2006 Annual Report 1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? NATIONAL PROGRAM: 304 - Crop Protection and Quarantine. Corn rootworms are among the most serious insect pests in the United States, with an estimated cost of $1 billion annually to the U.S. economy in terms of crop losses and insecticide costs. Developments, such as resistance to crop rotation in both the western corn rootworm and the northern corn rootworm, insecticide resistance in Nebraska, and the establishment of this pest in Europe have made corn rootworms an even more important problem. Until 2003, insecticides were the only viable control option for corn rootworm management in continuous corn. On February 25, 2003, transgenic corn that expresses endotoxins from the bacterium Bacillus thuringiensis (Bt) was registered for commercial sale by the Environmental Protection Agency (EPA). An additional product was registered in 2005. The EPA requires an insect resistance management plan for registration of all Bt crops, but an optimal plan requires biological information that has not been available. We have collected basic biological data on corn rootworm larval establishment, movement after establishment, alternate hosts, and other aspects of basic biology that are needed in order to effectively maintain susceptibility (resistance management) to transgenic and native rootworm resistance sources. Currently, we are developing colonies which survive the first Bt product. An understanding of western corn rootworm survival on rootworm-resistant Bt corn will help us determine the risk of resistance evolving in the field and can serve as a model system for understanding resistance management needs for other lower dose transgenic events. Finally, major effort is also put forward to identify and improve native sources of resistance to this major pest toward the release of resistant germplasm that includes molecular marker information. When available, native resistance would likely be widely utilized in refuge areas of transgenic fields, in areas with moderate infestation, and in Europe. 2.List by year the currently approved milestones (indicators of research progress) 2005 (12 months) Objective 1: Make top-crosses of CRW3(C6) with inbred lines in the winter nursery. Evaluate topcrosses for yield with and without insecticide in paired-row tests. Also evaluate damage and agronomic traits such as plant height, ear height, cob color, etc. Increase CRW3(C6) for release, should the data from cycle 5 warrant this. Conduct first year of seed treatment study. Objective 2: Initiate the four colonies of wild-type X nondiapausing western corn rootworms with varying exposure to Bt corn. Conduct the greenhouse experiment western corn rootworm larvae will have a choice between weed roots and Bt corn where feeding will be monitored by the relative amount of 13C (13C:12C). Conduct first year of the weed density field study. 2006 (24 months) Objective 1: Evaluate 100 new accessions not previously evaluated and retest selected germplasm from 2005. Second year of seed treatment study. Second year of phenotypic damage data for mapping population, if needed. QTL analysis if phenotypic data from 2005 are good enough. Release CRW3(C6) if 2004/5 data justify this. Objective 2: Continue colony development. Second year of weed density study. Behavioral bioassay and dose-response studies with different generations of each colony. 2007 (36 months) Objective 1: Evaluate 100 new accessions not previously evaluated and retest selected germplasm from 2006. Evaluate status of GEM recurrent selection studies in multiple location study. Objective 2: Continue colony development. Behavioral bioassay and dose-response studies with different generations of each colony. 2008 (48 months) Objective 1: Evaluate 100 new accessions not previously evaluated and retest selected germplasm from 2007. Initiate new populations for recurrent selection. Objective 2: Continue/wrap up colony work with Bt corn. Behavioral bioassay and dose-response studies with different generations of each colony. Initiate new preliminary studies for the next 60 month project plan. 2009 (60 months) Objective 1: Evaluate 100 new accessions not previously evaluated and retest selected germplasm from 2008. Continue breeding work in general by following up on leads from earlier years. Objective 2: Consider initiating colonies resistant to Cry34/35. Behavioral bioassay and dose-response studies with different generations of each colony. Follow up on 2008 studies and initiate new studies for the next project plan. 4a.List the single most significant research accomplishment during FY 2006. Transgenic corn with resistance to corn rootworm larval feeding expressing the Cry3Bb1 protein has been commercially available since 2003. The Environmental Protection Agency (EPA) has mandated that all registrants submit an Insect Resistance Management (IRM) Plan prior to registration of any Bt crop. IRM (i.e., maintaining pest susceptibility to control measures) can extend the lifetime of management options. The corn rootworm Bt products do not fit the high-dose refuge paradigm of other Bt crops because significant survival will occur under high corn rootworm infestations. Scientists at the Plant Genetics Research Unit, Columbia, Missouri, have been working to gain an understanding of how western corn rootworm larvae survive transgenic corn with rootworm resistance. Four western corn rootworm colonies have been developed with exposure to transgenic roots as larvae varying from full rearing on transgenic corn to a no exposure control. Progeny from the sixth generation of selection for survival on Bt corn were evaluated in a small-scale field trial for larval establishment (no adult emergence allowed). Establishment on Bt plants was between 12 and 45 fold greater for the strain that was reared on Bt corn for six generations than for two susceptible rootworm strains when compared to establishment on isoline corn. The colonies will serve as a resource for understanding of western corn rootworm survival on Cry3Bb1 corn and will help us determine the risk of resistance evolving in the field. This system can serve as a model for understanding resistance management needs for other lower dose transgenic events. This accomplishment addresses NP301 component "Genetic Resource Management" and NP304 component "Pest Control Technologies." 4b.List other significant research accomplishment(s), if any. None. 4c.List significant activities that support special target populations. None. 4d.Progress report. None. 5.Describe the major accomplishments to date and their predicted or actual impact. The current project is just over one year old. Four western corn rootworm colonies have been developed with exposure to transgenic roots as larvae varying from full rearing on transgenic corn to a no exposure control. Progeny from the sixth generation of selection for survival on Bt corn were evaluated in a small-scale field trial for larval establishment (no adult emergence allowed). Establishment on Bt plants was between 12 and 45 fold greater for the strain that was reared on Bt corn for six generations than for two susceptible rootworm strains when compared to emergence on isoline corn. The colonies will serve as a resource for understanding of western corn rootworm survival on Cry3Bb1 corn and will help us determine the risk of resistance evolving in the field. This accomplishment addresses NP301 component "Genetic Resource Management" and NP304 component "Pest Control Technologies." 6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? A CRADA with a seed company has recently been approved to evaluate plant-pest interactions and to determine the selection intensity of their rootworm-resistant product. Identification of quantitative trait loci (QTL) will facilitate the utilization of native sources of resistance that we have developed during the previous project. Another seed company is also providing phenotypic data for rootworm feeding on this mapping population. Constraints to utilizing native resistance sources are getting these genes into elite inbred lines. Our approach utilizing QTL mapping should facilitate this. 7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). None. Review Publications Hibbard, B.E., Vaughn, T.T., Oyediran, I.O., Clark, T.L. 2005. Effect of Cry3Bb1 expressing transgenic corn on plant-to-plant movement by western corn rootworm larvae (Coleoptera: chrysomelidae). Journal of Economic Entomology. 98:1126-1138. Chege, P., Clark, T.L., Hibbard, B.E. 2005. Alternate host phenology affects survivorship, growth and development of western corn rootworm (Coleoptera: chrysomelidae) larvae. Environmental Entomology. 34:1441-1447. Wilson, T.A., Clark, T.L., Hibbard, B.E. 2006. Number of point sources of western corn rootworm (Coleoptera: chrysomelidae) eggs in artificial infestations affects larval establishment and plant damage. Journal of Kansas Entomological Society. 79:119-128. Oyediran, I.O., Hibbard, B.E., Clark, T.L. 2005. Western corn rootworm (Coleoptera:Chrysomelidae) beetle emergency from weedy Cry3Bbl rootworm-resistant transgenic corn. Journal of Economic Entomology. 98:1679-1684.