A researcher is investigating the impact of an invasive insect and the chemicals used to combat it on the species residing in ancient hemlock forests. The hemlock woolly adelgid (HWA) has been causing significant damage to forests in southwestern Nova Scotia for nearly ten years. To control its spread, various entities such as Parks Canada, the province, local organizations, and private landowners have been employing insecticides like imidacloprid and dinotefuran.
Despite these efforts, Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the lack of knowledge regarding how the woolly adelgid and the insecticides are impacting other species. Christjansen emphasized that imidacloprid, designed to target insect nervous systems, has been detected in the brains of other animals like fish and tadpoles.
To gain insights into the broader ecosystem, rather than studying all species across hemlock forests individually, the research team is using the eastern red-backed salamander as a bioindicator species. This salamander is particularly sensitive to environmental changes and pollutants, making it a valuable indicator of overall forest health.
For their study, scientists placed coverboards in forests last year to serve as salamander habitats, periodically surveying them to assess the salamander population underneath. Some forests are being treated with insecticides to combat HWA, while others are left untreated. Behavioral tests were conducted on the salamanders found, including assessing their reactions to predation stimuli and their agility in righting themselves when flipped upside down.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, emphasized the significance of salamanders as indicators of forest health due to their abundance and biomass in Eastern Canada woodlands surpassing that of deer.
The study is also examining how dying hemlocks impact salamanders, as these trees create ideal habitat conditions with their dense canopies that maintain cool and moist microclimates. The project involves collaboration between Mount Allison University, the Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan, as part of a larger study on forest health in Eastern Canada.
The research led by Mathilde Christjansen is ongoing and scheduled to continue until next year. After collecting data over the summer, the team will analyze the information and field videos gathered during the study.