Submitted to: Journal of Agricultural and Urban Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/3/2003
Publication Date: 10/20/2003
Citation: Adamczyk, Jr., J. J., and Gore, J. 2003. Varying levels of Cry Ac in transgenic Bacillus thuringiensis Berliner (BE) cotton leaf bioassays. Journal of Agricultural and Urban Entomology. 20: 49-53. Interpretive Summary: Bioassays are commonly used in entomology to measure the effect an insecticide has on a particular insect species. Plants now exist where they contain a transgene from another organism. These transgenes often make the plant (i.e. cotton and corn) tolerance to certain pests as well as herbicides. When evaluating transgenic cotton plants, researchers often use bioassays to assess tolerance to caterpillar pests. As of 2003, a standardize bioassay method has yet to be developed. We examined four different, commonly used bioassays involving transgenics and documented that major differences in the amount of transgene product was found among the different bioassay types. We conclude that careful descriptions of bioassay methodology are essential for laboratory studies documenting transgenic products and corresponding efficacy against certain caterpillar pests.
Technical Abstract: Research was conducted to determine levels of Cry1Ac in transgenic Bacillus thuringiensis Berliner (Bt) cotton leaves from four different, commonly used bioassays. Significant differences in the amount of Cry1Ac were found among the different bioassay types. For bioassay arenas that prevented desiccation of leaf material, Cry1Ac levels remained stable for 10 days after being excised from the plant. In other bioassay types, Cry1Ac levels increased in excised leaves over time because of desiccation that concentrated the transgenic protein. We conclude that careful descriptions of bioassay methodology are essential for laboratory studies documenting Cry1Ac levels and corresponding efficacy against lepidopteran pests.