GAS-EXCHANGE, VENTILATORY PATTERNS, AND WATER-LOSS IN 2 LUBBER GRASSHOPPERS - QUANTIFYING CUTICULAR AND RESPIRATORY TRANSPIRATION

The respiratory physiology and water relations of two acridid grasshoppers (Romalea guttata and Taeniopoda eques) were examined with a flow-through system that simultaneously measures O2 consumption, CO2 excretion, and evaporative water loss. Both species exhibited a cyclic pattern of resting gas exchange that was characterized by intermittent ''bursts'' of O2 uptake and CO2 emission. Increasing temperature shortened both the burst and especially the interburst periods. Metabolic rates were strongly affected by temperature, but not hydration state. Dehydration, however, degraded the regularity of the respiratory cycles. Water loss rates (WLRs) for Romalea were significantly higher than for Taeniopoda at each temperature, with rates for hydrated animals (both species) greater than for dehydrated individuals. Respiratory transpiration accounted for only 2.1 % to 3.8% of the total water loss in Romalea and 3.8% to 5.3% in Taeniopoda between 15-degrees and 30-degrees-C These data raise serious questions regarding the presumed water conservation function for cyclic release of CO2 in these insects.