by W.D. McIlveen

The situation regarding invasive species is never static. Periodically we get good news mixed in with the gloomy reports of some new species that has appeared at our door. And so it is that we have some recent changes in local matters pertaining to invasive alien species.

Starting with the bad news first, the Asian Longhorn Beetle (Anoplophora glabripennis) which attacks a wide range of tree hosts had been declared eradicated from the Cities of Toronto and Vaughn. By 2003, the beetle had established a modest area of infestation in the boundary area between those municipalities. An intensive program was launched to eliminate the infestation by cutting and destroying all of the host trees within a 400 metre radius of the infestation. After detailed surveys of the area had found no more indications of the beetle for a period of five years, the pest was declared eradicated by the Canadian Food Inspection Agency (CFIA) on April 5, 2013. Unfortunately, a new infestation was detected in an industrial area on American Drive near Pearson International Airport in Mississauga on September 20, 2013. It is not known if the two areas of infestation are connected. They are not located too far apart so a connection cannot be ruled out though a new source of infestation is presumed. Multiple points of infestation are known at other locations in North America where similar eradication programs had been carried out. Some trees have already been cut down and it is expected that a similar form of eradication program will be undertaken to insure that the beetles do not spread.

On August 23, 2013, Credit Valley Conservation (CVC) reported that two round gobies (Neogobius melanostomus) were caught in the west Credit River at Hillsburgh. Additional surveys found at least 50 more of the fish just downstream. Previously, the species had been found only at sites in the catchment area where the water was closely connected to Lake Ontario, a location where the species has become well – established. It seems improbable that the fish had made it to Hillsburgh across dams and other obstacles without some sort of human intervention, whether intentionally or unintentionally. A program to manage the problem species needs to be developed in concert with MNR, CVC, local land owners and other stakeholders.

Not all news concerning invasive species is bad. In 2006, moth larvae were found feeding on swallow-worts in southern Ukraine. The larvae were brought to the Commonwealth Agricultural Bureau International (CABI), a highly recognized facility that studies biological control agents, in Switzerland for rearing and initial testing. The moths were found to be host-specific and very effective in controlling the host plant. Additional testing was done at the control facility at the University of Rhode Island to verify the results. The tests were so successful that the University petitioned the U.S. Department of Agriculture in 2012 to allow for the release of the moth to control the Swallow-wort problem. The US still requires one additional step before approval is granted but that approval appears to be easily achievable (after the current political financial situation is resolved in that country). The application though has met all of the conditions set by Canada concerning the release of a biological control agent. As a result, 500 of the moth larvae were released at infested sites near Ottawa. So far, the caterpillars appear to be surviving well and the populations are being monitored. In time, it is not unreasonable to expect to see the moths make their way to our area. While there are many areas in the Province where Swallow-worts are a problem, there are many places around Toronto (e.g. Don River Valley) where the populations are very dense. The moth is known as Hypena opulenta (Figure 10). It resembles a few other Hypena species that occur in our area; however, those other species do not feed on Swallow-wort. This similarity and any resulting confusion may hinder the monitoring of the spread of the species into our area but the presence of the distinctive caterpillars (Figure 2) feeding on the plants should be easy enough. Naturalists should be on the lookout for these caterpillars wherever the Swallow-wort is present though it may take several years to reach here on its own.