Global swarming
Is climate change bringing the state more bugs?
|
|
State entomologist Jon Turmel examines an Asian long-horned beetle at the Vermont Agency of Agriculture, Food and Markets laboratory in Waterbury. Photo by Jeb Wallace-Brodeur |
Toolbox
By KEVIN O’CONNOR
Staff Writer - Published: August 26, 2007
As state entomologist, Jon Turmel speaks with authority about bugs: "They're just so cool."
But ask him about the new insects arriving with the onset of global warming and he admits they're not so hot.
Turmel points to ticks spreading Lyme disease northward. Mosquitoes flying up with West Nile virus and several forms of encephalitis. Plant-eating pests such as the hemlock woolly adelgid, a tree-munching troublemaker recently discovered in the southeastern corner of the state.
Scientists can report with certainty the appearance of new and more numerous insects statewide. They also note the creatures are coming as the state's average temperatures are rising as a result of global warming.
So is there a connection? Turmel and his Vermont colleagues can't yet say. Entomologists have just begun studying whether climate change is drawing more insects to New England and, as a result, lack definitive proof. That said, they're already voicing suspicions.
"A warming New England region (especially warming winters) will support the introduction and expansion of exotic pests into the region," the government's U.S. Global Change Research Program says in its New England Regional Assessment of the Potential Consequences of Climate Variability and Change.
Experts fear that fighting back may exacerbate the sting. The Union of Concerned Scientists, in its new report "Confronting Climate Change in the U.S. Northeast," says the region annually sprays an estimated 12 million pounds of pesticides.
"Just as with weeds," the group warns, "increasing pest outbreaks and crop damage will quite likely lead to greater use of chemical controls and an increased risk of environmental damage."
What to do? In Vermont, more farmers and foresters are turning to Turmel for guidance.
Bitten by the bug
Turmel, 55, was a student majoring in environmental conservation when he signed up for a course in entomology at the University of New Hampshire in his home state.
"It was a fluke," he says today. "I thought I should know something about the largest group of organisms on the face of the earth. Insects outnumber everything — animals, plants, microbes. They're just fascinating."
Figuratively bitten by the bugs, Turmel went on to earn a bachelor's and master's degree in entomology from UNH. After graduation, he worked three years in the field before he was hired as Vermont's state entomologist 30 years ago. An employee of the Vermont Agency of Agriculture, Food and Markets, he advises farmers about plant-eating pests and monitors disease-carrying insects with epidemiologists from the Department of Health.
"When I first got here, I thought I would be totally bored in the winter."
Freezing temperatures, he knows, stop bugs cold. But in recent years, the amount and array of pests have risen with the thermometer. Ask Turmel what he has noticed most and he doesn't start with an insect (a critter with a three-segment body, six legs and usually two pairs of wings, he explains) but instead an "ixodid."
That, he says, is the scientific term for a tick.
"Years ago when I would get a sample of a lone star tick, I would say, ‘Where did you go down South?' But now they're definitely here."
Same with black-legged ticks, also known as deer ticks. The size of a sesame seed, they lurk in woods, brush and grass before latching onto skin to feed on blood. Increasingly, they're also transmitting Lyme disease, a bacteria-based ailment that can lead to skin rash, fatigue, swollen joints and flu-like symptoms.
Cases of Lyme disease contracted in Vermont rose almost tenfold from seven in 1999 to 62 this past year, the state Health Department says. (The 2007 figure so far is 49.) Although experts suspect the jump is linked to global warming, they can't yet scientifically pinpoint the spread of ticks to any specific cause.
"Could be milder winters and the warming weather, could be we have good deer populations, could be a number of things." Turmel says.
The entomologist has similar questions about a spiraling number of mosquitoes. He points to the Aedes japonicus, an Asian species usually found in China, Japan, Korea and Taiwan and first reported in Vermont five years ago. It spreads not only West Nile virus — which causes fever and headaches and, in rare cases, paralysis and death — but also the viral brain infections known as Japanese encephalitis and St. Louis encephalitis.
The state has recorded 299 instances of West Nile virus since the first report in 2000, with 264 in birds (all died) compared with only four in humans (all lived) and the rest in horses and mosquitoes. The state has yet to report West Nile virus this year, although experts caution the season peaks in late summer and runs through October.
Branching out
Mosquitoes and ticks may generate the biggest media buzz, but Turmel says Vermonters should be equally concerned about three particular tree-eating pests.
The first, he says, is the emerald ash borer, an Asian beetle yet unseen in the state that has killed 25 million ash trees in Illinois, Indiana, Maryland, Michigan and Ohio since its discovery in the country five years ago.
"We used to tell people to plant ash because no insect likes it," Turmel says.
But now that Vermonters have placed thousands around homes and sidewalks, the beetle is drilling its way northeast. After Pennsylvania discovered the pest in June, neighboring New York responded by asking out-of-state campers not to import firewood for fear it may be harboring the insect.
"It's just devastating to ash," Turmel says. "It will be the Dutch elm disease of ash. With mosquitoes and ticks, you can put on repellent or take antibiotics. But if the emerald ash borer gets here, there's not much we're going to be able to do."
Scientists still are debating whether the beetle is spreading because of warmer weather. But they agree that climate change is feeding Turmel's second concern, the hemlock woolly adelgid.
The pinhead-sized pest, first found nationally in Virginia in 1951, has moved northward about 20 miles a year, reaching Massachusetts in 1989. Many Vermonters thought their hemlocks were immune, as the adelgid can't survive cold weather. But as average temperatures warm, the insect — which often cocoons in a white, cottony mass on the underside of needles — popped up in Brattleboro and Rockingham earlier this summer.
The state agencies of Agriculture and Natural Resources believe they have contained the problem, in part by cutting and burning one of the infested hemlocks. But Turmel points to ongoing studies by University of Vermont professor Bruce Parker and colleagues at the school's Entomology Research Laboratory, all of whom are investigating how adelgids are affected by cold and heat.
"Temperature is a definite factor in keeping the hemlock woolly adelgid from spreading throughout the state," Turmel says. "We think they're at the northern end of their range, but with warm winters, they could continue to migrate up. Global warming would definitely have an effect on that one."
The third pest on Turmel's list is the Asian long-horned beetle that targets maples. Scientists believe the insect arrived in North America in wood used to ship cargo from China. First reported in New York in 1996, the beetle since has cropped up in Chicago and New Jersey, although not yet in Vermont.
"They don't expand their range very quickly — it is an extremely slow mover," Turmel says. "And of the spots where people have found it, they're managing it quite well."
But in a state known for spring syrup and fall foliage, any bug hungry for maple is considered a threat.
New arrivals
Not every new insect in Vermont is arriving because of climate change. When Turmel began as state entomologist 30 years ago, he saw termites only along the southern border. Today he's receiving reports of them as far north as Williston.
"They can adapt — I think these are adapting."
But Turmel knows the weather is drawing more bugs. His office warns that armyworms currently are eating field corn, hay grass and pasture crops in every county in the state.
"We have some that are here in the natural environment, but the huge influx usually blows up on storms from down South."
Other infestations are rising with the temperature. Turmel is receiving calls this month about the soybean aphid — a native of China and Japan — in Addison and Franklin counties.
"It sucks the juices out of the plant and turns them yellow."
At the University of Vermont, Parker and colleagues continue to spark press coverage for their study of the hemlock woolly adelgid. At Middlebury College, assistant professor Jeffrey Munroe has been part of a national team that recently found that global warming was changing the types of midges that live in remote mountain lakes, with warmer-water species replacing cooler-water ones.
The Union of Concerned Scientists, an offshoot of the Massachusetts Institute of Technology, fears what else could happen in the Northeast if average temperatures and carbon dioxide levels continue to increase.
"Global warming may also spur the earlier arrival of migratory insects and allow some species to produce more generations within a single season," the union said in a report last month. "Plant-feeding pests may also eat more and cause greater crop damage as rising CO2 lowers the nutritional value of plant tissues."
Specifically, the report warns of fruit pests such as the apple maggot producing more generations as temperatures rise. It also cautions that warmer winters could increase the number of corn earworms and flea beetles that carry Stewart's wilt, a bacterial disease that can ruin crops of sweet and field corn.
"It is reasonable to assume that other insect pests will similarly increase in population and expand in range as the Northeast warms," the report continues.
That could be costly to Vermont's $3 billion a year agricultural sector: "An increasing number of outbreaks of a wider variety of insects would likely boost pesticide use by farmers in the region," the report says.
But one segment might be spared: "Organic farms, which invest more in labor-intensive pest control, tend to grow a more diverse set of crops that may be less vulnerable to increasing insect pest populations."
In the meantime, Turmel is working with farmers and gardeners as well as exterminators who need help identifying new pests.
"There are millions of insect species," the entomologist says. "I'm still working on the first 100,000."
Even so, he's not looking to see everything. Take fire ants, a pest found in 13 Southern states that can ravage crops, inflict pain on humans and kill birds and small animals.
"Our cold weather is keeping a lot of things away. But if it warms up, fire ants conceivably could move up this far and live. We're such a global economy, it wouldn't be hard for anything to show up here. There are species of insects that I hope I'm long gone before they're here."
Then again, that's what he said about the hemlock woolly adelgid before seeing it this summer.
"When it comes to insects, we're going to win a few battles, but we're never going to win the war. They can fly, they can hide, they can multiply, they can become resistant, they can adapt to any environment. Insects affect our lives in so many ways. That's why with global warming, things that aren't a problem now could be down the road."
Contact Kevin O'Connor at kevin.oconnor@rutlandherald.com.