Studies on the excretory and neuroendocrine systems of some orthopterian insects, with particular reference to Jamaicana flava (caudell)

Abstract

Some aspects of the general physiology, structure and biochemistry of Jamaicana flava were examined. Measurements of growth and oxygen consumption were made, throughout the stadium, for individuals of the sixth instar. The anatomy and histology of the stomatogastric nervous, neurosecretory and retrocerebral endocrine systems of this species are described. The effect of temperature on these systems was examined in insects of the sixth instar. Temperature was found to markedly influence the rate of larval development. These findings are discussed in relation to the present knowledge of neurosecretory activity and protein synthesis. A detailed account is given of the structure of the excretory system of Jamaioana flava and a brief description of the Malpighian tubules and rectum of Locusta migratoria. In both species the electron microscopic structure of the Malpighian tubules and rectum were found to be similar to that reported for other terrestrial insects. The ultrastructure of these tissues is discussed in relation to current theories of water transport across epithelia. The ultrastructure of the ileum is discussed in relation to its possible role in the excretory process. The excretory system of Jamaicana flava and several other Orthopteran species, was examined for Na(^+) – K(^+)-, and Mg(^2+) ATPase activity. Two bio chemical methods of obtaining microsomal preparations with ATPase activity were used and are described. Only one, involving homogenization in raannitol and deoxycholate medium, followed by extraction with sodium iodide, provided preparations with measurable Na(^+) –K(^+)- ATPase activity. In all species examined, Na(^+) – K(^+) - and Mg(^2+) ATPase activity was present in microsomal preparations obtained from the Malpighian tubules, ileum and rectum. The properties of Na(^+) – K(^+) ATPase were determined and were generally found to be similar to those reported by other workers. Ebcperiments to determine the distribution of Na(^+) – k(^+) ATPase within the excretory epithelia of Locusta migratoria, using histochemical methods were unsuccessful. The possible role(s) of Na(^+) – K(^+) ATPase in the functioning of the excretory system is discussed.