Beech leaf-mining weevils are small. But researchers say they shouldn’t be underestimated

The beech leaf-mining weevil may be small in size, measuring only two millimetres in length, but its impact on American beech trees is significant. Acadia University biology professor Kirk Hillier emphasizes that despite its tiny stature, this green-and-gold invasive species can bring down a mature beech tree in just a few short years.

A collaborative effort between entomologists from Acadia University and Natural Resources Canada has been focused on studying ways to trap, track, and monitor the spread of the weevil throughout the Maritimes. The arrival of these weevils in the region over a decade ago, possibly introduced through shipping materials from Europe, has raised concerns about their rapid spread to provinces like P.E.I and New Brunswick.

The team of researchers has developed a specialized prism trap designed specifically for capturing these weevils. Similar to traps used for the emerald ash borer, these devices serve as a monitoring tool rather than a population control method. Hillier explains that while the traps alone may not be sufficient to manage the weevil population, they do provide valuable data for assessing population levels and the need for insecticidal treatments.

One effective method of population monitoring involves physically shaking branches to dislodge weevils, a task that requires manpower but offers real-time data on infestation levels. Additionally, recent experiments have shown that the placement of traps at head level versus high up in the canopy yields similar results, making the monitoring process more accessible and efficient.

Jonathan Sweeney, a research scientist with the Canadian Forest Service, underscores the importance of these research efforts in guiding management strategies and protecting the American beech tree, which serves as a vital habitat and food source for local wildlife. Joel Goodwin, a biologist and PhD candidate, highlights the need for wider deployment of traps by government agencies to map infestations and implement targeted management strategies.

With a growing awareness of the threat posed by the beech leaf-mining weevil, continued research and collaborative efforts are essential in safeguarding the health and longevity of American beech trees in Nova Scotia and beyond. By leveraging innovative trapping methods and monitoring techniques, researchers aim to mitigate the impact of this invasive species and preserve the ecological balance of local habitats.