Cavallaro and fellow students organized an Earth Day 'pollinator extravaganza' to tidy up a Saskatoon riverbank park and make it solitary bee-friendly by installing bee houses and planting native wildflowers.
Seasoned, untreated wood blocks were used to build three bee houses. Bundles of hollow reeds and hollow concrete blocks were also incorporated in the design to attract different varieties of bee species.
"Essentially what we've created is a bee condo," said Cavallaro. "Bees will be attracted to the area and make it their permanent home and nest. A group of volunteers will be looking after the houses and making sure they're OK in the long run."
Cavallaro's PhD research involves studying the effects of chronic pesticide exposure on aquatic insects in Prairie wetlands. While bees may not be in that study group directly, he has an understanding of the effects of pesticides on non-target insects.
"Saskatchewan has the highest provincial pesticide use in Canada and there are growing concerns about how this affects ecosystem services provided by a range of insect species, especially bees," said Cavallaro. "Solitary bees are also under threat from native grassland and habitat loss. Anything we can do to encourage their populations is positive."
Cavallaro has the following tips for encouraging bees to take up residence in backyards around the city:
Plant wildflowers that attract solitary bees to your backyard. Flowers such as Bergamot, Black-eyed Susan, Hyssop, Hedysarum, Prairie Coneflower, Purple Prairie Clover, Smooth Aster, Goldenrod and Yellow Evening Primrose are good choices and are all native to Saskatchewan.
Build a bee house. A wooden box that is open on one side or both sides works well. Fill it with blocks of wood or small logs that have 10 cm deep by 2-10 mm wide holes drilled into them. Make sure to use untreated wood and remove any sawdust. Placing bundles of hallowed reeds in crevices in the wood box works well to attract mason and leafcutter bee species. Place the finished house in the sun, facing east or south.
Protect the house from birds. If woodpeckers or other birds are attacking the tunnels, attach a piece of chicken wire across the front of the house.
Protect the house from wet winter weather. In late fall, take the occupied logs and place them in a dry, unheated place like a shed. If occupied pieces are too large, protect the entryways from snow with a piece of plywood or a tarp. Bee pupae need to be cold and dry during the winter.