A stressful shortness of breath Oxygen consumption patterns associated with molting and thermal challenge in the mayfly Cloeon cognatum

Meeting Abstract

1.3  Saturday, Jan. 4 08:30  A stressful shortness of breath: Oxygen consumption patterns associated with molting and thermal challenge in the mayfly Cloeon cognatum. CAMP, A.*; BUCHWALTER, D.; North Carolina State University; North Carolina State University david_buchwalter@ncsu.edu

In insects, one of the more fascinating and improbable aspects of the molt is the fact that not only does the individual discard its exoskeleton, but that the lining of the respiratory (tracheal) system is also shed and renewed. While conducting respirometry experiments on thermally ramped mayfly (Cloeon cognatum) larvae, we discovered radical changes in oxygen consumption patterns associated with the molting process. The signature pattern includes a precipitous drop in oxygen consumption (likely associated with the temporary blockage of the trachea), followed by a surge of oxygen consumption to compensate for the preceding oxygen deficit. The magnitude of this respiratory disruption increases with increasing temperature. To our knowledge, this is the first report of molting causing oxygen deficit in an aquatic insect, and provides a potential explanation for anecdotal observations of increased mortality rates in aquatic insect larvae during the molt. We further compared standard metabolic rates (SMRs) and respiratory Q10s in C. cognatum larvae reared at different temperatures. The SMR of 22°C reared larvae was 80% higher than 17°C reared larvae, while the SMR of 27 °C reared larvae was only 39% higher than 22°C reared larvae. Q10s were highest (2.41 ± 0.32) in larvae ramped from an optimal rearing temperature (22°C), somewhat lower (2.13 ± 0.36) at a sub optimally warm rearing temperature (27 °C), and significantly lower (1.82 ± 0.17) in sub optimally cold (17°C) reared individuals. The importance of linking physiological performance to known life history outcomes will be discussed.

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