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Acid-base status and spiracular control during discontinuous ventilation in grasshoppers
The Journal of Experimental Biology
|January 1, 1995
Summary
Discontinuous ventilation (DV) in grasshoppers is triggered by internal carbon dioxide (CO2) buildup, not oxygen levels. This insect respiration mechanism differs significantly from that of lepidopteran pupae.
Area of Science:
- Insect Physiology
- Respiratory Physiology
- Comparative Physiology
Background:
- Many insects exhibit discontinuous ventilation (DV) during quiescence, characterized by prolonged periods of minimal gas exchange.
- Understanding the physiological triggers and acid-base consequences of DV is crucial for insect respiratory studies.
Purpose of the Study:
- To investigate the effects of DV on haemolymph acid-base status in the grasshopper Taeniopoda eques.
- To determine if spiracular opening during DV is regulated by internal gas tensions.
Main Methods:
- Measurements of haemolymph acid-base status and PCO2 during resting periods in T. eques at 15°C.
- Exposure of grasshoppers to varying atmospheric PCO2 and PO2 levels to observe effects on DV patterns.
Main Results:
- During interburst periods, haemolymph PCO2 increased from 1.8 to 2.26 kPa with minimal haemolymph acidification.
- DV ceased when ambient PCO2 reached 2.9 kPa, indicating a CO2 threshold for spiracular opening between 2 and 2.9 kPa.
- Unlike lepidopteran pupae, atmospheric PO2 did not affect interburst duration in grasshoppers.
Conclusions:
- Internal CO2 accumulation to a threshold level triggers spiracular opening in T. eques.
- Grasshopper DV physiology differs from lepidopteran pupae, with lower internal PCO2, a lower CO2 threshold for opening, and higher spiracular conductance.
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