A researcher is investigating the impact of an invasive insect and the chemicals used to combat it on the wildlife in aged hemlock forests. Hemlock woolly adelgid (HWA) has been causing significant damage to forests in the southwestern region of Nova Scotia for nearly ten years. Various entities, including Parks Canada, the province, local organizations, and private landowners, have been employing insecticides like imidacloprid and dinotefuran to control its spread.
Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the lack of knowledge regarding the effects of woolly adelgid and the insecticides on other species. She mentioned that imidacloprid, designed to impact insect nervous systems, has also been detected in the brains of other animals like fish and tadpoles. Instead of individually studying all species across hemlock forests, the research team is focusing on using the eastern red-backed salamander as a bioindicator species to assess the overall ecosystem health.
Last year, scientists placed coverboards in the forests to serve as salamander habitat and conducted periodic surveys to monitor the salamander populations, measuring and tagging them during the process. Some forests under observation are undergoing HWA treatment with either or both insecticides, while others remain untreated. The team also conducted behavioral tests on the salamanders found, assessing their responses to predation stimuli and their agility.
According to Christjansen, the condition and characteristics of the salamanders can provide insights into the broader impact on the ecosystem. Julia Riley, an associate professor at Mount Allison University and a supervisor of the study, emphasized the significance of salamanders in indicating forest health due to their abundance and biomass in Eastern Canadian woodlands.
The study also examines how the decline of hemlock trees affects salamanders. Chris Edge, another supervisor and a scientist with the Canadian Forest Service, mentioned that dying hemlocks alter the forest habitat, leading to potential impacts on salamanders due to their sensitive skin and moisture requirements.
The project, conducted in collaboration with multiple institutions, including Mount Allison University, Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan, is part of a broader investigation into forest health in Eastern Canada. Christjansen plans to continue her study until the following year, analyzing the collected data and field videos obtained during the summer research period.
