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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: Genetic and behavioral differences among purported species of the weevil Trichosirocalus (Coleoptera: Curculionidae) for biological control of thistles (Asteraceae, Cardueae)

Authors
item DE Biase, Alessio -
item Primerano, Simona -
item Belvedere, Silvia -
item Colonnelli, Enzo -
item Smith, Lincoln
item Cristofaro, Massimo -

Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Abstract Only
Publication Acceptance Date: September 11, 2011
Publication Date: N/A

Technical Abstract: Technical Abstract and Interpretive Summary: Provide electronically in Word. Trichosirocalus horridus was introduced to North America, New Zealand and Australia for biological control of Carduus nutans. Since then two more species of Trichosirocalus have been described (Alonso-Zarazaga and Sánchez-Ruiz. 2002. Aust. J. Entomol. 41: 199-208), and the three species are thought to have different host plant associations: T. horridus on Cirsium vulgare and possibly on other Carduineae, T. mortadelo on C. nutans, and T. briesei on Onopordum spp. This raises the question of which species were previously released for biological control of C. nutans. Subsequent studies by Groenteman et al. (2009, XII International Symposium on Biological Control of Weeds, pp. 145-149.) raises uncertainty about which species are in New Zealand and whether T. mortadelo was a valid species. Trichosirocalus briesei was introduced to Australia to control Onopordum spp. and is being evaluated for introduction to North America. We analyzed part of the mtDNA cytochrome oxidase I (COI) gene sequence of adult specimens representing the three species collected in Spain, Italy, USA, New Zealand and Australia. All specimens morphologically identified as T. briesei formed one clade that was clearly distinct from all the other specimens. The COI sequences for specimens of T. horridus and T. mortadelo were intermixed within the same clade, suggesting that they represent one heterogeneous species. Furthermore, the morphological characters attributed to T. mortadelo are of little significance to reliably isolate two different species, so that we combine them under the name of T. horridus. In laboratory choice experiments, specimens from Spain identified as T. briesei preferred Onopordum acanthium to Carduus or Cirsium spp., whereas those from North America, identified as T. horridus preferred Carduus spp. but also attacked Cirsium spp.

Last Modified: 10/31/2014
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