Seasonal Infestation by Pink Bollworm of Transgenic Cotton, NuCOTN 33, and Parental Cultivar DPL-5415 in Commercial Fields: the Second Season

Bolls from transgenic cotton, NuCOTN 33 (Delta and Pine Land Co.) containing the Bollgard™ gene (Monsanto Co.) and from the parental cultivar DPL-5415 were examined for mature larvae of the pink bollworm (78,240 total bolls). Bolls from paired fields were collected in the Queen Creek, Buckeye, Maricopa, and Marana, AZ, areas. Equal numbers of bolls were collected from the edges of each field each week July - October except for Marana where a single collection was made 30 October. Bolls were incubated for 2 weeks and/or dissected from 1 September onward. Numbers of pink bollworm larvae were very low in all fields through August and increased to extremely high levels (up to 3.4 larvae/boll at Marana) in some control fields in October. Numbers of pink bollworm found in NuCOTN 33 were extremely low or nonexistent, even in fields immediately adjacent to heavily infested control fields. The overall numbers of larvae found in NuCOTN 33 were comparable to those found in 1995. In 1995, the percent worms of bolls were: NuCOTN 33 = 0.0003 (13 larvae /38320 bolls) compared to 11.80% for DPL -5415 (4711 larvae /39920 bolls). Overall percent worms of bolls for 1996 were: NuCOTN 33 = 0.0004% (14 larvae/33350 bolls) compared to 34.19% (11572 larvae/33850 bolls) in DPL-5415