Flight energetics and dispersal capability of the fire ant, Solenopsis invicta Buren

Experiments were conducted to estimate the flight capabilities of fire ant (Solenopsis invicta Buren) alates. These experiments were designed to: (1) quantify energetic expenditure during fixed flight; (2) characterize metabolic substrates of male and female alates; (3) estimate flight speed of male and female alates; and (4) quantify wingbeat frequency and water loss of females during flight. Flying males (in closed-system respirometry) increased metabolic rate approximately 38.4-fold over resting rate. Females increased metabolic rate approximately 51-fold (closed-system respirometry) and 48-fold (flow-through respirometry) over resting rate. Female alates had a mean respiratory quotient (RQ) of 0.999, indicating reliance on carbohydrates. The mean RQ of males was significantly lower (0.867). The flight speed of females on a circular flight mill averaged approximately 0.7 m s−1, and increased with temperature but decreased with increasing body mass. The flight speed of males was 43% greater (approximately 1.0 m s−1) and increased linearly with temperature and increasing body mass. Female alates lost an average of 1.8 mg water h−1 during flight. A simple energetics model, combined with previous work on the nutrient content of S. invicta and patterns of CO2 release observed in this study, indicate that the flight capability of S. invicta female alates is limited to <5 km in the absence of wind.