In Nova Scotia, as the snow of winter starts to melt away, researchers at Dalhousie University are urging the public to be on the lookout for abandoned paper wasp nests. The nests are being gathered from various locations across the province to investigate possible heavy metal contamination. Carlie Ashton, an environmental science student at Dalhousie’s agricultural campus in Bible Hill, Nova Scotia, is spearheading this study as part of her honours project.
Aerial yellowjackets and bald-faced hornets, the two species of interest, construct their nests by gathering wood or plant fibers from their surroundings. These materials are chewed by the insects to form a pulp that is regurgitated to shape the nest. Ashton anticipates that nests in urban settings may exhibit higher levels of copper and chromium, common wood preservatives, compared to those in rural areas.
For those who come across abandoned nests during this period when the wasps have perished due to cold temperatures, Ashton is requesting them to contribute to the research. The mated queens are typically sheltering in places like under tree bark, logs, woodpiles, or leaf litter at this time. Nests can often be found in barns, sheds, or trees. Ashton aims to gather all specimens by May when the wasps begin constructing new nests.
Despite potential wear and tear on the nests after winter, Ashton stresses that this does not affect the research. The nests will be dried in a microwave, and the material will be dissolved and analyzed for heavy metals using specialized equipment. While similar studies have been conducted on other species elsewhere, Ashton believes this is the first of its kind on aerial yellowjackets and bald-faced hornets in Canada.
Assistant professor Paul Manning, one of Ashton’s project supervisors, highlights the importance of understanding the presence and levels of contaminants to comprehend the challenges faced by these insects. He emphasizes the current global decline in insect populations due to various factors such as habitat loss, heat stress, and pesticides. Although the research does not delve into the effects of contamination on the wasps, previous studies have indicated potential adverse impacts like reduced lifespan and reproductive abilities.
The project seeks to determine if aerial yellowjackets and bald-faced hornets can serve as indicators of heavy metal concentrations. Manning underscores the need to grasp the multiple stressors affecting insect survival in today’s environment.