Developmental and Adult Thermal Environments Interactively Shape Calling Song Plasticity in the Decorated Cricket Gryllodes sigillatus

Deep Sehgal , Tuba Rizvi , Klaus Reinhold

Temperature influences insect development and adult behaviour, yet the extent to which thermal conditions experienced during development shape thermally sensitive communication in adulthood remains poorly understood. We investigated the independent and interactive effects of developmental and recording temperature on the calling song of the decorated cricket, Gryllodes sigillatus. Crickets were reared continuously from egg stage at either 27 °C or 36 °C and, after reaching adulthood, males were recorded at both temperatures in a full-factorial design. We quantified ten temporal properties of the calling song, including chirp and syllable rates, chirp duration, chirp period, interchirp interval, syllable duration, and the number of syllables per chirp. Recording temperature had pronounced effects on song structure: at 36 °C, males produced faster songs, with higher chirp and syllable rates, shorter chirps, shorter chirp periods, shorter interchirp intervals, shorter penultimate syllables, and fewer syllables per chirp. Developmental temperature produced contrasting effects on several traits. Males reared at 36 °C had lower chirp rates but longer chirps, chirp periods, and interchirp intervals than males reared at 27 °C. Developmental and recording temperatures interacted significantly for last-syllable duration, intersyllable interval, and syllable period, indicating that developmental thermal history modified the adult response to acute heat exposure. Our results demonstrate that developmental and adult thermal environments independently and interactively shape the temporal organisation of cricket acoustic signals. Developmental thermal plasticity may therefore alter the sensitivity of reproductive communication to warming and should be incorporated into assessments of insect responses to increasing thermal variability.