A researcher is investigating the impact of an invasive insect and the chemicals used to combat it on species residing in ancient hemlock forests. Hemlock woolly adelgid (HWA) has been causing significant damage to forests in southwestern Nova Scotia for nearly ten years. To curb its spread, various entities including Parks Canada, the province, local organizations, and private landowners have employed insecticides like imidacloprid and dinotefuran.
Mathilde Christjansen, a master’s student at Mount Allison University in Sackville, N.B., highlighted the limited knowledge regarding the effects of woolly adelgid and insecticides on other species. She pointed out that while imidacloprid is primarily designed to impact insect nervous systems, it has also been detected in the brains of other creatures such as fish and tadpoles.
Rather than examining all species in every hemlock forest individually, Christjansen and her team are using the eastern red-backed salamander as a bioindicator species to provide insights into the overall ecosystem health. The salamander’s sensitivity to environmental conditions and pollutants makes it an ideal candidate for this study.
In their research, scientists placed coverboards in forests last year to serve as salamander habitats, allowing them to monitor and tag salamanders living beneath these boards. Some of the forests under investigation are treated with one or both insecticides, while others remain untreated.
Behavioral tests were conducted on the salamanders discovered, including gentle prodding to observe their response to predation and flipping them over to assess their agility. Christjansen emphasized that the salamanders’ well-being, population size, and health comparisons between treated and untreated forests could shed light on broader ecosystem impacts.
Julia Riley, an associate professor at Mount Allison University and a Canada Research Chair in integrative wildlife ecology, explained that salamanders are not only responsive to environmental changes but also serve as valuable indicators of forest health due to their abundance in Eastern Canada woodlands.
The study also examines how dying hemlocks influence salamander populations. Chris Edge, a supervisor and scientist with the Canadian Forest Service, noted that as hemlock trees perish due to HWA infestation, they disrupt the unique habitat conditions these forests offer, such as cool and moist microclimates.
Sensitive to moisture levels, salamanders could face challenges if the forest becomes drier due to reduced foliage shielding the soil from sunlight. The project involves collaboration among Mount Allison University, Canadian Forest Service, Acadia University, Environment and Climate Change Canada, and the University of Saskatchewan as part of a broader investigation into forest health in Eastern Canada.
Christjansen plans to continue her study until next year, analyzing the data and videos collected during the summer to draw conclusions.
