Scaling of resting and maximum hopping metabolic rate throughout the life cycle of the locust Locusta migratoria

The hemimetabolous migratory locust Locusta migratoria progresses through five instars to the adult, increasing in size from 0.02 to 0.95?g, a 45-fold change. Hopping locomotion occurs at all life stages and is supported by aerobic metabolism and provision of oxygen through the tracheal system. This allometric study investigates the effect of body mass (M _b) on oxygen consumption rate (Ṁ _O2,μmol?h ^-1) to establish resting metabolic rate (ṀR _O2), maximum metabolic rate during hopping (ṀM _O2) and maximum metabolic rate of the hopping muscles (ṀM _O2,hop) in first instar, third instar, fifth instar and adult locusts. Oxygen consumption rates increased throughout development according to the allometric equations ṀR _O2=30.1M _b ^0.83±0.02, ṀM _O2 155M _b ^1.01±0.02, ṀM _O2,hop=120M _b ^1.07±0.02 and, if adults are excluded, ṀM _O2,juv=136M _b ^0.97±0.02 and ṀM _O2,juv,hop=103M _b ^1.02±0.02. Increasing body mass by 20-45% with attached weights did not increase mass-specific ṀM _O2 significantly at any life stage, although mean mass-specific hopping Ṁ _O2 was slightly higher (ca. 8%) when juvenile data were pooled. The allometric exponents for all measures of metabolic rate are much greater than 0.75, and therefore do not support West, Brown and Enquist's optimised fractal network model, which predicts that metabolism scales with a 3/4-power exponent owing to limitations in the rate at which resources can be transported within the body.