Thermal performance under constant temperatures can accurately predict insect development times across naturally variable microclimates

External conditions can drive biological rates in ectotherms by directly influencing body temperatures. While estimating the temperature dependence of performance traits such as growth and development rate is feasible under controlled laboratory settings, predictions nature are difficult. One major challenge lies translating constant to fluctuating environments. Using butterfly Pieris napi model system, we show that rate, an important fitness trait, be accurately predicted field using models parameterized Additionally, a factorial design, accurate made across microhabitats but critically hinge on adequate consideration non-linearity reaction norms, spatial heterogeneity microclimate temporal variation temperature. Our empirical results also supported comparison published simulated data. Conclusively, our combined suggest that, discounting direct effects temperature, insect generally unaffected thermal fluctuations.