A sticky affair: resin collection by Bornean stingless bees

Plant resins are used by stingless bees for nest construction and maintenance. To reveal factors that influence the bees' decision about where and when to collect resin, resin collection was studied in ten stingless bee species (Apidae, Meliponini) collecting resin at natural and artificially induced wounds of nine tree species in Borneo. Artificially induced wounds were found by bees within 1-2 d. The number of foragers at artificial wounds increased during the subsequent 5 d until resin secretion stopped or the resin hardened. At natural resin wounds, species identity and number of foragers remained constant during the observation period. Bees collected resin from some trees and ignored others. Agathis borneensis (Araucariaceae) was the most attractive resin source. The bees' visitation rate did not correlate significantly with resin wound size. Inter- and intraspecific aggression occurred at ten resin wounds. In Tetragonilla collina and Tetragonula melanocephala, we additionally recorded resin intake at colony entrances. The proportion of workers retuning with resin varied considerably between colonies. We observed attacks by ants at three of our eight focal colonies, which resulted in a significant increase in resin intake while the nest was under attack and until 1-2 d after the attack had stopped. The increase in resin collection triggered by ant attacks was even stronger than the increase following a manual destruction of the nest entrance tube