ARS | Publication request: Fitness of Bt-resistant Western Corn Rootworm on Mon863 and Isoline Corn

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: February 15, 2009
Publication Date: April 7, 2009
Citation: Bagley, M., Oswald, K., French, B.W., Nielson, C.N. 2009. Fitness of Bt-resistant Western Corn Rootworm on Mon863 and Isoline Corn. IWGO Meeting, Munich, Germany, April 5-8, 2009.

Technical Abstract: Abstract: To help ensure that insect resistance management plans mandated by the US Environmental Protection Agency are based on the best science available, we evaluated fitness costs associated with resistance development in artificially selected laboratory lines of the western corn rootworm, Diabrotica virgifera. Five independent short-diapause lines were selected for resistance to MON863 (Bt) corn under either a moderate selection (3 lines) or intensive selection (2 lines) regime and compared to randomly selected controls (2 lines). At the end of the study interval (10 generations of moderate selection, 7 generations of intensive selection) all selected lines achieved a high level of resistance. Fitness parameters selected and control lines were compared on Bt corn and its nontransgenic isoline to evaluate possible fitness costs. All selected lines achieved higher adult emergence on Bt corn compared to controls while emergence of selected lines was equivalent to controls on the isoline corn. Fecundity of emergent females was similar for selected and control lines, regardless of the type of corn. Thus, we found no evidence that resistant lines were less fit than control lines when reared on nontransgenic corn - an important result for resistance models and insect resistance management plans. Interestingly, fecundity of both resistant and control lines was higher when reared on MON863 compared to the isoline. It is not clear whether this is an artifact of the experimental design or whether this same phenomenon can occur in the field. This potential fecundity difference has implications for resistance management plans and requires further investigation.