| Aspects of the respiratory physiology and energetics of the red imported fire ant, Solenopsis invicta Buren, were investigated. Mass and temperature were significant predictors of metabolic rate for all castes. Metabolic rate of workers, female alates, and larvae fell within predicted values based upon a log-log regression of metabolic rate over mass for several ant species, while male and pupal rates fell above (177%) and below (42%) predicted values, respectively.; Female alates ventilated most rapidly at all temperatures and did not exhibit a DGC at temperatures >25°C. Males ventilated slower than other castes in the temperature range 15--30°C, and workers ventilated at an intermediate rate. DGC rate increased with increasing temperature.; Flight speed increased linearly with increasing temperature for both sexes, but decreased with increasing mass in females and increased with mass in males. Metabolic substrate of male and female alates differed significantly, with female RQ indicating carbohydrate metabolism and male RQ indicating possible protein metabolism, or a mix of substrates.; Respiratory rate of workers from a laboratory colony was elevated when confined in groups of 20 and 40 ants (closed-system respirometry), ca. 2.5X greater than respiratory rate of individuals. In flow-through respirometry, increasing group size resulted in decreased respiratory rates, an approximate 50% reduction from single workers to groups of 80 and 100 workers. Increasing rate of air flow through the respirometry system significantly reduced respiratory rate of groups of 40 workers. Clumping behavior in response to dry, CO 2-free air may help explain these results.; Locomotory activity increased respiratory rates of individual workers. The relationship between metabolic rate and speed was independent of temperature, which is consistent with studies on iguanid lizards, cockroaches, and another ant species. (Abstract shortened by UMI.)... |
