Researcher’s love of cockroaches rooted in human courtship rituals

by Atsuko Kawaguchi

Kyodo

Ayako Katsumata says it is her love of “cute” cockroaches that motivated her to try to solve the mystery behind the newfound ability of some of them to survive certain poison bait.

Katsumata, 43, a research scholar at North Carolina State University, and her colleagues there recently discovered that formerly effective sweet-tasting poison bait stopped killing German cockroaches because they developed an aversion to sugars.

“We’re probably the only ones in the world who have studied how things taste to cockroaches,” Katsumata said.

Poison bait that contained sugars like glucose designed to lure and kill the pests became widely used during the 1980s, but the insects evolved a glucose aversion after a few years.

Katsumata’s group found out why by examining the 0.02-mm taste hairs around cockroaches’ mouths. Nerve cells that are supposed to sense bitter substances were in fact responding to the sugars in the bait — meaning their brains processed the sweet bait as bitter.

When the cockroaches tasted glucose, they ran away as fast as they could, according to their research unveiled in the May 24 issue of the U.S. magazine Science.

A native of Sapporo, Katsumata has loved observing animals since her childhood.

“Any kind of animal looks happy when it likes its food, while it looks sad when it doesn’t,” she said.

Katsumata, with a Ph.D. from Iwate University, researched the tastes of insects such as ants and butterflies at Kyoto Institute of Technology. At Kyoto University, she focused on cockroaches.

In 2009, she joined a research team studying glucose-averse cockroaches in the Department of Entomology at North Carolina State University.

Katsumata said she was not originally fond of cockroaches, but now loves them.

“I find them so cute when I see males work hard to attract females,” she said. “Their courtship behaviors are just like those of human beings.”

Katsumata is curious about how cockroaches have been able to adapt themselves to people’s living environment and have long survived.

She believes the key to solving the question may be found in their diverse feeding habits.

“They may have similar tastes to those of human beings,” she said.

Katsumata said research has been held back by the fact that cockroaches have been subject to attempts at extermination.

“I hope to see more (researchers) in this area,” she said.