The regulation of respiration in the flea, xenopsylla cheopis , Roths. (Pulicidea)

Abstract

The gaseous exchanges of terrestrial insects are regulated by (i) the opening and closing of the spiracles—the “diffusion control” of Hazelhoff (1926, 1927)—and, in the larger and more active forms by (ii) the mechanical aeration of the tracheal system by pumping movements—“ventilation control.” Spiracular and pumping movements may occur at the same time; for example, in those insects in which a directed stream of air is driven through the main tracheal branches (Fraenkel, 1932; McGovran, 1931); and then the spiracles, by allowing air to pass through them in one direction only, are believed to play a part in the mechanism of ventilation. The object of the present work was to study in greater detail than hitherto the spiracular movements of an insect in which these are not complicated by mechanical ventilation. For this purpose the common rat flea of the tropics, Xenopsylla cheopis , has proved an ideal subject.