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European Gypsy Moths
April 2004
Health information
on various products/methods used for control.
Bacillus thuringiensis kurstaki (Btk),
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The most
commonly used product for gypsy moth control.
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Btk is a natural
soil organism that is produced commercially in large fermentation
batches and then sprayed on foliage.
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It was first discovered when
scientists isolated it as a natural disease agent in caterpillars.
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When
caterpillars eat sprayed leaves, they stop eating and die.
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There is
extensive human health information on Btk products used for
caterpillar control.
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Its toxicity is specific to caterpillars
and it has been shown to have very little toxicity to mammals, birds,
or fish.
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Many years of
experience with Btk products have shown that the vast majority of
persons living in sprayed areas report no symptoms.
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Some members of the
general public have complained of mild skin reactions; eyes nose,
and throat irritation; and worsening of asthma or allergies after
aerial spraying. It is not clear whether this is due to the spray or
dust and pollens disturbed during the spray operation.
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DOH recommends that
people in the sprayed area remain inside for 30 minutes after
spraying to minimize exposure.
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Btk is not considered a human pathogen.
Human infections of Btk have been looked for but not seen in several
large studies of people who lived in sprayed areas.
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Btk is used extensively in organic
agriculture and is available in many home gardening products
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The Btk product commonly used in WA is
called Foray 48B.
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When applied with ground equipment, it is diluted with
water so that 99 percent of the spray is water.
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A small amount of another agent is usually
added (0.125% of the spray) to help the Btk stick to leaves.
Health information about Btk is summarized in
numerous fact sheets including:
Top
Gypsy moth nucleopolyhedrosis virus (NVP).
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This virus was discovered to be a cause for
the natural collapse of gypsy moth populations after large outbreaks.
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Commercial version of a natural gypsy moth virus is called Gypchek.
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It was isolated and developed for use by
the US Forest Service and has been used mostly in undeveloped forest
land.
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It is specific to gypsy moth caterpillars.
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It is not commercially available but is
sometimes available to state governments.
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It is a possible skin, eye, and respiratory
irritant probably due to the ground up caterpillar parts that comprise
80 percent of the product.
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This product has been tested in animals and
appears to have little to no toxicity to mammals, birds, or fish.
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This product, however, has not been used in
populated areas and the possible impact to human health as an allergen
and irritant is uncertain.
For more information:
The
Forest Service fact sheet on NVP
or
The EPA fact sheet on NVP.
Top
Diflubenzuron
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Diflubenzuron is an insect growth
regulator in a product called Dimilin.
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It does not kill caterpillars
on contact.
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Instead, caterpillars and other vulnerable organisms
continue to grow and feed after exposure but die when they begin to
molt.
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By disrupting the normal molting process, diflubenzuron prevents
insects and other invertebrates from becoming adults and breeding.
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Animal testing shows that diflubenzuron has a very low toxicity to
mammals at the levels used in caterpillar control;
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However, at very
high levels it can affect the blood’s ability to carry oxygen.
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A minor
breakdown product of this chemical is considered a probable human
carcinogen although lifetime studies in test animals have not shown
the chemical to cause cancer.
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Dimilin may have broader ecosystem
effects than the more selective Btk and NVP products.
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Because of
Dimilin's toxicity to crab, shrimp, and other aquatic invertebrates,
it is a
restricted pesticide and the label warns of hazards to aquatic
invertebrates.
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The National Park Service does not allow the use of Dimilin in national parks because of its non-target and other
environmental impacts.
For more information, visit:
EPA fact sheet on diflubenzuron
University Cooperative – Extension Toxicology Network fact sheet
Chemical fact sheet on Dimlin from Cornell University
Top
Table of
Contents
Mass trapping with pheromone-baited traps.
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Mass trapping uses a pheromone (an insect hormone) to lure male
gypsy moths onto a sticky board in a trap.
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Mass trapping does not pose any known health risk to people.
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It is very effective for pinpointing an introduction. This helps
inspectors find and manually destroy egg masses.
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It also helps target control efforts to the smallest possible area.
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It has been used in some areas, with mixed success, in lieu of
spraying.
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One problem with trapping as an eradication tool is that only the
males are captured in the traps. Any mated female moths will
continue to reproduce.
Top
Release of adult sterile males moths.
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Large numbers of sterile male gypsy moths
can be reared and released into the infested area to mate with
females.
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Control is achieved when the sterile males
mate with females to produce infertile eggs.
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This breaks the gypsy moth life cycle and
suppresses the population.
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Release of sterile male does not pose any
risk to human health.
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This technique requires very large numbers
of sterile moths. A supply of sterile male gypsy moth is not always
available.
Information
on the curious history of sterile male research
Top
Mating disruption with the gypsy moth
pheromone disparlure.
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Gypsy moth mating disruption can be achieved
by flooding the air in the infested area with a pheromone specific to
gypsy moths.
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This prevents the male moths from locating the pheromone
trail produced by the female moth.
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If mating does not occur, the
population dies out.
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Currently the pheromone is available in white
sticky flakes that release the pheromone slowly over time.
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In
standard animal testing, disparlure was considered practically nontoxic to
mammals and birds.
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Toxicity testing has not been extensive.
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Disparlure
apparently does not break down easily in human bodies.
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Application should be done in such a
way that children and others do not touch or handle the flakes.
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The
sticky flakes can also damage the finish on cars and hard surfaces.
Top
Next page: Environment Impact Statement
Return to European Gypsy Moth homepage
For more information about the Pesticides Program, please contact
Cynthia López
or 360-236-3340.
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