Have you seen a wasp nest like this? These researchers want to study it

As winter’s snow in Nova Scotia begins to fade — at least temporarily — some researchers at Dalhousie University are asking people to keep an eye out for abandoned paper wasp nests.

They are collecting the nests from across the province to study them for signs of heavy metal contamination.

Carlie Ashton is an environmental science undergraduate student at Dal’s agricultural campus in Bible Hill, N.S., and is conducting the research as part of her honours project.

She says the two species she is interested in, aerial yellowjackets and bald-faced hornets, build their nests by collecting wood or plant fibres from their surrounding neighbourhoods. The insects chew the material, creating a kind of pulp they then regurgitate to form the nest.

Ashton expects to find that wasp nests in urban areas will be more contaminated with copper and chromium — two common wood preservatives — than nests found in rural areas.

“If the wasp is in an urban area, they might be chewing on something like a deck, which is more likely to have wood preservatives, which would be a source of heavy metals compared to a wasp in a rural area, which might be chewing on more natural sources like trees and things,” she said.

Ashton is asking anyone who finds a nest to contact her to contribute it to the study.

Nests are abandoned this time of year, as the wasps have died due to the cold temperatures, and the mated queens are hiding elsewhere, such as under tree bark or in logs, woodpiles or leaf litter.

Ashton said people may find them hanging in barns, sheds or trees. She hopes to collect all her specimens by May, which is when the wasps begin building new nests.

The nests may be a little worse for wear after the winter, but Ashton said that doesn’t matter to her research. She will dry the nest in a microwave, then dissolve the material and use a machine to analyze it for the heavy metals.

Ashton says this type of research has been conducted elsewhere on other species, but not on these species, and not in Canada, as far as she is aware.

Some species cannot be used as biological indicators of heavy metal presence, so Ashton’s project will help determine if the aerial yellowjackets and bald-faced hornets are able to show any concentrations at all.

One of Ashton’s supervisors on the project, assistant professor Paul Manning, said knowing whether contaminants are present, and in what quantities, can help researchers understand what pressures the insects are facing.

“We’re living in a time where we’re seeing insect populations declining around the world as a combination of different stresses from heat stress to habitat loss to pesticides,” Manning said. “There’s lots of different kind of co-occurring stresses on insects that makes it tough to eke out a living.”

Although their purpose is not to study the effects of the potential contamination on the wasps, Manning said other research has suggested copper can reduce their lifespan and impact the capacity of males to reproduce and the ability of the queen to lay eggs.

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