The York University Magazine

YorkU Fall 2014

The alumni magazine of York University

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very April for three years, York University PhD candidate Scott MacIvor placed 200 "bee condos" all over Toronto – in backyards and ravines, on balconies and green roofs. He even attached one to a stop sign. MacIvor designed and built the bee condos (or nest boxes) to collect data for his doctoral research on wild bee diversity in urban settings. Condos consist of about 30 cardboard tubes inserted into polyvinyl chloride (PVC) piping. A few were fitted with electronic sensors to monitor humidity and temperature, factors that could have a bearing on whether or not bees choose to nest there. Cavity-nesting bees and wasps then entered the cardboard tubes – varying in diameter to accommodate different-sized species – built their nests and laid the eggs that would emerge as the next generation of bees the following spring. Every October MacIvor would bring the bee condos back to the lab, unravel each cardboard tube, collect the pollen and document the nesting material. He would label and refrigerate the larvae over the winter and then rear them in the spring. Solitary bees and wasps – ones that don't live in hives – pollinate flowers, trees and plants. Wasps control scales, aphids, spiders, crickets and other plant-destroying pests. Some bees are specialists, feeding on the pollen of a single flower or plant, and only emerge when that flower blossoms. Hence, bees emerge at different times throughout the season depending on which flower species are in bloom. MacIvor would observe whether the bees would feed on only one flower's pollen or pollen from a variety of plants, keeping in mind that the specialists are less adaptable than the generalists. He also recorded the abundance and diversity of the emerging bees and their parasite loads. MacIvor has identified about 70 species of bees, wasps and their parasites out of an estimated 250 species in Toronto. Through "citizen science" – engaging local residents to mon- itor, observe and keep records – he has conducted one of the largest studies of urban solitary bees and wasps in North America. He has discovered some surprising adaptations, such as bees building nests using bits of plastic from shopping bags, which is evidence of flexibility to a changing environment. Through his field research, he hopes to find out what condi- tions create urban bee losers and winners, and to quantify bee populations across the city. His data can be used to model where bees and wasps are likely to be found in Toronto and in similar cities in North America. Studies in urban biodiversity typically focus on birds, butter- flies, plants and trees. MacIvor's research is unusual for its focus on bees and wasps. Why is this important? Without bees and wasps, most plants, trees and flowers would fail to persist. "If we know what leaves bees and wasps are using to build nests and what pollen they are feeding on, we can integrate that knowledge into planning for an ecological city," says MacIvor. As part of his research, MacIvor dispatched students and others to collect pollen and created an accessible online data- base of microscopic images of pollen grains from more than 300 flowers used in gardening in Toronto. Using a confocal microscope, he also generated coloured, three-dimensional and rotatable computer images of a number of pollen grains. They are so beautiful – evening primrose pollen, for example, is a brilliant pink and purple – that he projected them on walls and presented them as art at the Gladstone Hotel's Grow Op urban design show in April. "It was another way to communicate my research," says MacIvor, who often gives public talks. MacIvor has never bought into the pervading notion that cities are wildlife dead zones. As a child growing up in Kitchener, Ont., he collected insects from a nearby meadow before it became a strip mall. "It drove me to the crux of my career," he says. As a biology student, he became interested in ecosystems and how nature can be harnessed to solve problems. He specialized in the ecology of green roofs, co-wrote the City of Toronto guidelines on biodiversity of green roofs and continues to do research with the Green Roof Innovation Testing Laboratory at the University of Toronto. He is also an ecology consultant for a Toronto landscape architect. "My real focus is extending the concept of buildings as land- scape," says MacIvor. "We should design buildings that interact positively with landscape." In fact, he believes ecologists like him should be involved at every step in urban building and planning. "I want to make a strong case for that globally," he says. "I want to integrate ecology into urban design for the benefit of humans and nature." Through his research and citizen science on diversity of bees and wasps, MacIvor says "we can understand how urban green space can improve." Y E YorkU Fall 2014 6 U niverse Condos for Bees?

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