Gene flow within and among E and Z pheromone races of European corn borer (Lepidoptera: Crambidae) in the Northeastern US

As a serious and widely distributed economic pest of corn production in North America, European corn borer (Ostrinia nubilalis) (ECB) is now largely managed with transgenic Bt corn. Although resistance monitoring efforts have focused on the Corn Belt where corn acreage is the greatest, the real danger may lie in the Northeast. Corn in the Northeast is often grown in landscapes of highly variable topography, including numerous isolated valleys bordered by mountain ridges and extensive forest which may serve as barriers to ECB dispersal. Moreover, in the Northeast the two pheromone races (E and Z) of ECB coexist, and it is possible that the less-common E race is more sedentary than the Z race whose movement is better characterized. Such features may result in populations with restricted gene flow where resistance may evolve quickly. In this project we are investigating population differentiation and gene flow within and between populations of ECB in New York and Pennsylvania. We are genotyping 50 SNP markers for both temporal and spatial genetic analysis of paired populations of the two ECB pheromone races from nine locations, and measuring gene flow within the E pheromone race. We expect to find higher population differentiation and restricted gene flow to be caused by the topographic barriers and/or by a lower dispersal rate of the E pheromone race. If so, an increase in the spatial concentration and frequency of monitoring for Bt resistance in the Northeastern US would be justified.