A researcher is investigating the impact of an invasive insect and the chemicals used to combat it on the wildlife residing in aged 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 groups, and private landowners have resorted to insecticides like imidacloprid and dinotefuran.
However, Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., has highlighted the lack of understanding regarding the effects of woolly adelgid and the insecticides on other species. She emphasized that while imidacloprid is primarily designed to impact insect nervous systems, it has been detected in the brains of other creatures like fish and tadpoles.
Rather than individually examining all species in multiple hemlock forests, Christjansen’s team is using the eastern red-backed salamander as a bioindicator species to provide insights into the overall ecosystem. These salamanders are known for their sensitivity to environmental changes and pollutants, making them ideal for assessing forest health.
As part of the study, researchers placed coverboards in forests last year to serve as salamander habitats. They conducted regular surveys to count the salamanders living under the coverboards, measuring and tagging them during the process. Some of the forests under investigation are treated with either or both insecticides, while others remain untreated.
The team also performed behavioral tests on the salamanders, including light poking to observe their response to predation and flipping them upside down to assess their agility. Christjansen explained that the salamanders’ well-being, population size, and health conditions can indicate potential impacts on other parts of the ecosystem.
Julia Riley, an associate professor at Mount Allison University and a supervisor of the study, noted that salamanders are significant forest health indicators due to their abundance. She emphasized that the biomass of eastern red-backed salamanders in woodlands in Eastern Canada often surpasses that of deer, underlining their ecological importance.
The study also examines how the decline of hemlock trees affects salamanders. Chris Edge, another project supervisor and scientist from the Canadian Forest Service, pointed out that dying hemlocks disrupt the unique habitat structure these trees provide, leading to changes in moisture levels that can impact salamander populations and behavior.
Edge mentioned that the project is a collaborative effort involving Mount Allison University, Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan. It is part of a larger initiative focusing on forest health in Eastern Canada.
Christjansen stated that the study will continue until the following year, with data collected during the summer set to undergo analysis. The research aims to shed light on the broader implications of HWA and insecticide impacts on forest ecosystems and wildlife populations.