Kerns addresses resistance to Bt traits with an emphasis on Vip traits in cotton. He begins by reviewing past and current Bt cotton technologies and presenting the results of surveys that assess resistance and technology efficacy. He goes on to suggest that much of the resistance is being driven by Bt corn, and he discusses types and levels of damage caused by Helicoverpa zea. Kerns also reviews data on the prevalence of H. zea resistance genes in the environment; for Vip cotton, the level of resistant alleles was only 1.2%. Based on percentage survivorship, the Vip resistance appears to be controlled by a single recessive gene. In terms of field performance, Kerns states that failures in Vip cotton technology are the exception, not the rule.
