Colorado potato beetle resistance management strategies for transgenic potatoes

NewLeaf potatoes could provide substantial ecological and economic benefits to potato growers. A concern with NewLeaf potatoes, however, is that Color ado potato beetle may develop resistance to the Bt endotoxin because of the intense selection pressure imposed by its constant presence in the transge nic crop. Before these cultivars were released, however, entomologists thro ughout North America conducted biological research needed for a strategy to prevent or delay resistance in Colorado potato beetle. This paper describe s the considerations and research behind the proposed strategy. Because New Leaf potatoes express a relatively constant and high concentration of Bt en dotoxin throughout the foliage of each plant, reducing selection for resist ance must come from planting standard potatoes as a refuge for susceptible beetles. Avoiding resistance through random mixtures of NewLeaf and standar d potatoes was evaluated in laboratory and field studies. The conclusion fr om this research was that the seed mixture would not provide an effective r efuge. The most effective alternative refuge was judged to be a block of st andard potatoes planted in the same field as the NewLeaf potatoes. By allow ing susceptible beetles to survive in their fields, potato growers might su stain the benefits of very effective controls.