Energetics and Thermoregulation of Popillia japonica Newman (Scarabaeidae, Coleoptera) during Flight and Rest

Abstract

Total oxygen consumption ($V_{O_{2}}$ averaging 4.66 mL/h) of Japanese beetles (Popillia japonica Newman, Scarabaeidae, Coleoptera) during free flight was independent of body mass, while the mass-specific oxygen consumption $\dot{V}_{O_{2}}$ (averaging 52.14 mL/g · h⁻¹) was inversely related to body mass. Variations in wing beat frequency, ambient temperature ($T_{a}$), and thoracic temperature ($T_{th}$) did not alter $\dot{V}_{O_{2}}$. However, during the first few seconds following takeoff, flight metabolism was substantially increased. No change in wing beat frequency occurred during this time period; however, in separate experiments, larger wing beat amplitudes were observed during initial flight. Correspondingly, thermoregulation was more pronounced during takeoff and gradually disappeared in prolonged flight. Measured $T_{th}$ excesses were supported by data on metabolic heat gain and heat loss based on cooling curves. In resting beetles, whole-animal $\dot{V}O_{2}$ (0. 16 mL/h, averaged over a ran...