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We have completed
a two year study of Eustenopus villosus, one of three weevils that
we introduced, with the assistance of USDA-ARS scientists from Greece
for the management of yellow starthistle. This insect causes significant
damage and impact to the weed, feeding as adults on young buds and
as larvae within the seed heads of larger buds. Plants attacked
by this insect produce few seeds. This insect will be a central
player in the management of this weed.
We also completed
a study evaluating the seasonal synchrony of Eustenopus villosus
and its host plant, yellow starthistle. This insect was originally
collected in Greece; thus, the question was whether it had adapted
to Idaho conditions. The good news is, "yes," so much so that the
adults were well synchronized with the presence of small buds that
they fed upon and that the female were later synchronized with the
larger buds that she needed to lay eggs. Again, this is another
reason why the insect is a central player in yellow starthistle
management.
Development
of Protocols for the Collection, Release and Monitoring of
Biological Control Agents of Yellow Starthistle
In cooperation with USDA-Forest Service, we have developed draft
protocols for the implementation of biological control of yellow
starthistle. The purpose of these protocols is to facilitate the
proper handling and implementation of biological weed control agents
by inexperienced practitioners. These protocols will be assessed
and modified as needed next year.
Biological
Control of Weeds: Hawkweeds
We have just completed the first of a two-year study, funded by
a NRI competitive grant, to assess the response of yellow hawkweed
to damage. We artificially damaged flower stems and stolons of hawkweed
and assessed its growth response under different levels of nitrogen
fertility and grass competition. The goal is to imitate the damage
of potential biological control agents that we know to occur in
Europe. Stolons are important sites of attack because they do not
occur in native hawkweed species: thus, they are a safe site that
protects the native species from potential attack. If the plants
dramatically compensate to our damage by putting out more stolons
or flowers, then it may not be appropriate to spend money on host
specificity testing and future colonization of this insect. Final
assessment of this work will be conducted in 1998.
For more information contact:
Mark
Schwarzlaender
Phone: 208-885-9319
Fax: 208-885-7760
E-mail: markschw@uidaho.edu
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