Tuesday, August 5, 2008

PS 22-68: The use of non-native plants by native bees

Alexandra N. Harmon-Threatt and Claire Kremen. University of California, Berkeley

Background/Question/Methods

The loss of native flora is believed to be a contributing factor to the decline of native bees. However, the loss of native plants has often been accompanied by the addition of non-native plants to many ecosystems. Understanding the role non-native plants play in the diets of native bees could be important to consider when designing conservation plans. In order to assess how generalist native bees use native and non-native plants pollinator observations of Bombus vosnesenskii were conducted. Each bees foraging was timed and documented as they moved from plant to plant. We also determined the overall prevalence of each flowering plant species and recorded morpological characteristics of plants known to be used by Bombus. 

Results/Conclusions

We found that plants more similar to the native vegetation were more likely to be incorporated into the diets of the bee. We also found that the bees floral choices were explained primarily by floral constancy. Comparisons of the plants chosen by B.vosnesenskii also allowed us to better understand the mechanisms behind the choice to incorporate non-native plants. This study allowed us to determine native plants that B.vosnesenskii use and that can be incorporated in pollinator specific restoration efforts. In the future we hope to look more into assemblages of traits for native and non-native plants specifically as it relates to pollination and how optimal this foraging method is.