The gut tissues and associated nervous system of the African migratory locust, Locusta migratoria, were found to contain
FMRFamide-like immunoreactive (FLI) material throughout the five larval instars and 2 weeks into the adult stage in both males and females.
FMRFamide-like immunoreactivity associated with the locust gut was described using camera lucida techniques.
FMRFamide-like immunoreactivity is observed in the frontal connectives, recurrent nerve, and oesophageal nerves; projections from the ingluvial
ganglion onto the anterior midgut, and from the proctodeal nerve onto the hindgut and posterior midgut; in the neuropils of the frontal
ganglion, hypocerebral
ganglion and ingluvial ganglia; 30 cell bodies in the frontal
ganglion; multipolar sensory cells on the foregut; and endocrine-like cells in the gastric caecae and midgut. Radioimmunoassay (RIA) was used to determine the quantities of FLI material in foreguts, gastric caecae, anterior and posterior midguts, and hindgut of first-fifth instar larvae, 1-3- and 14-17-day male and female adult locusts. As expected, as the tissue size (assessed by total
protein content) increases, so does the amount of FLI material in each tissue. Normalizing for tissue size reveals significant differences in FLI content among the stages for each tissue tested. Reversed phase-high pressure liquid chromatography (RP-HPLC) followed by RIA has identified four groups of FLI fractions present in the gut, and different members of these groups are present in the various gut tissues.