The beech leaf-mining weevil isn’t very big at only two millimetres in length.
But Acadia University biology professor Kirk Hillier says it shouldn’t be underestimated because of its size. The tiny green-and-gold invasive species can take down a mature American beech tree in just a few years.
A team of entomologists from Acadia University and Natural Resources Canada studied ways to trap, track and monitor the spread of the weevil throughout the Maritimes.
The weevils arrived in the region more than a decade ago. Humans have added to their spread.
The entomologists have used a number of methods to trap the weevils. They designed a prism trap for this specific species. The traps are similar to those used to trap the emerald ash borer, another invasive species in Nova Scotia.
“The ideal way to use these traps, in my opinion, is to monitor the movement and spread of these weevils, but also to give some sense of population levels and whether you need to actually engage in other things like insecticidal treatments,” Hillier said.
He said the traps are not enough to control the population, but they provide a measuring tool.
Hillier said the weevils arrived in Nova Scotia from Europe, possibly through shipping materials. From there, they spread to P.E.I and New Brunswick.
Jonathan Sweeney, a research scientist with the Canadian Forest Service in Fredericton, said banging on branches and counting how many bugs fall out is an effective method of population monitoring.
But he said it involves having people available to do the work. He said traps don’t require constant supervision.
Sweeney also said a recent experiment shows that there is no substantial difference between hanging the prism traps at head level versus high up in the canopy, which makes the process easier.
“The research was done to provide a tool to agencies or provincial governments that may be concerned about the American beech — to know where they have to be concerned, where they have to maybe potentially manage this pest,” he said.
Joel Goodwin, a biologist and PhD candidate at the University of Toronto, said he originally led similar research while at Acadia University. He said this latest study validates his research and he hopes it brings more public interest in this weevil species.
Goodwin said the conservation of other tree species in Nova Scotia often gets more attention. However, he said the American beech plays a role in Nova Scotia habitats as shelter and food for many local species.
“If you have massive hemlock trees with a lot of cultural significance and value as a timber resource, of course the resources are going to be allocated to that over this quirky little beech tree,” said Goodwin.
“Wider deployment of traps, especially by government agencies, could help map infestations and guide management strategies in targeted areas.”
