Hypena opulenta caterpillars for biological control of DSV
Note added 10 August 2018: The biological control agent Hypena opulenta is not available for redistribution.
In late June and early July 2014, we released Hypena opulenta caterpillars in Ottawa to combat dog-strangling vine (DSV). Like its host plant, Hypena opulenta is native to Ukraine. Before it could be released as a control agent, it underwent stringent testing to make sure it would not feed on other plants, especially DSV’s relatives in the milkweed family, some of which are endangered. Once the panel of expert reviewers was convinced that the risk of Hypena attacking other plants was vanishingly small, the release was approved.
The first release was a success. In late August, we saw a new generation of caterpillars feeding on DSV at the release site. One caterpillar was even found 200 meters from the original site, indicating that the adult moths are capable of dispersing at least this far (and probably much, much farther!).
In late August 2014, we released some caterpillars in large field cages. They spent the winter as pupae in the leaf litter at the base of the plants. A new generation of adult moths emerged in the cages in May 2015, indicating that Hypena was able to survive Ottawa winters.
Below is a link to the host-specificity testing conducted at the University of Rhode Island. This study was used to determine that Hypena was safe to release in Canada:
http://digitalcommons.uri.edu/dissertations/AAI1497502/
Every year since 2015, the Hypena population in Ottawa has grown and spread from the initial release site. In 2016, it was spotted in the Dominion Arboretum. In 2017, damage was seen at Hog's Back Park. This year, we have seen damage in the Fletcher Wildlife Garden. Mostly these sightings were a few holes in leaves, rather than large aggregations of caterpillars. This summer (2018), however, we are starting to see larger concentrations of feeding damage in isolated areas, slowly approaching the population levels we will need if Hypena is to have a negative impact on DSV. This paper summarizes the establishment and population growth of Hypena opulenta from 2014 through 2018:
https://www.tandfonline.com/doi/abs/10.1080/09583157.2019.1608511