Ph. Dunn et G. Campobasso, FIELD-TEST OF THE WEEVIL HADROPLONTHUS-TRIMACULATUS AND THE FLEABEETLE PSYLLIODES-CHALCOMERA AGAINST MUSK THISTLE (CARDUUS-NUTANS), Weed science, 41(4), 1993, pp. 656-663
This study was conducted to determine if field evaluations could be us
ed to select insects for biological control of musk thistle. Host spec
ificity and larval development of a weevil, Hadroplonthus trimaculatus
, and a fleabeetle, Psylliodes chalcomera, were studied in field trial
s near Rome, Italy, in which insects were allowed free choice of sever
al hosts. Natural populations of these two insects, which do not occur
in North America, were exposed to North American species of Cirsium,
Carduus, and selected crops. Adult insects and larvae on host plants w
ere identified and counted on test plants from North America and nativ
e attraction plants. In addition to infesting musk thistle, weevil adu
lts and larvae were recorded on flodman thistle, wavyleaf thistle, and
spinosissimum thistle. Consequently, this insect was not suitable for
introduction into North America. The fleabeetle would be satisfactory
for biological control since no adults or larvae were recorded on Cir
sium spp. or economic plants. These studies show that field trials are
a valid method for identifying specific and nonspecific candidate ins
ects for biological control of weeds.