Journal Article

An update on the identity of Longitarsus (Coleoptera: Chrysomelidae) species introduced or relocated in Canada for the biological control of tansy ragwort (Asteraceae)

De Clerck-Floate, Rosemarie A., Toševski, Ivo, Floate, Kevin D.

2024

Overview

Starting in the 1960s, the flea beetle Longitarsus jacobaeae (Waterhouse) (Coleoptera: Chrysomelidae) has been imported and relocated to North America for the control of the weed tansy ragwort, Jacobaea vulgaris (Asteraceae). Some Longitarsus species are morphologically almost indistinguishable, leading to questions regarding the taxonomic identity of the beetles released. Here, we present the results of a molecular study that addresses these questions and updates a list of the releases of Longitarsus within Canada. Our findings confirm the suspected release of the cryptic species L. flavicornis concurrent with releases of L. jacobaeae at sites in British Columbia, Canada, in the 1970s. However, we find no evidence for the continued presence of L. flavicornis at historical release sites in British Columbia nor in Nova Scotia, Canada, where it might potentially have been redistributed. We confirm the presence of L. gracilis Kutschera in Nova Scotia and British Columbia, the latter population likely established from a 2005 release of Longitarsus from Nova Scotia. To our knowledge, this study provides the first published confirmation of L. gracilis in Canada. Finally, we provide evidence that what were recognised in earlier work as three separate taxa (L. succineus (Foudras), L. near noricus, and Longitarsus sp.) are likely all L. succineus.

• Publisher: Cambridge University Press
• Subject: Asteraceae / Beetles / Biological control / Chrysomelidae / Coasts / Coleoptera / Cryptic species / Historic sites / Introduced species / Longitarsus / Longitarsus jacobaeae / Longitarsus succineus / Morphology / Population studies / R&D / Research & development / Research Paper / Senecio jacobaea