Biocontrol Agent Fails Again

Biocontrol agents, such as foreign insects, can theoretically be used to control invasive, foreign plants. But scientists in Montana have found that through complex community interactions the presence of an introduced fly meant to control spotted knapweed actually accomplishes the opposite. The story goes like this:

Imported Eurasian fly infects spotted knapweed which produces galls.
Galls feed local deer mice which allows mouse population to grow.
The more numerous mice eat a larger portion of the native plant seeds.
Native plant seedlings become rarer which allows the weed to spread, and...