Combined use of Cry1Ca and Cry1Ab proteins for insect resistance management

This is a national phase application, filed pursuant to 35 U.S.C. §371, of PCT application No. PCT/US10/60819 filed on Dec. 16, 2010, which claims the benefit of U.S. provisional application No. 61/284,292, filed on Dec. 16, 2009. The prior applications are incorporated herein by reference in their entirety.

Humans grow corn for food and energy applications. Humans also grow many other crops, including soybeans and cotton. Insects eat and damage plants and thereby undermine these human efforts. Billions of dollars are spent each year to control insect pests and additional billions are lost to the damage they inflict. Synthetic organic chemical insecticides have been the primary tools used to control insect pests but biological insecticides, such as the insecticidal proteins derived from Bacillus thuringiensis (Bt), have played an important role in some areas. The ability to produce insect-resistant plants through transformation with Bt insecticidal protein genes has revolutionized modern agriculture and heightened the importance and value of insecticidal proteins and their genes.

Several Bt proteins have been used to create the insect-resistant transgenic plants that have been successfully registered and commercialized to date. These include Cry1Ab, Cry1Ac, Cry1Fa and Cry3Bb in corn, Cry1Ac and Cry2Ab in cotton, and Cry3A in potato.

The commercial products expressing these proteins express a single protein except in cases where the combined insecticidal spectrum of 2 proteins is desired (e.g, Cry1Ab and Cry3Bb in corn combined to provide resistance to lepidopteran pests and rootworm, respectively) or where the independent action of the proteins makes them useful as a tool for delaying the development of resistance in susceptible insect populations (e.g., Cry1Ac and Cry2Ab in cotton combined to provide resistance management for tobacco budworm).

That is, some of the qualities of insect-resistant transgenic plants that have led to rapid and widespread adoption of this technology also give rise to the concern that pest populations will develop resistance to the insecticidal proteins produced by these plants.

Several strategies have been suggested for preserving the utility of Bt-based insect resistance traits which include deploying proteins at a high dose in combination with a refuge, and alternation with, or co-deployment of, different toxins (McGaughey et al. (1998), “B.t. Resistance Management,” Nature Biotechnol. 16:144-146).

The proteins selected for use in an insect resistance management (IRM) stack need to exert their insecticidal effect independently so that resistance developed to one protein does not confer resistance to the second protein (i.e., there is not cross resistance to the proteins). If, for example, a pest population selected for resistance to “Protein A” is sensitive to “Protein B”, one would conclude that there is not cross resistance and that a combination of Protein A and Protein B would be effective in delaying resistance to Protein A alone.

In the absence of resistant insect populations, assessments can be made based on other characteristics presumed to be related to mechanism of action and cross-resistance potential. The utility of receptor-mediated binding in identifying insecticidal proteins likely to not exhibit cross resistance has been suggested (van Mellaert et al. 1999). The key predictor of lack of cross resistance inherent in this approach is that the insecticidal proteins do not compete for receptors in a sensitive insect species.

In the event that two B.t. Cry toxins compete for the same receptor, then if that receptor mutates in that insect so that one of the toxins no longer binds to that receptor and thus is no longer insecticidal against the insect, it might also be the case that the insect will also be resistant to the second toxin (which competitively bound to the same receptor). However, if two toxins bind to two different receptors, this could be an indication that the insect would not be simultaneously resistant to those two toxins.

Cry1Ab is an insecticidal protein currently used in transgenic corn to protect plants from a variety of insect pests. A key pest of corn that Cry1Ab provides protection from is the European corn borer.

Additional Cry toxins are listed at the website of the official B.t. nomenclature committee (Crickmore et al.; lifesci.sussex.ac.uk/home/Neil_Crickmore/Bt/). See Appendix A, attached. There are currently nearly 60 main groups of “Cry” toxins (Cry1-Cry59), with additional Cyt toxins and VIP toxins and the like. Many of each numeric group have capital-letter subgroups, and the capital letter subgroups have lower-cased letter sub-subgroups. (Cry1 has A-L, and Cry1A has a-i, for example).

The subject invention relates in part to the surprising discovery that Cry1Ca is very active against sugarcane borer including a sugarcane borer population that is resistant to Cry1Ab. As one skilled in the art will recognize with the benefit of this disclosure, plants producing Cry1Ca and Cry1Ab (including insecticidal portions thereof), will be useful in delaying or preventing the development of resistance to either of these insecticidal proteins alone. A cry1Fa gene, for example, could also be stacked with these two base pair genes/proteins.

The subject invention also relates to the discovery that Cry1Ca and Cry1Ab do not compete with each other for binding gut receptors from fall armyworm ( Spodoptera frugiperda ; FAW).

FIG. 1-Competition for binding to Spodoptera frugiperda BBMV's by Cry1Ab core toxin, Cry1Ca core toxin, and 125I-labeled Cry1Ca core toxin protein

FIG. 2-Competition for binding to Spodoptera frugiperda BBMV's by Cry1Ca core toxin, Cry1Ab core toxin, and 125I-labeled Cry1Ab core toxin protein.

SEQ ID NO:1—Cry1Ca core/Cry1Ab protoxin chimeric protein 1164 aa (DIG-152)

SEQ ID NO:2—a Cry1Ca core toxin

SEQ ID NO:3—a Cry1Ab core toxin

The subject invention relates in part to the surprising discovery that Cry1Ca is very active against a sugarcane borer (SCB; Diatraea saccharalis ) population that is resistant to Cry1Ab. Accordingly, the subject invention relates in part to the surprising discovery that Cry1Ca can be used in combination with, or “stacked” with, Cry1Ab to combat the development of resistance to either of these insecticidal proteins alone. Stated another way, the subject invention relates in part to the surprising discovery that that a sugarcane borer population selected for resistance to Cry1Ab is not resistant to Cry1Ca; sugarcane borer that are resistant to Cry1Ab toxin are susceptible (i.e., are not cross-resistant) to Cry1Ca. Thus, the subject invention includes the use of Cry1Ca toxin to control populations of sugarcane borer that are resistant to Cry1Ab.

As one skilled in the art will recognize with the benefit of this disclosure, plants expressing Cry1Ca and Cry1Ab (including insecticidal portions thereof), will be useful in delaying or preventing the development of resistance to either of these insecticidal proteins alone.

The subject invention includes the use of Cry1Ca to protect sugarcane and other economically important plant species from damage and yield loss caused by sugarcane borer or to sugarcane borer populations that have developed resistance to Cry1Ab. The sugarcane borer can also be a pest of corn. This is particularly true in some Central and South American countries such as Brazil and Argentina. Thus, corn, for example, can also be protected according to the subject invention.

The subject invention thus teaches an insect resistance management (IRM) stack to prevent or mitigate the development of resistance by sugarcane borer to Cry1Ab and/or Cry1Ca.

In addition, receptor binding studies using radiolabeled Cry1Ca and Spodoptera frugipera ; fall armyworm (FAW) insect tissues show that Cry1Ab does not compete for the high affinity binding site to which Cry1Ca binds. These results indicate that the combination of Cry1Ab and Cry1Ca can be used as an effective means to mitigate the development of resistance in insect populations (such as FAW and SCB) to Cry1Ab and/or Cry1Ca for plants (such as maize and sugarcane) producing both proteins. While toxin overlay studies demonstrated that Cry1Ca protein bound to two proteins in BBMV's from S. frugiperda , one of 40 kDa and one of 44 kDa, whereas Cry1Ab protein bound to a single protein of 150 kDa (Aranda et al., 1996), that did not relate to non-competitive binding studies.

Thus, the subject invention also includes the combination of Cry1Ca and Cry1Ab as an IRM stack to mitigate against the development of resistance by fall armyworm and/or sugarcane borer to either protein, or to sugarcane borer populations that have developed resistance to Cry1Ab.

The present invention provides compositions for controlling lepidopteran pests comprising cells that express a Cry1Ca core toxin-containing protein and a Cry1Ab core toxin-containing protein;

a host transformed to express both a Cry1Ab core toxin-containing protein and a Cry1C core toxin containing protein, wherein said host is a microorganism or a plant cell (the subject polynucleotide(s) are preferably in a genetic construct under control of (operably linked to/comprising) a non- Bacillus - thuringiensis promoter; the subject polynucleotides can comprise codon usage for enhanced expression in a plant);

a method of controlling lepidopteran pests comprising contacting said pests or the environment of said pests with an effective amount of a composition that produces a Cry1Ab core toxin-containing protein and a cell expressing a Cry1C core toxin-containing protein;

a plant (such as a maize plant, or soybeans or cotton or sugarcane, for example) comprising DNA encoding a Cry1Ca core toxin-containing protein and DNA encoding a Cry1Ab core toxin-containing protein, and seed of such a plant;

a plant (such as a maize plant, or soybeans or cotton or sugarcane, for example) wherein DNA encoding a Cry1Ca core toxin-containing protein and DNA encoding a Cry1Ab core toxin-containing protein have been introgressed into said maize plant, and seed of such a plant.

We demonstrated, for example, that Cry1Ca (protein from recombinant Pseudomonas fluorescens strain MR1206/DC639; plasmid pMYC2547) is very effective in controlling sugarcane borer (SCB; Diatraea saccharalis ) populations, in artificial diet bioassays, that have been selected for resistance to Cry1Ab. This indicates that Cry1Ca is useful in controlling SCB populations that have developed resistance to Cry1Ab or in mitigating the development of Cry1Ab resistance in SCB populations.

Based in part on the data described herein, co-expressing Cry1Ca and Cry1Ab can produce a high dose IRM stack for controlling SCB. Other proteins can be added to this combination to add spectrum. For example in corn, the addition of Cry1Fa would create an IRM stack for European corn borer (ECB), Ostrinia nubilalis (Hübner), while adding yet another MOA for control of SCB.

For a review of Cry1C as a potential bioinsecticide in plants, see (Avisar et al. 2009). Avisar D, Eilenberg H, Keller M, Reznik N, Segal M, Sneh B, Zilberstein A (2009) The Bacillus thuringiensis delta-endotoxin Cry1C as a potential bioinsecticide in plants. Plant Science 176:315-324.

Insect Receptors.

As described in the Examples, competitive receptor binding studies using radiolabeled Cry1Ca core toxin protein show that the Cry1Ab core toxin protein does not compete for the high affinity binding site present in FAW insect tissues to which Cry1Ca binds. These results indicate that the combination of Cry1Ab and Cry1Ca proteins would be an effective means to mitigate the development of resistance in FAW populations to Cry1Ab (and likewise, the development of resistance to Cry1Ca), and would likely increase the level of resistance to this pest in corn plants expressing both proteins.

These data also suggest that Cry1Ca would be effective in controlling SCB populations that have developed resistance to Cry1Ab. One deployment option would be to use these Cry proteins in geographies where Cry1Ab has become ineffective in controlling SCB due to the development of resistance. Another deployment option would be to use Cry1Ca in combination with Cry1Ab to mitigate the development of resistance in SCB to Cry1Ab.

Combinations of the toxins described in the invention can be used to control lepidopteran pests. Adult lepidopterans, i.e., butterflies and moths, primarily feed on flower nectar. The larvae, i.e., caterpillars, nearly all feed on plants, and many are serious pests. Caterpillars feed on or inside foliage or on the roots or stem of a plant, depriving the plant of nutrients and often destroying the plant's physical support structure. Additionally, caterpillars feed on fruit, fabrics, and stored grains and flours, ruining these products for sale or severely diminishing their value. As used herein, reference to lepidopteran pests refers to various life stages of the pest, including larval stages.

The chimeric toxins of the subject invention comprise a full core N-terminal toxin portion of a B.t. toxin and, at some point past the end of the toxin portion, the protein has a transition to a heterologous protoxin sequence. The N-terminal toxin portion of a B.t. toxin is referred to herein as the “core” toxin. The transition to the heterologous protoxin segment can occur at approximately the toxin/protoxin junction or, in the alternative, a portion of the native protoxin (extending past the toxin portion) can be retained with the transition to the heterologous protoxin occurring downstream.

As an example, one chimeric toxin of the subject invention has the full core toxin portion of Cry1Ab (amino acids 1 to 601) and a heterologous protoxin (amino acids 602 to the C-terminus). In one preferred embodiment, the portion of a chimeric toxin comprising the protoxin is derived from a Cry1Ab protein toxin. As a second Example, a second chimeric toxin of the subject invention, as disclosed in SEQ ID NO:1 (DIG-152) has the full core toxin portion of Cry1Ca (amino acids 1 to 619) and a heterologous protoxin (amino acids 620 to the C-terminus). In a preferred embodiment, the portion of a chimeric toxin comprising the protoxin is derived from a Cry1Ab protein toxin.

A person skilled in this art will appreciate that B.t. toxins, even within a certain class such as Cry1Ca, will vary to some extent in length and the precise location of the transition from toxin portion to protoxin portion. Typically, the cry1Ca toxins are about 1150 to about 1200 amino acids in length. The transition from toxin portion to protoxin portion will typically occur at between about 50% to about 60% of the full length toxin. The chimeric toxin of the subject invention will include the full expanse of this core N-terminal toxin portion. Thus, the chimeric toxin will comprise at least about 50% of the full length cry1Ca or Cry1Ab B.t. toxin. This will typically be at least about 590 amino acids. With regard to the protoxin portion, the full expanse of the Cry1A(b) protoxin portion extends from the end of the toxin portion to the C-terminus of the molecule. It is the last about 100 to 150 amino acids of this portion which are most critical to include in the chimeric toxin of the subject invention.

Genes and Toxins.

The genes and toxins useful according to the subject invention include not only the full length sequences disclosed but also fragments of these sequences, variants, mutants, and fusion proteins which retain the characteristic pesticidal activity of the toxins specifically exemplified herein. As used herein, the terms “variants” or “variations” of genes refer to nucleotide sequences which encode the same toxins or which encode equivalent toxins having pesticidal activity. As used herein, the term “equivalent toxins” refers to toxins having the same or essentially the same biological activity against the target pests as the claimed toxins.

As used herein, the boundaries represent approximately 95% (Cry1Ab's and 1Ca's), 78% (Cry1A's and Cry1C's), and 45% (Cry1's) sequence identity, per “Revision of the Nomenclature for the Bacillus thuringiensis Pesticidal Crystal Proteins,” N. Crickmore, D. R. Zeigler, J. Feitelson, E. Schnepf, J. Van Rie, D. Lereclus, J. Baum, and D. H. Dean. Microbiology and Molecular Biology Reviews (1998) Vol 62: 807-813. These cut offs can also be applied to the core toxins only (for Cry1Ab and Cry1C toxins). The GENBANK numbers listed in the attached Appendix A can also be used to obtain the sequences for any of the genes and proteins disclosed or mentioned herein.

It should be apparent to a person skilled in this art that genes encoding active toxins can be identified and obtained through several means. The specific genes or gene portions exemplified herein may be obtained from the isolates deposited at a culture depository as described above. These genes, or portions or variants thereof, may also be constructed synthetically, for example, by use of a gene synthesizer. Variations of genes may be readily constructed using standard techniques for making point mutations. Also, fragments of these genes can be made using commercially available exonucleases or endonucleases according to standard procedures. For example, enzymes such as Bal31 or site-directed mutagenesis can be used to systematically cut off nucleotides from the ends of these genes. Also, genes which encode active fragments may be obtained using a variety of restriction enzymes. Proteases may be used to directly obtain active fragments of these toxins.

Fragments and equivalents which retain the pesticidal activity of the exemplified toxins would be within the scope of the subject invention. Also, because of the redundancy of the genetic code, a variety of different DNA sequences can encode the amino acid sequences disclosed herein. It is well within the skill of a person trained in the art to create these alternative DNA sequences encoding the same, or essentially the same, toxins. These variant DNA sequences are within the scope of the subject invention. As used herein, reference to “essentially the same” sequence refers to sequences which have amino acid substitutions, deletions, additions, or insertions which do not materially affect pesticidal activity. Fragments retaining pesticidal activity are also included in this definition.

A further method for identifying the gene-encoding toxins and gene portions useful according to the subject invention is through the use of oligonucleotide probes. These probes are detectable nucleotide sequences. These sequences may be detectable by virtue of an appropriate label or may be made inherently fluorescent as described in International Application No. WO93/16094. As is well known in the art, if the probe molecule and nucleic acid sample hybridize by forming a strong bond between the two molecules, it can be reasonably assumed that the probe and sample have substantial homology. Preferably, hybridization is conducted under stringent conditions by techniques well-known in the art, as described, for example, in Keller, G. H., M. M. Manak (1987) DNA Probes, Stockton Press, New York, N.Y., pp. 169-170. Some examples of salt concentrations and temperature combinations are as follows (in order of increasing stringency): 2×SSPE or SSC at room temperature; 1×SSPE or SSC at 42° C.; 0.1×SSPE or SSC at 42° C.; 0.1×SSPE or SSC at 65° C. Detection of the probe provides a means for determining in a known manner whether hybridization has occurred. Such a probe analysis provides a rapid method for identifying toxin-encoding genes of the subject invention. The nucleotide segments which are used as probes according to the invention can be synthesized using DNA synthesizer and standard procedures. These nucleotide sequences can also be used as PCR primers to amplify genes of the subject invention.

Certain toxins of the subject invention have been specifically exemplified herein. Since these toxins are merely exemplary of the toxins of the subject invention, it should be readily apparent that the subject invention comprises variant or equivalent toxins (and nucleotide sequences coding for equivalent toxins) having the same or similar pesticidal activity of the exemplified toxin. Equivalent toxins will have amino acid homology with an exemplified toxin. This amino acid homology will typically be greater than 75%, preferably be greater than 90%, and most preferably be greater than 95%. The amino acid homology will be highest in critical regions of the toxin which account for biological activity or are involved in the determination of three-dimensional configuration which ultimately is responsible for the biological activity. In this regard, certain amino acid substitutions are acceptable and can be expected if these substitutions are in regions which are not critical to activity or are conservative amino acid substitutions which do not affect the three-dimensional configuration of the molecule. For example, amino acids may be placed in the following classes: non-polar, uncharged polar, basic, and acidic. Conservative substitutions whereby an amino acid of one class is replaced with another amino acid of the same type fall within the scope of the subject invention so long as the substitution does not materially alter the biological activity of the compound. Table 1 provides a listing of examples of amino acids belonging to each class.

In some instances, non-conservative substitutions can also be made. The critical factor is that these substitutions must not significantly detract from the biological activity of the toxin.

Recombinant hosts. The genes encoding the toxins of the subject invention can be introduced into a wide variety of microbial or plant hosts. Expression of the toxin gene results, directly or indirectly, in the intracellular production and maintenance of the pesticide. Conjugal transfer and recombinant transfer can be used to create a B.t. strain that expresses both toxins of the subject invention. Other host organisms may also be transformed with one or both of the toxin genes then used to accomplish the synergistic effect. With suitable microbial hosts, e.g., Pseudomonas , the microbes can be applied to the situs of the pest, where they will proliferate and be ingested. The result is control of the pest. Alternatively, the microbe hosting the toxin gene can be treated under conditions that prolong the activity of the toxin and stabilize the cell. The treated cell, which retains the toxic activity, then can be applied to the environment of the target pest.

Where the B.t. toxin gene is introduced via a suitable vector into a microbial host, and said host is applied to the environment in a living state, it is essential that certain host microbes be used. Microorganism hosts are selected which are known to occupy the “phytosphere” (phylloplane, phyllosphere, rhizosphere, and/or rhizoplane) of one or more crops of interest. These microorganisms are selected so as to be capable of successfully competing in the particular environment (crop and other insect habitats) with the wild-type microorganisms, provide for stable maintenance and expression of the gene expressing the polypeptide pesticide, and, desirably, provide for improved protection of the pesticide from environmental degradation and inactivation.

A large number of microorganisms are known to inhabit the phylloplane (the surface of the plant leaves) and/or the rhizosphere (the soil surrounding plant roots) of a wide variety of important crops. These microorganisms include bacteria, algae, and fungi. Of particular interest are microorganisms, such as bacteria, e.g., genera Pseudomonas, Erwinia, Serratia, Klebsiella, Xanthomonas, Streptomyces, Rhizobium, Rhodopseudomonas, Methylophilius, Agrobactenum, Acetobacter, Lactobacillus, Arthrobacter, Azotobacter, Leuconostoc , and Alcaligenes ; fungi, particularly yeast, e.g., genera Saccharomyces, Cryptococcus, Kluyveromyces, Sporobolomyces, Rhodotorula , and Aureobasidium . Of particular interest are such phytosphere bacterial species as Pseudomonas syringae, Pseudomonas fluorescens, Serratia marcescens, Acetobacter xylinum, Agrobactenium tumefaciens, Rhodopseudomonas spheroides, Xanthomonas campestris, Rhizobium melioti, Alcaligenes entrophus , and Azotobacter vinlandii ; and phytosphere yeast species such as Rhodotorula rubra, R. glutinis, R. marina, R. aurantiaca, Cryptococcus albidus, C. diffluens, C. laurentii, Saccharomyces rosei, S. pretoriensis, S. cerevisiae, Sporobolomyces roseus, S. odorus, Kluyveromyces veronae , and Aureobasidium pollulans . Of particular interest are the pigmented microorganisms.

A wide variety of ways are available for introducing a B.t. gene encoding a toxin into a microorganism host under conditions which allow for stable maintenance and expression of the gene. These methods are well known to those skilled in the art and are described, for example, in U.S. Pat. No. 5,135,867, which is incorporated herein by reference.

Treatment of cells. Bacillus thuringiensis or recombinant cells expressing the B.t. toxins can be treated to prolong the toxin activity and stabilize the cell. The pesticide microcapsule that is formed comprises the B.t. toxin or toxins within a cellular structure that has been stabilized and will protect the toxin when the microcapsule is applied to the environment of the target pest. Suitable host cells may include either prokaryotes or eukaryotes, normally being limited to those cells which do not produce substances toxic to higher organisms, such as mammals. However, organisms which produce substances toxic to higher organisms could be used, where the toxic substances are unstable or the level of application sufficiently low as to avoid any possibility of toxicity to a mammalian host. As hosts, of particular interest will be the prokaryotes and the lower eukaryotes, such as fungi.

The cell will usually be intact and be substantially in the proliferative form when treated, rather than in a spore form, although in some instances spores may be employed.

Treatment of the microbial cell, e.g., a microbe containing the B.t. toxin gene or genes, can be by chemical or physical means, or by a combination of chemical and/or physical means, so long as the technique does not deleteriously affect the properties of the toxin, nor diminish the cellular capability of protecting the toxin. Examples of chemical reagents are halogenating agents, particularly halogens of atomic no. 17-80. More particularly, iodine can be used under mild conditions and for sufficient time to achieve the desired results. Other suitable techniques include treatment with aldehydes, such as glutaraldehyde; anti-infectives, such as zephiran chloride and cetylpyridinium chloride; alcohols, such as isopropyl and ethanol; various histologic fixatives, such as Lugol iodine, Bouin's fixative, various acids and Helly's fixative (See: Humason, Gretchen L., Animal Tissue Techniques, W. H. Freeman and Company, 1967); or a combination of physical (heat) and chemical agents that preserve and prolong the activity of the toxin produced in the cell when the cell is administered to the host environment. Examples of physical means are short wavelength radiation such as gamma-radiation and X-radiation, freezing, UV irradiation, lyophilization, and the like. Methods for treatment of microbial cells are disclosed in U.S. Pat. Nos. 4,695,455 and 4,695,462, which are incorporated herein by reference.

The cells generally will have enhanced structural stability which will enhance resistance to environmental conditions. Where the pesticide is in a proform, the method of cell treatment should be selected so as not to inhibit processing of the proform to the mature form of the pesticide by the target pest pathogen. For example, formaldehyde will crosslink proteins and could inhibit processing of the proform of a polypeptide pesticide. The method of treatment should retain at least a substantial portion of the bio-availability or bioactivity of the toxin.

Characteristics of particular interest in selecting a host cell for purposes of production include ease of introducing the B.t. gene or genes into the host, availability of expression systems, efficiency of expression, stability of the pesticide in the host, and the presence of auxiliary genetic capabilities. Characteristics of interest for use as a pesticide microcapsule include protective qualities for the pesticide, such as thick cell walls, pigmentation, and intracellular packaging or formation of inclusion bodies; survival in aqueous environments; lack of mammalian toxicity; attractiveness to pests for ingestion; ease of killing and fixing without damage to the toxin; and the like. Other considerations include ease of formulation and handling, economics, storage stability, and the like.

Growth of cells. The cellular host containing the B.t. insecticidal gene or genes may be grown in any convenient nutrient medium, where the DNA construct provides a selective advantage, providing for a selective medium so that substantially all or all of the cells retain the B.t. gene. These cells may then be harvested in accordance with conventional ways. Alternatively, the cells can be treated prior to harvesting.

The B.t. cells producing the toxins of the invention can be cultured using standard art media and fermentation techniques. Upon completion of the fermentation cycle the bacteria can be harvested by first separating the B.t. spores and crystals from the fermentation broth by means well known in the art. The recovered B.t. spores and crystals can be formulated into a wettable powder, liquid concentrate, granules or other formulations by the addition of surfactants, dispersants, inert carriers, and other components to facilitate handling and application for particular target pests. These formulations and application procedures are all well known in the art.

Formulations.

Formulated bait granules containing an attractant and spores, crystals, and toxins of the B.t. isolates, or recombinant microbes comprising the genes obtainable from the B.t. isolates disclosed herein, can be applied to the soil. Formulated product can also be applied as a seed-coating or root treatment or total plant treatment at later stages of the crop cycle. Plant and soil treatments of B.t. cells may be employed as wettable powders, granules or dusts, by mixing with various inert materials, such as inorganic minerals (phyllosilicates, carbonates, sulfates, phosphates, and the like) or botanical materials (powdered corncobs, rice hulls, walnut shells, and the like). The formulations may include spreader-sticker adjuvants, stabilizing agents, other pesticidal additives, or surfactants. Liquid formulations may be aqueous-based or non-aqueous and employed as foams, gels, suspensions, emulsifiable concentrates, or the like. The ingredients may include rheological agents, surfactants, emulsifiers, dispersants, or polymers.

As would be appreciated by a person skilled in the art, the pesticidal concentration will vary widely depending upon the nature of the particular formulation, particularly whether it is a concentrate or to be used directly. The pesticide will be present in at least 1% by weight and may be 100% by weight. The dry formulations will have from about 1-95% by weight of the pesticide while the liquid formulations will generally be from about 1-60% by weight of the solids in the liquid phase. The formulations will generally have from about 10 2 to about 10 4 cells/mg. These formulations will be administered at about 50 mg (liquid or dry) to 1 kg or more per hectare.

The formulations can be applied to the environment of the lepidopteran pest, e.g., foliage or soil, by spraying, dusting, sprinkling, or the like.

Plant Transformation.

A preferred recombinant host for production of the insecticidal proteins of the subject invention is a transformed plant. Genes encoding Bt toxin proteins, as disclosed herein, can be inserted into plant cells using a variety of techniques which are well known in the art. For example, a large number of cloning vectors comprising a replication system in Escherichia coli and a marker that permits selection of the transformed cells are available for preparation for the insertion of foreign genes into higher plants. The vectors comprise, for example, pBR322, pUC series, M13 mp series, pACYC184, inter alia. Accordingly, the DNA fragment having the sequence encoding the Bt toxin protein can be inserted into the vector at a suitable restriction site. The resulting plasmid is used for transformation into E. coli . The E. coli cells are cultivated in a suitable nutrient medium, then harvested and lysed. The plasmid is recovered. Sequence analysis, restriction analysis, electrophoresis, and other biochemical-molecular biological methods are generally carried out as methods of analysis. After each manipulation, the DNA sequence used can be cleaved and joined to the next DNA sequence. Each plasmid sequence can be cloned in the same or other plasmids. Depending on the method of inserting desired genes into the plant, other DNA sequences may be necessary. If, for example, the Ti or Ri plasmid is used for the transformation of the plant cell, then at least the right border, but often the right and the left border of the Ti or Ri plasmid T-DNA, has to be joined as the flanking region of the genes to be inserted. The use of T-DNA for the transformation of plant cells has been intensively researched and sufficiently described in EP 120 516, Lee and Gelvin (2008), Hoekema (1985), Fraley et al., (1986), and An et al., (1985), and is well established in the art.

Once the inserted DNA has been integrated in the plant genome, it is relatively stable. The transformation vector normally contains a selectable marker that confers on the transformed plant cells resistance to a biocide or an antibiotic, such as Bialaphos, Kanamycin, G418, Bleomycin, or Hygromycin, inter alia. The individually employed marker should accordingly permit the selection of transformed cells rather than cells that do not contain the inserted DNA.

A large number of techniques is available for inserting DNA into a plant host cell. Those techniques include transformation with T-DNA using Agrobacterium tumefaciens or Agrobacterium rhizogenes as transformation agent, fusion, injection, biolistics (microparticle bombardment), or electroporation as well as other possible methods. If Agrobacteria are used for the transformation, the DNA to be inserted has to be cloned into special plasmids, namely either into an intermediate vector or into a binary vector. The intermediate vectors can be integrated into the Ti or Ri plasmid by homologous recombination owing to sequences that are homologous to sequences in the T-DNA. The Ti or Ri plasmid also comprises the vir region necessary for the transfer of the T-DNA. Intermediate vectors cannot replicate themselves in Agrobacteria . The intermediate vector can be transferred into Agrobacterium tumefaciens by means of a helper plasmid (conjugation). Binary vectors can replicate themselves both in E. coli and in Agrobacteria . They comprise a selection marker gene and a linker or polylinker which are framed by the Right and Left T-DNA border regions. They can be transformed directly into Agrobacteria (Holsters et al., 1978). The Agrobacterium used as host cell is to comprise a plasmid carrying a vir region. The vir region is necessary for the transfer of the T-DNA into the plant cell. Additional T-DNA may be contained. The bacterium so transformed is used for the transformation of plant cells. Plant explants can advantageously be cultivated with Agrobacterium tumefaciens or Agrobacterium rhizogenes for the transfer of the DNA into the plant cell. Whole plants can then be regenerated from the infected plant material (for example, pieces of leaf, segments of stalk, roots, but also protoplasts or suspension-cultivated cells) in a suitable medium, which may contain antibiotics or biocides for selection. The plants so obtained can then be tested for the presence of the inserted DNA. No special demands are made of the plasmids in the case of injection and electroporation. It is possible to use ordinary plasmids, such as, for example, pUC derivatives.

The transformed cells grow inside the plants in the usual manner. They can form germ cells and transmit the transformed trait(s) to progeny plants. Such plants can be grown in the normal manner and crossed with plants that have the same transformed hereditary factors or other hereditary factors. The resulting hybrid individuals have the corresponding phenotypic properties.

In a preferred embodiment of the subject invention, plants will be transformed with genes wherein the codon usage has been optimized for plants. See, for example, U.S. Pat. No. 5,380,831, which is hereby incorporated by reference. While some truncated toxins are exemplified herein, it is well-known in the Bt art that 130 kDa-type (full-length) toxins have an N-terminal half that is the core toxin, and a C-terminal half that is the protoxin “tail.” Thus, appropriate “tails” can be used with truncated/core toxins of the subject invention. See e.g. U.S. Pat. No. 6,218,188 and U.S. Pat. No. 6,673,990. In addition, methods for creating synthetic Bt genes for use in plants are known in the art (Stewart and Burgin, 2007). One non-limiting example of a preferred transformed plant is a fertile maize plant comprising a plant expressible gene encoding a Cry1Fa protein, and further comprising a second plant expressible gene encoding a Cry1Ca protein.

Transfer (or introgression) of the Cry1Ab and Cry1C trait(s) into inbred maize lines can be achieved by recurrent selection breeding, for example by backcrossing. In this case, a desired recurrent parent is first crossed to a donor inbred (the non-recurrent parent) that carries the appropriate gene(s) for the Cry1Ab and Cry1C traits. The progeny of this cross is then mated back to the recurrent parent followed by selection in the resultant progeny for the desired trait(s) to be transferred from the non-recurrent parent. After three, preferably four, more preferably five or more generations of backcrosses with the recurrent parent with selection for the desired trait(s), the progeny will be heterozygous for loci controlling the trait(s) being transferred, but will be like the recurrent parent for most or almost all other genes (see, for example, Poehlman & Sleper (1995) Breeding Field Crops, 4th Ed., 172-175; Fehr (1987) Principles of Cultivar Development, Vol. 1: Theory and Technique, 360-376).

Insect Resistance Management (IRM) Strategies.

Roush et al., for example, outlines two-toxin strategies, also called “pyramiding” or “stacking,” for management of insecticidal transgenic crops. (The Royal Society. Phil. Trans. R. Soc. Lond. B . (1998) 353, 1777-1786). On their website, the United States Environmental Protection Agency (epa.gov/oppbppd1/biopesticides/pips/bt_corn_refuge — 2006.htm) publishes the following requirements for providing non-transgenic (i.e., non-B. t.) refuges (a block of non-Bt crops/corn) for use with transgenic crops producing a single Bt protein active against target pests.

The specific structured requirements for corn borer-protected Bt (Cry1Ab or Cry1F) corn products are as follows:

Structured refuges:

20% non-Lepidopteran Bt corn refuge in Corn Belt 50% non-Lepidopteran Bt refuge in Cotton Belt

Blocks

1. Internal (i.e., within the Bt field) 2. External (i.e., separate fields within ½ mile (¼ mile if possible) of the Bt field to maximize random mating)

In-field Strips

Strips must be at least 4 rows wide (preferably 6 rows) to reduce the effects of larval movement

The National Corn Growers Association, on their website (ncga.com/insect-resistance-management-fact-sheet-bt-corn), also provides similar guidance regarding the requirements. For example:

Requirements of the Corn Borer IRM:

Plant at least 20% of your corn acres to refuge hybrids In cotton producing regions, refuge must be 50% Must be planted within ½ mile of the refuge hybrids Refuge can be planted as strips within the Bt field; the refuge strips must be at least 4 rows wide Refuge may be treated with conventional pesticides only if economic thresholds are reached for target insect Bt-based sprayable insecticides cannot be used on the refuge corn Appropriate refuge must be planted on every farm with Bt corn

As stated by Roush et al. (on pages 1780 and 1784 right column, for example), stacking or pyramiding of two different proteins each effective against the target pests and with little or no cross-resistance can allow for use of a smaller refuge. Roush suggests that for a successful stack, a refuge size of less than 10% refuge, can provide comparable resistance management to about 50% refuge for a single (non-pyramided) trait. For currently available pyramided Bt corn products, the U.S. Environmental Protection Agency requires significantly less (generally 5%) structured refuge of non-Bt corn be planted than for single trait products (generally 20%).

Any of the above percentages (such as those for 1F/1Ab), or similar refuge ratios, can be used for the subject double or triple stacks or pyramids. The subject invention includes commercial acreage—of over 10 acres for example—planted with (or without) such refuge and with plants according to the subject invention.

There are various ways of providing the refuge, including various geometric planting patterns in the fields (as mentioned above), to in-bag seed mixtures, as discussed further by Roush and, for example, U.S. Pat. No. 6,551,962.

All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety to the extent they are not inconsistent with the explicit teachings of this specification. Unless specifically indicated or implied, the terms “a”, “an”, and “the” signify “at least one” as used herein.

The following examples illustrate the invention. The examples should not be construed as limiting.

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