Video-tracking and On-plant Tests Show Cry1Ab Resistance Influences Behavior and Survival of Neonate <i>Ostrinia nubilalis</i> Following Exposure to Bt Maize

To examine how resistance to Bacillus thuringiensis (Bt) toxins influences movement and survival of European corn borer (Ostrinia nubilalis [Hübner]) neonates, the responses of Cry1Ab-resistant , -susceptible, and hybrid (F1) larvae were examined using two different techniques. First, using an automated videotracking system, aspects of O. nubilalis movement were quantified in the presence of artificial diet incorporating 50% non-Bt or insect-resistant Cry1Ab maize tissue. Second, O. nubilalis dispersal and survival were measured 48–72 h after hatching on a Cry1Ab maize plant surrounded by two non-Bt maize plants. Video tracking indicated the presence of Cry1Ab tissue increased the total distance moved (m), time moving (%), and time away from the diet (%) for O. nubilalis while decreasing meander (degrees/cm). However, resistant larvae showed reduced movement and increased meander (≈localized searching) relative to susceptible or hybrid larvae on diet J Insect Behav DOI 10.1007/s10905-009-9190-3 J. R. Prasifka (*) Energy Biosciences Institute, Institute for Genomic Biology, University of Illinois, Room 1117, 1206 West Gregory Drive, Urbana, IL 61801-3838, USA e-mail: [email protected] R. L. Hellmich Corn Insects and Crop Genetics Research Unit, USDA Agricultural Research Service, Ames, IA, USA A. L. B. Crespo Syngenta Biotechnology, Inc., Research Triangle Park, NC, USA B. D. Siegfried Department of Entomology, University of Nebraska, Lincoln, NB, USA D. W. Onstad Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IA, USA incorporating Cry1Ab tissue. Conversely, when placed onto Cry1Ab maize plants, resistant larvae were more likely than susceptible O. nubilalis to disperse onto adjacent non-Bt plants. The difference in on-plant dispersal seems to reflect greater survival after toxin exposure for resistant larvae rather than increased activity. These results suggest that simplified ‘Petri dish’ tests may not be predictive of larval movement among non-Bt and insect-resistant Bt maize plants. Because models of O. nubilalis resistance evolution incorporate various movement and survival parameters, improved data for on-plant behavior and survival of Btresistant , -susceptible, and hybrid larvae should help preserve the efficacy of transgenic insect-resistant maize.