BOLLGARD AND BOLLGARD II EFFICACY IN NEAR ISOGENIC LINES OF DP50 UPLAND COTTON IN ARIZONA

Authors: MARCHOSKY, RUBEN - U OF AZ, MARICOPA; ELLSWORTH, PETER - U OF AZ, MARICOPA; MOSER, HAL - U OF AZ, MARICOPA; HENNEBERRY, THOMAS

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2001
Publication Date: 7/1/2001
Citation: N/A

Interpretive Summary:

Technical Abstract: In lines containing only one transgene, Cry1Ac or Cry2Ab, bolls had consistently fewer PBWs than the non-Bt variety. Very few PBWs developed into 3rd instar larvae in these Bt varieties. The majority of PBWs recovered were dead first instar larvae. PBW age and mortality distributions confirmed that the single transgenes were effective in stopping PBW development and killing young instars. Cry2Ab displayed a broader spectrum of efficacy as it was significantly more effective against citrus peelminer (Marmara spp.), an incidental lepidopteran present in high densities in the tests. The two-gene line showed better efficacy than the single-gene lines against PBW large larvae infestation. The PBW age distributions found in this variety consisted almost entirely (98%) of dead first instar larvae. Less than 0.6% of the bolls of the two-gene variety in the NTO study were infested with 3rd instar larvae, and there was no infestation by large larvae in any of the naturally-infested bolls in the Isoline study. Yields and other agronomic parameters of the two-gene and single-gene varieties were superior or similar to the null parent. Second pick yields of all Bt varieties were significantly higher than the recurrent parent non-Bt line, suggesting a high degree of efficacy against typically high PBW densities during the late season. Cotton lines with transgenes (Cry1Ac & Cry2Ab) separately and combined demonstrated a high degree of efficacy and agronomic performance for usage in Arizona against PBW.