First Instance of Field Failure of First-Generation Bt Cotton Documented with Pink Bollworm In Gujarat State, India

The first instance of confirmed field failure of single-gene, Bt cotton producing Cry1Ac protein was documented in Gujarat State, India, in the 2009 season.   In this paper we will explain what is currently known about the geographical distribution of this resistance, based on boll infestation rates in the field and  laboratory-based bioassays of susceptibility to Cry1Ac.  Resistant pink bollworm are susceptible to Cry2Ab and thus are controlled by the second generation of Bt Cotton, Bollgard II.  We will discuss the unique factors that have contributed to this problem in this region of India.  Mitigation measures are focused on improving effectiveness of refuges.