The role of dopaminergic signaling in insect response to repeated acute heat and cold stress.

Abstract

As climate change accelerates, organisms face increasing exposure to unpredictable heat and cold extremes, threatening survival, reproduction, and long-term population stability. Understanding the physiological mechanisms underlying thermal resilience is essential to predict species responses and mitigate biodiversity loss. This study investigates the role of dopamine (DA) and its related receptors in mediating thermal tolerance and regulating life history traits in Drosophila melanogaster. Using wild-type Canton-S flies, we exposed adults to repeated acute thermal stress-daily 1-h cold (15 °C) or heat (35 °C) shocks for five to seven days-alongside a control group maintained at 25 °C. We assessed survival, fecundity, developmental time, adult emergence, and sex ratio. DA levels, measured by HPLC, significantly increased under heat stress and declined under cold exposure, suggesting its involvement in thermal response signaling. To further explore receptor-specific roles, we examined dopaminergic receptor mutants in Dop1R1, Dop1R2, Dop2R, DopEcR under the same thermal conditions described above. Our findings reveal that deficiencies in specific DA receptors markedly influenced survival and reproduction under thermal stress. For instance, Dop1R2 mutants exhibited high fecundity but poor survival under heat shock, while DopEcR mutants showed reduced fecundity under both cold and heat stress without affecting survival. Dop1R1 and Dop2R mutants exhibited developmental delays under thermal stress, indicating their contribution to life cycle regulation. These findings highlight dopaminergic signaling as a critical modulator of thermal adaptation, with implications for understanding how neurophysiological plasticity may buffer or limit insect resilience to future climate variability.