RELEASES OF ALTICA CARDUORUM (CHRYSOMELIDAE: COLEOPTERA) AGAINST THE WEED CANADA THISTLE (CIRSIUM ARVENSE) IN CANADA

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Abstract
The flea beetle Altica carduorum Guer. was released in four provinces in Canada to aid in the control of Cirsium arvense (L.) Scop, but did not survive in open fields with the exception of a small colony at Lacombe, Alta. It thrived, however, at four locations in different climates when protected by field cages. The mortality of the eggs and(or) the larvae reached 91%, that of the overwintering adults 83%. The mortality of the immature stages was apparently mainly due to predation and at a release site near Belleville Leptus sp. near curtipes Schweizer and Sphaerolophus sp. (Erythraeidae: Acarina) were implicated in tests with A. carduorum eggs labelled with P32. Field and laboratory experiments showed that dry continental summers, such as occur at Summerland, B.C., and Lacombe, Alta., were probably not detrimental to either egg development or pupation.