Armed with bee suits ordered off Amazon (that may or may not work as [thankfully] no one has tested them out yet), red lights to see but not disrupt the hornets, a FLIR thermal imaging camera, soft foam, shrink wrap and a vacuum, entomologists successfully eradicated the first Asian giant hornet nest found in the United States on Saturday.
Just two days earlier, entomologists with the Washington State Department of Agriculture (WSDA) located the nest in a tree on private property thanks to a nano-RFID tracker tagged to a hornet that was captured and released earlier in the week. The trackers were shipped overnight to WSDA by the U.S. Department of Agriculture (USDA).
“We don’t find this nest without the USDA trackers unless it’s a very bad day for someone,” said Sven Spichiger, managing entomologist at WSDA, during a press conference announcing the nest eradication.
Spichiger said Asian giant hornets almost always make their nests in the ground, but this happened to be one of the “supposedly low percentage” of tree nests, making extraction even more difficult and dangerous.
Starting at 5:30 a.m. to ensure as many hornets were in the nest as possible, the entomologists set up scaffolding around the tree to reach the nest, which sat about 10 feet up. They then stuffed foam padding into a crevice above and below the nest entrance and wrapped the tree with cellophane, leaving just a single opening. A vacuum with a special collection chamber was inserted into the opening, extracting 85 hornets. Anticipating the extraction did not get all the hornets, the team then pumped carbon dioxide into the tree to kill or anaesthetize any remaining specimens before sealing it back up with spray foam and cellophane. Finally, the entomologists placed traps nearby to catch any potential survivors or hornets who may have been away from the nest during extraction. (You can watch a video of the extraction below)
Beside the vacuum extraction, the entomologists collected an additional 13 hornets by net when the team was simply observing the nest on Friday. In all, 98 invasive hornets were extracted and the rest of the nest is dead, resulting in a successful eradication.
While all of the hornets appeared lifeless during vacuum extraction, they sparked back to life once in the warmer temperature of the WSDA laboratory. Several of these live hornets will be sent to the USDA to continue research on what attracts them.
“We will be doing assays to see what type of chemicals they react to,” Spichiger explained. “We have not had this opportunity yet as most of them are alive over in Japan and Korea. This is the first time a researcher in the U.S. will be able to look at them.”
Spichiger said some specimens will be flash frozen in a -80˚ freezer, allowing researchers to complete work on their genome. Still others will be examined for chemicals that may be involved in pheromone cues, as well as distributed to land-grant universities for research and community outreach programs.
The Asian giant hornet, or Vespa mandarinia, is an invasive species from Asia that is a significant predator of honey bees. One hornet can kill dozens of honey bees in just a couple minutes. A group of 10 hornets can decimate a small colony of 10,000 honey bees in less than 1.5 hours. That’s the highly concerning part for entomologists as honey bees are crucial to the American food supply, with farmers relying on them to pollinate important crops like apples and berries.
From 2006 to 2013, more than 10 million bee colonies across the world were lost to colony collapse disorder. In the years since, bees have finally started to rebound, with honey-producing colonies in the U.S. increasing 4 percent in 2018. If Asian giant hornets establish a foothold in the U.S., all that progress—and more—would be lost.
Although one nest has been successfully eradicated, there is still work to be done. Based on trappings this year, Spichiger said there are most likely three more nests in the state of Washington. While the hornets usually stop flying after the first freeze of the year, Spichiger said the WSDA will keep responding to calls of sightings and trying to locate nests well into the winter.
“Anytime you introduce an invasive species and it’s successful in establishing, it replaces other species that were meant to be here and that are important parts of the ecosystem. Even though we are fighting this fight just here in Washington right now, it is literally for the rest of the country. It’s a battle that is worth fighting,” said Spichiger.
Photo: WSDA entomologists prepare the tree for extraction. Credit for photo and video: WSDA