How to use black dot leafy spurge flea beetle for biocontrol
Biocontrol category: Classical - released once and persists
Where to use: Leafy spurge flea beetle establishment is best on silt loam, silt clay loam, clay loam and clay soils with an organic matter content of 6 to 9.5 percent. In addition, the release area needs to be well drained and not subject to frequent prolonged flooding or standing water, which will kill the larvae. Initial releases have been most successful on south-facing slopes in moderate densities of leafy spurge (60 to 90 stems per square yard) with minimal grass cover and thatch. Establishment in dense leafy spurge stands is often difficult.
When to use: Before moving black dot leafy spurge flea beetles, you should confirm with your local regulatory agency that this is permitted. Flea beetles should be collected as adults from established stands and moved to establish new populations. The “nursery” area should be monitored from late-June through mid-July when adults emerge from the soil and begin feeding on leafy spurge topgrowth. The best time to collect flea beetles for redistribution is from 10 AM to 3 PM when the air temperature is greater than 70 F, there is little or no wind, and the skies are generally sunny. Leafy spurge should be dry before collecting flea beetles because wet conditions will make sweeping difficult and reduces the adult survival during transportation.
Rate: Several hundred to 1000 adults should be released per spot as a group rather than spreading them thinly through the leafy spurge infestation. Flea beetles establish best in moderate densities of leafy spurge (60 to 90 stems per square yard) with minimal grass cover and thatch. Establishment in dense leafy spurge stands is often difficult. Release flea beetles on the margins of dense infestations and allow the insect to work into denser stands as the population builds.
Maximizing effectiveness: Once collected, the flea beetles should be transported in paper bags or containers. Do not use plastic containers because moisture condensing on the plastic can drown the insects. Add some leafy spurge to the container and place in a cooler containing ice or ice packs. Do not allow the containers or cooler to sit in the sun. Flea beetles should be released as soon as possible after collection. Releasing the same day as collection is ideal; however, insects can survive several days when refrigerated at 40 to 45 F. The more similar collection and release environments are, the sooner the flea beetles are likely to become established and begin to control leafy spurge.
Pest stage: Aphthona larvae feed on leafy spurge roots from the time eggs are laid and hatched in mid-summer until near soil freeze-up in mid-October. This is the primary way in which this biocontrol agent damages leafy spurge.
Mode of action: Weed-feeder
Commercially available: No
Compatibility: Several options are available for leafy spurge control besides biological control agents, including the use of herbicides, grazing, seeding competitive grasses, and cultivation. Before beginning a leafy spurge control program, consider the best options suited for the situation and utilize more than one. Most successful control programs have used multiple control methods combined over several years. (Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.)
