Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA 92697, USA.
J Exp Biol. 2013 Dec 1;216(Pt 23):4473-82. doi: 10.1242/jeb.088450. Epub 2013 Sep 12.
Insects exchange respiratory gases via an extensive network of tracheal vessels that open to the surface of the body through spiracular valves. Although gas exchange is known to increase with the opening of these spiracles, it is not clear how this event relates to gas flow through the tracheal system. We examined the relationship between respiratory airflow and spiracle activity in a ventilating insect, the hissing cockroach, Gromphadorhina portentosa, to better understand the complexity of insect respiratory function. Using simultaneous video recordings of multiple spiracular valves, we found that abdominal spiracles open and close in unison during periods of ventilation. Additionally, independent recordings of CO2 release from the abdominal and thoracic regions and observations of hyperoxic tracer gas movement indicate that air is drawn into the thoracic spiracles and expelled from the abdominal spiracles. Our video recordings suggest that this unidirectional flow is driven by abdominal contractions that occur when the abdominal spiracles open. The spiracles then close as the abdomen relaxes and fills with air from the thorax. Therefore, the respiratory system of the hissing cockroach functions as a unidirectional pump through the coordinated action of the spiracles and abdominal musculature. This mechanism may be employed by a broad diversity of large insects that respire by active ventilation.
昆虫通过广泛的气管血管网络进行气体交换，这些气管血管通过气门瓣膜开口通向体表。虽然已知气体交换随着这些气门的打开而增加，但尚不清楚这一事件与气管系统中的气流之间的关系。我们研究了呼吸气流与通风昆虫——嘶嘶蟑螂（Gromphadorhina portentosa）气门活动之间的关系，以更好地了解昆虫呼吸功能的复杂性。通过对多个气门瓣膜的同步视频记录，我们发现腹部气门在通风期间会同时打开和关闭。此外，对来自腹部和胸部区域的 CO2 释放的独立记录以及对过氧示踪气体运动的观察表明，空气被吸入胸部气门并从腹部气门排出。我们的视频记录表明，这种单向流动是由腹部气门打开时腹部收缩驱动的。然后，当腹部放松并充满来自胸部的空气时，气门关闭。因此，嘶嘶蟑螂的呼吸系统通过气门和腹部肌肉的协调作用作为单向泵起作用。这种机制可能被广泛的大型昆虫采用，它们通过主动通风进行呼吸。
