Introduced Leaf Beetles of the Maritime Provinces, 6: The Common Asparagus Beetle, Crioceris asparagi (Linnaeus), and the Twelve-Spotted Asparagus Beetle, Crioceris duodecimpunctata (Linnaeus) (Coleoptera: Chrysomelidae)

Abstract

The common asparagus beetle, Crioceris asparagi (Linnaeus) and the twelve-spotted asparagus beetle, Crioceris duodecimpunctata (Linnaeus) are introduced Palearctic leaf beetles that feed exclusively on asparagus. The introduction history of these species in North America is reviewed and their dispersal to and distribution in the Maritime Provinces of Canada are described. Both species were first reported in Canada in 1899 in asparagus production areas in Queenston, Ontario, and other parts of the Niagara Peninsula where they caused serious crop damage. However, we discovered that both species were already found around Quebec City 22 years earlier. Populations now established in the Maritime Provinces of Canada probably originated from southwestern Ontario where most commercial asparagus production in Canada began and now occurs. Crioceris asparagi and C. duodecimpunctata spread steadily throughout eastern Canada by adult flight dispersal abetted by wind, by the dissemination of seeds by birds, and by commercial movement of root crowns and spears of asparagus. Asparagus escaped from cultivation, growing along transportation corridors (such as railway tracks, power utility right-of-ways and roads) and in vacant lands, which facilitated the spread and establishment of C. asparagi and C. duodecimpunctata throughout North America. Now, both these adventive pest species occur wherever asparagus is grown. Both C. asparagi and C. duodecimpunctata are confirmed to occur in New Brunswick and Nova Scotia, but not Newfoundland and Labrador. However, C. duodecimpunctata is newly recorded from Prince Edward Island. These introduced beetles are not regulated by Canada or by the U.S.A., and they are readily controlled at economically acceptable damage thresholds.