Assessing Bee Attractiveness of Woody Landscape Plants and Mitigating Potential Bee Hazard from Neonicotinoid Insecticides

Maintaining bee-friendly habitat and food resources in cities and suburbs can help conserve bees’ vital pollination services to gardens, ornamental landscapes, and native plants in remaining fragments of semi-natural habitat.1-4 With bee populations being imperiled by habitat loss, diseases, parasites, and other stresses5, 6 and public awareness of those problems increasing7 the issue of pollinator health poses new challenges for the horticultural industry. Research based guidelines are needed to help growers and landscape managers manage insect pests without harming bees, and to ensure that plants sold in garden centers are non-hazardous to bees after being transplanted to the landscape. Our recent research verified that hazard to bumblebees foraging on flowering weeds in treated lawns can be mitigated by adhering to label precautions, or if blooms are inadvertently contaminated, by mowing to remove them. 4,14 Imidacloprid or clothianidin residues in nectar of directly contaminated white clover blooms averaged about 6000 and 3000 ng/g, respectively, but levels nectar of blooms formed after the first mowing were reduced by > 99.6%. Moreover, urban bees forage on diverse flowering plants1,16 most of which are not treated with systemic pesticides. The proposed research extends my programs pollinator research, which heretofore has focused on lawns, lawn care, and golf courses, to woody ornamental plants.