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UBC Theses and Dissertations

Pollinator associations across a range of floral resources at the UBC Farm Lipka, Jennifer Ann


Pollinators rely on floral resources for food and reproduction. They require access to sufficient forage throughout their active periods, yet agricultural intensification alters the landscape causing a loss of essential floral resources. To increase pollinator abundance for pollination services, land managers can incorporate floral resources through habitat amendments, including intercrops, floral strips, and hedgerows. Using the UBC farm as a case study, I first compared two floral strip types, a common cover crop blend of mixed ryegrass and crimson clover and the floral intercrop sweet alyssum, to experimentally investigate the abundance and diversity of pollinators attracted to each floral strip type within a kale production field. Secondly, I conducted an observational survey of four single flower species strips (borage, buckwheat, dill, and ryegrass with crimson clover) to determine potential suitability of these intercrops for larger-scale experimental trials. Finally, I conducted floral and bumble bee surveys over the growing season across the entirety of UBC Farm to examine the relationship between bumble bee foraging choice and the availability of floral resources to determine bumble bee preferences. Overall, I found that different floral resources attracted a different assemblage of pollinators. I found that within the kale production field, the common cover crop blend of rye/clover supported more species of Apidae (Hymenoptera), including (Bombus spp.), while sweet alyssum supported more Syrphidae (Diptera) species. The four single species flower strips attracted insects in the genera (Hymenoptera) Apis, Bombus, Dolichovespula, Halictus, Polistes; (Coleoptera) Coccinella, Harmonia, Rhagonycha; (Diptera) Eristalis, Toxomerus. Bumble bees visited Dahlia pinnata, Rosa nutkana, Symphoricarpos albus, Rubus parviflorus, and Phacelia tanacetifolia more often than expected given the availability of the flowers. Bumble bees visited Phacelia tanacetifolia, Trifolium incarnatum, and Symphoricarpus albus over consecutive sampling sessions. Trifolium pratense, Trifolium repens, and Taraxacum officinale bloomed the entire study period and bumble bees visited them but never beyond the null expectation. My thesis provides insight into floral species favoured by pollinators in agricultural environments, which can aid in future land management decisions and conservation efforts to ensure that pollinators have access to consistent, reliable, and plentiful forage throughout their active periods.

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