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2024-09-09 22:17:08 [休閑] 来源：有聲有色網

Giant hornets, like you, need protein.

The two-inch-long wasps Vespa mandarinia— regrettably dubbed “murder hornets”— attack bee colonies because they teem with prey. These hornets are remarkable, tenacious-looking animals. They're the biggest wasps in the world. The problem is they’re native to Asia, but in 2019 and 2020 people have spotted over a dozen of them (so far) in a corner of Washington. This makes the hornets an invasive species, and with no natural enemies in a new land, a big potential threat to honey bees in the U.S.

In 2020, news stories have hyped the Asian giant hornets, mostly due to their clickbaity, unfortunate nickname. (The nickname is absurd because even in Japan, where the insects are common, "no one calls them 'murder hornet,'" Akito Kawahara, an entomologist at the Florida Museum of Natural History, told Mashable.) The eager stories about these supposedly murderous animals (humans murder, animals don’t) will almost certainly continue as the Washington State Department of Agriculture seeks to stomp out the giant hornets before they establish themselves in the region. This is a necessary, though truly challenging, endeavor.

In the months (and years?) ahead, however, the national and globalattention repeatedly given to "murder hornets" may potentially stoke a fear of or misunderstanding about insects, even thousands of miles away from northwestern Washington (as of Oct. 12, 18 giant hornets have been found in the state). Yet, critically, there are some insects and arthropods that increasingly threaten humans over big swathes of the U.S. that might deserve more of your attention, particularly the recent expansion of disease-spreading insects and ticks. It’s also valuable to remember that most insects aren’tterrible, scary critters. Rather, we should all grow comfortable with (most) bugs. They’re the foundation of our food web. And we are, of course, vastly outnumbered.

"Insects rule the world," said Marc Lame, an entomologist at Indiana University.

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The big threats

Giant hornets don’t care about people. "They're not after you," said Heather Mattila, a biologist at Wellesley College who researches honey bees and other insects. "They’re after their prey." To be sure, it’s not wise to bother a big hornet or disturb their nest, much like it’s not wise to pester a honey bee. Then, the big hornets might sting, with a rather large stinger.

It’s unknown how the giant hornet situation will play out in Washington, where their range is still pretty limited. The good news is government agencies are taking the wasps' presence seriously. "People are on it — pros are on it," said Mark Willis, an entomologist at Case Western Reserve University. "This is definitely an animal we don't want in North America, if we can avoid it." Biologists with the Washington State Department of Agriculture are trying to follow live, captured hornets back to their nest, so they can destroy it. They’ve both glued and tied radio tagsto the large, feisty bugs, but haven’t yet successfully tracked the hornets.

Though most insects are hugely beneficial to humans (they, for example, are major pollinators), what follows are insects and arthropods that pose some serious, growing threats to people in the United States. In the U.S., diseases from biting insects, ticks, and mosquitoes (commonly called vector-borne diseases) tripledbetween 2004 and 2018.

"Their ranges are exploding in size," said Mattila.

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Mosquitoes

The climate is relentlessly warming, and will almost certainly keep warming through much of this century(even if we slashed all carbon emissions, there’s still bounties of heat baked into the climate system, particularly from the oceans). Gradually warming climes have allowed mosquitoes that carry tropical diseases to migrate farther north.

It’s already begun. The mosquito species that spreads the Zika and dengue viruses, Aedes aegypti, better transmits diseases in warmer conditions, meaning the viruses can now spread more effectively in more places. Zika, which can cause serious birth defectsand neurological disorders, expandedinto South America, Central America, Puerto Rico, and elsewhere in 2015 and 2016. Mosquitos then transmitted the virus in Florida and Texasin 2016 and 2017.

"These are little hypodermic syringes that are able to transmit new diseases," said Willis. "Suddenly we’re getting diseases we never had before."

Though still rare, Eastern Equine Encephalitis (EEE) has expanded north, first appearing in Maine, for example, in 2013. The mosquito-borne virus, when it causes encephalitis (brain swelling), kills around one in three people. The number of reported cases in the U.S. rose sharply in 2019(38 cases) compared to previous years.

In the humid Gulf Coast, where most tropical diseases appear in the U.S., poverty combined with wet environmental conditions favorable for breeding mosquitos leaves this region especially vulnerable to disease. In this southern area, public health researchers concluded that "changing rainfall patterns, flooding, and warmer temperatures are promoting the emergence of both parasitic infections and arbovirus infections such as Zika, dengue, and chikungunya."

"I do think global climate change is allowing vectors [disease-carriers] to extend their range," said Indiana University's Lame.

Importantly, we're not completely helpless as vector-borne diseases spread. The Michigan Department of Health and Human Services uses aircraft to treat hundreds of thousands of acres deemed "high-risk" with insecticide to limit the potential spread of EEE. And you can make a difference, too. "Dumping over standing water in your yard can actually be important," noted Willis, of Case Western Reserve University, as mosquitoes flourish in these pools. "You need to be aware of your environment," he said.

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Ticks

Ticks are exploding in the U.S. Unfortunately, they carry human diseases, notably the bacterium that causes Lyme disease. According to the Centers for Disease Control and Prevention, "the number of counties in the northeastern and upper midwestern United States that are considered high-risk for Lyme disease increased by more than 300 percentbetween 1993 and 2012."

"Ticks are in more places than they ever were," said Thomas Mather, a public health entomologist at the University of Rhode Island and director of the university's TickEncounter Resource Center.

Mather hears from lots of people about ticks, which aren't technically insects but are closely related (ticks are arachnids, like spiders). Mather recounted a typical question he receives: "I've lived here for 30 years and I've never seen a tick. Now I’ve seen six in a week. What’s going on?"

What's largely going on, explained Mather, is that animals that carry ticks, particularly deer, are living in closer proximity to humans (he noted a warmer climate plays a role, though less so, in expanding the range of ticks, too). We've moved into their territory. Deer commonly walk through our neighborhoods and backyards, carrying ticks. And there's lots of deer, as we've depleted their natural predators in many areas (wolves, bears, mountain lions). "It used to be that you find ticks in the forest," said Mather. "Now hosts have come out of the woods and live in urban environments."

Where diseases from ticks are expanding.Credit: cdc

Today, the ticks that carry the bacterium that causes Lyme disease — infected blacklegged ticks — have plentiful opportunities to infect people. These ticks actually carry germs that cause five different human diseases, and half of these ticks in the Northeast, Mid-Atlantic, and Upper Midwest carry the Lyme disease germ, explained Mather. What's more, species like lone star ticks are expanding too. Their bites can cause rash and illness.

But we're not helpless as ticks expand. "Be tick smart," emphasized Mather, recommending five critical actions to avoid tick bites. "Knowing what kind of tick lives near you and when they're active is a "tick smart action," he said.

Native killers

Beyond the spread of human disease, large regions of the U.S. have another existential woe: invasive insects that devour native trees, vegetation, and crops. Once an invasive species establishes itself here, there's often little to nothing to naturally check their populations. "They don't have natural enemies in new territories," said Lame.

Take the spotted lanternfly. Since its discovery in Pennsylvania in 2014, the bug (native to China, Bangladesh, and Vietnam) has spread to 26 counties. The state says "it's imperative to immediately report" sightings, as the flies seriously damage and kill trees. Pennsylvania isn't messing around. "Kill it! Squash it, smash it...just get rid of it," the state wrote online. "These are called bad bugs for a reason, don't let them take over your county next."

"The biggest invasive species that I’m aware of are humans."

The lanternflies have many invasive colleagues. The crop-devouring brown marmorated stink bug has spread rapidly across the Eastern U.S. and elsewhere. The emerald ash borer, a critter with a majestic green coat, "is responsible for the destruction of tens of millions of ash trees in 30 states," says the U.S. Department of Agriculture. The Asian long-horned beetles chew through and kill some well-known trees, like maple, elm, and ash.

Of course, the insects themselves are not the problem. It's that we've transported them (often as stowaways in shipping crates) to the U.S. We'll do our best to limit their spread, but in the end, they have more in common with us than perhaps we'd like to admit.

"In the big picture almost all species are invasives," said Lame. "The biggest invasive species that I’m aware of are humans."

They're not murderers or murderous

The giant hornets are undoubtedly thrilling, big insects. But entomologists say these wasps shouldn't be vilified. They're just doing what they must to survive.

Insects often get a bad rap.

"We have this horror movie idea of what insects are," said Willis. "It becomes everyone's worst nightmare."

"In reality, there are insects that are so part of our environment that we don't notice them," he added.

Yes, the giant hornets have a "slaughter phase" wherein they decapitate honeybees en masse to feed their young. That's what they've evolved to do. But does that make them inherently bad, or just, wild? (Humans slaughter cattle on conveyor belts after driving a steel bolt through their heads, which seems on par or perhaps worse than decapitation.)

"It makes me sad when very remarkable insects, like these giant hornets, get maligned for being so good at what they do," said Wellesley College's Mattila. "They’re such an interesting group of species. I feel badly when there’s more fuel in that fire."

"We have this horror movie idea of what insects are."

In an insect world we might view as violent, the giant hornets get attacked, too. In Asia, bees have found ways to kill the giant hornets by forming a "hot defensive bee ball” around the hornets. The bees essentially cook the hornets alive. It's a wild world. "It's fascinating," said Mattila.

Overall, insects are a great boon to humans and our hungry civilization. "They are really important pollinators," said Allen Gibbs, an evolutionary physiologist who researches insects at the University of Nevada, Las Vegas. And they are the foundation of the food chain, Gibbs emphasized. "They are the diet of a lot of bird species."

In some parts of the world, like German forests, researchers have reported dramatic declines in insect abundance, which may be largely due to a loss of habitat. A world with far fewer, less diverse insects would be troubling.

"It would be a pretty devastated world," said Mattila. Beyond their critical place in the food web, insects are amazing lifeforms who survive in curious niches all over the globe. They glide atop streams, can migrate thousands of miles, and dwell in some of our deepest caves. "They are just amazing stories of survival," she said. "They're the most diverse animal taxa we have."

Unfortunately, of course, invasive insects like the giant hornets can threaten our agriculture. So we'll do our best to keep them out. But in a world now forever linked by trade and travel, more hornets will inevitably be on their way, someday.

"If they got here once, they can get here twice," said Gibbs.