Complex responses to plant stress by bumble bee (Bombus impatiens) foragers and impacts on colonial fitness

Background/Question/Methods

Climate change and agricultural intensification are altering landscapes around the world, increasing severe weather patterns, and decreasing biodiversity and habitat for native animals and plants. These changes have direct impacts on native plants and crops, by increasing both the intensity and duration of stressors. Beyond the fitness impacts on plants themselves, plant stress alters the floral display and can have cascading impacts on pollinators utilizing them. In North America bumblebees play an important role in delivering pollination services in both native and agricultural landscapes. This makes them particularly susceptible to changes in host plant physiology. Using Bombus impatiens and Canola, Brassica napus, as a model, we investigated the impact of multiple plant stressors on bumblebee foraging behavior and colony fitness, using a novel choice bioassay technique and no choice assays, assessing larval development within the colony.

Results/Conclusions

Preliminary results indicate that Bombus impatiens foragers can distinguish between some types of stressed plants and healthy (non-stressed) plants and preferentially visit the healthy plants. Currently experiments are in progress that will evaluate the fitness consequences of these stressors and choices on bee colony health. These preliminary results indicate that due to plant stress and the implications of the Waage motivational foraging model there may be a decline in pollination services due to changes in the foraging choices of bumble bee foragers, further impacting host plant reproductive fitness.