. Three types of stimuli were used in the study: colored paper, pictures of wasp faces, and smells of chemicals called alkenes, which resemble the scents wasps use to identify their nestmates.

Laboratory tests showed that wasps trained with visual stimuli were able to apply the concept of similarity and difference to olfactory stimuli.

“Remarkably, wasps applied the concept of similarity and difference across sensory modalities, as they transferred concepts learned in the visual domain to the olfactory domain,” Weise said. “Therefore, our results illustrate that Polistes are able to master the abstract interrelationships between stimuli.”

Paper wasps are the second invertebrate that form same and different concepts, after bees. Paper wasps and honeybees have considerably smaller brains (less than a million neurons) than vertebrates known to form the same and different concepts. Pigeons, for example, have brains with 310 million neurons, and macaque brains have 6 billion neurons.

Interestingly, paper wasps in this study made over 80% correct choices after training involving only eight trials with eight pairs of stimuli, while pigeons need 100 unique stimuli and thousands of trials to learn patterns. identical concepts, according to Tibbetts.

The paper wasps used in the current study may have been better at concept forming than the pigeons because they were trained with different methods, including the use of biologically relevant stimuli, Tibbetts said.

“We trained and tested wasps using wasp face images, colors and smells,” she said. “All three types of stimuli are important in the behavior of wild wasps.”

The other author of Proceedings of the Royal Society B study is former UM graduate student Christian Cely Ortiz. The work was supported by National Science Foundation grant IOS-1557564.

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