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Mechanisms regulating salt intake in fifth‐instar nymphs of Locusta migratoria
Author(s) -
TRUMPER S.,
SIMPSON S. J.
Publication year - 1994
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1111/j.1365-3032.1994.tb01044.x
Subject(s) - biology , nymph , mealworm , locust , meal , instar , food science , salt (chemistry) , schistocerca , taste , zoology , botany , larva , chemistry
. Investigations were undertaken into the mechanisms controlling regulation of salt intake in fifth‐instar nymphs of Locusta migratoria L. Initially, the pattern of feeding was recorded for 24 h in locusts fed a chemically‐defined food either with or without salt. Differences were apparent from the first meal, with smaller meals being eaten more frequently on the salt‐free food over the next 8h. As a result, total food intake over the first 8h was similar on the two foods. By 24 h, however, intake of the salt‐free food was considerably reduced and the rate of prefeeding rejections was high. Next, following a period of pretreatment (24 or 48 h) on one of these two foods, responses were recorded to glass‐fibre discs impregnated with salts, artificial foods differing in salt content, and wheat germ. Haemolymph amino acid titres were also recorded in locusts feeding ad libitum on salt‐free or salt‐containing food to test the ‘metabolic bottleneck’ hypothesis for explaining rejection of a salt‐free food after a period of feeding on it. Finally, the role of learning was investigated in experiments in which distinctive plant odours and flavours were paired with foods lacking or containing salt. Results across all the experiments indicate that regulation of mineral intake in locust nymphs involves a number of mechanisms, including modulation of locomotory behaviour, innate taste responses and learning. Additionally, there was evidence of a sex difference in salt appetite.