As the winter snow in Nova Scotia starts to disappear, researchers at Dalhousie University are urging people to be on the lookout for abandoned paper wasp nests.
They are gathering these nests from various locations across the province to investigate any signs of heavy metal contamination.
Carlie Ashton, an undergraduate student in environmental science at Dal’s agricultural campus in Bible Hill, N.S., is leading this research as part of her honours project.
She is focusing on two specific species, aerial yellowjackets, and bald-faced hornets, which construct their nests by gathering wood or plant fibers from their surroundings. These insects chew the material, creating a pulp that they then regurgitate to build their nests.
Ashton anticipates that nests in urban areas will show higher levels of copper and chromium contamination, common wood preservatives, compared to nests in rural areas.
“Wasps in urban settings may be chewing on materials like decks that contain wood preservatives, leading to heavy metal exposure, whereas wasps in rural areas might be using natural sources like trees,” she explained.
Anyone who comes across a nest is encouraged to reach out to Ashton to contribute to the study.
During this time of year, the nests are abandoned as the wasps perish due to the cold weather, while the mated queens seek shelter elsewhere, such as under tree bark or in logs, woodpiles, or leaf litter.
These nests can be spotted hanging in barns, sheds, or trees. Ashton aims to collect all specimens by May when the wasps begin constructing new nests.
Despite potential wear and tear on the nests over winter, Ashton assured that it won’t affect her research. She plans to dry the nests in a microwave, dissolve the material, and analyze it for heavy metal content using a specialized machine.
According to Ashton, similar research has been conducted on other species elsewhere, but not on these particular species and not in Canada to her knowledge.
Some species cannot serve as reliable indicators of heavy metal presence, so Ashton’s project aims to determine whether aerial yellowjackets and bald-faced hornets can indicate any concentrations at all.
Paul Manning, an assistant professor supervising Ashton’s project, highlighted that understanding the presence and amounts of contaminants can shed light on the challenges these insects are up against.
“Given the global decline in insect populations due to various factors like heat stress, habitat loss, and pesticides, it’s crucial to comprehend the multiple stressors insects are facing,” Manning stated. “There is a combination of stresses making it difficult for insects to survive and thrive.”
While the study does not focus on the impact of potential contamination on the wasps, Manning mentioned that other research suggests copper exposure can reduce the lifespan of wasps and affect their reproductive capabilities and the queen’s egg-laying capacity.
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