Confirmation and response to pink bollworm resistance to Bollgard (Cry1Ac) cotton in localized regions of India

Unusual survival events of Pectinophora gossypiella(pink bollworm) in Bollgard hybrids were documented during the 2009 growing season in the Indian state of Gujarat. Upon subsequent lab testing, these populations were found to be resistant to Cry1Ac, the Bt protein in Bollgard cotton. This field resistance was confirmed in 2010. These populations were fully susceptible to Cry2Ab, the second Bt component of Bollgard II, and field observations confirmed full control of PBW in Bollgard II fields in local areas of resistance. Factors possibly contributing to the development of Cry1Ac-resistant populations in the field in Gujarat include the illegal deployment of unapproved hybrid Bt events with lower Cry1Ac levels and the accompanying failure to plant refuges adequate to produce sufficient susceptible PBW moths. A broad team of experts was a critical asset in addressing the scientific issues along with the farmer education and extension needs associated with this phenomenon.