Monday, December 14, 2009
Hall D, First Floor (Convention Center)
Releases of Trichosirocalus horridus (Coleoptera: Curculionidae),
native to Europe, began in Tennessee in 1989 as part of a biological control program against musk
thistle (Carduus nutans). In surveys conducted to investigate
non-target feeding of T. horridus on native Cirsium thistle species from 2005
through 2008, adults of T. horridus were observed on all five native Cirsium thistles. These data represent the first documentation
of T. horridus
occurring on three of these native species [C.
carolinianum, C. horridulum
and C. muticum],
and the first record of T. horridus occurring in the Great Smoky Mountains National Park. While C.
carolinianum and C. horridulum did not show symptoms of
larval feeding in the meristematic tissues, C. altissimum,
and C. muticum
all had damaged meristems and possible oviposition scars on the midribs of the leaves. However, the impact of feeding by larvae of T. horridus on
the reproductive potential of native plants is uncertain, because even in the
target species (musk thistle and other introduced Cirsium species) plant death
rarely occurs, and seed production continues.