Diphosphoglycerate and phytic acid as feeding stimulants for the blood-feeding bug Rhodnius prolixus

1. The compounds 2,3-diphosphoglycerate (DPG), phytic acid (PA) and adenosine triphosphate (ATP) were tested as gorging stimulants for Rhodnius prolixus. All three are potent phagostimulants, with ED50 values less than 10 microM; in contrast, only ATP stimulates the black fly Simulium venustum, with an ED50 of 13 microM. 2. Equimolar mixtures of DPG and ATP showed pronounced synergism, causing 75% of test R. prolixus to gorge at a dose of 0.3 microM. 3. The response to DPG and PA supports the hypothesis that R. prolixus detects blood during biting by tasting signal chemicals released from red blood cells.