CAHNRS NewsCollege of Agricultural, Human, and Natural Resource Science
Scientists study how wasps learn for better trap
On lingering warm fall days, hungry wasps are often unwelcome guests at picnics and tailgates, homing in on hamburgers and buzzing bottles.
It’s worse in parts of the southern United States, where paper wasp species swarm air traffic control towers and other tall, solitary buildings during fall mating season.
Scientists at Washington State University aim to take the sting out of these encounters. Partnering with the U.S. Department of Defense, WSU entomologists are studying wasps’ ability to learn and respond to chemical signals, with the goal of building a better paper wasp trap.
Hungry, unwanted visitors
The European paper wasp, Polistes dominula, gains its name from the paper it makes to build its umbrella-shaped nests, often found under eaves across North America.
While less aggressive than their yellowjacket cousins, from whom they subtly differ in appearance, paper wasps will deliver a painful sting if their nests are threatened.
Paper wasps will occasionally feed on nectar and fermenting substances, but also prey on insects as a protein source for their young. That makes human food especially attractive as summer ends and insect prey, such as aphids and caterpillars, become rare.
“They’re looking for protein and sugar,” said Megan Asche, a WSU Department of Entomology doctoral student. “That’s why they show up at your house, zoom around your garbage can, and take a bite out of your sandwich.”
Paper wasps can be hard to eliminate from homes and yards, because they’re different from other wasp species.
“They’re not attracted to the same things that yellowjackets and hornets are,” Asche said. “We’re trying to find something that works better for these animals—a better wasp trap.”
Buzzing the control tower
Funded by a five-year, $366,000 Department of Defense grant, Asche’s research is spurred by an annual wasp invasion of military airstrips in the southern U.S.
Like many flying insects, paper wasps seek a preferred place to mate. Drones look for queens at places called hill-topping sites: “Basically a really tall thing surrounded by flat, open space,” Asche said. “An air control tower is exactly what wasps are looking for.”
The presence of thousands of wasps in and around the tower, crawling on radar screens and personnel, makes the job of air traffic controllers much harder.
“We need to figure out what we can use to attract wasps away from the towers,” Asche said.
Can wasps learn?
To do that, she is studying wasps’ ability to learn and react to chemical signals.
“Wasps are a lot more flexible in their behavior than most insects,” Asche said. “They eat a lot of different foods, plants, and animals, so they’re capable of adjusting to their environment and changing their routine.”
In Asche’s lab, wasps are put into a flight tunnel—a large see-through plastic box with electric fans on both ends. Near one end is a nozzle emitting scent, either extracted from flowers or isolated from the wasps themselves.
Wasps are released one at a time into the tunnel, and Asche carefully notes how they react to the scent.
“That’s a perfect flight!” Asche remarked as one male wasp was put through the paces. He soon reacted to the odor, questing and landing near the nozzle’s tip.
“I’m trying to see how quickly they can learn,” she explained. “If we understand how they learn, we can teach them to associate an odor with food, and replace it with a working trap.”
Deciphering wasps’ chemical signals
Asche and other WSU entomologists are also exploring the chemistry behind wasp reactions. They are isolating and identifying the compounds they use to communicate and congregate.
The team has had surprising success using synthetic lures to successfully trap and remove wasps, both in Washington state and the southern U.S.
“Paper wasps are a beneficial part of our ecology, but they don’t belong in our buildings,” Asche said. “For people who don’t want to interact with wasps, our research could really bring peace of mind.”
Megan Asche, doctoral student, WSU Department of Entomology,