Behavior of major insect pollinators of teak ( Tectona grandis L. f.): A comparison of clonal seed orchard versus wild trees

Abstract

Insect pollinators that frequently visited teak ( Tectona grandis L. f.) flowers in a wild (W) and a clonal seed orchard (CSO) near the Maegar Seed Orchard, Phayao in Thailand were stingless bees and small carpenter bees. There were differences between the two habitats in numbers of pollen grains deposited on the stigma by these pollinators and in the pollinators foraging movements. The mean numbers of pollen grains observed on the stigma in the W was lower than in the CSO. Pollinators in the CSO moved longer distances, flying among inflorescences rather than staying within the same inflorescence. However, there were no differences in the number of flowers visited per minute between the two habitats. The time pollinators spent on each flower visit did not alter the percentage of pollinated flowers. Large pollinators typically landed on the tops of the flowers, whereas stingless bees and small carpenter bees approached flowers from both the top and side. Trigona collina was the most important pollinator in the CSO. It made the most frequent visits and contributed to 67% of teak flowers being pollinated. Its foraging time was high in the morning (10:00–12:00 h), which coincided with the receptive period of teak flowers. The behavior of other pollinators that may promote out-crossing is discussed.