Monday, December 11, 2006 - 10:35 AM
0259

Survival of Cry1Ab resistant European corn borer (Lepidoptera: Crambidae) on Bt and non-Bt corn

Andre Luiz Barreto Crespo, crespo@unlserve.unl.edu, Terence A. Spencer, tspencer1@unl.edu, and Blair D. Siegfried, bsiegfried1@unl.edu. University of Nebraska - Lincoln, Entomology, 202 Plant Industry Building, Lincoln, NE

Transgenic corn expressing the Cry1Ab toxin from Bacillus thuringiensis (Berliner) has high efficacy against European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). The resistance management plan proposed to manage Bt resistance in O. nubilalis is based on the high dose refuge strategy and monitoring of field populations to detect resistance. A collection obtained from Kandiyohi County, Minnesota exhibited significantly lower mortality at a diagnostic Cry1Ab concentration based on the LC99 derived from baseline data. Whole plant assays were performed on vegetative and reproductive stage MON 810 plants and a near isoline of non-Bt plants to assess the potential of resistant individuals to survive on Cry1Ab expressing plants. Resistant larvae did not survive on vegetative stage plants expressing Cry1Ab. On reproductive stage plants, although resistant larvae were inhibited by Cry1Ab, many individuals survived 15 days after infestation, and some individuals grew to fourth or fifth instar. These results indicate that vegetative and reproductive stage plants do not express Cry1Ab at the same level and that reproductive plants can support the development of moderately resistant populations.


Species 1: Lepidoptera Crambidae Ostrinia nubilalis (European corn borer)