Individual Variations in Worker Polyethism of the Sumatran Stingless Bee, Trigona (Tetragonula) minangkabau (Apidae, Meliponinae)

We analyzed individual variations in polyethism of the same cohort of workers that emerged at almost the same period in the same colony, in the Sumatran stingless bee, Trigona (Tetragonula) minangkabau (Apidae, Meliponinae), by new indices and multivariate statistical analyses to detect temporal relationship of task performance. We find four distinguishable task groups I-IV. I. "Core brood carers" stay in the nest almost throughout all the life span, with the following general trend of task sequence : (1) Preparatory period (age, a=1-5 days after emergence) for maturation by eating pollen and honey, (2) Early cell making period (a=6-9) for exercise, (3) Middle cell making period (a=10-20) with attending the provisioning and oviposition process (POP). Wax gland develops mostly in this period. (4) Late cell making period (a=21-28), carrying cerumen to the oviposition front and preparation of cell base, (5) Peripheral task period (a=29-49), making storage pot, resinous wall and entrance tube, dehydrating nectar received from foragers, and (6) Foraging and scouting (a=over 50). Only this group participates in POP. II. "Subsidiary brood carers" skip the middle cell making phase of group I and start pot making from a=15. Until a=31 workers of this group make only pots and after a=31 make wall and entrance, gather and carry trash inside the nest and dehydrate nectar at the same time. From a=39 workers start walking in entrance tube. III. "Foragers" skip almost all the intranidal tasks and enter into entrance tube at a=25. After exercise flight for 4 days workers start foraging significantly earlier than the above groups. IV. "Ephemeral workers" with some handicaps before or at emergence virtually do not any tasks during the short life of about two weeks.