Asian Long-Horned Beetle
On September 4, 2003, curiosity, research and perseverance led to one of the most important discoveries of tree infestations in Ontario. Fascinated by an unusual insect found in Vaughan, north of Toronto, a member of the public called the Canadian Food Inspection Agency (CFIA) who confirmed the insect’s identity as the Asian long-horned beetle (ALHB).
Bluish-black in colour with a scattering of white spots, and over an inch long, adult ALHBs are easily identified. After mating, adult females will deposit eggs under the bark of susceptible trees from June to October. Within two weeks, larvae emerge from the eggs and feed on the cambium layer of trees, interrupting the flow of nutrients and water in the tree, before tunnelling into the heartwood. Larvae become pupae and then adults who tunnel their way back through the cambium layer to the surface. Adult females may stay on the same tree or may fly to another host tree within a few hundred metres before repeating the cycle. A major infestation can weaken a tree, eventually causing it to starve and die.
Originally from Asia, the adult ALHB has no natural predators in Ontario, and tunnels protect the larvae and pupae from predation. Furthermore, there are no parasites or diseases to control ALHB populations. Nor is Ontario’s weather a limiting factor. Without the normal population controls, ALHB populations could spread to hardwood trees throughout Ontario and beyond. Maple trees are particularly susceptible, but so are horse chestnut, poplar, birch, willow, elm and mountain ash. Toronto has 485,000 susceptible trees on public land, and many more on private land.
By late September 2003, a central area of infestation in Vaughan and three satellite infestations had been found, and a plan developed by the CFIA several years ago had been activated. Two control methods had been identified – removal of all infested and susceptible trees or application of the pesticide imidacloprid. Public information sessions and extensive media coverage helped inform the public. A ministerial Order prohibiting the movement of nursery stock and wood through and out of the infested area unless authorized was issued by CFIA on February 26, 2004. By spring 2004, all susceptible trees within 400 metres of each infestation – over 15,000 trees, or more than half of the tree canopy in the infested area – had been removed, chipped and composted.
Since imidacloprid was not authorized for controlling ALHB in Canada, CFIA requested emergency registration of the pesticide. Treatment involves injecting the pesticide into the soil where it is absorbed by the roots. It then travels up the cambium layer of the tree. Since ALHBs have only brief contact with the cambium, imidacloprid is not 100 per cent effective and must be applied annually for several years. In addition, since adult ALHBs may actually avoid treated trees when selecting their next hosts, imidacloprid may actually cause ALHBs to travel further to find suitable hosts.
The CFIA plans to use a combination of removing susceptible trees and treating trees with imidacloprid within 400 – 800 metres of an infested area. Combating the ALHB has been expensive. The City of Toronto has estimated that it will spend $6 – $8 million in 2003 and 2004 on combating the ALHB, and the province is providing $1 million toward the cost of replacing the cut trees in ALHB- and emerald ash borer-infested areas. Imidacloprid treatment could cost $6.5 million annually for four years. The infestation in Vaughan will be considered eradicated if no ALHB are found for four years. Since ALHB probably arrived in wood packaging used to ship goods to Canada four to six years ago, there is a possibility that it has already spread to any locations where residents and wood from the infested area have travelled.
| Incidents of Asian long-horned beetle in North America 1992-2003 | |
|---|---|
| Contained at port of entry/warehouse | |
| 1992 | Vancouver |
| 1997 | British Columbia, Ontario, California, N. Carolina,
Ohio, Washington, Michigan and New York |
| 2000 | Seattle |
| Required eradication measures | |
| 1996 | New York |
| 1998 | Chicago |
| 2002 | Jersey City |
| 2003 | Toronto |
| This is an article from the 2003/04 Annual Report to the Legislature from the Environmental Commissioner of Ontario. |
Citing This Article
Environmental Commissioner of Ontario. 2004. "Invasive Alien Species - A Threat to Biodiversity." Choosing our Legacy, ECO Annual Report, 2003-04. Toronto, ON : Environmental Commissioner of Ontario. 51.
