Gypsy moths in the United States - AbsoluteAstronomy.com

The gypsy moth
Gypsy moth
The gypsy moth, Lymantria dispar, is a moth in the family Lymantriidae of Eurasian origin. Originally ranging from Europe to Asia, it was introduced to North America in the late 1860s and has been expanding its range ever since...

(Lymantria dispar) was introduced in 1868 into the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

by Leopold Trouvelot, a French scientist living in Medford, Massachusetts

Medford, Massachusetts

Medford is a city in Middlesex County, Massachusetts, in the United States, on the Mystic River, five miles northwest of downtown Boston. In the 2010 U.S. Census, Medford's population was 56,173...

. Because native silk-spinning caterpillars were susceptible to disease, Trouvelot imported the species in order to breed a more resistant hybrid species. Some of the moths escaped, found suitable habitat, and began breeding. The gypsy moth is now a major pest of hardwood

Hardwood

Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...

trees in the eastern United States.

The first US outbreak occurred in 1889, and by 1987, the gypsy moth had established itself throughout the northeast US, southern Quebec

Quebec

Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

, and Ontario

Ontario

Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

. The insect has now spread into Michigan

Michigan

Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....

, Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

, Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

, West Virginia

West Virginia

West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...

, and Wisconsin

Wisconsin

Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...

. Small, isolated infestations have sporadically occurred in Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, Oregon

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

, Washington, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

, and British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

, but these have been eradicated.

Since 1980, the gypsy moth has defoliated over one million acres (4,000 km²) of forest each year. In 1981, 12.9 million acres (52,200 km²) were defoliated. In wooded suburban areas, during periods of infestation, gypsy moth larvae crawl over man-made obstacles and sometimes enter homes. When feeding, they leave behind a mixture of small pieces of leaves and frass

Frass

Frass is the fine powdery material phytophagous insects pass as waste after digesting plant parts. It causes plants to excrete chitinase due to high chitin levels, it is a natural bloom stimulant, and has high nutrient levels. Frass is known to have abundant amoeba, beneficial bacteria, and fungi...

, or excrement. During outbreaks, the sound of moths chewing and dropping frass may be loud enough to sound like light to moderate rainfall. Gypsy moth populations usually remain low, but occasional increases to very high levels can result in partial or total defoliation of host trees.

The gypsy moth is now one of the most destructive insects in the eastern United States; it and other foliage-eating pests cause an estimated $868 million in annual damages in the U.S.

Host species

Gypsy moth larvae prefer oak

Oak

An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...

trees, but may feed on many species of trees and shrubs, both hardwood and conifer. In the eastern US, the gypsy moth prefers oaks, aspen

Aspen

Populus section Populus, of the Populus genus, includes the aspen trees and the white poplar Populus alba. The five typical aspens are all native to cold regions with cool summers, in the north of the Northern Hemisphere, extending south at high altitudes in the mountains. The White Poplar, by...

, apple

Apple

The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family . It is one of the most widely cultivated tree fruits, and the most widely known of the many members of genus Malus that are used by humans. Apple grow on small, deciduous trees that blossom in the spring...

, sweetgum, speckled alder, basswood, gray

Gray Birch

Betula populifolia is a deciduous tree native to North America. It ranges from southeastern Ontario east to Nova Scotia, and south to Pennsylvania and New Jersey, with disjunct populations in Indiana, Virginia, and North Carolina. It prefers poor, dry upland soils, but is also found in moist...

, paper birch

Paper Birch

Betula papyrifera is a species of birch native to northern North America.-Description:...

, poplar

Poplar

Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar , aspen, and cottonwood....

, willow

Willow

Willows, sallows, and osiers form the genus Salix, around 400 species of deciduous trees and shrubs, found primarily on moist soils in cold and temperate regions of the Northern Hemisphere...

, and hawthorns

Crataegus

Crataegus , commonly called hawthorn or thornapple, is a large genus of shrubs and trees in the rose family, Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. The name hawthorn was originally applied to the species native to northern Europe,...

, amongst other species. The gypsy moth avoids ash trees, tulip-tree, cucumber tree

Cucumber tree

Magnolia acuminata, commonly called the cucumber tree , cucumber magnolia or blue magnolia, is one of the largest magnolias, and one of the cold-hardiest. It is a large forest tree of the Eastern United States and Southern Ontario Canada...

, American sycamore

American sycamore

Platanus occidentalis, also known as American Sycamore, American plane, Occidental plane, and Buttonwood, is one of the species of Platanus native to North America...

, butternut

Butternut (tree)

Juglans cinerea, commonly known as Butternut or White Walnut, is a species of walnut native to the eastern United States and southeast Canada. Its range extends east to New Brunswick, and from southern Quebec west to Minnesota, south to northern Alabama and southwest to northern Arkansas...

, black walnut

Black Walnut

Juglans nigra, the Eastern Black walnut, is a species of flowering tree in the hickory family, Juglandaceae, that is native to eastern North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central...

, catalpa

Catalpa

Catalpa, commonly called catalpa or catawba, is a genus of flowering plants in the trumpet vine family, Bignoniaceae, native to warm temperate regions of North America, the Caribbean, and East Asia....

, flowering dogwood

Flowering Dogwood

Cornus florida is a species of dogwood native to eastern North America, from southern Maine west to southern Ontario, Illinois, and eastern Kansas, and south to northern Florida and eastern Texas, with a disjunct population in Nuevo León and Veracruz in eastern Mexico.-Classification:The flowering...

, balsam fir

Balsam Fir

The balsam fir is a North American fir, native to most of eastern and central Canada and the northeastern United States .-Growth:It is a small to medium-size evergreen tree typically tall, rarely to tall, with a narrow conic crown...

, cedar, American holly

American Holly

Ilex opaca, the American Holly, is a species of holly, native to the eastern United States, from coastal Massachusetts south to central Florida, and west to southeastern Missouri and eastern Texas.-Description:...

, and mountain laurel and rhododendron

Rhododendron

Rhododendron is a genus of over 1 000 species of woody plants in the heath family, most with showy flowers...

shrubs, but will feed on these in late instar

Instar

An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...

s when densities are extremely high. Older larvae feed on several species of softwood that younger larvae avoid, including cottonwood, hemlock

Tsuga

Tsuga is a genus of conifers in the family Pinaceae. The common name hemlock is derived from a perceived similarity in the smell of its crushed foliage to that of the unrelated plant poison hemlock....

, Atlantic white cypress, and pine

Pine

Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...

and spruce

Spruce

A spruce is a tree of the genus Picea , a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal regions of the earth. Spruces are large trees, from tall when mature, and can be distinguished by their whorled branches and conical...

species native to the east.

Effects of defoliation

The effects of defoliation depend on the species of tree, amount of foliage removed, the health of the tree, the number of consecutive defoliations, and available soil moisture. If less than half of the crown is defoliated, most hardwood species will experience only a slight reduction in radial growth. If more than half of the crown is defoliated, most hardwoods will produce a second flush of foliage by midsummer. Healthy trees can usually withstand one or two consecutive major defoliations. Trees weakened by previous defoliation or subjected to other stresses like droughts are frequently killed after a single half-defoliation.

Trees use their energy reserves during re-foliation and may become weakened and exhibit symptoms such as the death of twigs and branches in the upper crown and sprouting of old buds on the trunk and larger branches. Weakened trees experience radial growth reduction of approximately 30 to 50 percent. Weakened trees are vulnerable to attack by disease organisms and other insects, or example, the Armillaria fungus may attack the roots, and the two-lined chestnut borer may attack the trunk and branches. Affected trees will eventually die two or three years after they are attacked by these pests.

Although not preferred by the larvae, pines and hemlocks are subject to heavy defoliation during gypsy moth outbreaks and are more likely to be killed than hardwoods. A complete defoliation can kill approximately half of pine species and 90 percent of mature hemlocks because conifers do not store energy in their roots; an exception is larch

Larch

Larches are conifers in the genus Larix, in the family Pinaceae. Growing from 15 to 50m tall, they are native to much of the cooler temperate northern hemisphere, on lowlands in the north and high on mountains further south...

Factors that affect gypsy moth populations

Natural predators play an important role during periods of low population. Predators include wasps, flies

Fließ

Fließ is a municipality in the Landeck district and is located5 km south of Landeck on the upper course of the Inn River. It has 9 hamlets and was already populated at the roman age; the village itself was founded around the 6th century. After a conflagration in 1933 Fließ was restored more...

, ground beetles, ants, many species of spider

Spider

Spiders are air-breathing arthropods that have eight legs, and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other groups of organisms...

, several species of birds such as chickadees, blue jay

Blue Jay

The Blue Jay is a passerine bird in the family Corvidae, native to North America. It is resident through most of eastern and central United States and southern Canada, although western populations may be migratory. It breeds in both deciduous and coniferous forests, and is common near and in...

s, nuthatches, towhees, and robin

Robin

Robin may refer to:* Robin , a common given name and a surname.It may also refer to:- Birds:Most birds called "robins" belong to the superfamily Muscicapoidea:* European Robin...

s and approximately 15 species of common woodland mammals, such as the white-footed mouse

White-footed mouse

White-footed Mouse is a rodent native to North America. It ranges from Ontario, Quebec, Labrador and the Maritime Provinces to the southwest USA and Mexico. It is also known as the Woodmouse, particularly in Texas.Adults are in length, not counting the tail, which can add another . A young adult...

, shrews, chipmunks, squirrels, and raccoons. Small mammals are the largest predators in low density gypsy moth populations and are apparently critical in preventing outbreaks. Calosoma
Calosoma
Calosoma is a genus of large ground beetles that occur primarily throughout the Northern Hemisphere, and are referred to as caterpillar hunters or searchers. Many of the 167 species are largely or entirely black, but some have bright metallic coloration...

(ground beetles of European origin), cuckoos, and flocking birds such as starling

Starling

Starlings are small to medium-sized passerine birds in the family Sturnidae. The name "Sturnidae" comes from the Latin word for starling, sturnus. Many Asian species, particularly the larger ones, are called mynas, and many African species are known as glossy starlings because of their iridescent...

, grackle

Grackle

Grackle can refer to any of eleven black passerine birds native to North and South America. All are members of the Icterid family but belong to multiple genera.* Genus Quiscalus** Boat-tailed Grackle, Quiscalus major...

s, and red-winged blackbird

Red-winged Blackbird

The Red-winged Blackbird is a passerine bird of the family Icteridae found in most of North and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and...

s, are attracted to infested areas in high gypsy moth population years.

Diseases caused by bacteria, fungi, or viruses contribute to the decline of gypsy moth populations, especially during periods when populations are dense and are stressed by a lack of preferred foliage. Wilt disease caused by a particular nucleopolyhedrovirus (LdNPV) that is specific to the gypsy moth is its most devastating natural disease, causing a dramatic collapse of outbreak populations by killing both the larvae and pupae. Larvae infected with wilt disease are shiny and hang limply in an inverted "V" position. Infection with NPV is the most common source of mortality in high density populations and NPV epizootics usually cause the collapse of populations.

Since the 1980s, the fungus Entomophaga maimaiga has also had a large impact on gypsy moth populations in North America.

Weather conditions can affect the survival and development of gypsy moth life stages, regardless of population density. Temperatures of −20°F (−29°C.) lasting from 48 to 72 hours can kill exposed eggs; alternate periods of freezing and thaw in late winter and early spring may prevent eggs from hatching; and cold, rainy weather inhibits dispersal and feeding and slows the growth of newly-hatched larvae.

Natural gypsy moth control

Gypsy moth larvae have several predators which can help decrease their population. Lack of predation is one reason they can change from being a normal part of the ecosystem to an actual threat to trees. Among their predators are:

deer mice
Peromyscus
The genus Peromyscus contains the animal species commonly referred to as deer mice. This is a genus of New World mouse only distantly related to the common house mouse and laboratory mouse, Mus musculus...

– are considered the most important predator of low-density gypsy moth populations and their abundance may be critical in determining whether populations go into an outbreak mode. Their abundance is strongly affected by the amount of mast (e.g., acorns) in the previous year.
tachinid flies – parasitize gypsy moth populations. While they may become quite abundant during a gypsy moth outbreak, they apparently have little effect on the population dynamics.
braconid wasps – also parasitize gypsy moths but play a minor role in their dynamics.

There is no evidence that releasing or enhancing gypsy moth predators or parasites can reduce gypsy moth populations. Manual removal of gypsy moths may be a viable method for reducing damage on small, open-grown trees and shrubs.

Management

Several methods of managing the gypsy moth are used; these include the monitoring of populations, maintaining the health and vigor of trees, concentrating and killing caterpillars, removing egg masses and treating with insecticides to kill larvae and protecting tree foliage. To concentrate the caterpillars, a strip of dark cloth about 12 inches wide – for example, burlap or old blue jeans, is tied around the tree at eye height. A string is tied around the cloth at its midpoint to create a fold of cloth around the tree. At mid-morning or later, the bands of cloth are checked for caterpillars, which are killed.

The egg masses – 3/4 inch long ovals that look like tan felt or velour – will be present from late July until May when they hatch. The egg masses are scraped off the tree and burnt or dumped in the trash. If they remain on the ground, the eggs will still be viable. Tactics suggested for homeowners may be too costly and labor intensive for managers to use in forest stands.

The gypsy moth currently occupies less than a third of its potential range in North America and considerable resources are directed at minimizing its expansion into these areas. Every year, over 100,000 pheromone traps are placed in uninfested areas in order to detect new infestations that occasionally arise when people inadvertently transport life stages into uninfested areas (for example, egg masses on recreational vehicles). When captures are positive for several consecutive years, this indicates that a population is establishing and these are eradicated, usually via the application of the bacterial pesticide Bacillus thuringiensis
Bacillus thuringiensis
Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. B...

('Bt').

In 2008 California agriculture officials quarantined a rural 5 square miles (12.9 km²) section of Ventura County near Ojai to prevent the spread of a newly-found gypsy moth colony.

Pesticides

The decision to use pesticides is influenced by a number of factors, such as the quantity of visible egg masses, The percentage of preferred hosts, presence of dead or dying branches, and proximity to heavily infested woodlands. When numbers of gypsy moth larvae are high, pesticides may be the most effective method of killing larvae.

Available pesticides fall into two groups: microbial or biological and chemical (table 1). Microbial and biological pesticides contain living organisms that must be consumed by the pest. These include bacteria, viruses, and other organisms; biologicals include man-made synthetics of naturally occurring organisms. These pesticides are applied before the larvae reach the third stage of development. As they mature, larvae develop resistance to microbial pesticides. Low dose pheromone systems are used in Jersey

Jersey

Jersey, officially the Bailiwick of Jersey is a British Crown Dependency off the coast of Normandy, France. As well as the island of Jersey itself, the bailiwick includes two groups of small islands that are no longer permanently inhabited, the Minquiers and Écréhous, and the Pierres de Lecq and...

, Channel Islands

Channel Islands

The Channel Islands are an archipelago of British Crown Dependencies in the English Channel, off the French coast of Normandy. They include two separate bailiwicks: the Bailiwick of Guernsey and the Bailiwick of Jersey...

, to flood areas with synthetic pheromone and effectively 'blind' males so they are unable to locate females.

Nucleopolyhedrovirus (NPV), a naturally occurring organism, has been developed as a microbial pesticide. It is presently registered under the name Gypchek and is available for use in USDA

United States Department of Agriculture

The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...

Forest Service sponsored suppression programs. NPV and Gypcheck are specific to the gypsy moth.

Bacillus thuringiensis (Bt) is microbial and biological. It is the most commonly used pesticide and is used against other pests, including the western spruce budworm and other Choristoneura and the tent caterpillar

Tent caterpillar

Tent caterpillars are moderately sized species in the genus Malacosoma and in the moth family Lasiocampidae. Species occur in North America, Mexico, and Eurasia. Twenty-six species have been described, six of which occur in North America. Some species are considered to have subspecies as well. ...

. When Bt is taken internally, the insect is paralyzed, stops feeding, and dies of starvation or disease.

Chemical pesticides are contact poisons and stomach poisons. The timing of application is less critical than that of microbials and biologicals. Chemical pesticides can affect non-target organisms and may be hazardous to human health.

Table 1 – Microbial and chemical pesticides used to control gypsy moth
Active ingredient	Representative trade names	Comments
Bacillus thuringiensis Bacillus thuringiensis Bacillus thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a biological pesticide; alternatively, the Cry toxin may be extracted and used as a pesticide. B...	Foray	Registered for aerial and ground application. Available under various trade names. Toxic to other moth and butterfly larvae. Can be used safely near water.
Acephate Acephate Acephate is an organophosphate foliar insecticide of moderate persistence with residual systemic activity of about 10-15 days at the recommended use rate. It is used primarily for control of aphids, including resistant species, in vegetables and in horticulture...	Orthene	Registered for aerial and ground application. Available under various trade names. Toxic to bees and some gypsy moth parasites. Often used from the ground to treat individual trees.
Carbaryl Carbaryl Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958...	Sevin Carbaryl Carbaryl is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid commonly sold under the brand name Sevin, a trademark of the Bayer Company. Union Carbide discovered carbaryl and introduced it commercially in 1958...	Registered for aerial and ground application. Available under various trade names. Toxic to bees and gypsy moth parasites. Once the most widely used chemical in control programs.
Diflubenzuron Diflubenzuron Diflubenzuron is an insecticide of the benzamide class. It is used in forest management and on field crops to selectively control insect pests, particularly forest tent caterpillar moths, boll weevils, gypsy moths, and other types of moths. The mechanism of action of diflubenzuron involves...	Dimilin	A restricted-use pesticide that can be applied only by certified applicators.

The most commonly used chemical pesticides currently registered by the US Environmental Protection Agency (EPA) for use against the gypsy moth contain carbaryl, diflubenzuron, or acephate. Malathion

Malathion

Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity, however one recent study has shown that children with higher levels of organophosphate pesticide metabolites in their urine are more likely...

, methoxychlor, phosmet, trichlorfon, and synthetic pyrethroids (permethrin

Permethrin

Permethrin is a common synthetic chemical, widely used as an insecticide, acaricide, and insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to...

) are registered by EPA but are used infrequently.

Several studies by Peter G. Kevan et al of the University of Guelph

University of Guelph

The University of Guelph, also known as U of G, is a comprehensive public research university in Guelph, Ontario, Canada. It was established in 1964 after the amalgamation of Ontario Agricultural College, the Macdonald Institute, and the Ontario Veterinary College...

conducted between 1975 and 1995 showed serious reduction in pollination of blueberry

Blueberry

Blueberries are flowering plants of the genus Vaccinium with dark-blue berries and are perennial...

and other crops due to aerial applications of insecticide

Insecticide

An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...

s that killed non-target wild bee

Bee

Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...

s. Diflubenzuron is an insect growth regulator

Insect growth regulator

An insect growth regulator is a substance that inhibits the life cycle of an insect. IGRs are typically used to control populations of harmful pests, such as cockroaches or fleas.- Advantages :...

and interferes with the normal molting process of the larvae but does not affect adult insects. Aquatic crustaceans and immature, non-target insects that undergo stages of molting are often sensitive to this pesticide.

External links

asiangypsymoth.org
Gypsy moth in North America at the USDA Forest Service
Gypsy Moth Slow the Spread Foundation, Inc.
"Gypsy moth leads to Ventura County area quarantine", Ventura County Star 30 October 2008

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.