Highly diversified circadian rhythms in the calling activity of eneopterine crickets (Orthoptera: Grylloidea: Gryllidae) from Southeast Asia

Circadian rhythms are endogenously generated and self-sustaining oscillations that occur at a 24 hours scale and are ubiquitous amonganimals.. Animals rely on their circadian clocks to anticipate cyclical external environmental oscillations to find mates and reproduce, among other activities. Hence, animals that sing to attract mates can modulate their calling activity across the circadian cycle and species can exhibit different circadian rhythms in their calling activity. Crickets are among the most studied sound-producing animals, but concerted efforts to examine their circadian rhythms in their calling activity across multiple species remain limited for Southeast Asian species. Here, we recorded the calls of eleven Southeast Asian species of Eneopterinae – known for their diverse calling songs – across the phylogeny and compared their circadian rhythms based on the number of echemes and amount of sound produced. Using standardised ex-situ recordings to produce precise data about the circadian patterns, we verified sporadic observations about their calling activity made in the field. We also found that the eneopterines exhibit highly diversified circadian rhythms in calling activity, ranging from strictly diurnal and nocturnal calling to complex calling patterns with multiple peaks across day and/or night.