Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: June 1, 1996
Publication Date: N/A
Interpretive Summary: The first genetically engineered plant to be passed by the Environmenal Protection Agency was transgenic cotton. Transgenic cotton contains a bacterial gene which is toxic to moth pests of cotton. Scientists and the cotton producing industry are concerned that moths will develop resistance to the toxic plants. The pink bollworm moth is the primary pest of cotton in the southwestern United States. We monitored the susceptibility of pink bollworm moths to transgenic cotton in Arizona during the 1995-96 seasons. Our results indicate almost complete moth susceptibility to the plants for both years. Our data are important because they form the basis for comparisons of susceptibility over the coming seasons. If resistance begins to develop the industry can institute changes to help preserve efficacy.
Bolls from transgenic cotton, NuCOTN 33 (Delta and Pine Land Co.) containing the BollgardTM 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 five paired fields were collected in one study (Queen Creek, Buckeye, and Gila Bend areas) and a composite of 10 fields of each cultivar were collected in a second study (Paloma Ranch area). Bolls were incubated for 2 weeks (dissected late season) or dissected to find mature larvae, respectively. Collections of 100 or 80 bolls per field were made weekly or biweekly from July through November, 1995. Numbers of pink bollworm larvae were very low in all fields through August and thereafter increased steadily in the control fields. Numbers of larvae found in transgenic cotton were extremely low or non- existent throughout the season, even in fields which were adjacent to heavily infested control fields. These results show that NuCOTN 33 retained a high degree of efficacy for preventing development of mature pink bollworm larvae (diapause larvae) during the late season. Most important, these data provide baseline information against which efficacy in subsequent years can be compared.