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![[Photo]: Gypsy moth killed by virus](../images/i_4502_1.gif) Chemical sprays were long considered the best way to control
insect pests that feed upon and damage urban or forest trees.
However attitudes about how to protect our nation's forests
have changed dramatically over the past 10 years because of
the public's concern about human health and the environment.
Chemical pesticides have been replaced largely by microbial
pesticides such as Bacillus thuringiensis (Bt), while industry
is pursuing development of more specific viral pesticides
such as Gypchek, the natural gypsy moth viral product, and
other biorational pest control products such as pheromones.
Additionally, there is national interest in using classical
biological control agents such as parasites and pathogens
to manage pest populations that threaten the health of America's
trees and forests. This new emphasis is welcomed by scientists
in the Center, who have quietly but effectively been pursuing
these avenues of research for many years and represent the
only unit of its kind in the Forest Service. Unit scientists
are trained in insect pathology, microbiology, and entomology
and are experienced in conducting both laboratory bioassays
and large area replicated field experiments.
The team conducts research to better understand the effects
that natural disease agents such as viruses, bacteria, fungi,
and microsporidia have on pest insect populations and to develop
strategies for enhancing their effectiveness in mitigating
damage by pests. By knowing the details of how disease agents
are transmitted among insect populations and what environmental
factors affect their multiplication and spread, scientists
will be able to predict the onset of natural disease outbreaks
and thereby defer the use of pesticides where they will not
be needed.
Through the efforts of project scientists and support staff,
Gypchek, the gypsy moth virus product, was registered
by the EPA in 1978, and Neochek, an effective virus of the
European pine sawfly, was registered in 1983. When
exotic insects such as the Asian gypsy moth are introduced
into this country, unit scientists must quickly evaluate the
efficacy of environmentally safe microbial products such as
Gypchek and Bt before they can be used in eradication programs
such as those recently conducted in British Columbia and North
Carolina.
Efforts continue in several areas to improve Gypchek: scientists
are working with industry to improve the formulation and efficacy
of the virus and thereby accelerate its commercialization
and availability; researchers are cooperating with the Northeastern
Station's biotechnology unit at Delaware, OH, to identify
more virulent natural strains of the virus and evaluate genetically
engineered strains; and Center scientists are cooperating
with the National Center of Forest Health Management to improve
the performance of the virus and other microbial products.
Project scientists have had a major impact on the public's
acceptance and use of the bacterial pesticide Bt for management
of the gypsy moth, spruce budworm, and other
forest defoliators. Research is being conducted cooperatively
with industry to evaluate and select Bt strains and commercial
formulations that possess enhanced potency against these species.
Another factor in the acceptance of microbial pesticides such
as Bt has been the major improvement in technology for aerial
application. Center scientists, in collaboration with specialists
from universities, other Federal agencies, and the Forest
Pest Management Institute in Sault Ste. Marie, Ontario, developed
protocols for the aerial application of Bt that have dramatically
improved its performance against forest defoliators. The Ansonia
field facility is integral to the unit's research program
and is a focus for activities such as the production and evaluation
of microbial pesticides and their simulated application.
Widespread use of Bt has caused concern about its impact
on other species of Lepidoptera, that is, moths and butterflies.
Consequently, unit scientists are conducting laboratory and
field assessments of the effects of Bt on native Lepidoptera
species of oak forests.
Scientists at the Center also are examining classical biological
controls that could better manage the gypsy moth and other
forest defoliators while minimizing disruption to forest biodiversity.
Several species of microsporidia (bacterial pathogens) that
are native to the gypsy moth in Eurasia but not North America,
are being evaluated for introduction and establishment against
the gypsy moth. These pathogens, which cause chronic diseases
and are important mortality factors in Eurasian gypsy moth
populations, could significantly increase the natural control
of the gypsy moth in the United States. In addition, Center
scientists are collaborating with scientists in Central and
Eastern Europe to identify additional pathogens of defoliator
species and evaluate their potential for introduction to North
America.
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