Pollen Food Sources of the Stingless Bees Trigona apicalis Smith, 1857, Trigona collina Smith, 1857 and Trigona fimbriata Smith, 1857 (Apidae, Meliponinae) in Thailand

Abstract

The pollen collected by three species of Trigona; T. apicalis Smith 1857, T. collina Smith, 1857 and T. fimbriata Smith, 1857 were studied at the Phitsanulok Wildlife Conservation Development and Extension Station in Thailand, from January to December 2004. Pollen loads were sampled from bee baskets of forager bees returning to their colonies. We created a pollen key for the variety of local plant species. Pollen samples were prepared for analysis by acetolysis. Having developed the key, we determined the origin of pollen loads carried by returning foragers. In total, 2,160 pollen loads from bee baskets of forager bees were identified into 29 plant species of 18 families; Acathaceae (Ruellia tuberose), Agavaceae (Agave angustifolia), Alangiaceae (Alangium salviifolium), Arecaceae (Caryota bacsonensis), Asteraceae (Tridax procumbens), Bignoniaceae (Rernandoa adenophylla), Caesalpiniaceae (Cassia bakeriana, Delonix regia and Senna siamea), Convolvulaceae (Ipomoea aquatica and Merremia vitifolia), Cucurbitaceae (Coccinia grandis), Euphorbiaceae (Croton roxburghii), Lythraceae (Lagerstroemia calyculata, L. macrocarpa and L. tomentosa), Mimosaceae (Mimosa pigra and M. pudica), Papilionaceae (Butea monosperma, Dalbergia lanceolaria, Erythrina stricta and Millettia brandisiana), Rubiaceae (Ixora grandifolia and Paederia linearis), Scrophulariceae (Torenia fournieri), Thunbergiaceae (Thunbergia laurifolia), Verbenaceae (Tectona grandis) and Zingiberaceae (Costus speciosus and Zingiber officinale). T. collina was by far the most polylectic species collecting 29 plant species, while T. apicalis foraged on 20 and T. fimbriata only 16. This suggests that the small T. collina is the most important pollinator among the three species.