Acoustically Mediated Predator Detection and Risk Assessment in the Fall Field Cricket, Gryllus pennsylvanicus

Abstract

Insects are highly acoustic animals that use their acoustic sensory systems for a variety of purposes, including detection and evasion of predators. The focus of research on acoustically mediated predator detection in insects has been on detection of bat predators by eavesdropping on echolocation signals. However, insects are prey to an array of non-bat predators that produce acoustic signals and cues that may be used to evade predators. It has been proposed that insects may use such sounds and vibrations for predator detection, but evidence for this is limited. I tested the hypothesis that insects use sounds and vibrations from non-bat predators for predator detection and risk assessment using a locally abundant species of field cricket (Gryllus pennsylvanicus) as a model organism. Live recordings of American toads (Anaxyrus americanus) and playbacks of pre-recorded sounds from breaking branches and communication signals and flight sounds from insectivorous birds showed that non-bat predators of Gryllus pennsylvanicus produce sounds that at least partially overlap with sensitivity of their tympanal organ. Recordings of vibrations produced by live toads and playbacks of pre-recorded bird communication signals, bird flight, and breaking branches showed comparatively less overlap with vibrational sensitivity. Playbacks of bird communication signals and bird flight induced freezing responses in G. pennsylvanicus, suggesting that crickets use these sounds to detect and evade predators. This study provides the first evidence that fall field crickets are attending to sounds produced by non-bat predator species to avoid predation.