The blow fly Lucilia sericata (Diptera: Calliphoridae) as a forensic indicator: Thermal requirements of the immature stages and field validation of thermal summation data
摘要
The blow fly Lucilia sericata (Meigen) (Diptera: Calliphoridae) is a necrophagous species of major forensic relevance, widely used to estimate the minimum post-mortem interval (PMImin) in suspicious death cases. As environmental temperatures and the geographic origin influence insect developmental rates and other life history traits, region-specific developmental datasets are required to provide accurate PMImin estimates. The present study determines the developmental times, lower developmental thresholds and thermal summation constants for six developmental landmarks from a central Spanish population of L. sericata, reared under ten constant temperatures within the range of 15–37.5 °C. The time required to complete each developmental landmark decreased with increasing temperatures within the range of 15–30 °C, but slightly increased with increasing temperatures within the range of 30–37.5 °C. The complete development from oviposition to adult emergence required 264.84 ± 15.94 degree days, with the lower developmental threshold for each developmental landmark ranging from 8.16–10.14 °C. To validate these data, the resulting thermal summation models were applied to field data from an experimental study using pig carcasses in an indoor scenario during autumn and spring seasons. Estimated oviposition dates based on post-feeding and adult emergence developmental landmarks closely matched the earliest recorded colonisation of carcasses by L. sericata, particularly when using the first day with a significant number of emerging adults. Overall, the present results confirm that L. sericata can reliably be used as a forensic indicator and provide robust reference data for its application in casework in central Spain and other Mediterranean regions.