A scholar is investigating the impact of an invasive insect and the chemicals utilized to combat it on the wildlife inhabiting ancient hemlock forests. Hemlock woolly adelgid (HWA) has been causing devastation in forests in southwestern Nova Scotia for close to ten years. To control its spread, various entities such as Parks Canada, the local province, organizations, and private landowners have been employing insecticides like imidacloprid and dinotefuran.
However, Mathilde Christjansen, a postgraduate student at Mount Allison University in Sackville, N.B., pointed out the limited understanding regarding how the woolly adelgid and the insecticides used against it are impacting other species. She highlighted that imidacloprid, designed to target insect nervous systems, has also been detected in the brains of other creatures such as fish and tadpoles.
Rather than examining all species in each hemlock forest individually, Christjansen’s team is utilizing a small amphibian as a representative of the ecosystem. According to her, the eastern red-backed salamander is an excellent bioindicator due to its sensitivity to environmental conditions and pollutants, providing insights into the overall forest health.
In their research, scientists placed coverboards in forests last year to serve as salamander habitats. They regularly monitored the coverboards to tally the salamanders living beneath them, conducting measurements and tagging exercises. Some forests under investigation are treated with one or both insecticides to combat HWA, while others remain untreated.
The team also conducted behavioral assessments on the salamanders, such as gentle prodding to observe their response to predation and flipping them over to gauge their agility in returning upright. Christjansen explained that the salamanders’ population size, health status, and physical attributes in treated and untreated forests could indicate broader ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, emphasized the salamanders’ significance as indicators of forest health due to their adaptability to environmental changes and their substantial presence in forest ecosystems.
The study also examines how dying hemlock trees affect salamanders. Chris Edge, another project supervisor and a scientist with the Canadian Forest Service, highlighted the loss of unique habitat characteristics when hemlocks succumb to HWA-induced mortality, potentially impacting salamander populations due to reduced moisture levels in the forest environment.
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 initiative investigating forest health in Eastern Canada.
Christjansen noted that her study will continue until the following year after collecting data and video footage during the summer fieldwork, to be analyzed subsequently.
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