Historical occurrence of alien arthropods and pathogens on trees in Canada

The Canadian Forest Invasive Alien Species (CanFIAS) database provides point records of alien arthropod (insects and mites) and pathogen (fungi) species found on trees in Canada extracted from more than 100 years of national surveys. Each record includes a species identification, location, year of observation, and host association and is linked electronically to its original source. More than 175 000 records of 329 alien arthropod species and 11 plant pathogens are available. Historical rates of detection, as indicated by first records, were greatest in the decades following the two world wars. The overall rate has been approximately three species per year since 1900. Richness of alien species is greatest in the Coastal and Great Lakes-St. Lawrence forest ecozones and lowest in the Subalpine and Tundra ecozones. The alien species most significant in terms of extent of invasion and damage to trees are tree-host specialists, feeding on or infecting mostly one or two genera in a single plant family. Important commercial trees including pine, spruce, poplar, and birch and amenity genera including willow, cherry, and maple host the greatest diversity of alien species. Sap-feeding insects are the most speciose feeding group, but foliage-feeding and wood-boring insects and plant pathogens cause the most damage.