Summary
We examined the effect of extracellular acid-base status and tracheal gas levels on the ventilation rate of resting Romalea guttata and Schistocerca americana grasshoppers. We manipulated haemolymph pH and [HCO3-] within normal physiological ranges using injections of HCl, NaOH, NaHCO3 and NaCl into the haemocoel. In contrast to terrestrial vertebrates, there was no evidence that extracellular acidification increases ventilation rate in grasshoppers. Elevation of haemolymph bicarbonate levels (by NaHCO3 injection) increased ventilation rate, while depression of haemolymph bicarbonate levels (HCl injection) had no effect. Injection of NaHCO3 also increased tracheal PCO2, suggesting that the effect of the NaHCO3 injection might be mediated by a sensitivity of the ventilatory system to tracheal gases. We tested for effects of tracheal gases on ventilation rate by independently manipulating tracheal PCO2 and PO2 using tracheal perfusions. Ventilation rate was positively correlated with tracheal PCO2 and negatively correlated with tracheal PO2. Increasing tracheal PO2 above normal resting levels or decreasing tracheal PCO2 below normal levels decreased ventilation rate. We conclude that quiescent grasshoppers regulate tracheal PCO2 and PO2 by varying ventilation rate and that both PCO2 and PO2 in the trachea stimulate ventilation in normal, resting grasshoppers.
Article navigation
Related articles
Cited by...
Similar articles
Other journals from The Company of Biologists
Editor’s choice – A cognitive map in a poison frog
For more than 20 years, frogs and lizards were considered to lack place memory. Now, however, Sabrina Burmeister and her team use a modification of the classic Morris water maze to demonstrate the presence of a cognitive map in green-and-black poison dart frogs.
“Getting the JEB Fellowship was really important early on in my career.”
Cosima Porteus is a Postdoctoral Fellow at the University of Exeter, UK, where she studies how fish sense, interact with and respond to their environment. In this interview, Cosima talks about what motivated her to become a scientist, the people that influenced her career, and her opinion on improving the peer-review system for early career researchers.
Path integration is a navigational strategy that gives an animal an estimate of its position relative to some starting point. In his Review, Thomas Collett details the features of path integration in foraging desert ants and honeybees and explains how, in some cases, well-ordered behaviour might substitute for complex neural circuitry.
The Peter Baker Fellowship is for post-doctoral scientists interested in marine biology research, especially physiological research. It will provide living and travel expenses (up to £3,000) to spend approximately two months working at the Laboratory of the Marine Biological Association, Plymouth, at any time of the year. Bench fees will be waived and a small sum may be available to assist with research expenses. This fund is held in trust by the Physiological Society, The Company of Biologists and the Marine Biological Association. Application deadline: 31 January 2020.
If you’re going to the ICCPB meeting in Ottawa from 5 to 9 August, you can meet some of our Monitoring Editors, chat to JEB Reviews Editor Charlotte Rutledge and pick up free JEB goodies from the Plenary Room!
The Company of Biologists provides grants to fund scientific meetings, workshops and conferences in the fields covered by our journals. Typically, meetings with fewer than 100 people may be granted up to £2,000, increasing up to £6,000 for about 400 people. The next deadline to apply is 02 September 2019.
Rasmus Ern highlights a preprint from Josefin Sundin and colleagues, who found that reducing brain temperature of Atlantic cod by mounting cooling plates on their head only marginally increases the fish’s maximum thermal tolerance.