Bugs Enlisted in the War on Weeds and Invasive Ornamentals
Jul 11, 2005 | 251 views | 0 0 comments | 5 5 recommendations | email to a friend | print
It sounds so simple: Enlist bugs as soldiers in the war on noxious weeds and invasive ornamentals.

To that end, flea beetles were recently released in southwest Colorado in an effort to stop the proliferation of leafy spurge.

The tiny beetles "work really well in some places," says San Miguel County Weed Manager Sheila Grother, and "have been released in some of the big problem areas in Ouray County for a number of years."

But it's more complicated than just breed and release, she emphasizes. With flea beetles, for example: "Some of them like to be on the south side of the mountain; some of them like the north side," she says.

And so "you have to release a suite - a whole bunch of different subspecies - to get established."

The trick, Grother explains, is "finding the exact subspecies that will exist at a certain elevation in a certain climate." And even then, with "the bugs that do get established and start to work, you can get a bad winter, and suddenly your population can crash."

In the battle against leafy spurge, Grother says, scientists experimented with flea beetles after noticing, on a visit to northern Europe, that "leafy spurge is not a dominant plant species.

"They figured out what was controlling" the weed's proliferation, discovered it was flea beetles, "and brought them here."

Before the insects are sent out to wage war on weeds, however, extensive laboratory work is done. First in the line of defense is to "put them on the plant and figure, 'Yup, it will eat it,' and then keep them in 'caged release'" while experimenting "in every way possible" to discover what else the insect might want to eat.

Caution prevails because of incidents like that of the Hawaii planters who imported the mongoose, from Africa, to help control rats. With no natural predator, the mongoose preyed on the Nene goose and more, with disastrous consequences.

Sometimes the bugs' background check can take years, Grother says. "It can be multiple years now before they do any releases, and they're pretty sure by the time they do a release that the bugs won't be getting something they don't know about."

Colorado, she says, was the first state to conduct insect releases "in the late 1970s," releasing beetles in an effort to curb musk thistle. "They unfortunately didn't do their research," she says of that early effort; as a result, those beetles "are endemic."

Scientists are currently experimenting with a "little leaf-eating beetle that will defoliate tamarisk," an invasive plant that can consume up to 300 gallons of water a day, that is desertifying the West, where it out-competes native plants for water. Studies of the beetles "are being conducted at an "insectary" in Palisades. "They are getting some control in small areas," Grother reports, "but the bugs aren't moving very fast, and they're having trouble climatically.

"The goal would be to have millions and millions of bugs out there," she says.

"As far as I know," says Grother, Colorado is unique in that it even has an insectary. "There are private ones and some federal government ones, but Colorado is the only state, as far as I'm aware."

The Palisades insectary is threatened, she adds, by budget cuts. "Until someone fixes the Tabor Amendment," she says, "the insectary is on the chopping block."

Locally, she says, "we do releases here every year" on milk thistle and yellow toad flax; this summer, a group of bugs has been released to eat musk thistle; and a new group of insects is being developed to attack bindweed. "Last year," she says, "we did a release on bull thistle.

"I do want people to know that our program involves more than just using herbicides," says Grother, of the county weed program. The Greenbucks weed-pulling program too is now at full throttle. Greenbucks cleanups run Saturdays through Sept. 24, 10 a.m.-2 p.m. To participate, call Doug Rowden, Greenbucks project coordinator, at 970/901-0188. Greenbucks can be exchanged for discounts at participating area businesses or for tickets to summer festivals in Telluride.
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