Sex pheromone traps may help U.S. stop the spread of ‘murder hornets’

SAN DIEGO, Calif. — “Murder hornets” have been a not-so-tiny terror plaguing the western United States over the last few years. Now, scientists may finally have a way of trapping these insects before they devastate local bee colonies. Researchers say sex pheromone traps could help stop the Asian giant hornet from invading more states and wreaking havoc.

A team from the University of California-San Diego says stimulating odors produced by a hornet queen can bait and trap the invasive insects. Asian giant hornets, more commonly known as “murder hornets,” have been spreading across parts of North America and Europe.

While their nickname is misleading, they are threatening bee populations along with millions of pounds worth of crops. Honeybees, some of the world’s most important pollinators, have few defenses against these destructive insects, which can quickly destroy an entire colony.

So far, coming up with a solution to eliminate them has proven challenging, and even knowing where to look for them is tricky. Now, scientists have come up with a cunning plan to track their movements and end the invasion.

“My usual plea is that people should stop calling them ‘murder hornets’ because they are large and perhaps frightening but not truly murderous,” says study author Professor James Nieh in a university release. “They are amazing social insects, but they don’t belong in North America and harm our critical bee populations, so we should remove them.”

The secret mix is the queen’s pheromone

The team identified three of the major chemicals found in the giant hornet queen’s sex pheromone, including hexanoic, octanoic, and decanoic acid. They then captured male hornets by laying traps near their nests and places where they typically reproduce.

The study finds the hornets’ brain activity and antennae were highly sensitive to the pheromone. Researchers add that it’s possible to easily purchase and deploy these compounds in the field immediately.

“The males are drawn to the odors of the females since they typically mate with them near their nests,” Nieh says. “In two field seasons we were able to rapidly collect thousands of males that were attracted to these odors.”

The researchers are hoping to test their traps in more field locations to see whether they can chemically attract hornets over distances of a kilometer or more.

“Because these pheromone-based traps are fairly inexpensive I think they could be readily deployed for sampling across a large geographic range,” Nieh explains. “We know where they have been found, so the big question is whether they are expanding. Where is that invasion front?”

Tracking the hornets before they head east

How Asian giant hornets, or Vespa mandarinia, first came to North America is still a mystery. However, there have been sightings in both British Columbia and Washington state. Models suggest they could rapidly spread across Washington, Oregon, and possibly the eastern United States in the future.

Rather than patent their discovery, the researchers have published their findings in the hopes that it will help document the hornet’s spread. Predictive models could map where and how rapidly they are spreading once researchers deploy more traps.

“We hope that others, especially in invaded areas, will take the protocol we have established and test this method,” Nieh concludes. “We’ve described the chemical blends needed for these traps, which could reduce the number of males available to mate with females to help depress the population but primarily would help us figure out where they are.”

The findings are published in the journal Current Biology.

South West News Service writer Tom Campbell contributed to this report.

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