Hormonal control of diuresis in the blood-feeding bug, Rhodnius prolixus

Rhodnius prolixus larvae ingest blood meals which are up to IO times their initial body weight They then undergo a rapid elimination of urine during which time the insect may lose 40% of the weight of the meal. This diuresis has been shown to be under the control of diuretic hormones (Maddrell ef al., 1991), which increase the rate of fluid transport by the Malpighian tubules. A number of factors may act as diuretic hormones in insects, including CRF-like diuretic peptides, kinin-like peptides and serotonin. Of these, only serotonin has been well described as a diuretic hormone in Rhodnius, although it is clear that peptides must also be involved. Using fluorescence immunohistochemistry with antibodies to Locusta CRF-like diuretic peptide, Leucophaea leucokinin 1 and serotonin, we have mapped the distribution of neurons and neurohaemal areas displaying these phenotypes in Rhodnius prolixus and found that their intensity of staining is altered by feeding.