Plant protecting and regulating compositions – Seed coated with agricultural chemicals other than fertilizers
Reexamination Certificate
2001-10-05
2003-04-22
Pryor, Alton (Department: 1616)
Plant protecting and regulating compositions
Seed coated with agricultural chemicals other than fertilizers
Reexamination Certificate
active
06551962
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to the control of pests that cause damage to crop plants, and in particular to corn plants, by their feeding activities directed to root damage, and more particularly to the control of such plant pests by combining a crop plant seed comprising one or more transgenes which express one or more proteins toxic to said plant pests in a mixture of seeds with non-transgenic refuge crop seeds, and the treatment of such seed with a chemical or peptide associated pesticide prior to planting the seed.
(2) Description of the Related Art
Insects, nematodes, and related arthropods annually destroy an estimated 15% of agricultural crops in the United States and even more than that in developing countries. In addition, competition with weeds and parasitic and saprophytic plants account for even more potential yield losses.
Some of this damage occurs in the soil when plant pathogens, insects and other such soil borne pests attack the seed after planting. In the production of corn, for example, much of the rest of the damage is caused by rootworms—insect pests that feed upon or otherwise damage the plant roots; and by cutworms, European corn borers, and other pests that feed upon or damage the above ground parts of the plant. General descriptions of the type and mechanisms of attack of pests on agricultural crops are provided by, for example, Metcalf, in
Destructive and Useful Insects,
(1962); and Agrios, in
Plant Pathology,
3rd Ed., Academic Press (1988).
Corn is the most important grain crop in the Midwestern United States. Among the most serious insect pests of corn in this region are the larval forms of three species of Diabrotica beetles. These include the Western corn rootworm,
Diabrotica vergifera vergifera
LeConte, the Northern corn rootworm,
Diabrotica berberi
Smith and
Diabrotica berberi
Lawrence, and the Southern corn rootworm,
Diabrotica undecimpunctata howardi
Barber. In fact, more chemical insecticide is used for the control of corn rootworm than for any other pest of corn, and the total acreage treated with chemical insecticides is greater than for any other pest in the United States.
Corn rootworms (CRW) overwinter in the egg stage in fields where corn was grown the previous season. The eggs hatch from late May through June. If a corn crop is not followed by another corn crop in the subsequent year, the larvae will die. Accordingly, the impact of corn rootworm is felt most directly in areas where corn is systematically followed by corn, as is typical in many areas of the Midwestern United States.
After hatching, the larvae pass through three larval stages or instars, during which they feed on the corn root system. About three weeks is required for completion of the larval stage. Damage to the corn root system caused by the feeding of larvae is the major cause of harvest losses in corn due to corn rootworm. Corn plants that fall over and lodge in the field after weakening or destruction of a major part of the root system are the cause of a major portion of this loss, since this lodged corn cannot be harvested by conventional mechanized machinery and is left in the field.
Following completion of larval development, the larvae transform into immobile pupae, and thence into the adult beetles that emerge from the soil throughout the summer, with the period of emergence depending upon the growing location. After emergence, the adult beetles feed for about two weeks before the females start laying eggs. Initially, the adults feed predominantly in the same field from which they emerged, but later will migrate to other fields. Peak adult activity normally occurs in the U.S. Corn Belt during late July or early August in fields planted to continuous corn, but activity may peak later in first year or late maturing cornfields. Rootworm beetles begin depositing eggs in cornfields approximately two weeks after they emerge. (For more information, see, e.g.,
Corn Rootworms,
Field Crops Pest Management Circular #16, Ohio Pest Management & Survey Program, The Ohio State University, Extension Division, Columbus, Ohio; available online at www.ag.ohio-state.edu/~ohioline/icm-fact/fc-16.html, Sep. 13, 2000; and McGahen et al.,
Corn Insect Control: Corn Rootworm,
PENpages number 08801502, Factsheet available from Pennsylvania State University, State College, Pa., 1989).
There is evidence of the emergence of a new race of Corn rootworm which ovipositions its eggs for overwinter onto adjacent soybean plants. The most common practice in the mid-western United States has been for fields to be rotated annually with corn, followed the next year with soybeans, in order to manage the development of an epidemic of corn rootworm pressure on fields of corn. While this strategy overall has been successful in reducing the corn rootworm feeding pressure on corn in many areas, the evolutionary emergence of this new race of corn rootworm creates a problem which was not anticipated and which could not have been easily foreseen. This new race, which preferentially deposits its eggs onto soybean fields, provides an unintended feeding pressure on the next years' intended corn crop in the field in which soybeans were grown the previous year, and the subsequent requirement for insecticidal control measures which adds unintended cost to the farmer in the form of additional labor for spraying and additional costs of goods, further reducing the return to the farmer on his/her investment in the crop and harvest.
One means for combating the corn rootworm pressures in the US, in particular in view of the introduction of recombinant crops containing genes which express proteins which are insecticidal to a selected few intended crop pest insect species, has been the regulatory agencies' requirement that farmers plant a non-recombinant refuge crop which provides a means for producing a steady and consistent population of adult insects which have never been exposed to the recombinant pesticide pressures and so have not had the opportunity to develop resistance as a result of the pesticide pressure when feeding on the recombinant plants. This is particularly true for the corn rootworm larvae as it is highly limited in its ability to move through the soil any great distance from the roots which are more or less adjacent to its local larval environment within the soil. In theory, the adult insects which emerge from the refuge environment will disperse and breed with any insects which emerge from the recombinant fields, and if any of the insects which emerge from the recombinant fields have developed a level of resistance to the recombinant insecticidal proteins, the availability of that trait in the subsequent generations will be diluted, reducing or delaying the onset of the emergence of a race which will be totally resistant to the recombinant insecticidal corn plant.
The western corn rootworm,
D. virigifera virigifera,
is a widely distributed pest of corn in North America, and in many instance, chemical insecticides are indiscriminately used to keep the numbers of rootworms below economically damaging levels. In order to assist in the reduction of chemical insecticides used in treatments to control the rootworm populations in crop fields, transgenic lines of corn have been developed which produce a one of a number of amino acid sequence variants of an insecticidal protein produced naturally in the bacterium
Bacillus thuringiensis.
This protein, generally referred to as Cry3Bb, has recently been modified by English et al. in U.S. Pat. No. 6,023,013 and related patents and applications, to contain one or more amino acid sequence variations which, when tested in insect bioassay against the corn rootworm, demonstrates a from about seven (7) to about ten (10) increase in insecticidal activity when compared to the wild type amino acid sequence. In particular, the enhanced expression of a gene encoding this particular protein in root tissue in corn provides for improved corn rootworm control without the requireme
Pershing Jay C.
Sachs Eric S.
Sanders Ernest F.
Ball Timothy K.
Hoerner, Jr. Dennis R.
Monsanto Technology LLC
Pryor Alton
LandOfFree
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