Bumblebee Thermal Tolerance
Maximal critical thermal tolerance (CTmax) of castes and larvae of a bumblebee (Bombus impatiens) and the effect of environmental temperature on the colony metabolic rate and nest temperature. Larval CTmax is significantly lower than the CTmax of adult castes. Whole-colony thermoregulation is energetically costly at high and low temperatures. Colonies experiencing 30°C and below successfully thermoregulate nest temperature. Above 30°C, nest temperature cannot be regulated via colonial thermoregulation.
Steps to reproduce
CTmax was measured using the thermolimit respirometry method outlined by Lighton and Turner (2004, J. Exp. Biol. 207, 1903–1913. https://doi.org/10.1242/jeb.00970). Activity and respiratory CTmax were determined workers, drones, queens and larvae. Whole-colony metabolic rate was measured using flow-through respirometry over three hours and monitoring CO2 production at 5, 15, 25, 30, 35 and 40 degree Celsius. Colony temperature was measured simultaneously using temperature loggers (iBottons) placed within the brood clumps. Colonies were tested with and without insulation inside.
Natural Sciences and Engineering Research Council of Canada