The amount of time it takes a predator to subdue and consume a prey item (i.e., handling time) impacts predator-prey interactions and food web dynamics. Predators may spend vastly different amounts of time handling prey depending on predator motivational state (e.g., gut fullness) or attributes of the prey (e.g., size). Differences in handling time are expected when prey species differ dramatically in morphological traits (e.g., shell thickness) that influence vulnerability to predation, but how much variation in handling time is expected for soft-bodied insect species like aphids? We measured the amount of time that ladybird beetles (Hippodamia convergens) spent handling two aphid species: pea aphids (Acythrosiphon pisum) and black bean aphids (Aphis fabae).

Results/Conclusions

Preliminary results indicate that H. convergens spends significantly more time handling black bean aphids than pea aphids even when controlling for size differences in the aphid species.  Black bean aphids are generally regarded as unsuitable prey and pea aphids as suitable prey for ladybird beetles (where suitable prey enable larval development and successful reproduction). Handling time, therefore, provides an indication of prey quality in these species and represents a foraging mechanism that may influence prey dynamics in the presence of a shared predator.