Patterns of intermittent ventilation and responses to perfusing gas mixtures in quiescent Blaberus craniifer

Abstract

Patterns of intermittent ventilation were recorded by means of long electromyogram wires from quiescent Blaberus craniifer (Burmeister) buried in vermiculite. While buried, cockroaches were subjected to perfusion with various mixtures of CO, in air and of oxygen in nitrogen. Quiescent cockroaches in air ventilated for mean periods of 138 s in cycles of 720 s duration, but much variability occurred within and between cockroaches. Mild hypercapnia or hypoxia shortened the overall cycle time while more severe treatment caused the cycle to be replaced by continual pumping. Intermittent ventilation persisted in decapitated insects but the threshold of the response to hypoxia or hypercapnia was elevated. Prevailing gas tensions normally determine the frequency and duration of each phase.

Reversible brain inactivation induces discontinuous gas exchange in cockroaches

“…ground squirrels show a depressed response to hypoxia and an elevated response to hypercapnia when breathing intermittently during hibernation (McArthur and Milsom, 1991)] and similar changes may also occur in insects displaying DGCs. Indeed, this response is seen in decerebrated insects that show decreased sensitivity to both hypoxia (Edwards and Miller, 1986) and hypercapnia (Matthews and White, 2011b;Miller, 1960;Myers and Retzlaff, 1963). However, similar changes have not been observed in intact insects showing DGCs.…”

“…Previous studies have used decapitation, decerebration and anaesthetisation to elicit DGCs in cockroaches (Edwards and Miller, 1986;Matthews and White, 2011b), ants (Duncan and Newton, 2000;Lighton, 1992;Lighton et al, 1993;Quinlan and Lighton, 1999) and moth pupae (Ito, 1954;Levy and Schneiderman, 1966). While it has been acknowledged that decerebration may alter the interactions between respiratory pattern generators, and so alter the behaviour of the DGCs produced by decapitated individuals (Quinlan and Lighton, 1999), the primary cause underlying the emergence of DGCs in decerebrated insects was believed to be their quiescence and low MR, a state that is not significantly different to that exhibited by resting individuals spontaneously displaying DGCs (Lighton et al, 1993;Lighton and Garrigan, 1995;Quinlan and Lighton, 1999).…”

Periodic muscular activity and its possible functions in pupae of Tenebrio molitor

“…It can be hypothesized that muscular activity periods in Tenebrio rnolitor pupae are controlled by such neural centres, and that the movements in pupae are brought about by the same muscles used in adults for respiration movements. The temporal pattern of the bouts of muscular activity is similar to that of intermittent ventilation in cockroaches (Miller, 1982;Edwards & Miller, 1986). The possible mechanism could be as follows: during periods of inactivity the haemolymph circulation is very slow, metabolites accumulate in the blood, and the critical concentration of pH then triggers muscular activity.…”

Respiratory physiology and water relations of three species of Pogonomyrmex harvester ants (Hymenoptera: Formicidae)

“…CO 2 ‐induced relaxation of spiracular closer muscles) with higher‐order nervous reflexes such as hypoxia‐induced ‘flutter’ of ganglionic outflow to closer muscles ( Miller 1974; Sláma 1988). Evidence for cephalic modulation of ventilation has been demonstrated clearly in the locust Schistocerca gregaria and the cockroach Blaberus craniifer ( Miller 1960; Edwards & Miller 1986). Unfortunately, little is known about the underlying nervous control of gas exchange in ants.…”

“…These data suggest that the open phase in intact ants is triggered at lower internal CO 2 levels than in decapitated animals. Enhanced sensitivity to CO 2 might derive from the activity of excitatory cephalic CO 2 receptors or from some general excitation originating in the subesophageal ganglia ( Miller 1960; Edwards & Miller 1986).…”