High Schoolers Learn About Biocontrol
Clark Israelson is the Agriculture Extension Agent for USU Extension in Cache County. Much of his work deals with forage crops, small grains and oilseed plants. A native of Cache County, Clark was raised on a diversified family farm. He enjoys being involved with commodity organizations and the Utah Farm Bureau Federation.
High school science students were involved in helping to collect and release Mecinus janthinus weevils as biocontrol agents to manage Dalmatian toadflax.
Weeds have been a menace since the time humans began cultivating fields and grazing livestock. Traditional methods of weed control include cultural, mechanical, and chemical means. Biological weed control is another method that shows much promise. This self-sustaining, environmentally-friendly method consists of introducing and managing selected natural enemies into invasive weed patches. These host-specific, plant-feeding organisms reduce the competitive advantage of weeds, thus allowing more desirable plant species to thrive. Biological control agents (BCAs) are on duty 24 hours a day, 7 days a week. For weeds growing in less accessible areas, biological control is an effective method for weed control. This long-term, self-perpetuating control method results in a lower cost per acre and allows BCAs to build up and disperse to the limits of the infestation.
Some of the disadvantages of BCAs include the limited availability of agents for some plants, and BCAs are often slower than other methods of weed control. Additional challenges to biocontrol methods have to do with the time required to monitor and evaluate beneficial insect numbers, collection of excess populations, and the redistribution of BCAs to new areas.
USU Extension, County Weed Departments, US Forest Service, BLM, and APHIS have worked cooperatively to establish thriving BCA populations. Our problem, however, has been our inability to properly monitor the effectiveness of BCAs, and then to collect and redistribute them to new areas when needed. It seems we never have sufficient time or manpower.
To remedy this dilemma, Cache County Weed Warriors obtained an IPM/WSARE grant for two years and involved local high school science students in collecting and distributing BCAs. Other participants included representatives from Cache County Weed Department, USU Extension, Amber Mendenhall from APHIS, and Carla Hoopes who was filming a documentary on biocontrol.
To introduce the concept of invasive species, Eric Bingham, Cache County Weed Department, presented a slide show to the students, focusing on the dangers of noxious weeds and the concept of biocontrol. Afterward, the students and other participants headed to Ogden Canyon where we collected 5,000 Mecinus janthinus weevils, which are the biocontrol agent for Dalmatian toadflax weed.
The following day, the group traveled to the release site just below first dam in Logan Canyon. Before releasing, we had the students try to find weevils that had survived the winter from release one year earlier. The students were excited to see that the weevils were able to survive at this site. The students then released 2,500 weevils at the Cache County site in Logan Canyon and sent 2,500 with Amber (APHIS) for release at other sites in Salt Lake County and surrounding areas. At the time we did our collection, M. janthinus weevils were selling for $1.50 each. As such, our one field day of collection netted $7,500.
We held another field day in late June to collect Aphthona nigriscutis flea beetles for control of leafy spurge weeds. We estimate that we collected approximately 5,000 bugs which would be valued at $500. We released them at a site near Cove in northern Cache County. Release survey sheets were completed prior to the release. Leaders also helped students assess the impact of reduced leafy spurge plant populations based on our release from the previous year. We saw significant impact, though more time will be needed to completely control the current infestation of weeds.
The students had enlightening educational experiences learning about biocontrol. They were amazed to see the difference between the collection sites and the release sites. The insects are doing an impressive job in controlling specific weeds at the collection sites. The field days were a success from both a financial and educational perspective.
We think we have made a significant improvement in our success by involving local high school science students who have an interest in plants and insects. Not only have they been helpful here and now, but they will carry the biocontrol concept to the next generation. In many cases, their parents or grandparents are the current landowners in areas where biological control of weeds is a sustainable approach.