Energy expenditure and food intake of territorial male Pachydiplax longipennis (Odonata: Libellulidae)

Field observations of males of the dragonfly, Pachydiplax longipennis (Burmeister), were used to determine how individuals of this species allocate energy to different activities during territory occupancy. The effects of biological and physical factors on the species’daily activity pattern were examined. The proportion of time spent in flight was independent of temperature but increased asymptotically with increasing population density. Measurements of assimilation efficiency and the quantity of faeces produced per day were used to calculate daily intake of food. An independent estimate of food consumption was derived from data on gut contents and clearance rate. Food intake appears to exceed only slightly the energy required to maintain a territory, with little available for other activities. The activity pattern may be determined in part by the amount of energy available to individuals.