Carleton University’s Naomi Cappuccino, associate professor in the Department of Biology is part of a research team that discovered a bio-control agent, the Hypena moth that may help in the battle against dog-strangling vine (DSV), an ominous-sounding plant threatening native vegetation in southern Ontario and eastern North America. The research team involved scientists from Carleton University, Agriculture and Agri-Food Canada (AAFC), the University of Toronto, the University of Rhode Island (URI), the Ontario Ministry of Natural Resources, the Commonwealth Agricultural Bureaux International (CABI) in Switzerland and forest management company SilvEcon.
“Since I arrived at Carleton in 1992, I’ve watched DSV completely fill the green spaces around the city,” said Cappuccino. “There are some special natural areas close to Ottawa, such as alvars, a globally rare habitat type with numerous threatened plant species. Landowners in this area need a remedy, as the plant is extremely difficult to eradicate.”
Cappuccino and the team seem to have found a weak link in the up-to-now impenetrable armour of DSV. This invasive plant, well named for its vines that form dense mats that strangle other vegetation, crowd out native plants and interfere with forest regeneration and agriculture. It is believed to have been brought to North America from the Ukraine in the 1800s and has now become a significant ecological threat to Canadian habitats, including rare species in Ontario’s Carolinian forest region. This weed, also known as swallowwort, is of particular concern because until now it has been spreading rapidly on this continent with no known natural enemies.
However, the team has been collaborating on the release program of a moth, Hypena opulenta, as a biological control agent for DSV in Ontario this summer. So far the released caterpillars are already making an impact on the weed in Ottawa and at field sites north of Toronto and will soon have completed a full generation from egg to adult.
“I have been monitoring the release site since early July to document the next generation of larvae feeding on the plants,” said Cappuccino. “It has been a cool July, which we think has slowed the emergence of the adult moths and development of their eggs, so we expect to see caterpillars within the next couple of weeks. The successful establishment of Hypena will open the door to many potential new studies, such as how it spreads through the landscape, the impact of the caterpillar damage on the plant and the response of other plant species once DSV has been knocked back.”
URI and CABI researchers first identified Hypena caterpillars, which are native to Ukraine, as a possible defence against the vine in 2006. Since then the insect has undergone extensive testing by the international team to confirm that it can only survive on DSV and will not feed on native plants. The insect was approved for release in Canada in 2013. Once established at the initial release sites, Hypena moths will disperse to find new patches of DSV. Hypena caterpillars will defoliate the DSV and because they can only survive on DSV, their populations will rise and fall with the availability of their host plant.
Successful biological control is a long-term proposition and it will take several years to get caterpillar populations widely established and observe impacts over the large areas affected by DSV. The team is optimistic about the outcome of the release.
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