Development of Synthesiomyia nudiseta (Diptera: Muscidae) Under Constant and Fluctuating Temperatures: Implications for Minimum Postmortem Interval Estimation

Synthesiomyia nudiseta (van der Wulp, 1883) is widely distributed across pantropical and subtropical biogeographic regions. Despite its recognized forensic importance, comprehensive developmental data for it remains scarce. This study observed the development of S. nudiseta from egg to adult at six constant temperatures in the range of 20–35 °C, and found that the times required were 732.7 ± 7, 587.3 ± 4.7, 449 ± 21.3, 393.7 ± 5.7, 361.3 ± 8.3 h, respectively. It cannot complete development at 35 °C. We established three development models to estimate the age of the immature insect: isomegalen diagram, isomorphen diagram, and thermal summation model. A regression analysis was performed on the relationship between body length and total development time from hatching to pupariation. The thermal summation constant during the development of S. nudiseta was 7870.1 degree-hours, and the developmental threshold temperature was 9.28 °C. In addition, we observed development of S. nudiseta under four fluctuating temperature regimes; developmental duration exhibited a negative correlation with increasing mean temperature; however, inclusion of 35 °C within the fluctuating temperature cycle prevented successful adult eclosion, with the vast majority of pupae succumbing to mortality before reaching the adult stage. The results of this experiment provide a basis for the use of S. nudiseta in the estimation of PMImin.