Seasonal infestation by pink bollworm, Pectinophora gossypiella (Saunders), of transgenic and non-transgenic cultivars of cotton, Gossypium hirsutum L., in central Arizona

Bells from transgenic cotton, NuCOTN 33 (Delta and Pine Land Co, Scott, MS) or Paymaster 1560 BG (Paymaster Cotton, Lubbock, TX) containing the Bollgard(TM) gene (Monsanto Co., St. Louis, MO) were compared to parental non-transgenic cultivars DPL-5415 and Paymaster 1560 in central Arizona in 1996 and 1997. Bells were collected from paired transgenic and non-transgenic fields in Queen Creek, Buckeye, Gila Bend, Maricopa, Marana, and Eloy. Approximately equal numbers of bolls were collected from the edges of each field on a weekly to biweekly schedule from July through October. One collection only was made in October at Marana (1996, 1997) and Eloy (1997). Infestations of pink bollworms were less than 10% in all fields through August in both years. Infestations increased to 100% in several non-transgenic fields in October. Infestations of pink bollworms found in transgenic cultivars were less than 1% in all fields except for a single field in 1997 where 6.1 pink bollworms per 100 bolls were found. Overall percentage pink bollworm infested bolls for 1996 was 0.0004% in transgenic cultivars (n = 33,350 bolls) compared with 34.19% in non-transgenic cultivars (n = 33,850 bolls). In 1997 the percentages were 0.0038% in transgenic cultivars (n = 36,650 bolls) including 61 pink bollworms from 1000 bolls in field pair G compared with 48.32% (n = 35,100 bolls). From these numbers it is apparent that pink bollworm remains a significant pest of cotton in central Arizona. We conclude that cultivars of transgenic cotton retained efficacy for control of pink bollworm through 1997.