Actual and potential distribution of an invasive canola pest, Meligethes viridescens (Coleoptera: Nitidulidae), in Canada

Meligethes viridescens (Fabricius), bronzed or rape blossom beetle, is a widespread and common pest of oilseed rape [Brassica napus L. and Brassica rapa L. (Brassicaceae)] in the western Palaearctic subregion. The establishment of M. viridescens in eastern North America has raised concern that its presence is a potential risk to the Canadian canola industry, especially to the prairie ecozone of western Canada where up to 4 million ha of summer canola (B. napus and B. rapa) are grown annually. Study of museum specimens indicated that M. viridescens was first recorded in Nova Scotia in 1947. Field surveys indicated that, as of 2001, M. viridescens was established as far west as Saint-Hyacinthe, Quebec. A CLIMEXTM model for M. viridescens in Europe was developed and validated with actual distribution records. In Canada the model predicted that once introduced, M. viridescens would readily survive in the canola-growing areas. The actual distribution of M. viridescens in eastern Canada matched the predicted distribution well. The westward dispersal to and establishment of M. viridescens in canola-growing areas of Ontario and western Canada, particularly southern Manitoba, appear to be inevitable. Establishment in these areas presents the risk of substantial production losses to canola producer