Invasive Asian giant hornets—popularly known as “murder hornets”—could spread rapidly throughout western North America if left unchecked, researchers have found.
Native to forested parts of eastern and southern Asia, the insect is the world’s largest hornet species, measuring up to two inches long. In September 2019, the hornet was detected in western British Columbia, Canada, and it has now spread into adjacent parts of Washington state near the border.
For a study published in the journal Proceedings of the National Academy of Sciences, a team of scientists examined records from the hornet’s native range in Japan, South Korea and Taiwan, and combined it with climate data in order to predict areas of the world where the insect could potentially thrive.
“These predictions are scientific sleuthing,” Javier Illan, an entomologist from Washington State University (WSU) and author of the study, said in a statement. “We’re making an educated guess on how fast and far these insects can move, their rate of success in establishing a nest, and offering different scenarios, from least bad to worst. No one has done this before for this species.”
They found that Asian giant hornets (Vespa mandarinia) are most likely to establish themselves in areas with warm summers, mild winters and high precipitation, as well as high human activity. Regions that experience extremes of heat, cold or precipitation are inhospitable to the hornets.
With this information, the scientists concluded that much of the U.S. interior would not be suitable habitat for the hornets—including eastern parts of Washington state and British Columbia, as well as California’s Central Valley.
But much of the U.S. west coast and eastern seaboard, adjacent regions of Canada, large parts of Europe, northwestern and southeastern South America, eastern Australia, most of New Zealand, and central regions of Africa, would be suitable habitats for the insects.
If the hornets are not contained, they could spread “rapidly” throughout western North America, according to computer simulations conducted by the scientists. When considering regional spread only, the scientists predicted that the hornets could reach northern Oregon in 10 years. And over a period of 20 years, they could have spread throughout western regions of Oregon, Washington and British Columbia, reaching as far south as southern Oregon.
These predictions are based on calculations that the hornets can fly up to 68 miles per year. But the researchers warn that they still lack important data on this issue, meaning these predictions are an educated guess.
“The information that we want—how fast and far queens can fly, and when they fly—is all unknown,” Illan said. “A lot of basic biology is unknown. So, we’re using a surrogate.”
A lot also depends on whether or not the hornet can establish a solid foothold in its current adopted home in northwestern North America, as well as the effectiveness of containment efforts. The United States Department of Agriculture and the Animal and Plant Health Inspection Service’s Plant Protection and Quarantine program are currently trying to eliminate the invasive insect before it gains a foothold.
“At this point, trying to locate any active hives and eradicate them before they produce queens that can hibernate and come out next year is really what we need to be doing,” David Crowder, an entomologist from WSU and another author of the latest study, told FOX 12. “It is almost unfortunate the area it got introduced is the perfect habitat.”
Crowder said the invasion was manageable at this present time, noting that the insects can only survive and multiply under specific conditions.
But if the hornets do manage to establish a permanent presence, there is a chance they could spread much further than the west coast if they are given a little help by humans, who are often responsible for inadvertently transporting invasive species around the world.
“Their ability to move on their own is somewhat limited. But they are very willing to hitch a ride in a truck, and this is how they will likely move larger distances,” David Ragsdale—professor in the Department of Entomology at Texas A&M University and member of the college’s Murder Hornet Task Force—previously told Newsweek.
“They did make it from Japan to British Columbia—likely using a container ship as the means of conveyance, but other methods, including intentional transport by people, is also possible.”
Despite their fearsome nickname, the hornets pose little risk to most people who are not allergic to bee stings. But the hornets do represent a significant threat to Western honeybees, which have no innate defense against them.
During the late summer and fall, Asian giant hornets attack beehives, destroying entire colonies.
“Economically, beekeepers should be especially worried; the hornets can wipe out a hive in an hour or two,” Allen Gibbs, an entomologist from the School of Life Sciences at the University of Nevada, Las Vegas, previously told Newsweek. “Honeybees are already facing many problems; these hornets would just add more stress to them. If honeybees are significantly affected, bee-pollinated crops would suffer.”
“The risk to honey bees and native insects is extremely high,” Crowder told FOX 12. “This could be, if it were to become established, one of the most damaging invasive species that we could almost imagine.”
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