Water loss assays
We used a gravimetric water loss assay to compare water loss in single and paired bees at roughly 0% humidity, at 24 ± 1°C. Bees were placed in 15 mL falcon tubes containing 5 mL desiccant (silica gel), from which they were separated by 2 mL of cotton. Bees were randomly assigned to a social condition treatment, as either singletons (1 bee per tube,n = 31 bees) or pairs (2 bees per tube, n = 28 bees). We kept bees in the 0% humidity tubes for 3 hours before re-weighing. We assumed that mass loss equaled water loss over this time interval [1] and estimated total water loss as the difference in mass before and after the 3 hour assay. We estimated water loss as a percentage of total body mass as follows:
% body mass lost = [(initial mass – final mass) / (initial mass)] x 100
Additionally, to estimate the total body water content of M. tepidus timberlakei females, we dried a subset of females (n = 6) in a drying oven for 3 days at 60°C, then subtracted dry mass from initial live mass.