STUDIES ON THE PROCESS OF INGESTION IN THE PREDATORY BUG PODISUS MACULIVENTRIS (HEMIPTERA: PENTATOMIDAE)

Abstract

The rate of ingestion by Podisus maculiventris Say feeding on larvae of Tenebrio molitor L. or Galleria mellonella L. is almost constant with time and from one predator to another. The rate is 1.80 ±.070 mg/hr/individual.No effect of the age or size of the predator nor of the species of prey on the feeding rate could be detected. Different periods of starvation before feeding directly affect the percentage of individuals that feed, but not the actual rate of feeding, until 60 hours of starvation. After 72 hours starvation, there is a drop in the feeding rate which we attribute, tentatively, to a weakening of the feeding mechanism by the starvation.The initial weight of the larva used as prey affects the rate of sucking during the first hour or two of each period of feeding and this relationship is responsible for a slight non-linearity in the individual curves of feeding. This may be an effect of the internal pressure of the body fluids in the prey.The process of ingestion is reviewed and compared with published studies of other species of Hemiptera. It is suggested that after insertion of the stylets of the predator into the body of the prey, the feeding process is affected by the internal pressure of the prey during the early part of a period of feeding but that, thereafter, the sucking action is maintained constant by the action of capillarity and the pharyngeal pump.