MSU Weed Science - Department of Crop and Soil Sciences
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Aug 2nd, 2015

Current Projects in the MSU
Field Crops Entomology Lab


WESTERN CORN ROOTWORM RESISTANCE to Bt
Reporting of field failures of Bt corn is appreciated during the field season. If I am contacted early enough, it is possible to assess problem fields for beetle numbers and damage. Assessment includes digging/washing/rating roots for feeding, estimating % lodging, documenting leaf, silk, or ear feeding, and estimating the number of beetles per plant. Plants can also be checked for Bt expression with commercial check strips. If it is early enough in the season, beetles can be collected and held in the lab for egg-laying. Samples are shipped to cooperators at the University of Guelph-Ridgetown in Ontario, where the eggs are used in a whole-plant assay on Bt and non-Bt plants. If young larvae can survive on Bt roots, this is good evidence that a particualr field collection  is less susceptible to that type of Bt. Coupled with the other evidence of a field failure - lodging, root damage, silk clipping from large numbers of beetles, and yield loss - survival on Bt roots is a good indicator that the population is resistant.