Rogowitz GL, Chappell MA (2000). Energy metabolism of eucalyptus-boring beetles at rest and during locomotion: gender makes a difference. Journal of Experimental Biology 203: 1131-1139

We studied metabolic rates during rest, maximal running exercise and tethered flight in the long-horned eucalyptus-boring beetles Phoracantha recurva and P. semipunctata. Simultaneous measurement of rates of O2 consumption (VO2) and CO2 production (VCO2) indicated that VCO2 closely approximated VO2 and hence was a good index of aerobic metabolic rate. The resting metabolic rate (RMR), peak VCO2 during running-wheel locomotion (MRrun) and factorial scope during running (MRrun/RMR) are similar to published values for several other insect taxa. MRrun was repeatable for most test groups over intervals of 48-96 h. Studies of P. semipunctata show that MRrun is relatively insensitive to changes in ambient temperature (Ta) between 20 and 30 degrees C, whereas resting metabolic rate increases with Ta with a normal Q10 (2.4). Consequently, factorial scope declines at the higher Ta: mean factorial scopes for male and female P. semipunctata are 17.7 and 13.6 at 20 degrees C versus 8.9 and 5.5 at 30 degrees C, respectively. Flight activity requires a considerably greater metabolic rate than terrestrial activity: at Ta values of 20-30 degrees C, the mean factorial scope for flight activity of male P. semipunctata is 72 (range 36-110). Nevertheless, our measurements of flight metabolic rate in Phoracantha spp. are considerably lower than predicted from allometric equations for other insects. Our most interesting finding was that males of both species had a substantially and significantly higher MRrun and aerobic scope than females. The gender differences in MRrun are consistent with differences in activity levels of males and females during mate-seeking behavior.