Invasive yellow toadflax (Linaria vulgaris (L.) P. Mill.) was introduced in British Columbia and has spread across the province; as of 2021, it has been recorded at 2058 locations in a range of habitats. Biological control agents are being used to reduce the abundance and slow the spread of yellow toadflax, but they will not eradicate it. Three federally permitted biological control agents have been released in the province to control this invasive plant. One agent, Rhinusa linariae Panzer, Curculionidae, a weevil, is suspected of being particularly effective. At a site on Nickel Plate Mountain (1710 m elevation), the weevil appears to have significantly reduced the frequency of occurrence of yellow toadflax within the plant community by 90.3% in 8 years. R. linariae density increased to 32 weevils per square metre or 0.96 weevils per plant before it rapidly declined in synchrony with its host plant to 4.7 weevils per square metre or 1.3 weevils per plant as weevils crowded into the remaining yellow toadflax plants.
Turner, Susan C., Bassett, Eleanor; and Cesselli, Sandy C.. 2023. Rhinusa linariae Effect on Yellow Toadflax (Linaria vulgaris) on Nickel Plate Mountain, British Columbia. Ministry of Forests. Technical Report (FLNRORD). TR145
Scientific Name: Linaria vulgaris
ISBN: ISBN 978-0-7726-8
English Name: Butter-and-eggs
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