The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is globally distributed and a destructive oligophagous pest of Brassicaceae crops (Talekar & Shelton 1993). Although P. xylostella is believed to have evolved in the Mediterranean area (Harcourt 1954) or Africa (Kfir 1998), North American populations are most probably of European origin and were likely introduced about 150 years ago (Hardy 1938).
Plutella xylostella was first reported from western Canada in 1885 (Harcourt 1962), and it now occurs almost annually throughout the Canadian prairies wherever its host plants are cultivated (Anonymous 1996; Dosdall et al. 2004, 2011). In both eastern and western Canada, P. xylostella re-establishes each year from annual immigration
Plutella xylostella was first reported from western Canada in 1885 (Harcourt 1962), and it now occurs almost annually throughout the Canadian prairies wherever its host plants are cultivated (Anonymous 1996; Dosdall et al. 2004, 2011). In both eastern and western Canada, P. xylostella re-establishes each year from annual immigration