The refuge provides a population of susceptible borers to mate with any resistant types that survive in the borer-resistant corn field. The refuge may be treated with insecticides if pest pressure reaches economic thresholds, but sprayable Bt insecticides must not be used. Fields of corn borer resistant hybrids must be marked at planting and then monitored during the season to identify any instances of resistant insect population development. This article explains the concepts of insect resistance management, how to establish an effective refuge, and the importance of monitoring fields and reporting damage. Corn field with ECB damage.
Corn borers are devastating pests in most corn-growing areas of the United States and Canada.
Entomologists estimate that corn borer feeding damage costs farmers over one billion dollars per year in the U.S. alone. In spite of these losses, damaging corn borer populations are often left untreated in many areas. Reluctance to treat results from the unpredictable nature of corn borer infestations, difficulty in scouting, and the high cost and uncertain effectiveness of treatment. In addition, corn borer tunneling is not always apparent to the grower. Growers have reacted enthusiastically to this Bt technology, planting resistant hybrids on millions of acres in corn borer areas.