Willows (Salix spp.) as pollen and nectar sources for sustaining fruit and berry pollinating insects

Ostaff, D. P., Mosseler, A., Johns, R. C., Javorek, S., Klymko, J. and Ascher, J. S. 2015. Willows (Salix spp.) as pollen and nectar sources for sustaining fruit and berry pollinating insects. Can. J. Plant Sci. 95: 505–516. Willows (Salix spp.) are ubiquitous in the northern hemisphere, serving as an important pollen and nectar resource for insect pollinators and for the enhancement of insect-pollinated agricultural crops such as fruits and berries. We used a common-garden field test containing seven native North American willow species to assess attractiveness of male and female flower catkins by documenting visits of Andrena spp. (Apoidea: Anthophila), other wild bees (all native), and flower flies (Syrphidae). Most willows in Canada's Maritimes begin flowering very early in spring, as the first wild pollinators become active following winter, and stop flowering by mid-May. A later-flowering group normally begins flowering in mid-May and stops flowering by mid-June. Pollinator species were largely oppo...