Digestion Limits the Functional Response of an Aphidophagous Coccinellid (Coleoptera: Coccinellidae)

The dynamics of predator-prey systems are strongly affected by the predators feeding rate on increasing prey density, that is, its functional response. Holling's assumptions concerning the biological process of handling time, that is, the time a predator spends on pursuing, subduing, eating, and digesting its prey, have been debated, as digestion represents a background component of predation. Therefore, predators are characterized either as digestion or handling limited. A study was initiated to identify the mechanism that limits the coccinellids' predation ability. The 14-spotted ladybird beetle, Propylea quatuordecimpunctata (L.) (Coleoptera: Coccinellidae), and its prey, Aphisfabae Scopoli (Hemiptera: Aphididae), were used in long- and short-term functional response experiments. Results showed that P. quatuordecimpunctata adults exhibit a type II functional response. The estimated attack rates and handling times differed significantly between long- and short-term experiments, indicating that the digestion process limits predation ability of P. quatuordecimpunctata.