The URI team began releasing the adult parasitoids in 1989 at Ryan Park off Oakhill Road in North Kingstown, and they have been monitoring the site ever since. The parisitoids spread quickly, but the build-up in population went slowly, Casagrande said.
The birch leafminer is not a fatal pest to birches. It disfigures the trees by mining within the leaves, and since birches are often used for landscaping, the effect became an aesthetic issue. Birches do have a fatal pestthe bronze birch borer which can kill white-bark birches very quickly, but no biocontrol has been found for this native pest.
Casagrande said it is satisfying to be able to state publicly that a biocontrol program has succeeded.
"It takes lot of people and lots of cooperation to pull it off," he said. "Biological control systems such as this can be quite inexpensive and result in permanent, selective control of target pests."
URI, he notes, is coordinating a new regional research project intended to assist researchers working on a number of other important insect pests and weeds.
"The birch leafminer program is a good example of the results of a coordinated, long-term approach to classical biological control," Casagrande said. "We're seeing similar success with programs for purple loosestrife, cypress spurge, mile-a-minute weed, and perhaps, lily leaf beetle, but as you can see, it takes time34 years in this case for complete control."
|Contact: Todd McLeish|
University of Rhode Island