Status Review of Three Formerly Common Species of Bumble Bee ...

TABLE OF CONTENTSI. Executive Summary………………………………..……………………………. 3II. Biology, Habitat Requirements, Pollination Ecology, and Taxonomy…………. 4A. Biology…………………………………………………………………. 4B. Habitat requirements…………………………………………………… 6C. Pollination Ecology…………………………………………………….. 6D. Taxonomy……………………………………………………………… 6III. The rusty patched bumble bee, Bombus affinis Cresson……………………….. 7A. Species Description…………………………………………………….. 7B. Pollination Ecology…………………………………………………….. 8C. Population Distribution and Status…………………………………….. 9IV. The yellowbanded bumble bee, Bombus terricola Kirby……………………… 13A. Species Description…………………………………………………….. 13B. Pollination Ecology…………………………………………………….. 14C. Population Distribution and Status…………………………………….. 14V. The western bumble bee, Bombus occidentalis Greene………………………… 17A. Species Description…………………………………………………….. 17B. Pollination Ecology…………………………………………………….. 18C. Population Distribution and Status…………………………………….. 19VI. Current and Potential Threats – Summary of Factors for Consideration……… 24A. Spread of Diseases and Pests by Commercial Bumble Bee Producers... 24B. Inadequacy of Existing Regulatory Mechanisms……………………… 27C. Habitat Alteration……………………………………………………… 28D. Pesticides………………………………………………………………. 29E. Invasive Species……………………………………………………….. 31F. Other Threats…………………………………………………………... 32VII. Conclusion…………………………………………………………………….. 33VIII. Literature Cited………………………………………………………………. 35IX. Acknowledgements and Personal Communication……………………………. 50X. Appendix I………………………………………………………………………. 51A. Bombus affinis Museum Records……………………………………….. 52B. Bombus terricola Museum Records…………………………………….. 54C. Bombus occidentalis Museum Records…………………………………. 55XI. Appendix II…………………………………………………………………….. 622