Location: Plant Genetics Research
2012 Annual Report
Objective 2: Develop and release corn germplasm with native resistance to major corn insect pests such as western corn rootworm, and determine genetic and chemical mechanisms of resistance.
For Objective 2, we will systematically screen exotic and GEM (Germplasm Enhancement of Maize) corn germplasm, identify potential sources of resistance, verify resistance, and move into adapted germplasm. In addition, we will conduct recurrent selection with the CRW17 synthetic population for resistance to western corn rootworm larval feeding damage. Finally, we will evaluate the CML333 family of the NAM (Nested Association Mapping) population for resistance to western corn rootworm larval feeding and identify Quantitative Trait Loci associated with reduced damage.
For the other objective of the project, we continued to select for sources of maize naturally resistant to western corn rootworm larval feeding, using maize germplasm sources including the Germplasm Enhancement of Maize (GEM) project. We evaluated ~100 new maize lines not previously evaluated from the GEM program. We conducted one generation of selection on a corn population (CRW17) in order to improve resistance to western corn rootworm larval feeding.
The overall research project is aimed at understanding the nature of resistance, any cross resistance that may occur, and whether or not refuges work in delaying resistance for low-dose rootworm products. This research serves as an alert to the U.S. corn industry of additional potential problems. Given that resistance has developed in the field to transgenic products targeting corn rootworms, our cross resistance work will enable industry to understand its transgenic options, and our native resistance breeding program will fill the management vacuum in the long run. Overall, this project separately facilitates the development of both native and transgenic sources of resistance to the corn rootworm by developing sources of native resistance and providing biological data for resistance management strategies for Bt corn and benefits U.S. corn growers and their seed providers.
Hibbard, B.E., Frank, D.L., Kurtz, R., Boudreau, E., Ellersieck, M.R., Odhiambo, J. 2011. Mortality impact of transgenic maize roots expressing eCry3.1Ab, mCry3A, and eCry3.1Ab + mCry3A on western corn rootworm larvae in the field. Journal of Economic Entomology. 104(5):1584-1591.
Frank, D.L., Bukowsky, R., French, B.W., Hibbard, B.E. 2011. Effect of MIR604 transgenic maize at different stages of development on western corn rootworm (Coleoptera: Chrysomelidae) in a central Missouri field environment. Journal of Economic Entomology. 104:2054-2061.
Ni, X., Chen, Y., Hibbard, B.E., Wilson, J.P., Williams, W.P., Buntin, G., Ruberson, J.R., Li, X. 2011. Foliar resistance to fall armyworm in corn germplasm lines that confer resistance to root- and ear-feeding insects. Florida Entomologist. 94(4):971-981.