HAGÅTÑA (The Guam Daily Post) — The Guam Department of Agriculture is asking residents to report invasive hornet nests so researchers can build a pheromone trap meant to combat the destruction of the local bee population by hornets.
Researchers from the U.S. Department of Agriculture Agricultural Research Service will be on Guam Aug. 6-14, looking to collect pheromone samples from the invasive greater banded hornet. From there, a lure can be developed from the pheromones, a scent which can be used to trick the troublesome pests, according to Guam state entomologist Christopher Rosario.
Since its discovery on Guam in 2018, the greater banded hornet has grown to be the biggest threat to the growing beekeeping industry and the island’s supply of local honey, Rosario told the Post. European honey bees, which make up the entirety of Guam’s honey bee stock, have no defense against attacks by the banded hornets, which hail from Southeast Asia.
At least 18 colonies cared for by beekeepers were destroyed by banded hornets last year and the problem may be much worse among feral bee colonies, Rosario said. Hornets will rip the wings and heads off of bee colony guards to gain access to a hive.
“Once all of them are killed, then they go in ripping out the larvae and start eating the brood, eating the larvae for nutrients,” he told the Post.
Just one hornet can take out 100 bees in less than an hour, the entomologist said, and a few easily can destroy an entire colony. The process is a gruesome and fascinating thing to watch and can be frustrating for beekeepers who have to watch the bee colony they’ve invested time and money into be decimated, Rosario said.
“It’s a massacre, for sure,” he said.
Besides that problem, the large and aggressive hornets also can spell trouble for kids and the elderly, or anyone with a sensitivity to getting stung.
The local Agriculture Department has received a grant to try to combat the destructive hornets, Rosario said, and will be getting backup next week from USDA researcher Jacqueline Serrano. Serrano has successfully synthesized “alarm pheromones” to deal with the northern giant hornet, a cousin of the greater banded hornet which invaded Washington state in 2019.
Once a chemical lure can be developed for the greater banded hornets, said Rosario, the lure can be put into traps.
"When we put out traps, instead of the hornets attacking the bees, they're going to be going to the trap.”
Pheromone traps also can be stationed at ports of entry to keep the hornets from making their way onto ships and escaping to other locales, Rosario said, adding that’s likely how the hornets made it to Guam in 2018.
Opinions differ on whether the greater banded hornets can be eradicated on Guam, or if they will go the way of the brown tree snake and become a permanent part of island life.
“I think, personally, they’re here, they're very well-established. But I think we can control their population with further research,” Rosario told the Post.
Progress toward possible eradication is all dependent on getting experts out to Guam for aid, he said. After a lure is developed, his next project will be to start placing radio trackers onto hornets so that they can be followed back to their hives with the aid of aerial drones.
“Once we find out where the colony is, then we eradicate it. And I think at that point, once we get that going, then it's possible for eradication,” Rosario said.
