Similarities in digestive proteinase production in Rhodnius prolixus (Hemiptera: Reduviidae) and Stomoxys calcitrans (Diptera: Muscidae)

Abstract Proteinase assays that have been optimized for stable fly, Stomoxys calcitrans , trypsin and aminopeptidase and Rhodnius prolixus cathepsin B and aminopeptidase were used to measure proteinase activity in the posterior midgut. A positive correlation between protein content of this midgut region and either extracellular trypsin or cathepsin B activity has been demonstrated using samples collected at various times after ingestion of a blood meal. In both insects intracellular aminopeptidase activity did not correlate with protein content of the posterior midgut. Extracellular trypsin in the stable fly and cathepsin B in Rhodnius prolixus are controlled by a secretagogue mechanism. Aminopeptidase levels are not controlled by a protein secretagogue.