Luke Bemish

Acoustic communication signals often contain a complex temporal structure, yet how this temporal structure contributes to signal recognition is poorly understood, particularly in eavesdropping receivers. The parasitoid fly Ormia ochracea localises host crickets by eavesdropping on their calling songs. In Florida, preferred host songs consist of sound pulses repeated at ∼50 pulses s−1, and flies exhibit matching preferences. However, it is unclear whether this preference reflects sensitivity to individual temporal parameters or to derived temporal relationships that emerge from their combination. We independently varied pulse duration and interpulse interval across a broad stimulus space and quantified tethered-walking phonotaxis using a switch-following paradigm. Behavioural responses formed a structured tuning surface, with elevated responses for pulse durations of ∼5–15 ms across a broad range of interpulse intervals, together with high performance along a diagonal corresponding to 50 pulses s−1. Responses failed to collapse across stimuli sharing the same pulse rate or pulse period, indicating that these parameters alone do not determine recognition. Models allowing behavioural responses to vary jointly across combinations of temporal parameters substantially outperformed models based on single parameters. Although pulse duration strongly constrained recognition, behavioural responses also varied systematically with interpulse interval and could not be explained by pulse duration, interpulse interval, pulse rate, pulse period or duty cycle alone. The apparent preference of O. ochracea for ∼50 pulses s−1 therefore represents one component of a broader temporal recognition landscape rather than recognition based on pulse rate alone.

Acoustic communication signals often contain complex temporal structure, yet the features underlying signal recognition remain poorly understood, particularly in eavesdropping receivers. The parasitoid fly Ormia ochracea localises host crickets by eavesdropping on their calling songs. In Florida, preferred host songs consist of sound pulses repeated at ~50 pulses/s, and flies exhibit matching preferences. However, it remains unclear whether this preference reflects sensitivity to individual temporal features (e.g., pulse duration, interpulse interval) or to derived temporal relationships (e.g., pulse rate, pulse period, duty cycle) that emerge from their combination. We independently varied pulse duration and interpulse interval across a broad stimulus space and quantified tethered-walking phonotaxis using a switch-following paradigm. Behavioural responses formed a structured tuning surface, with high performance along a diagonal corresponding to 50 pulses/s, as well as elevated responses for a restricted range of pulse durations across a wide range of interpulse intervals. Responses failed to collapse across stimuli sharing the same pulse rate or pulse period, indicating that these features alone do not determine recognition. Instead, behaviour was best explained by the interacting effects of pulse duration and interpulse interval. These results demonstrate that song recognition in O. ochracea is multidimensional, with pulse rate tuning emerging from an underlying feature space rather than a single encoded parameter.