Competition for Food Among Four Sympatric Species of Apini in Sri Lanka (Apis Dorsata, Apis Cerana, Apis FloreaandTrigona Iridipennis)

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Abstract
Competition experiments at an artificial feeding dish revealed interactions among the species according to body size: Trigona attacked mainly A. florea and A. cerana; A. florea reacted to A. cerana, and A. cerana attacked A. dorsata. In exclusion experiments, smaller species proved more successful than larger ones. Altogether 51 comb samples with honey and pollen stores were examined microscopically; 46 pollen types recorded are listed, and most of them identified. The average number of different pollens in individual samples, and the absolute number in all samples from one bee species, were highest for T. iridipennis and lowest for A. dorsata. There was a correlation between the aggressiveness of a bee species and the versatility of the pollens in food stores. For some of the most common bee plants, correlations were found between body size of the bee species and the frequency of occurrence of the pollen grains in its food stores. Competition for food is not a limiting factor for the co-existence of the four bees studied. The disadvantage of the limited flight range of a small species is compensated by a more aggressive behaviour, which allows it to defend food sources in its smaller territory, and then to prevent disastrous competition.