Lauren Baugus

Bumble bees ( Bombus spp.) are keystone pollinators in early seral managed conifer plantations, yet little is known about how floral availability influences their foraging behaviour, diet breadth and nutritional intake. In a 2‐year observational study of bumble bee communities in 21 regenerating Douglas‐fir ( Pseudotsuga menziesii ) stands in western Oregon, USA, we quantified relationships between floral availability and diet breadth, resource partitioning and protein:lipid ratio of collected pollen. We also assessed bee floral preferences across time and between native and exotic plants. We sampled 2,220 individuals representing 12 bumble bee species visiting 34 flowering plant species. Neither pollen diversity nor macronutrient composition varied with floral availability. Although most foragers collected pure pollen loads, visitation diversity at species and community scales increased with local floral abundance and diversity, while resource partitioning remained consistent. Floral preferences varied seasonally with no bias towards native or exotic plants. Our results indicate that bumble bees exploit a wider range of floral resources when available while maintaining a similar macronutrient balance, suggesting that selective foraging across varying resource conditions regulates intake. Pollen protein:lipid ratios were lower than in other bumble bee studies, potentially indicating nutrient limitation. The diverse bumble bee communities we observed in regenerating timber stands suggest that these areas provide important forage in otherwise resource‐limited forest landscapes. Additionally, bees' lack of preference for exotic plants suggests that invasive plant management should not conflict with bumble bee conservation if weeds are replaced with native species that provide comparable rewards.

The use of native plant cultivars in pollinator plantings is somewhat controversial. Although some cultivars originate from wild populations, others are bred for novel ornamental traits, which may have unintended impacts on floral rewards, such as nectar and pollen. It is unclear whether changes in floral displays and/or rewards may alter plant–pollinator relationships. We established an experimental garden of Pacific Northwest native plants and native cultivars to evaluate differences in their floral traits and bee communities. We used a combination of methodologies to quantify variation in plant traits that could influence pollinator foraging, including those associated with floral displays (eg petal color, corolla morphology) and floral rewards (pollen and nectar). We also measured changes in bee community composition (eg species associations, functional diversity) across plant groups. We found that cultivars varied significantly from native plants across multiple floral display or reward traits. No plants were bred for nectar or pollen traits, thus changes in rewards were likely pleiotropic. Nine out of 10 tested cultivars had dissimilar bee communities to their native plant counterpart, though minimally developed cultivars were associated with similar bee species and functional traits. Our results suggest that the development of native plant cultivars can come at the cost of pollinator functional richness, though some variation in bee composition may be expected among wild plant populations with diverse phenotypes. Plants with phenotypes consistent with wild-type plants tended to support functionally rich bee communities and should be emphasized in plantings to maximize potential benefits to pollinators.

Specialty crops like blueberries depend heavily on pollinators, particularly bees, for enhanced fruit set and optimized yield. The Northern highbush blueberry, widely cultivated in the Pacific Northwest of the United States, includes several key cultivars such as ‘Duke’ and ‘Elliott’. Given that pollination efficiency is directly linked to the availability and quality of pollen, understanding the pollen production of these cultivars is critical for optimizing pollination strategies and maximizing fruit yield throughout the growing season. Additionally, as bees depend on floral resources like nectar and pollen for their nutrition, the nutritional quality of pollen from these blueberry cultivars plays a key role in supporting healthy bee populations. This study compares key pollen parameters, including production and nutritional quality, between the ‘Duke’ and ‘Elliott’ cultivars. ‘Elliott’ produced nearly twice the amount of pollen per flower by weight compared to ‘Duke’. Both cultivars showed relatively low pollen protein content and comparable pollen lipid levels. The analysis of phytosterol composition revealed significant differences between the cultivars. This study contributes to a more detailed understanding on the quantitative and qualitative differences in pollen, and ultimately provides insights that can inform cultivation practices and enhance overall blueberry production.