Speaking of science: UW researchers find size does matter for wasps

Is bigger really better?

Yes — if you’re talking about insect brains.

After studying tropical wasps, UW researchers have found that processing regions of male and female wasp brains, which grow with age, are also linked to social dominance.

Different development patterns occur in males and females, with some sub-regions larger and some smaller in each sex. The study showed that a particular part of the brain, which changes based on experience, was more developed in dominant females that spend more time in the nest. Since males rely more heavily on vision and females on antennae, these regions were more developed in each sex, respectively.

The increased growth was found in mushroom bodies — areas in the wasp brain that are similar to human cerebrum.

Sean O’Donnell and Yamile Molina led the UW’s part of the National Science Foundation-funded study.

The team looked at the social paper wasp, an unusual breed among social insects because males are dominant over females. Other types of wasps, as well as ants and bees, are chiefly female with some subordinate males.

“The fact that the males are dominant and long-lived makes this species interesting from a neurobiological standpoint,” O’Donnell said in a press release. “We think they have pretty sophisticated cognition compared to males of other wasp species.”

The project studied seven wasp colonies in Monteverde, Costa Rica, during summer 2004. Each colony was observed for eight hours total during two consecutive days. The researchers recorded departures and arrivals as well as dominance interactions. The dominant wasp was obvious in all instances, the study reported.

After observation, the brains were evaluated under a microscope.

Since the team looked at the wasps for only 42 days, it remains uncertain of their longevity and rate of cognitive decline.

O’Donnell said that whether being dominant drives brain capacity or brain capacity drives dominance is still ambiguous. This study, however, implies the demands that come with being dominant drive brain size.

“Increased brainpower may be part of being social, no matter who you are,” O’Donnell said. “What makes this exciting is we see some common patterns in how brains change as societies evolve. As we see changes in social complexity, there are changes in brain structure. If it is good for people it should be good for wolves, dolphins and paper wasps.”

[Reach columnist Meghan Peters at news@thedaily.washington.edu.]