[PDF] Biological Control Of Tansy Ragwort Senecio Jacobaea L On A Disturbed Coastal Prairie In Del Norte County California eBook

Author : Carla C. Bossard
Publisher : Univ of California Press
Page : 366 pages
File Size : 37,67 MB
Release : 2000
Category : Invasive plants
ISBN : 9780520225466

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"Invasive nonnative plants threaten native species with habitat loss, displacement, and severe population declines, thus seriously reducing biodiversity. Invasive Plants of California's Wildlands is a tremendous source for land managers and others who are interested in protecting the rich natural heritage of California and surrounding states."--John C. Sawhill, President and CEO, The Nature Conservancy

Author : Rosalind R. James
Publisher :
Page : 134 pages
File Size : 23,36 MB
Release : 1989
Category : Arctiidae
ISBN :

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Field experiments were done to test the relative effectiveness of single and multiple biological control agents in reducing weed populations using two insects, the cinnabar moth, Tvria iacobaeae (L.), and the ragwort flea beetle, Lonqitarsus iacobaeae (Waterhouse). These two insects were released for biological control of the biennial weed tansy ragwort. Together, they had a greater impact on ragwort, at the experimental site, than either alone. Artificial defoliation simulated the cinnabar moth feeding behavior of defoliating and defoliating bolting plants in the early summer. Flea beetle larvae and adults were sampled to determine their seasonality and the plant parts and stages they most frequently fed on. Larvae fed internally in the leaf petioles and roots from October to July. Adults fed on leaves year round with their greatest activity occurring in late summer and fall. Flea beetles alone reduced vegetative plant densities by about 95%, but only with simulated cinnabar feeding did they affect flowering plants, reducing regrowth of leaves and flowers. Cinnabar moths alone had an effect only on flower and seed production. This combination of herbivores with little nicheoverlap, spread out attack over time, plant stages, and parts, and yielded stronger host population depression than either insect yielded alone.

Author : Susan C. Turner
Publisher :
Page : 19 pages
File Size : 15,18 MB
Release : 2022
Category : Invasive plants
ISBN : 9780772680631

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The flea beetle, Longitarsus jacobaeae (Swiss biotype), exhibited a classical biological control pattern on its host plant tansy ragwort (Senecio jacobaea L.) in Naramata, B.C. by rapidly increasing in number after its release and causing the decline of the plant. L. jacobaeae's presence was identified by approximately 1.6-mm2 feeding holes in the ragwort's leaves. L. jacobaeae fed preferentially on rosettes (p=0.0333) as opposed to bolted plants (p=0.4621). It caused a visibly significant decrease in the number of rosettes and bolted plants combined at the trial sites in 3-4 years (p=0.0221). From the point of release, L. jacobaeae dispersed 100 m over the study site in 4 years.