Programs Directed Against Insect Pests
Alfalfa Weevil feeds on foliage, a heavy infestation can significantly reduce crop yield. Several kinds of wasps native to Europe have been established in New Jersey. They control the pest by attacking and killing both larval and adult weevils. Before the introduction of the parasites, most of the 25,000 acres of alfalfa produced in New Jersey each year required chemical treatment to control this pest. Since the establishment of the beneficial insects, chemical spraying for this pest has been reduced by over 95%.
- Status of biological control agents: 4 species released, 4 established. This is a classical biological control program in which four parasites have been released and all four have established.
Aphids feed on the sap of many ornamental plants, fruits, vegetable, and field crops. Weakened plants produce lower yields and may even die. In addition, aphids can transmit a variety of diseases to plants. Since 1989 several kinds of European ladybugs and a hover fly have been reared in the Phillip Alampi Beneficial Insect Rearing Laboratory and released throughout the state to reduce the aphid population.
- Status of biological control agents: 4 species released, 2 established. This is a classical biological control program in which three predators and one parasite have been released and two have established.
Gypsy Moth is the most damaging insect pest of forest, fruit and shade trees in New Jersey and the eastern United States; oak-forested areas are particularly at risk of losses of trees due to repeat feeding damage by gypsy moth caterpillars (larvae).
This is a classical program where the beneficials hold the population of gypsy moth significantly below past levels. Gypsy moth populations are cyclical, during the 1950’s and 1960’s the cycle peaked about every four to five years, since the 1970’s the cycle is about seven to eight years. In the late 1970’s to early 1980’s the gypsy moth population reached its zenith with 798,790 acres defoliated. During that period the Department reared massive amounts of parasites to control the gypsy moth in New Jersey. The highest levels of defoliation since then was in the early 1990’s at 411,975, and again in 2007 at 325,000 acres or about half the amount prior to the parasite release program. A fungus disease has also exerted tremendous effects on the gypsy moth population, but it is totally weather dependent.
As mentioned previously, in 2007, while over 320,000 acres of the 2.2 million forested acres in New Jersey experienced heavy or severe defoliation by gypsy moth, assays showed that approximately 50% of the individual eggs in the egg masses were parasitized and did not hatch, preventing an even greater devastation. There is less gypsy moth pressure due to the presence of the beneficials than there would be otherwise. This results in less stress for the homeowner, less tree mortality, and an increase in the quality of life for which one cannot assign a dollar value.
- Status of biological control agents: 39 species released, 10 established.
The Hemlock Woolly Adelgid is a small sap-sucking insect, originally from Asia, which is killing hemlock trees throughout the state. In cooperation with the USDA Forest Service and Connecticut Agricultural Experiment Station, the Phillip Alampi Beneficial Insect Rearing Laboratory mass reared a predatory beetle that feeds on Hemlock woolly adelgid, Sassajiscymnus (=Pseudoscymnus) tsugae. Since 1998, more than 272,000 beetles have been produced and released in 69 sites in New Jersey, and an additional 387,500 have been distributed among the eight northeastern states. In addition, starter colonies and the technology necessary to raise the beetles has been made available to private companies, universities, and other government agencies.
In 2005, the Laboratory switched production to rear another a predator of hemlock woolly adelgid, a newly described beetle from China, Scymnus sinuanodulus. New Jersey has become the primary producer of S. sinuanodulus and has provided 18,000 of the predators for release in the state and to four other states (West Virginia, Maryland, North Carolina, and Pennsylvania). New Jersey has also shared its technology for raising the beetles with workers at the University of Georgia and at the North Carolina Department of Agriculture.
In 2006 the Laboratory also began rearing of Laricobius nigrinus, a native adelgid predator found in the western US. L. nigrinus produced in the lab were released in New Jersey’s hemlock stands. Some hemlock stands are slowly rebounding, indicating the beetles released in the past might be impacting the adelgid problem.
- Status of biological control agents: 3 species released, 3 established.
Mexican bean beetles feed on the foliage of soybeans, snap beans and lima beans, reducing the crop yield. This is an inundative release program where Pediobius foveolatus (a wasp) is used to control the Mexican bean beetle in soybeans. These very small wasps, known as parasitoids, attack and kill Mexican bean beetle larvae. The parasitoids cannot over-winter in New Jersey, and must be reared in the Laboratory each winter and released into soybean fields during the summer. The wasp has been released in New Jersey soybean fields annually since 1980. A total of 174,000 parasites were released into 55 nurse plots in 2006. No New Jersey soybean growers have had to spray to control Mexican bean beetle since 1985.
- Status of biological control agents: 1 species released yearly, now being reared in the laboratory; none established.
Scale insects suck the sap from stems and leaves. Euonymus scale and alatus scale feed on ornamental euonymus bushes, causing them to drop their leaves. This is a particularly serious problem in landscapes. Cybocephalus sp. nr. nipponicus, a tiny scale-eating beetle from China, has successfully been laboratory reared and released in the landscape on plants infested with Euonymus scale and Euonymus alatus scale.
Cybocephalus will feed on a number of species of hard-shell scales, including the Elongate Hemlock Scale, commonly found in hemlock trees feeding on needles and causing a decline in the trees. Beetles were observed feeding on Elongate Hemlock Scale in Mercer and Monmouth Counties through natural dispersal from Euonymus Scale release sites.
The Department of Agriculture has established a number of release sites in hemlock stands in Northern New Jersey and has cooperated with University researchers, as well as out of state agencies in the Northeast to study its effects on Elongate Hemlock Scale.
- Status of biological control agents: 6 species released, 3 established.
Programs Directed Against Weed Pests
Canada Thistle is a persistent weed that spreads by both seed and an extensive underground root system. Unless it’s controlled, it can crowd out the crop that was planted in the field. Thistle can be controlled by herbicides, but a small fly was being evaluated for its usefulness in controlling the weed as an alternative to chemicals. The fly lays its eggs only in the stem of Canada thistle plants. When hatched, the larvae feed on the stem, causing the plant to produce a gall, or swelling, on the stem of the plant. The gall weakens the weed by reducing the flow of nutrients, thereby limiting seed production and food storage in late summer. This beneficial fly was released in 1989 and is now established in the state.
- Status of biological control agents: 1 species released, 1 established.
Musk Thistle is another very aggressive weed that causes major problems for farmers who raise animals. Most animals will not feed on musk thistle and the weed quickly spreads, replacing valuable pasture grasses. Three kinds of beneficial insects have been released to attack musk thistle. The larvae of one feeds on the seeds of the weed, while the other, a weevil, attacks the young plants that emerge in the spring. The seed-eater can be found throughout the state and is reducing the musk thistle population.
- Status of biological control agents: 3 species released, 2 established.
In 1996, a program was initiated to control purple loosestrife. Purple loosestrife (Lythrum salicaria L.) is an invasive weed in wetlands that is native to Eurasia. Since its accidental introduction to North America in the early 1800s, purple loosestrife is found in all contiguous states of the United States (except Florida) and all Canadian provinces. Two species of beetle native to Europe were obtained from scientists at Cornell University to rear beetles for release to control loosestrife in our infested wetlands. The following year, the New Jersey Department of Agriculture and the New Jersey Department of Environmental Protection, Division of Fish and Wildlife cooperated in a pilot project to release the beetles within five Wildlife Management Areas.
The program was expanded to include known bog turtle sites in 1998. The bog turtle, Clemmys muhlenbergii, is an endangered native species that is adversely affected by purple loosestrife. From 1998 until the project ended in 2004, the New Jersey Department of Agriculture, working with the Division of Fish and Wildlife, Endangered and Nongame Species Program released 722,464 beetles in 36 bog turtle sites over the project’s seven-year existence.
Since 1997, approximately 1.7 million beetles have been released at 101 sites in 17 New Jersey counties. Purple loosestrife is no longer a dominant plant in many of the study sites. The natural dispersal of beetles into other loosestrife infestations continued in 2006 with the discovery of 39 new sites inhabited with the beetles. As populations of beetles continue to rise in release sites, their dispersal into more and more areas of new loosestrife infestations can be expected. This eventually should lead to a corresponding reduction of purple loosestrife throughout the state.
In addition, releases have been made at a number of sites including National Park Service lands, and sites managed by Natural Lands Management, The Nature Conservancy of NJ, Mercer County Park Commission, Union County Park System, Allentown Borough, Rider University, property managed by the NJ Meadowlands Commission, a number of mitigation sites and private landowner properties.
Also, 770,400 beetles have been shipped to other states including Maine, Massachusetts, Rhode Island, New York, Delaware, Pennsylvania, Tennessee, Michigan and New Hampshire in an effort to establish field colonies within those states.
- Status of biological control agents: 3 species released, 2 established.