Meeting Abstract

P2-170  Sunday, Jan. 5  Differences in critical thermal maximum between crepuscular vs. diurnal species of Xylocopa PULLEY, KL*; PERCIVAL, C; TAPSAK, ST; TSCHEULIN, T; PENTANIDOU, T; GONZALEZ, VH; HRANITZ, JM; BARTHELL, JF; University of Texas at El Paso; Pomona College, Claremont, CA; Bloomsburg University of Pennsylvania; University of the Aegean, Mytilene, Greece; University of the Aegean, Mytilene, Greece; University of Kansas, Lawrence; Bloomsburg University of Pennsylvania; University of Central Oklahoma, Edmond Klpulley@miners.utep.edu

Predicting the response of pollinators to temperature has become increasingly important due to global warming trends. The critical thermal maximum (CT_max), the temperature at which an organism loses motor control when exposed to high temperatures, serves as a good indicator for their response to rising temperature. However, this remains unknown for many pollinating bees. Here we compared the heat tolerances of three species of carpenter bees (Xylocopa violaceae, X. olivieri, and X. iris), which differ in their daily foraging patterns. One of them is crepuscular (X. olivieri) while the other two are diurnal, thus we expect the latter species to be more heat tolerant. We also assessed the effect of sex, body size, relative age, and body water content on their CT_max and measured bees’ thoracic temperature. The crepuscular species was as heat tolerant as X. violacea, but less heat tolerant than X. iris. Sex, body size, relative age and body water content did not have an effect on CT_max. Thoracic temperatures were always higher than 40 °C, independent of ambient temperature, and a few Celsius degrees lower than CT_max. Our results are consistent with our expectation that diurnal species tend to display greater thermal tolerance and provide additional explanations supporting the hypothesis of interspecific interference competition as the main factor driving the evolution of dim-light foraging behavior in these bees.