News

The below information was provided to the garden club by our friends at Morton Arboretum. 

Q: Is it true the gypsy moth disaster is going to be as bad as we are hearing in the news?  
A: The gypsy moth is coming into IL and unfortunately we can't stop them.  It helps to know the life cycle of the gypsy moth to understand the control methods. The female gypsy moth has finished laying eggs for this season (in September). For the next 7-8 month the egg cases are visible on trees,

Q:  How did the moth get here, how does it migrate, what does it like to eat, and what can we do to stop it?

A:  GYPSY MOTH (Lymantria dispar)   The gypsy moth was introduced into this country in 1869 and has since become a serious pest in the northeastern part of the United States. In some areas, it has changed the ecology of native forests, defoliating more than 13 million acres of woodlands in one season.

In recent years, the gypsy moth invasion has slowly moved westward, with established populations in Michigan and eastern Wisconsin. Recent surveys by the Illinois Department of Agriculture and the US Forest Service conclude that the westward invasion of gypsy moths is now threatening Indiana and Illinois.

DAMAGE AND THREATENED TREES

The gypsy moth is a general feeder, devouring on more than 450 species of plants. Populations fluctuate from year to year, but when numbers are low, oaks are the preferred host. They also feed on alder, apple, aspen, beech, birch, black gum, cherry, hawthorn, hemlock, hornbeam, larch, linden, maple, pine, sassafras, and spruce. Trees showing the most resistance include ash, balsam fir, butternut, black walnut, catalpa, red cedar, dogwood, holly, locust, sycamore, and tulip tree.

When populations are high, entire forests may be defoliated, but trees are rarely killed unless they are already in a weakened condition. However, consecutive years of defoliation make them more susceptible to insect and disease problems, and eventually death. Needled evergreens are at the greatest risk when defoliated because they cannot produce a second crop of needles and usually die.

The gypsy moth goes through four stages of development-egg, larvae (caterpillar), pupa (cocoon), and moth. It has one generation a year.

Eggs are laid in a single mass containing 100 to 1,000 eggs. The masses are about 1 ½" long, and covered with velvety, buff or yellow colored hairs from the abdomen of the female moth. The gypsy moth over-winters as eggs, hatching from April to late May. The young, tiny larvae (caterpillars) spin a silken thread suspended from a leaf, where winds disperse the larvae several hundred feet, spreading the population.

Caterpillars typically feed in groups during the night, chewing small holes in leaves, and progress to feeding from the outer edge of the leaf toward the center. They rest on branches and trunks during the day, but when populations are dense, they feed continually day and night until the tree is stripped. They do not make or inhabit tents or webs.

(Gypsy moth larvae grow by moulting, five moults for males and six for females. Feeding occurs in the "instar" stage or period between each moult. As might be expected, a caterpillar’s appetite increases with each moult.)

The mature caterpillars are up to 2 ½ inches long, brown, and hairy with five pairs of blue spots and six pairs of red spots along their back. About mid-June, the full-grown caterpillars stop feeding and find a sheltered place to pupate.

In early July, the adult male moth will emerge first and begin searching for the females. The female moth emerges egg-laden and too heavy to fly. The moths do not feed in the adult stage.

The male moth is brown with black markings and has a wing span of 1 ½ inches. The female moth has a wing span of 2 to 2 ½ inches and is white or cream-colored with black, wavy markings on the wings. Male moths are attracted to a sex pheromone that the female moths release. Once the eggs are fertilized, the female moth lays her egg mass under loose bark, in woodpiles, outdoor furniture, or any other concealed location. Both moths die and the eggs do not hatch until the following spring.

The gypsy moth is attacked by a number of predators, parasites, and pathogens. The bacterial insecticide known as Bt (Bacillus thuringiensis) is sprayed to kill gypsy moth caterpillars. A natural virus has appeared on the East Coast that also kills the caterpillar. In 1990, a fungus that attacked gypsy moths in Europe was released and is showing potential for reducing large populations. With a little help from nature, over-wintering eggs die when temperatures fall below -20ºF or lower for three consecutive days.

As government agencies continue to search for natural controls to assist with spray programs, eradication efforts have been successful in eliminating isolated infestations. With nearby states containing large numbers of gypsy moths, however, the potential spread of this insect is high in areas dominated by trees (i.e., parks, cemeteries, golf courses, forest preserves) and on residential property where trees are landscaped in a more natural setting.

As an individual, if you have recently moved to Illinois or traveled in an infested area during the egg-laying period, examine your outdoor furniture, firewood, and vehicles (even the wheel wells), for pupae and egg masses. Scrape egg masses from their location with a putty knife, remove other life stages by hand, and dispose of them in a container of hot water, household bleach, ammonia, or kerosene.

Gypsy moth hairs, found attached to all life stages, can cause allergic (skin rashes) or respiratory reactions. Wear gloves, protective clothing, and a dust mask.

If you find egg masses, or have questions or concerns, you can call the Illinois Department of Agriculture at (847) 294-4343 for further information.  the USDA Forest Service also has a good website on the gypsy moth - check it out.  

University of Wisconsin at Madison
Current Studies w/Antibiotics and Bt:

By Environmental News Network

In an effort to control the destructive moths, state and local authorities
have sprayed pesticides over millions of acres of forest lands and whole towns, including residential areas and schools, drawing angry protests from residents and environmental groups.

A variety of natural agents are known to kill gypsy moths in nature,
including more than 20 insect parasitoids and predators that were introduced over the last 100 years from Asia and Europe. But so far the moths have defied every effort to control them.

Now, a team at the University of Wisconsin-Madison has found that a
combination of an antibiotic and a naturally occurring bacterium has exposed a chink in the armor of this insect that defoliates thousands of acres of forests, causing millions of dollars in damage every year.

By using the antibiotic zwittermicin A to alter microbes that inhabit the
stomachs of gypsy moth caterpillars, the researchers are discovering an improved strategy to combat moth infestations.

They have found that the antibiotic zwittermicin A enhances the lethality of Bacillus thuringiensis (Bt), a bacterium routinely used to control gypsy moths and other insect pests. The combination of these two substances looks like a solution to halting infestations of moths.

"Zwittermicin has no measurable effect on gypsy moths directly, but when added to Bt, it increases its ability to kill insects," said Nichole
Broderick, a UW-Madison graduate student studying the microbial ecology of the gypsy moth gut. "What's of interest to us is how this works."

Broderick's discovery that zwittermicin A amplifies the ability of Bt to
kill gypsy moths may provide new biological insights that will permit
science to devise even more deadly methods of controlling insect pests.

Bt, because it is a naturally occurring microbe that is nontoxic to humans and because it has proven to be the most effective substance to control gypsy moth caterpillars, is already the weapon of choice when infestations do occur.

But Ken Raffa, a UW-Madison professor of entomology, said Bt has had only limited success, and new strategies are needed to keep the gypsy moth in check. Widespread use of Bt has also raised fears that insect pests such as gypsy moths may develop resistance, and new techniques must be devised to maintain the effectiveness of such weapons as Bt.

Zwittermicin A is an antibiotic discovered in the laboratory of Jo
Handelsman, a UW-Madison professor of plant pathology and a collaborator on the insect project. Used to coat the seeds of several crop plants to keep them free of soil pathogens, the antibiotic is produced by a bacterium known as Bacillus cereus. They know how to produce it, but the researchers are still theorizing about exactly how the antibiotic works to enhance the killing power of Bt.

"Perhaps zwittermicin A kills gut bacteria that keep the insect healthy.  Perhaps it changes the internal chemistry. Right now, we just don't know,"  Broderick said.

In experiments, the antibiotic seems to suppress some of the bacteria that make their home in the stomach of the gypsy moth. By eliminating or suppressing the bacteria that normally occur in the insect's gut, zwittermicin A may create broader niches or opportunities for Bt to become established and perform its lethal work, said collaborator Robert Goodman, a UW-Madison professor of plant pathology.

What we are wondering now, Handelsman said, is "does zwittermicin A set the table for Bt to come in and do its work? We don't know, but our intent is to explore the question and gain a better understanding of the roles that these normally occurring bacteria play."

Figuring that out may help scientists find ways to manipulate them to better control the gypsy moth, universally recognized as the most devastating forest and shade tree insect pest in North America.

Copyright 2001, Environmental News Network
All Rights Reserved

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Gypsy Moth - Member Solutions?  Got any good ideas? please let us know, and we'll post your suggestions here.  We'll also contact officials at the Morton Arboretum and get their opinion for you on their effectiveness!

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