Age-Related Behavioral Changes Across the Adult Lifespan of a Cricket: A Longitudinal Analysis Using DeepLabCut

<title>Abstract</title> Aging in insects is characterized by progressive behavioral changes, including declines in locomotion, altered sleep, and disrupted circadian rhythms. The two-spotted cricket ( <italic>Gryllus bimaculatus</italic> ) is a useful model for behavioral senescence studies because of its experimentally tractable adult lifespan, distinct behavioral repertoire, and ease of laboratory rearing. However, studies simultaneously tracking multiple behaviors across the entire adult lifespan remain limited. In this study, continuous behavioral recordings and DeepLabCut-based markerless pose estimation were used to quantify age-related behavioral changes in eight adult male crickets maintained under a 12:12 h light–dark cycle. Behaviors were classified into locomotion, resting, sleep-like state (SLS), feeding, drinking, and calling, with an additional “other” category. We then assessed age-related changes in hourly and total activity during the light and dark phases by dividing each individual's record into three lifespan-normalized stages—early, mid, and late. Locomotion, resting, and SLS differed significantly between light and dark phases and changed with age. Total distance travelled varied across lifespan segments in a time-of-day dependent manner. Male calling displayed significant light-dark differences and age-related shifts, whereas feeding and drinking showed no detectable differences. Correlation analysis revealed that reductions in calling were associated with increased SLS but not locomotion, suggesting that declines in reproductive communication may not simply reflect generalized locomotor decline. These findings demonstrate that behavioral aging in adult crickets is behavior-specific rather than a uniform decline, providing a framework for studying behavioral senescence in crickets and other nontraditional insect models.