Identification of pollen sources of stingless bees (Trigona biroi) in Camarines Sur [Bicol, Philippines]

Results showed there were 96 species of flowering plants with 81 genera and 43 families identified as important bee plants. Of these species, 33 were trees, 32 were herbaceous plants, 16 were shrubs, 8 were vines, and 7 were palms. Twenty families and 31 species of trees were the predominant group of plants visited by stingless bees. Among the 20 families, six species of family Leguminosae and three species of families Myrtaceae and Rutaceae were foraged by stingless bees. The herbaceous plants with 17 families and 32 species were the second major group of plants forged by the bees and among the families, Compositae family obtained the highest number of species, which included weeds and ornamental plants. Meanwhile, Leguminosae and Rubiaceae dominated the shrub species followed by Malvaceae. Majority were ornamental plants and some were weeds. Five families (Acanthaceae, Convolvulaceae, Cucurbitaceae, Passifloraceae, and Polygonaceae) and eight species of climbing plants were also forged by stingless bees. On the other hand, seven species of Palmae were visited by bees. The most common of which was Cocos nucifera. Furthermore, 61% of the plants visited by the bees were found to be non-seasonal thus, having the ability to provide year round for the bees. Twenty-eight percent were seasonal plants or those plants that bloom only once or twice a year and 11% showed irregular bloom pattern. Findings also revealed that 50% of the plants were sources of pollen and nectar, majority of which were trees, climbers, and palms. Of the total identified species, majority or 32% were visited because of their pollen rewards while 12% and 6% because of nectar rewards and propolis, respectively. In addition, coconut and other palms, citrus and banana were considered major pollen and nectar sources among the non-seasonal plants. The family Compositae was considered a major pollen source providing about 22.5% of the total identified pollen sources followed by Leguminosae comprising of 12.90%. On the other hand, palms were considered a major contributor of both pollen and nectar representing 15.22% of the total identified pollen and nectar sources, which was followed by Compositae with about 10.87%, and Rutaceae (Citrus spp.). Lastly among cultivated plants, corn, which is second major crop grown in Bicol can also be an important source of pollen since these could be easily grown close to the hives and may be a major pollen source all through out the year.