Print PageNative bees, especially bumblebees, provide beneficial pollination services to agricultural communities. Bumble bees are one of the first species to decline in human altered landscapes, most likely due to limited nest and food resources. Specifically, it is hypothesized that bumble bees are limited by floral resource availability in human-altered habitat because they do not utilize non-native flowering plants. This research examines the nectar and pollen preferences of the bumblebee Bombus vosnesenskii (Hymenoptera: Bombiidae) to identify factors that aid bumblebee colony success. We collected pollen load samples from 100 B. vosnesenskii individuals in 8 field sites in Northern California. Four field sites were within agricultural landscapes and four were within natural landscapes. The pollen loads of B. vosnesenskii were analyzed to identify the species of plants they were collecting pollen from.
Results/Conclusions
Analysis of the corbicula pollen loads showed that B. vosnesenskii prefer native plant species, wtih 64% of the pollen grains coming form native plants. However, the bees will will also gather non-native pollen. Twenty-six distinct species were identified in the pollen loads, with an average of 6.44 species at any one site. Managed sites had a greater diversity of pollen on average. Bee visitation to a site exhibited a positive correlation with the proportion of native flowers at the site, and semi-natural areas on average had greater bee visitation than managed sites. P. This research shows that B. vosnesenskii prefer native plant species, but will utilize non-native pollen resources in human-altered landscapes.
