We sought to understand the causes of honey poisoning originating from hives in the basin of the Lancang River in Lanping, Nujiang, Yunnan Province. The river valley contains many Apis cerana cerana colonies bred by the traditional method, as well as wild colonies of A. cerana cerana, Apis andreniformis, and Apis laboriosa Smith. Fagopyrum esculentum Moench is the most common nectariferous plant in the area, while localized distributions of Vaccinium bracteatum Thunb and Tripterygium hypoglaucum (Levl.) Hutch are also present. We surveyed honeybees and nectar plants from June to September,2013, observed honeybee collection behavior, and recorded the distributions of toxic plants. We further investigated honey and pollen storage in hives of A. cerana cerana, employing melissopalynology and trophic niche analysis of all colonies producing samples. The artificially bred colonies of A. cerana cerana were found to be similar in internal structure to wild colonies:hives contained plenty of honey and pollen, while parts of the hives were seriously affected by pests. Our analyses demonstrated that many honey samples contained pollen from Tripterygium hypoglaucum (Levl.) Hutch and Vaccinium bracteatum Thunb. The trophic niche breadth of A. cerana cerana is 0.22, smaller than that of other species. We speculate that construction of the Lancang River hydropower station and other human factors have influenced the structure and composition of both bee and nectariferous plant communities.