Biocontrol/Parasitic Wasps Release Project
In the summer of 2011 Dr. Ken Raffa and Todd Johnson, from UW-Madison, released 5400 tiny parasitic wasps at Riveredge to feed on EAB larvae & eggs. Their hope was that the wasps would survive and multiply enough to eventually eliminate EAB from this area sometime in the future.
In January, 2013 Dr. Raffa & Todd returned to Riveredge to determine if the wasps are successfully reproducing. To do this they harvested four EAB infested ash trees from the parasitic wasp release site in Mayhew Woods. The felled trees were cut into three foot sections and placed in sealed rearing tubes. The rearing tubes (~100) were stored in the Wallner barn and monitored last summer for emerging wasp parasitoids by volunteer, Chuck Ritzenthaler.
On November 7, 2013 Todd Johnson informed us that one of the biocontrol agents successfully emerged and were found in the samples Chuck collected from the rearing tubes. A total of 38 females and 2 male Tetrastichus planipennisi (parasitic wasps) emerged over four dates from two logs from the same tree. Juli Gould, from the USDA, told Todd that “this shows that the parasitoids have actually established themselves at Riveredge, since they are not only reproducing in the field but also have gone through several summer/winter cycles.” With any luck these wasps will continue to thrive and help control EAB in this area.
At the end of this five year study (2016), USDA guidelines call for a total of 96 of our ash trees (48 in the control and 48 in the release plots) to be harvested and examined for wasp parasitoids. This may not be feasible given the location of these trees at Riveredge but the logistics will be reevaluated at the time.
EAB Detection Methods
Riveredge has become a showcase for demonstrating to other property owners the various methods used to detect and deal with the EAB. During thesummer of 2009, the Department of Agriculture, Trade and Consumer Protection (DATCP) placed purple traps of various sizes
and shapes on the property. The traps were made out of thin, corrugated, purple plastic coated with different sticky, non-toxic substances used to lure the ash borers to them. Similar traps were placed in other parts of the county and state. If you see a trap in your area it doesn’t mean that EAB are in your neighborhood. The traps are simply used to determine if EAB are present and if so in what quantity.
A study initiated by Jane Cummings Carlson, forest health coordinator for the WDNR, in June, 2009 involved creating five EAB “sinks” near our west entrance. Each sink consisted of a cluster of one control and three girdled ash trees. The clusters were located within 50 feet of an existing trail to allow easy access and removal. The dying, girdled trees emitted a scent which drew in emerald ash borers that were looking for brood trees. These girdled trees were cut down and hauled out using Percheron horses on February 20, 2010 during a small-scale logging demonstration. Samples from each of the tree clusters were examined by DNR experts to determine their degree of the infestation. Over 2,000 board feet of ash lumber was cut here that day.