Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues
Reexamination Certificate
2001-09-28
2003-08-12
Low, Christopher S. F. (Department: 1653)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
C514S012200, C514S04400A, C435S252300, C435S252500, C435S410000, C435S440000, C435S091400, C435S468000, C435S471000, C435S476000, C435S480000, C536S023100, C536S023700, C536S023710
Reexamination Certificate
active
06605701
ABSTRACT:
BACKGROUND OF THE INVENTION
Insects and other pests cost farmers billions of dollars annually in crop losses and in the expense of keeping these pests under control. The losses caused by insect pests in agricultural production environments include decrease in crop yield, reduced crop quality, and increased harvesting costs.
The corn rootworm (a coleopteran insect pest) is a serious plant pest. Extensive damage occurs to the United States corn crop each year due to root feeding by larvae of corn rootworm (Diabrotica spp.). It has been estimated that approximately 9.3 million acres of U.S. corn are infested with corn rootworm species complex each year. The corn rootworm species complex includes the Western corn rootworm (
Diabrotica virgifera virgifera
), Northern corn rootworm (
Diabrotica barberi
), and Southern corn rootworm (
Diabrotica undecimpunctata howardi
).
The life cycle of each Diabrotica species is similar. The eggs of the corn rootworm are deposited in the soil. Newly hatched larvae (the first instar) remain in the ground and feed on the smaller branching corn roots. Later instars of Western and Northern corn rootworms invade the inner root tissues that transport water and mineral elements to the plants. In most instances, larvae migrate to feed on the newest root growth. Tunneling into roots by the larvae results in damage which can be observed as brown, elongated scars on the root surface, tunneling within the roots, or varying degrees of pruning. Plants with pruned roots usually dislodge after storms that are accompanied by heavy rains and high winds. The larvae of Southern corn rootworm feed on the roots in a similar manner as the Western and Northern corn rootworm larvae. Southern corn rootworm larvae may also feed on the growing point of the stalk while it is still near the soil line, which may cause the plant to wilt and die.
After feeding for about 3 weeks, the corn rootworm larvae leave the roots and pupate in the soil. The adult beetles emerge from the soil and may feed on corn pollen and many other types of pollen, as well as on corn silks. Feeding on green silks can reduce pollination level, resulting in poor grain set and poor yield. The Western corn rootworm adult also feeds upon corn leaves, which can slow plant growth and, on rare occasions, kill plants of some corn varieties.
The soil-dwelling larvae of these Diabrotica species feed on the root of the corn plant, causing lodging. Lodging eventually reduces corn yield and often results in death of the plant. By feeding on cornsilks, the adult beetles reduce pollination and, therefore, detrimentally effect the yield of corn per plant. In addition, adults and larvae of the genus Diabrotica attack cucurbit crops (cucumbers, melons, squash, etc.) and many vegetable and field crops in commercial production as well as those being grown in home gardens.
It has been estimated that the annual cost of insecticides to control corn rootworm and the annual crop losses caused by corn rootworm damage exceeds a total of $1 billion in the United States each year (Meycalf, R. L. [1986] in
Methods for the Study of Pest Diabrotica
, Drysan, J. L. and T. A. Miller [Eds.], Springer-Verlag, New York, N.Y., pp. vii-xv). Approximately $250 million worth of insecticides are applied annually to control corn rootworms in the United States. In the Midwest, $60 million and $40 million worth of insecticide were applied in Iowa and Nebraska, respectively, in 1990. Even with insecticide use, rootworms cause about $750 million worth of crop damage each year, making them the most serious corn insect pest in the Midwest.
Control of corn rootworm has been partially addressed by cultivation methods, such as crop rotation and the application of high nitrogen levels to stimulate the growth of an adventitious root system. However, chemical insecticides are relied upon most heavily to guarantee the desired level of control. Insecticides are either banded onto or incorporated into the soil. Economic demands on the utilization of farmland restrict the use of crop rotation. In addition, an emerging two-year diapause (or overwintering) trait of Northern corn rootworms is disrupting crop rotations in some areas.
The use of insecticides to control corn rootworm also has several drawbacks. Continual use of insecticides has allowed resistant insects to evolve. Situations such as extremely high populations of larvae, heavy rains, and improper calibration of insecticide application equipment can result in poor control. Insecticide use often raises environmental concerns such as contamination of soil and of both surface and underground water supplies. The public has also become concerned about the amount of residual chemicals which might be found on food. Working with insecticides may also pose hazards to the persons applying them. Therefore, synthetic chemical pesticides are being increasingly scrutinized, and correctly so, for their potential toxic environmental consequences. Examples of widely used synthetic chemical pesticides include the organochlorines, e.g., DDT, mirex, kepone, lindane, aldrin, chlordane, aldicarb, and dieldrin; the organophosphates, e.g., chlorpyrifos, parathion, malathion, and diazinon; and carbamates. Stringent new restrictions on the use of pesticides and the elimination of some effective pesticides from the market place could limit economical and effective options for controlling costly pests.
Because of the problems associated with the use of organic synthetic chemical pesticides, there exists a clear need to limit the use of these agents and a need to identify alternative control agents. The replacement of synthetic chemical pesticides, or combination of these agents with biological pesticides, could reduce the levels of toxic chemicals in the environment.
A biological pesticidal agent that is enjoying increasing popularity is the soil microbe
Bacillus thuringiensis
(B.t.). The soil microbe
Bacillus thuringiensis
(B.t.) is a Gram-positive, spore-forming bacterium. Most strains of B.t. do not exhibit pesticidal activity. Some B.t. strains produce, and can be characterized by, parasporal crystalline protein inclusions. These “&dgr;-endotoxins,” which typically have specific pesticidal activity, are different from exotoxins, which have a non-specific host range. These inclusions often appear microscopically as distinctively shaped crystals. The proteins can be highly toxic to pests and specific in their toxic activity. Certain B.t. toxin genes have been isolated and sequenced. The cloning and expression of a B.t. crystal protein gene in
Escherichia coli
was described in the published literature more than 15 years ago (Schnepf, H. E., H. R. Whiteley [1981
] Proc. Natl. Acad. Sci. USA
78:2893-2897). In addition, with the use of genetic engineering techniques, new approaches for delivering B.t. toxins to agricultural environments are under development, including the use of plants genetically engineered with B.t. toxin genes for insect resistance and the use of stabilized intact microbial cells as B.t. toxin delivery vehicles (Gaertner, F. H., L. Kim [1988
] TIBTECH
6:S4-S7). Thus, isolated B.t. endotoxin genes are becoming commercially valuable.
Until the last fifteen years, commercial use of B.t. pesticides has been largely restricted to a narrow range of lepidopteran (caterpillar) pests. Preparations of the spores and crystals of
B. thuringiensis
subsp. kurstaki have been used for many years as commercial insecticides for lepidopteran pests. For example,
B. thuringiensis
var. kurstaki HD-1 produces a crystalline &dgr;-endotoxin which is toxic to the larvae of a number of lepidopteran insects.
In recent years, however, investigators have discovered B.t. pesticides with specificities for a much broader range of pests. For example, other species of B.t., namely israelensis and morrisoni (a.k.a. tenebrionis, a.k.a. B.t. M-7), have been used commercially to control insects of the orders Diptera and Coleoptera, respectively (Gaertner, F. H. [1989] “Cellular Delivery S
Lee Stacey Finstad
Narva Kenneth E.
Schnepf H. Ernest
Stockhoff Brian A.
Sturgis Blake
Kam Chih-Min
Low Christopher S. F.
Mycogen Corporation
Saliwanchik Lloyd & Saliwanchik
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