Temperature-dependent development and the significance for estimating postmortem interval of Chrysomya nigripes Aubertin, a new forensically important species in China.

Abstract

In forensic entomology, the developmental duration and larval body length of sarcosaprophagous flies are presently the two major approaches to estimate minimal postmortem interval (PMImin). A full characterization of the developmental stages of Calliphoridae, a predominating species on corpses, is especially important for PMI estimation. Chrysomya nigripes Aubertin, which appears on the corpse mainly during the decay and the post-decay stages, is of significant value for PMImin estimation. However, there are limited detailed reports on the development of such species. Hence, this study was conducted to address the development pattern of C. nigripes, in order to provide the basic data related to PMI estimation. In this study, the larvae of C. nigripes were collected from pig carcasses that were placed in the field. The colonies were cultured at constant temperatures of 16, 20, 24, 28, and 32 (±1) °C. The biological features of C. nigripes, the developmental pattern, and the body length with time at different temperatures were studied. The results showed that the average developmental duration of the C. nigripes larvae at 20, 24, 28, and 32 (±1) °C were 608.0 ± 68.0h, 327.0 ± 53.8h, 254.0 ± 36.5h, and 217.0 ± 28.0h, respectively. There were two phases of body length increment with developmental time: growing phase and plateau phase. The maximal body length was 11-12mm, and the relationship between body length and developmental time can be simulated using the following equation: L = a + bT + cT(2) + dT(3). The data for developmental duration and larval body length at 16°C were not obtained. In summary, this study comprehensively studied the developmental biology of C. nigripes, which has a significant value for estimating PMI from highly decayed carcasses.