Potential pollinators of understory populations of Symphonia globulifera in the Neotropics.

Abstract

One difference between the forest canopy and the understory is that animals pollinate the majority of understory species in the tropical wet forest. Pollinators active in the understory are also different from those in the forest canopy and are adapted to the mesic conditions underneath the canopy. We used video cameras to observe flowers of understory Symphonia globulifera (Clusiaceae) in tropical wet forests of Costa Rica. We quantified the timing, frequency and behaviour of flower visitors to explore their potential contribution to pollination. A total of 82 flower visits were observed during 105 h of observations. Flowers were visited by ten insect species and one hummingbird species; the most active time period was between 1200-1700 h followed by the time between 0500-1000 h. The time period with fewer visitors was 1700-2200 h, during this period we observed flowers visited in multiple instances by a bushcricket (Tettigoniidae). The most frequent flower visitors were the stingless bee Tetragonisca angustula and the hummingbird Phaethornis longirostris; both came in contact with anther and stigma during visits. We observed different flower visitors from those reported for canopy populations of S. globulifera. Insects predominated, in contrast to observations in canopy populations of S. globulifera, wherein perching birds predominated. We also documented the consumption of pollen by visiting insects. These findings highlight differences in flower visitors between the forest canopy and the understory for the same tree species and contribute to better understanding of the pollination ecology of understory tropical wet forest species.