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United States Department of Agriculture

Agricultural Research Service

Research Project: Biological Control of Invasive Terrestrial and Riparian Weeds in the Far Western U.S. Region, with Emphasis on Thistles, Brooms and Cape-ivy

Location: Exotic and Invasive Weeds Research

Title: Field experiments to evaluate host plant specificity of prospective agents of Onopordum acanthium in Bulgaria

Authors
item Harizanova, Vili -
item Stoeva, Atanaska -
item DE Biase, Alessio -
item Di Cristina, Franca -
item Paolini, Alessandra -
item Cristofaro, Massimo -
item Smith, Lincoln

Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Abstract Only
Publication Acceptance Date: January 14, 2014
Publication Date: N/A

Technical Abstract: Scotch thistle, Onopordum acanthium, is an invasive alien weed in North America that originates from Europe. Previous field observations in Bulgaria have confirmed the presence of prospective biological control agents including Cassida rubiginosa, Chaetostomella cylindrica, Eublemma amoena, Larinus filiformis, Larinus latus, Lixus cardui, Myelois circumvoluta, Pyroderces argirogrammos, Tephritis postica and Trichosirocalus briesei. Although five of these species have been introduced to Australia as biological control agents, further host specificity evaluation must be done because of concern for potential risk to Cirsium species native to North America. Field garden experiments were conducted in the region of Plovdiv, Bulgaria to evaluate the host plant specificity of L. cardui and L. latus in 2012 and 2013. Non-target North American Cirsium species were grown indoors during the winter and planted in the garden in early spring. We released 90 adult L. latus on 22 June 2012, and 115 on 24 June 2013. Many of the Cirsum plants were attacked by soil fungi, nematodes and snails and many failed to bolt and flower. In 2012, L. cardui attacked 100% of Arctium lappa, 43% of artichoke (Cynara scolymus) and 67% of O. acanthium stems. In 2012 and 2013, Larinus latus infested seedheads of only O. acanthium and caused no damage to artichoke, Carthamus lanatus or Cirsium brevistylum. The results indicate that this population of L. cardui is not safe because of risk to artichoke, but that L. latus warrants further evaluation of non-target North American plants.

Last Modified: 12/19/2014
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