Changes in the Blood Potassium Concentration of the African Migratory Locust (<i>Locusta Migratoria Migratorioides</i> R. &amp; F.) During Food Deprivation, and the Effect on Neuromuscular Activity

Abstract

ABSTRACT The concentrations of sodium and potassium in the haemolymph of the locust Locusta migratoria migratorioides R. &amp; F. have been determined by flame photometry. The molar ratio of sodium to potassium is normally about 5:1. During a short period of starvation the potassium content of the haemolymph decreases by as much as 50 %. The change in potassium is adequate to account for observed differences in muscle membrane resting potentials and for variations in the mechanical responses of the muscles to nerve stimulation. The ability of 5th-instar hoppers to respond to stimulation by hopping or jumping is increased after a short period of starvation owing to the increased mechanical responses of the muscles. It is suggested that changes in diet potassium will be found to influence behaviour of locusts by the direct effect of the potassium on muscle fibre activity.