Growing beneficial bugs

by Bill Loftus

Rush skeletonweed plants grow in a greenhouse near Lapwai, carefully tended to serve as hosts for a moth from central Europe, the plant's natural enemy.

Nez Perce Biocontrol Center Coordinator
Paul Brusven examines rush skeletonweed
with Deanna Walker.
Photos by Mark LaMoreaux.

Owned by the Nez Perce Tribe, and run with the help of UI College of Agricultural and Life Sciences (CALS) faculty researchers, the Nez Perce Biocontrol Center grows insects that are natural enemies of noxious weeds, employing a strategy that dates back to at least the 1940s when St. Johnswort was the target.

Paul Brusven, tribal biocontrol center coordinator, said producing and distributing insects to control weeds is central to the modern facility's mission.

So is outreach, which the center pursues with UI CALS experts including Mark Schwarzlaender, an assistant professor focused on the biological control of invasive weeds. They host nearly two dozen workshops on biocontrol in the region each year.

Revolutionary food speeds growth

The tribal center also works with USDA Agricultural Research Service scientists to develop a new artificial food to produce beneficial insects.

Marvin Hanks, like Brusven a UI alumnus, displays a small plastic container similar to a condiment cup. The brown, pudding-like non-plant substance inside is revolutionary for those who want to raise biocontrol insects.

Some formulas also contain ground-up plant materials for flavor, Schwarzlaender said. Artificial insect diets and environments bring a major advantage: they can reduce rearing times from a year to two months by maintaining insects in an environment that is warmer and richer in nitrogen. Both factors accelerate the insects' maturity.

Marvin Hanks checks cups with
artificial diet for moths.

"We're trying to get the recipe down so we can get the moth numbers up," Brusven said.

For all the threat rush skeletonweed poses to Idaho's public and private lands, and its ease at finding and dominating suitable habitats in the wild, it can be a temperamental crop. The biocontrol center staff needs the plants for the root-feeding moth, Bradyrrhoa gilveolella, to multiply.

The partners also try to help nature along in wilder settings. In early summer, Schwarzlaender used a paintbrush to dab tiny larvae of the moth directly onto rush skeletonweed plants along the main Salmon River to get new populations started.

Bugs and purple loosestrife

Biocontrol efforts against purple loosestrife, the showy purple flower that escaped from gardens to clog waterways, show the war can be won, Schwarzlaender said. Leaf beetles strip the plant above ground and root-borers infest its roots below. Their attacks have effectively eliminated the weed in much of Idaho.

Testing potential new biocontrol agents is an important part of the center's mission. Schwarzlaender is the point man in the search, visiting Australia over the winter and planning trips across central Asia as far as Mongolia to find other agents to fight other weeds.

When new agents are found, the partners will document their effectiveness, multiply them, and distribute them to landowners. The UI-Nez Perce partnership is rare across the nation but has other tribes and universities interested in reproducing its successes, Schwarzlaender said.

Contact Schwarzlaender at markschw@uidaho.edu

Meet beneficial insects reared in north-central Idaho.

Photos by UI's Mark Schwarzlaender and Laura Parsons.

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