Colony size
We used the number of adult bees to represent the colony size, like
previous studies on other eusocial bees (Dornhaus et al. 2012). To count
the number of adult bees in individual colonies, hives were closed at
night on the day prior to the experiment using a fine metal gauze (5 x
10 cm) to cover hive entrances, which prevented adult bees from leaving
the colony while allowing adequate ventilation. The following day, hives
were transferred to a small laboratory and enclosed in a 1.5 x 1 m fine
mesh cage to aid collection of adult bees using a manual aspirator. For
the more populous species (F. longipes and S. aff.
postica ), carbon dioxide (glass cylinder, 95% concentration) was given
to the colony for up to two minutes to anesthetize the individuals
(Tustain and Faulke 1979) prior to their capture. Males and female
workers were not discriminated during counting, while the mated queen
and the gynes were counted and separated from other adult bees. At the
end of the bee counting, all brood combs, food pots and adult bees were
carefully returned to the hive and colonies received supplemental food
(sugar syrup and pollen) to aid their recovery post assessment. By
following these procedures, no colonies died due to our handling.