Hemlocks - Connecticut Beatles Working
From Knoxville News Sentinal
Tiny beetles ridding Conn. hemlocks of adelgids
Smokies national park is 'hoping to see same effect,' forester says
By MORGAN SIMMONS, simmonsm@knews.com
September 16, 2006
A tiny beetle that feeds on the hemlock woolly adelgid appears to be doing the job in Connecticut, a state that has been working to save its hemlock forests since 1986.
Carol Cheah, a research entomologist with the Connecticut Agricultural Experiment Station, said heavily infested hemlock sites treated with predator beetles now are recovering.
"Last year, we did an assessment comparing places where we released beetles to places where we didn't," Cheah said. "These areas all had similar levels of infestation. I was surprised the release sites appeared to be doing so much better."
In 1995, Connecticut became the first state to obtain permission from the federal government to import predator beetles from Japan and release them to control the hemlock woolly adelgid, a nonnative, aphidlike insect that feeds on hemlock trees.
Since the late 1990s, the Connecticut Agricultural Experiment Station has released approximately 200,000 predator beetles at 16 sites across the state.
By comparison, the Great Smoky Mountains National Park has released approximately 174,000 predator beetles at more than 100 sites since the hemlock woolly adelgid was discovered in the park in 2002.
Like Connecticut, the park releases predator beetles to combat the adelgid infestation on a forestwide scale. To treat individual trees near campground or roads, the park uses soap spray or insecticide.
Cheah said Connecticut's hemlock woolly adelgid population has been reduced to the point where she now has difficulty finding enough of the insect pests locally to feed the predator beetles she rears in a lab.
Connecticut's weather has been both a help and hindrance in recent years.
On the plus side, the predator beetles' job likely was made easier by a cold snap in 2003 and 2004 that reduced the adelgid population. On the other hand, a drought in the late 1990s and 2002 placed additional stress on hemlocks already weakened by the adelgid infestation.
"Our infestation peaked in the late 1980s and early 1990s," Cheah said. "We saw some decline in tree health after the beetles were released, but now we're seeing widespread recovery, even on sites where the hemlock trees appeared to be on the brink of death."
Kristine Johnson, supervisory forester for the Smokies, called the news from Connecticut "the first positive report on a landscape level" the park has received.
"We're hoping to see the same effect here," Johnson said.
While winters in the Smokies generally are not cold enough to kill the adelgids, the park does have excellent growing conditions. This summer, for example, the park received much more rain than Knoxville and the rest of the Tennessee Valley.
The University of Tennessee now raises two species of predator beetle for release in the Smokies and surrounding national forests in North Carolina and Tennessee. One species of beetle is more active in the spring and summer, while the other is active in the fall and winter, providing year-round predator activity.
Johnson said the park is monitoring beetle release sites for canopy health and that it's too early to gauge the beetle's effectiveness as a biological control.
This spring marked the first time the park's hemlocks showed obvious signs of needle loss and distress as a result of the adelgid infestation. To park visitors, the impacts were especially evident in the Chimneys area along U.S. Highway 441.
Park officials hope the combination of predator beetles and selective chemical treatments will save at least a healthy remnant of the park's hemlock ecosystem.
What they don't want is a situation like Virginia's Shenandoah National Park, where the hemlock woolly adelgid has virtually eradicated the entire hemlock forest.
Morgan Simmons may be reached at 865-342-6321.