Submitted to: Journal of Entomological Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/15/2003
Publication Date: 4/1/2004
Citation: Gore, J., Adamczyk Jr, J.J. 2004. Characterization of soybean looper (Lepidoptera: Noctuidae) Tolerance to Bollgard(R) Cotton: Implications for resistance management. J. Entomol. Sci. 39(2): 235-242 (April 2004) Interpretive Summary: Bollgard® cotton cultivars have been grown commercially since 1996. These cotton cultivars produce the Cry1Ac protein from Bacillus thuringiensis. During that time Bollgard® cultivars have provided acceptable control of the tobacco budworm but not other pests such as the soybean looper. Field and laboratory experiments were conducted to determine the effects Bollgard® cotton has on the development of soybean loopers. Based on results of these experiments, Bollgard® cotton delays development and reduces pupal weights of soybean loopers. These findings will help refine control strategies for this pest on Bollgard® cotton.
Technical Abstract: The soybean looper, Pseudoplusia includens, is an occasional pest of cotton and an annual pest of soybean in the southern United States. A series of field and laboratory experiments were designed to investigate the influence of transgenic Bacillus thuringiensis (Bt) or Bollgard® cotton on the development of soybean loopers. Soybean looper larvae and pupae were collected from plots of non-Bollgard® and Bollgard® cottons and weighed. Both larvae and pupae from Bollgard® cotton weighed less than larvae and pupae collected from non-Bollgard® cotton, respectively. Pupae collected from non-Bollgard® and Bollgard® cotton were maintained separately in the laboratory. No differences were observed in the susceptibility of F1 soybean looper from non-Bollgard® and Bollgard® cottons to Cry1Ac based on concentration-mortality data. Neonates from each of these colonies were allowed to complete development on non-treated and Cry1Ac-treated (1.0 µg/ml) meridic diet. Larval weights at 9 d and pupal weights were lower on Cry1Ac-treated diet than on non-treated diet. There were no apparent vigor differences in the two colonies based on development on non-treated diet. In addition, developmental times were longer on Cry1Ac diet than on non-treated diet. These data indicate that development of larvae that occur late in the season on Bollgard® cotton has little effect on the health of soybean loopers. These findings will help refine control strategies for this pest on Bollgard® cotton.