The physiological control of drinking behaviour in nymphs of Locusta migratoria

ABSTRACT. The changes in behaviour of nymphs of Locusta migratoria in relation to free water, during the course of two different deprivation regimes are described. With no access to food or water for 24 h at 30°C, the insects responded positively to free water when it was provided. If dry food was provided during water deprivation, positive responses occurred in 8 h. The physiological changes associated with the behavioural change indicate that positive responses were correlated with a reduction in abdominal volume; experimentally induced changes confirmed this. Increased osmotic pressure did not influence the onset of drinking, but the amount of water ingested was directly correlated with the size of osmotic pressure increases.