Susan T. Ratcliffe

Program Manager

Research Interests

  • On-farm research (with many cooperating farmers) to refine the decision-making threshold for western corn rootworms that lay eggs in soybeans in eastern Illinois
  • use of polymerase chair reaction (PCR) and restriction fragment length polymorphisms (RFLP) for species and subspecies insect identification
  • Development of an Expressed Sequence Tag (EST) database to evaluate gene express in western corn rootworms
  • Development of instructional materials for distribution via the internet and the use alternative deliverys ystems if connectivity is limited
  • Current Issues in Insect Management
  • University of Illinois Extension Information Technology
    • Use of the internet to deliver educational materials (
    • On-line instructional videos and interactive IPM decision tools
    • Development of state and regional IPM Programs
  • Western Corn Rootworm On-Farm Research Programs

Selected Articles in Journals

  • O’Neal, M.E., M.E. Gray, S.T. Ratcliffe, K.L. Steffey. 2001. Predicting western corn rootworm (Coleoptera: Chrysomelidae) injury to rotated corn by scouting with Pherocon AM traps in soybeans. J. Econ. Entomol. 94:1, pgs. 98-105.
  • Ratcliffe, S.T., H.M. Robertson, C. J. Jones, G. A. Bollero, R. A. Weinzierl. 2002. Assessment of Parasitism of House Fly and Stable Fly (Diptera: Muscidae) Pupae by Pteromalid (Hymenoptera: Pteromalidae) Parasitoids using a PCR Assay. J. of Med. Entomol. 39(1): 52-60.
  • Onstad, D.W., D.W. Crowder, S.A. Isard, E. Levine, J.L. Spencer, M.E. O’Neal, S.T. Ratcliffe, L.W. Bledsoe, D.C. DiFonzo, B. Eisley, C.R. Edwards, M.E. Gray. 2003. Does Landscape Diversity Slow the Spread of Rotation-Resistant Western Corn Rootworm (Coleoptera: Chrysomelidae)? Environ. Entomol. 32: 992-1001.
  • Ratcliffe, S.T., D.W. Webb, R.A. Weinzierl, H.M. Robertson. 2003. PCR-RFLP Identification of Diptera (Calliphoridae, Muscidae and Sarcophagidae); a generally applicable method, Journal of Forensic Sciences 48: 783-785.
  • Ratcliffe, S.T., M.E. Gray. 2004. Will the USDA IPM Centers and the National IPM Roadmap Increase IPM Accountability? – Responses to the 2001 General Accounting Office Report. Am. Entomol. 50: 6-9.
  • Crowder, D.W., D.W. Onstad, M.E. Gray, C.M.F. Pierce, A.G. Hager, S.T. Ratcliffe, K.L. Steffey. 2005. Analysis of the Dynamics of Adaptation to Transgenic Corn and Crop Rotation by Western Corn Rootworm (Coleoptera: Chrysomelidae) Using a Daily Time-Step Model. J. Econ. Entomol. 98:534-551.
  • Schroeder, J.B., S.T. Ratcliffe, M.E. Gray. 2005. Effect of four cropping systems on variant western corn rootworm (Coleoptera: Chrysomelidae) adult and egg densities and subsequent larval injury in rotated maize. J. Econ. Entomol. 98: 1587-1593.
  • Schroeder, J.B., M.E. Gray, S.T. Ratcliffe, J.L. Spencer. 2006. Illinois on-farm surveys of corn rootworm (Coleoptera: Chrysomelidae) larval injury in rotated corn. (In preparation).
  • Miller, N. J., K. S. Kim, S. T. Ratcliffe, A. Estoup, D. Bourguet, T. Guillemaud. 2006. Absence of genetic divergence between western corn rootworms resistant and susceptible to control by crop rotation. J. Econ. Entomol. 99: 685-690.
  • Schroeder, J.B., M.E. Gray, S.T. Ratcliffe, R.E. Estes, and S.P. Long. 2006. Effects of elevated CO2 and O3 on a variant of the western corn rootworm (Coleoptera: Chrysomelidae). Environ. Entomol. 35(3): 637-644.
  • Kim, K.S., S.T. Ratcliffe, B.W. French, T.W. Sappington. 2006. EST-derived microsatellites from an insect and their potential as parkers in population genetics studies. Molecular Ecology (Submitted).
  • Miller, N., T.W. Sappington, S.T. Ratcliffe, J. Spencer, T. Guillemaud. 2007. Genome scan of Diabrotica virgifera virgifera for genetic variation associated with crop rotation tolerance. Journal of Applied Entomology 131(6), 378-385.

Other Publications

  • Weinzierl, R.A., T. Royer, S. Ratcliffe. 1995. Apple insects and mites: An update on University of Illinois research and overall pest management developments. Transactions of the Illinois Horticultural Society, 128: 29-36.
  • Nixon, P.L., S.T. Ratcliffe. 1997. Control of Japanese beetle larvae with insecticide mixtures. Arthropod Management Tests: 1998, 23: 334.
  • Ratcliffe, S., M. Gray, M. O’Neal, K. Steffey. 1999. Western corn rootworm in soybeans: Is an adjustment in the economic threshold necessary?, pgs. 55-62. In Proceedings of the 1999 Integrated Crop Management Conference. University Extension, Iowa State University, Ames, Iowa. (Paper also published In Proceedings of the 2000 Illinois Crop Protection Technology Conference, University of Illinois at Urbana-Champaign).
  • Ratcliffe, S., M. Gray, M. O’Neal, K. Steffey. 2000. Western corn rootworm in soybeans: Is an adjustment in the economic threshold necessary?, pgs. 56-61. In Proceedings of the 2000 Illinois Crop Protection Conference, University of Illinois at Urbana-Champaign.
  • Ratcliffe, S., M. Gray, M. O’Neal, K. Steffey. 2000. Western corn rootworm problems increase in rotated corn: prospects for producers in 2000. Pp. 1-11. In Proc. 36th Illinois Corn Breeders’ School. University of Illinois at Urbana,-Champaign.
  • Ratcliffe, S., K. Steffey, M. Gray. 2000. Another Corn Rootworm Management Tool Fails: Assessing the Status of Western Corn Rootworms Laying Eggs in Soybeans. In Proceedings of the 2000 Integrated Crop Management Conference, University Extension, Iowa State University.
  • M.E. Gray, C.F. Pierce, S.I. Rondon, S.T. Ratcliffe, K.L. Steffey. 2000. Crop rotation Collapses as a Pest Management Tool for Western Corn Rootworms in the Eastern Corn Belt. American Society of Agronomy National Meeting, Minneapolis, Minnesota.
  • M.E. Gray, S.T. Ratcliffe, J.L. Spencer, E. Levine, K.L. Steffey. 2000. Crop Rotation Collapses as a Viable Pest Management Strategy for Western Corn Rootworms, Diabrotica virgifera virgifera, in the Eastern Corn Belt of the U.S.A. XXI International Congress of Entomology, Brazil.
  • Spencer, J., S. Ratcliffe, S. Isard, E. Levine, C. Pierce, S. Rondon. 2001. Western Corn Rootworms in the 21st Century: New Research on an Old Problem. Pgs. 113 – 114. In Proceedings of the 2001 Illinois Crop Protection Technology Conference, University of Illinois at Urbana-Champaign.