Washington State University researchers have predicted how and where the Asiatic giant hornet, an invasive newcomer to the Pacific Northwest popularly known as the “murder hornet”, could spread both in the US and around the world and find an ideal habitat.
Share your discoveries in a newly published article in the Procedure of the National Academy of SciencesThe team found that if the world’s largest hornet set foot in Washington state, it could spread over much of the west coast of the United States.
The Asian giant hornet could also find a suitable habitat on the east coast and in populous parts of Africa, Australia, Europe and South America if people accidentally transport it.
The team’s predictions underscore the importance of Washington State’s efforts to stop the large insects before they spread.
“We have found many suitable climates in the US and around the world,” said lead author Gengping Zhu, a postdoctoral fellow in the Department of Entomology at WSU.
Working with Washington State Department of Agriculture scientist Chris Looney and WSU entomologists David Crowder and Javier Illan, Zhu examined more than 200 records from the hornet’s range in Japan, South Korea and Taiwan and then used a number of ecological models , The climate data included predictions of likely global habitat on six continents.
“These predictions are scientific investigations,” Illan said. “We guess exactly how fast and far these insects can move, how successful they are in building a nest, and offer different scenarios, from the worst to the worst. Nobody has done that for this species before. ”
A wide range of suitable habitats
The Asian giant hornet Vespa mandarinia, native to forested parts of Asia, is a significant threat to western honey bees, which have no natural defense. In late summer and autumn, colonies of hornet attack beehives and destroy entire bee colonies to feed their brood and produce new queens.
Up to two inches long, the insect also employs a powerful sting that is more dangerous than that of local bees and wasps.
Asian giant hornets are most likely to thrive in locations with warm summers, mild winters, and high rainfall. Extreme heat is fatal, so their most suitable habitats are in regions with a maximum temperature of 102 degrees Fahrenheit.
Based on these factors, there is suitable habitat for the giant hornet on large parts of the west and east coasts of the United States, in adjacent parts of Canada, in large parts of Europe, in the northwest and southeast of South America, in central Africa, in eastern Australia, and in most parts of New Zealand .
Much of the interior of the United States is inhospitable to the hornet due to extreme heat, cold, and low rainfall. This includes the eastern portions of Washington state and British Columbia and California’s Central Valley, all of which have important fruit and nut crops that rely on honeybees pollination.
Risk of accidental spread
Using data from a similar species, Vespa velutina, scientists predicted that Asian giant hornets could spread to southern Washington and Oregon, as well as north through British Columbia, without containment. Calculating that hornets could fly up to 68 miles per year, their worst-case scenario found that the insects could spread to the western regions of Washington and Oregon in 20 years or less.
However, scientists cautioned that these predictions are an educated guess.
“The information we want – how fast and far queens can fly and when to fly – are all unknown,” Illan said. “A lot of basic biology is unknown. So we’re using a replacement. ”
“We know queens come out of their nest in the fall, mate, and fly – somewhere,” Looney said. But no one knows how far they fly or whether they fly repeatedly. We do not know whether they will set up nests near their hibernation in spring or whether they will fly again. These are some of the things that make predicting natural range a challenge. ”
Nature alone cannot predict where the hornet might land. Human activities play a role in transporting invasive species around the globe.
While colonies can only be started by mated queens, and USDA analysis found accidental human transport is unlikely, Looney said human spread could be a problem.
“It’s easy for some species to accidentally get from one side of the country to the other, even with a large amount of unacceptable habitats in between,” he said.
“Preventing the establishment and spreading of Asian giant hornets in western North America is critical to protecting bees and beekeepers,” said Crowder. “Our study can reveal strategies to monitor and eradicate these intruders before they become established.”
Reference: “Assessment of the ecological niche and the invasive potential of the Asian giant hornet” by Gengping Zhu, Javier Gutierrez Illan, Chris Looney and David W. Crowder, September 22, 2020, Procedure of the National Academy of Sciences.
DOI: 10.1073 / pnas.2011441117