Tiny brains, big surprise: Eavesdropping wasps gain insights about fighting abilities of potential rivals

June 25, 2020

Paper wasps eavesdrop on fighting rivals to rapidly assess potential opponents without personal risk. This new finding adds to mounting evidence that even mini-brained insects have an impressive capacity to learn, remember and make social deductions about others.

Many vertebrate animals--including some birds and fish and numerous primates--minimize the costs of conflict by using "social eavesdropping" to learn about the fighting ability of potential rivals before interacting with them personally.

Keeping track of a network of individually differentiated social relationships is thought to be cognitively challenging and, until recently, was considered to be beyond the reach of lowly insects like paper wasps, which have brains a million times smaller than the human brain.

But a growing body of evidence suggests that the miniature nervous systems of insects do not limit sophisticated behaviors. The capacity for complex insect behavior may be shaped more by social environment than brain size, according to University of Michigan biologist Elizabeth Tibbetts, senior author of a paper scheduled for publication June 25 in the journal Current Biology.

"It is surprising that wasps can observe and remember a complex network of social interactions between individuals without directly interacting with them," said Tibbetts, a professor in the U-M Department of Ecology and Evolutionary Biology. "Complex social relationships are thought to favor the evolution of large brains and increased social intelligence, but paper wasp brains are relatively small."

In the study, Tibbetts and her students collected female Polistes fuscatus paper wasps from sites around Ann Arbor, Michigan, in the early spring.

Unlike a honeybee colony--which has a single queen and multiple equally ranked female workers--paper wasp colonies contain several reproductive females called foundresses. These females battle their rivals and form complex, linear dominance hierarchies based on the outcomes of those fights. A wasp's rank in the hierarchy determines its share of reproduction, work and food.

In the laboratory, the researchers used enamel to mark all foundresses with unique color patterns on the thorax. Then, two at a time, "fighter" wasps were placed in a small container known as the fighting arena while two "bystander" wasps observed the pair through clear plastic partitions.

All trials were videotaped, and a research assistant assigned scores to each fighter using an aggression index that awards points for behaviors like biting, mounting, grappling and stinging. Dominance rank was determined using the number of mounts--a dominance behavior in which the dominant wasp drums her antennae on the subordinate while the subordinate crouches and lowers her antennae--during a fight.

Later, bystander wasps were paired in the fighting arena either with a wasp they had observed (experimental trial) or a fighter they had never seen before (control trial). Tibbetts and her students compared the behaviors in the experimental and control trials to determine the role of social eavesdropping.

They found that bystander wasps were more aggressive when paired with an individual that was the victim of lots of aggression in a previous bout, as well as individuals who initiated very little aggression in the previous fight.

By comparing experimental and control trials, the researchers were also able to reject non-eavesdropping explanations for the observations, including phenomena called priming and winner/loser effects.

"The results show that P. fuscatus wasps use social eavesdropping," Tibbetts said. "Bystanders observe other individuals fight, and they use information about the fight to modulate subsequent behavior."

In previous studies over more than a decade, Tibbetts and her colleagues showed that paper wasps recognize individuals of their species by variations in their facial markings, and they behave more aggressively toward wasps with unfamiliar faces.

They also demonstrated that paper wasps have surprisingly long memories and base their behavior on what they remember of previous social interactions.

But the previous work focused on how wasps use individual recognition during direct interactions and did not test--as this new study did--whether wasps learn about other individuals via observation alone.
In addition to Tibbetts, the authors of the Current Biology paper are Ellery Wong and Sarah Bonello of the U-M Department of Ecology and Evolutionary Biology. The work was funded in part by the National Science Foundation.

Elizabeth Tibbetts

Images: https://drive.google.com/drive/folders/16Mnm_5tFd9nanRwkt3KD4WM2nI3DgMij

Video: https://drive.google.com/file/d/1b-JEtsLyxfYHJDv8tF-CESMGb5Rk1AbO/view

University of Michigan

Related Science Articles from Brightsurf:

75 science societies urge the education department to base Title IX sexual harassment regulations on evidence and science
The American Educational Research Association (AERA) and the American Association for the Advancement of Science (AAAS) today led 75 scientific societies in submitting comments on the US Department of Education's proposed changes to Title IX regulations.

Science/Science Careers' survey ranks top biotech, biopharma, and pharma employers
The Science and Science Careers' 2018 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Science in the palm of your hand: How citizen science transforms passive learners
Citizen science projects can engage even children who previously were not interested in science.

Applied science may yield more translational research publications than basic science
While translational research can happen at any stage of the research process, a recent investigation of behavioral and social science research awards granted by the NIH between 2008 and 2014 revealed that applied science yielded a higher volume of translational research publications than basic science, according to a study published May 9, 2018 in the open-access journal PLOS ONE by Xueying Han from the Science and Technology Policy Institute, USA, and colleagues.

Prominent academics, including Salk's Thomas Albright, call for more science in forensic science
Six scientists who recently served on the National Commission on Forensic Science are calling on the scientific community at large to advocate for increased research and financial support of forensic science as well as the introduction of empirical testing requirements to ensure the validity of outcomes.

World Science Forum 2017 Jordan issues Science for Peace Declaration
On behalf of the coordinating organizations responsible for delivering the World Science Forum Jordan, the concluding Science for Peace Declaration issued at the Dead Sea represents a global call for action to science and society to build a future that promises greater equality, security and opportunity for all, and in which science plays an increasingly prominent role as an enabler of fair and sustainable development.

PETA science group promotes animal-free science at society of toxicology conference
The PETA International Science Consortium Ltd. is presenting two posters on animal-free methods for testing inhalation toxicity at the 56th annual Society of Toxicology (SOT) meeting March 12 to 16, 2017, in Baltimore, Maryland.

Citizen Science in the Digital Age: Rhetoric, Science and Public Engagement
James Wynn's timely investigation highlights scientific studies grounded in publicly gathered data and probes the rhetoric these studies employ.

Science/Science Careers' survey ranks top biotech, pharma, and biopharma employers
The Science and Science Careers' 2016 annual Top Employers Survey polled employees in the biotechnology, biopharmaceutical, pharmaceutical, and related industries to determine the 20 best employers in these industries as well as their driving characteristics.

Three natural science professors win TJ Park Science Fellowship
Professor Jung-Min Kee (Department of Chemistry, UNIST), Professor Kyudong Choi (Department of Mathematical Sciences, UNIST), and Professor Kwanpyo Kim (Department of Physics, UNIST) are the recipients of the Cheong-Am (TJ Park) Science Fellowship of the year 2016.

Read More: Science News and Science Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.