As the winter snow in Nova Scotia starts to melt away, researchers from Dalhousie University are urging the public to be on the lookout for abandoned paper wasp nests. They are gathering these nests from various locations across the province to examine them for 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 the 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 the environment. These insects chew and regurgitate the material to build their nests.
The study anticipates finding higher levels of copper and chromium, common wood preservatives, in wasp nests located in urban areas compared to those in rural settings. This is because urban wasps are more likely to use materials with wood preservatives, such as decks, while rural wasps tend to utilize natural sources like trees.
Anyone who discovers a nest is encouraged to reach out to Ashton to contribute to the research. The nests are deserted during this time of year as the cold temperatures cause the wasps to perish, leaving only mated queens hidden in places like tree bark, logs, woodpiles, or leaf litter.
Although the nests may be weathered after winter, Ashton is undeterred as she plans to dry the nests in a microwave, dissolve the material, and analyze it for heavy metals using specialized equipment. This type of research has been conducted on different species elsewhere but has not been explored with these particular species in Canada, according to Ashton.
The project aims to determine if aerial yellowjackets and bald-faced hornets can serve as biological indicators of heavy metal presence. Assistant professor Paul Manning, one of Ashton’s project supervisors, emphasized the importance of understanding the pressures facing these insects, considering the global decline in insect populations due to various factors like habitat loss and pesticides.
While the research does not focus on the effects of contamination on the wasps, previous studies have suggested that copper exposure can impact the lifespan of the insects, male reproductive capacity, and the queen’s egg-laying ability. Manning stressed the need to comprehend the presence and quantities of contaminants to shed light on the challenges insects face in the modern world.
