Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2007
Publication Date: December 8, 2007
Citation: Smith, L. 2007. Using our experiences with knapweeds and yellow starthistle to improve methods to evaluate new prospective biological control agents. Entomological Society of America Annual Meeting. Technical Abstract: Biological control projects for spotted, diffuse and squarrose knapweeds and yellow starthistle started 30 to 40 years ago. Twelve species of insects were introduced for the knapweeds and six for yellow starthistle. Less than half of these biological control agents have become widespread and abundant. However, all of these target weeds have begun to decline in at least part of their ranges. I review the attributes of agents in light of their subsequent ability to attain populations sufficiently high to impact the target weeds. In general, the agents must be adapted to the variety of plant that is targeted and to the abiotic environment, and must avoid predation. Both agents that attack seeds and those that attack vegetative parts of the plant have contributed to weed reduction. Insects having one generation per year have interfered sometimes with those that have multiple generations. Of greatest importance is the ability to attain high populations of the insects on the plants. These results can be used to help guide future biological control projects to improve the efficiency of selecting and evaluating prospective agents to achieve effective control of the target weed.