(Beyond Pesticides, August 29, 2007) Entomologists have recently begun studying whether increasing temperatures will attract more insects to the New England region, as scientists have begun reporting the appearance of new and more numerous unwanted insects. The colder winters of the New England region have historically limited insect populations, but in recent years as temperatures have warmed, the amount and variety of pests have increased. According to the government’s U.S. Global Change Research Program, in its New England Regional Assessment of the Potential Consequences of Climate Variability and Change, “A warming New England region (especially warming winters) will support the introduction and expansion of exotic pests into the region.”
Although scientists cannot definitively say that there is a relationship between increasing temperatures in the region and an increase in the number of insects, Vermont entomologist Jon Turmel, points out that ticks carrying lyme disease, as well as mosquitoes with West Nile virus (WNv) and encephalitis have been reported in the state. The Aedes japonicus, an Asian mosquito species, was first reported in Vermont five years ago. These mosquitoes can spread Japanese and St. Louis encephalitis, which are viral brain infections that can result in death, along with WNv.
Reported cases of lyme disease contracted in Vermont rose almost tenfold from seven in 1999 to 62 this past year; the 2007 figure so far is 49, the state Health Department says. However, experts cannot scientifically identify the cause of the spread of ticks to any one specific cause. “Could be milder winters and the warming weather, could be we have good deer populations, could be a number of things,” Mr. Turmel said.
Other problem insects, like tree-eating insects, should be of equal concern. The emerald ash borer, an Asian beetle discovered five years ago in the US, has decimated millions of ash trees and is making its way toward to Northeast. As for the hemlock woolly adelgid, many felt it could not survive the northeastern cold, however, it has made its appearance in the state this past summer.
“Temperature is a definite factor in keeping the hemlock woolly adelgid from spreading throughout the state,” Mr. Turmel said. “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.” Researchers have found that rising temperatures were affecting species distribution where warm-water species of midges were replacing colder-water ones. Such scenarios have caused the Union of Concerned Scientists to be troubled over the effects of increasing temperatures.
“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 recent report. “Plant-feeding pests may also eat more and cause greater crop damage as rising CO2 lowers the nutritional value of plant tissues.” The report adds, “It is reasonable to assume that other insect pests will similarly increase in population and expand in range as the Northeast warms.”
An increase in pest populations would affect not only native species but also the $3 billion dollar agricultural sector. Farmers may be prompted to increase pesticide use to control exotic pests. According to the Union of Concerned Scientists, “Just as with weeds, increasing pest outbreaks and crop damage will quite likely lead to greater use of chemical controls and an increased risk of environmental damage.”
Mr. Turmel remains concerned. “When it comes to insectsâ€¦[t]hey can fly, they can hide, they can multiply, they can become resistant, they can adapt to any environment. That’s why with global warming, things that aren’t a problem now could be down the road,” he said.
See Beyond Pesticides recent stories on pesticides and climate change: Climate Change Tied to Crop Losses, Increases in Pest Populations, Scientist Examines Global Warmingâ€™s Impact on Pollen Allergies, Climate Change and Pesticides Hot Issue for Fish.
Source: The Barre Montpelier Times Argus