title: Temperature-dependent variation in gas exchange patterns and spiracular control in Rhodnius prolixus.
abstract: Insects display an array of respiratory behaviors, including the use of discontinuous gas exchange. This pattern is characterized by periods of spiracular closure, micro-openings (flutter), and complete openings during which the majority of gas exchange takes place. A current model of insect spiracular control suggests that spiracles are controlled by two interacting feedback loops, which produce the discontinuous pattern. The flutter period is thought to be initiated by a critically low partial pressure of oxygen, while the open period is initiated by a critically high CO2 threshold. The goal of our study was to test this control model under conditions of feeding-induced or temperature-induced changes in metabolic rate. We manipulated the metabolic rate of the insect Rhodnius prolixus using two discrete mechanisms: (1) feeding the insects a bloodmeal or (2) exposing them to a range of temperatures (18-38°C). Examining the variation in the gas exchange patterns produced by insects in each of these treatments allowed us to determine whether spiracular control is sensitive to metabolic rate and/or temperature. We found that increases in temperature caused significant decreases in open phase burst volumes and premature abandonment of discontinuous gas exchange cycles. These effects were not observed in fed individuals maintained at a single temperature despite their higher metabolic rates. Our results indicate that some part of the spiracular control mechanism is temperature sensitive, suggesting a possible role for pH in CO2 sensing.
authors: University of California, Irvine, CA 92697, USA eheinric@uci.edu.
authors: Erica
authors: E
authors: Heinrich
authors: University of California, Irvine, CA 92697, USA.
authors: Timothy
authors: T
authors: Bradley
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D007814:Larva / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010313:Partial Pressure; D012143:Respiratory Physiological Phenomena; D012239:Rhodnius / Q000378:metabolism / Q000502:physiology*; D013696:Temperature
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: DGC; Insect; Metabolism; Respiration; Spiracles; Temperature