Quantifying Insect Predation in Laboratory Arenas: the Effect of Prey Acclimation

Abstract

There are drawbacks associated with current methods used to quantify insect predation. However, there has been relatively little effort to experimentally document the sources of biases associated with different methodologies. In this study, we investigated how methods used experimentally to quantify predation may influence insect antipredator defenses being observed, and thus alter the determination of the number of prey killed by predators, and potentially the conclusions reported in the study. We focused on acclimation period, which represents the time between the point at which a prey individual is made available, for example on a leaf, and when the experiment is initiated. In essence, this is the period of time during which an organism adjusts to the conditions that surround it before a treatment is imposed. We investigated if prey acclimation period on plants influences the antipredator behavior of larval Orgyia leucostigma (J.E. Smith) (Lepidoptera: Lymantriidae), and the number of prey killed in the laboratory by the predatory wasp Polistes fuscatus (Fabricius) (Hymenoptera: Vespidae). The results of this study provide evidence that acclimation time significantly affects the antipredator behavior observed and mortality of caterpillars exposed to predators. The majority of larvae allowed short acclimation periods did not drop in response to the attacks of wasps. These larvae suffered significantly higher mortality compared to caterpillars that were allowed to acclimate for longer periods of time.