Sensory-driven divergence in flight strategies of eared and earless moths evading horseshoe bats

The evolutionary arms race between insectivorous bats and moths has driven the development of elaborate anti-predator strategies, with ultrasound hearing considered a key adaptation in tympanate moths. However, whether this sensory capability translates into more effective evasive flight compared to earless moths, and whether last-ditch maneuvers are effective against high-duty-cycle (HDC) bats remains unresolved. We integrated controlled laboratory predation experiments involving three horseshoe bat species (Rhinolophus episcopus, R. osgoodi, R. sinicus) with field dietary analysis to address these questions. We found that while eared and earless moths shared a similar repertoire of flight maneuvers, eared moths more frequently employed the most effective tactics (e.g., flight cessation and erratic flight) and initiated behavioral transitions significantly faster upon bat attack. Flight behavior was the primary determinant of predation outcome, with flight cessation being the most effective strategy (12% predation), contrasting sharply with the high vulnerability of stationary wing fluttering (76% predation). In laboratory trials, eared moths experienced 14% lower overall predation probability than earless moths. This advantage was strongly corroborated by field data, which showed eared moths were disproportionately underrepresented in bat diets compared to their own abundance in the habitat. Our results demonstrate that moth last-ditch flight maneuvers are effective against HDC bats and that ultrasound hearing confers a significant survival benefit by enabling earlier and more strategic deployment of evasive flight. This supports a hierarchical model of anti-predator defence, where advanced sensory systems refine the performance of ancestral escape behaviors, shaping the dynamic bat-moth arms race.