Development of genetic markers for risk assessment of biological control agents

Prior to the release of any organism for use as a biological control agent, it is necessary to assess the possible effects of deploying a single isolate over a wide geographic area. There is a distinct possibility that a rare virulence gene ol allele could be introduced into a local population of the pathogen following release. Factors such as the isolation of populations by distance or natural barriers to dispersal can allow evolutionary forces such as selection, mutation, and genetic drift to affect gene frequencies in local populations. Analysis of the genetic structure of a species can reveal information about its population structure and permit risk analysis. We have developed a series of molecular markers to assess the impact of releasing selected isolates of the biological control fungus Chondrostereum purpureum. These markers were used to analyze gene flow between populations and to assess the risk of the deployment of C. purpureum as an agent for the biological control of forest weeds in Canada.