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Taking AIPM at the gypsy moth.

As the skirmish lines move south and west, researchers are rolling out new weapons in the fight to suppress this voracious insect, which is changing the makeup of eastern forests.

One spring morning exactly a century ago, residents of Medford, Massachusetts, began to witness the first gypsy-moth population explosion in the United States. It wasn't a pretty sight - or sound. By night, the clatter of caterpillars eating leaves sounded like the snipping of innumerable scissors. By day, people slid on caterpillar masses that clotted the sidewalks, and ran through a rain of caterpillar droppings. By early summer, when the moths stopped eating and began to pupate, most fruit and shade trees in a 360-square-mile are had been defoliated.

This spring the gypsy will "celebrate" its first full century of defoliating North America by continuing its westward spread. In the 1980s moths were found for the first time in Idaho, Wyoming, Oregon, South Dakota, Nebraska, even Alaska; potentially troublesome infestations afflict Colorado and Utah. Back in the East, where the moth's munchings have changed the composition of the forests, a century's worth of experience and frustration are being forged into a new approach to dealing with the pest's spread.

Forest where the gypsy first exploded in 1889 still unfurl into green every summer. But oaks, the moths' preferred food, are today significantly scarcer throughout the woodlands where the gypsy has become naturalized. Now gypsy moths are invading the Appalachian uplands, where white, red, black, scarlet, and chestnut oaks became kings of the forest when the chestnuts disappeared. Although defoliation by gypsy moths throughout the country has generally declined since the all-time high of 13 million acres in 1981, there is widespread fear of unprecedented spree of moths through the delectable Appalachia oaks.

For the past century, strategies against the gypsy moth have involved minimizing its nuisance impacts - in forested residential areas, for example, and in recreational sites such as campgrounds. Gypsy moths in general forest areas have rarely been considered a critical issue. But as the moth begins to threaten the hardwood lumber industry, Forest Service scientists are shifting their attention to manipulating moth population to save oak-dominance as the characteristics feature of Appalachian forest.

The Appalachian Integrated Pest Management Gypsy Moth Demonstration Project (known as AIPM) is breaking new ground in attempts to suppress the insect. Historically, efforts have been directed toward mitigating damage already under way. AIPM aims to do that, but also to hold moth populations below the 500-1,000 egg masses per acre that signal the imminence of heavy defoliation. And another AIPM goal is to postpone the invasion of new territory as long as possible - at least for the next three years of guaranteed federal funding.

Although the Forest Service is leading AIPM efforts, state and local cooperation are integral to the project's success, because of the emphasis on exact mapping of the advancing moth front.

"Monitoring is the key to AIPM." said Allan Bullard, program manager, from his office in Morgantown, West Virginia. Within the AIPM area of 13 million acres along the mountainous Virginia-West Virginia border, Bullard established a grid of survey points every two or three kilometers (1.2 to 1.8 miles) for the placement of pheromone (sex attractant) traps and evaluation of forest stands. Whenever the traps take in more than 200 male moths, egg masses will be counted.

"The project area is defined in the north by areas where moth populations are already causing defoliation, and limited in the south to where the monitoring grid indicates that no contiguous populations are established," Bullard explained. "So we're watching moth levels ranging from damaging to none whatsoever." States and countries have assigned or hired people to help with the monitoring effort.

By finding low and outlying populations of moths, AIPM personnel can apply any of a number of biological, chemical, and mechanical controls to keep the critters from exploding into giant munching machines. Eradication may be attempted on populations that have flung themselves beyond the "front". Though eradication efforts have consistently failed in the generally infested. Northeast, they have been surprisingly successful when directed at small population outside the quarantine borders maintained by the US Department of Agriculture since 1912. Tom Flanigan, operations officer for USDA Plant Protection and Quarantine, counted up 170 isolated outbreaks across the nation over the last 10 years. Only half a dozen of those still exists.

Lane Country, Oregon, is the latest example of an isolated infestation that was eradicated. In 1984, some 19,000 moths were collected in first traps set out, indicating that a major population buildup had gone undetected in the oaks and Douglas-firs of the Willamette Valley. Through intensive spraying with the biological insecticide Bt - three times at seven to 10-day. intervals - moths have been reduced to the point that only one was trapped in Lance Country 1988.

In explaining why localized eradication efforts such as Oregon's have worked, Flanigan hit squarely on the issue underlying the credibility of AIPM. "Eradication is feasible for small areas," he said, but becomes cost-prohibitive in large regions. And the public has been willing to support programs that involve only one or two years of treatment."

To keep moths down, however, AIPM-pioneered methods will have to be applied indefinitely. Fundamental to AIPM is the unwritten but candidly acknowledged assumption that states and localities will pick up where AIPM stops in 1992. Since gypsy months still reach damaging levels in France, where they are native, it is unlikely at least in the foreseeable future that any natural mechanisms will permanently suppress them.

"By concentrating on population reduction rather than foliage protection," explained Max McFadden, director of gypsy moth research and development for the Forest Service, "we can knock outbreak populations down to where natural regulators could take over."

A wide variety of birds and small mammals, especially mice and shrews, prey effectively on all life stages of the gypsy when moth populations are low to moderate. But sooner or later, for unknown reasons, the populations explode. McFadden figures that suppression treatments might have to be applied every two to six years, depending on effectiveness of the first treatment and the nature of the site.

McFadden's unit in Broomall, Pennsylvania, is looking closely at every variable - from parasites and predators to silvicultural prescriptions - that might influence population regulation.

"The first outbreaks are the works, because by reducing the oaks, gypsy moths start depleting their own food sources," McFadden said. His most significant recent research focuses on increasing the proven effectiveness of Gypchek, the gypsy-moth virus, and on aerial techniques for applying Gypchek and Bt. "Our research goal," McFadden said, " is to support AIPM."

Most of the lands within AIPM are National Forests, with National Parks and state, municipal, and private ownerships interspersed. The project is structured so that choice of treatment techniques on any given unit of land is determined through a process involving land manager, any private landowners involved, and the general public through written comments and participation at public meetings.

The Forest Service's draft Environmental Impact Statement for AIPM outlines six alternative combinations of gypsy-moth suppression measures. These measures range from no action to the application of a variety of mechanical and biological gypsy-moth-specific tactics (sex attractants, inherited sterility, mass trapping, virus disease, parasites, and predators). Also included is the use of Bacillus thuringiensis (Bt), a naturally occurring bacteria that can affect many species of moth and butterfly larvae of the order Lepidoptera, plus the use of the chemical Dimilin (diflubenzuron), which kills a wide variety of non-target insects and crustaceans.

The alternative preferred by the Forest Service includes use of all those techniques in general forest areas. It also includes use of all gypsy-moth-specific techniques, plus Bt, in Wilderness areas.

Treatment of Wilderness areas for moths is a precedent-setting issue. The Wilderness Act of 1964 does not address the invasion of forest by exotic insects pests. The Forest Service therefore, has assessed the likely impacts of various forms of treatment as well as non-treatment on Wilderness values.

"I've been favorably impressed by the range of alternatives and the way the Forest Service is presenting them," said Barry Flamm of the Wilderness Society. Concerning the use of Bt in Wildernesses, Flamm said," A decade ago we had to fight to have Bt even considered along with chemical insecticides for use in general forest areas. But I'm concerned about the justification for Bt and other treatments in Wilderness."

Many conservationists believe that Wilderness should be left alone to show how mutual processes work without distortion by man. The National Park Service, believing that the moth will establish itself regardless of human intervention, has adopted a policy in Shenandoah National Park of leaving gypsy moths untreated in Wilderness and Natural Areas. But Jeff Witcosky, AIPM Virginia field coordinator, points out that" making exceptions to keeping populations low will defeat the purpose of AIMP."

Foresters fear the inevitable loss of valuable oak timber if the gypsy goes untreated, particularly on highly productive West Virginia sites. Changes in wildlife values, however, are not so clear.

"Reducing the oaks in forest isn't necessarily bad for all wildlife," says ecologist Bob Whitmore of West Virginia University. "Some game managers think the gypsy moth is good for wildlife because the short-term effect is to open the canopy and stimulate blackberries and other soft mast."

No data exists on the long-term consequences of reduced amounts of acorns and hickory nuts. Concern for black bears, which rely on such hard mast to fatten up for winter denning, prompted Shenandoah National Park to inaugurate a bear radio-tracking study last year. The local chapter of Trout Unlimited worries about sunlight falling directly on streams normally kept just cool enough for native trout by leaf shade. Bob Glasgow, wildlife biologist for the George Washington National Forest, wonders how the rare Cow Know salamander will cope with the warmer, drier soil of newly denuded areas.

Whitmore has been studying moth impacts on nongame species, particularly songbirds. "Deep-forest species that require extensive tracts of undisturbed mature forest bail out and rare replaced by edge species," he said. It's much too early in Whitmore's research to know whether deep-forest species can come back when moth populations stabilize.

In addition to habitat changes caused by defoliation and oak decline, Whitmore is concerned about effects of insecticides used against the moths, particularly Dimilin, "We've studied Dimilin for six years now, and there's absolutely no acute toxicity to vertebrate wildlife species," he said. "But it is quite effective at killing insects that moult their skeletons. My question involves birds whose summer diet is 90 percent Lepidopteran larvae: when you kill an animal's food, is that the same as killing the animal?"

Whitmore has found that birds in sprayed areas change their diets, enlarge their territories, and spend more time foraging. But he has not yet] quantified the population effect of such behavior.

Dimilin in streams is also a concern. "There's no doubt it kills aquatic insects," Whitmore said." The issue is how fast the stream can recover. If Dimilin causes a population crash that takes a season or more to rebuild, that's an issue."

Reading from the Gypsy Moth Newsletter published by the Forest Service, Whitmore countered up three-quarters of a million acres that had been sprayed with Dimilin or Bt in 1987 in the East. "Toxicity or not," he said, "you've got to wonder what the loss of food species will mean when that much acreage is affected."

The irony of gypsy moths is that they will inevitably change forest - either indirectly through the effects of suppression methods, or directly if no treatments are applied. The AIPM project has been allocated almost $11 million for its first three years. Budget projections for the last years, 1990-91, are not yet available. The question looming ahead is whether we are willing to keep paying year after year, decade after decade, for one set of changes over

another.
 Acres of
 Defoliation
State 1986 1987
Connecticut 237,200 65,400
Delaware 3,100 2,500
Maine 11,600 600
Maryland 58,200 76,800
Massachusetts 343,100 28,700
Michigan 61,400 39,400
New Hampshire 0 300
New Jersey 280,300 95,100
New York 175,400 55,200
Pennsylvania 987,800 880,300
Rhode Island 219,200 5,100
Vermont 0 0
Virginia 27,330 67,700
Washington DC 0 12
West Virginia 8,300 12,600
 Total 2,412,900 1,329,712


Chris Bolgiano, a frequent contributor, lives on a tree farm within the AIPM area. Ninety percent of her trees are oaks.
COPYRIGHT 1989 American Forests
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1989, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:Appalachian Integrated Pest Management Gypsy Moth Demonstration Project
Author:Bolgiano, Chris
Publication:American Forests
Date:Mar 1, 1989
Words:2089
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