Insect succession on pig carcasses using different exposure time - A preliminary study in Guangzhou, China

The exposure time of carcasses in insect succession studies are generally not consistent and more than 40% studies start in the morning. How such an arrangement affects the succession of insects is worth evaluating. In this study, six piglet carcasses (15-17 kg) were exposed at 6 time points during the day: 11:00, 15:00, 19:00, 23:00, 03:00 and 07:00 on July 20th-July 21st 2006 in Guangzhou, China to investigate the potential effects of the time of day of carcass exposure on body decomposition and insect succession, and also to provide fundamental data on insect succession in summer for this area. The results showed that there were negligible differences in the decay process among the carcasses. We found the carcasses synchronized their decay stage after entering the bloated stage on July 21st. All 6 carcasses entered the remains stage on August 3rd (approximately 14 d after carcass placement). The carcasses yielded 30 species of arthropods, representing 3 orders and 12 families, and no obvious differences were found in species composition between the carcasses. However, we found that there were significant differences in the arrival and colonization of Calliphoridae. We found two batches of Chrysomya megacephala (Fabricius) larvae with significant differences in body length and instar on the carcasses placed at the site at 11:00, 15:00 and 19:00. By contrast, there was only one batch of C. megacephala larvae having similar body length and instar on the carcasses placed at the site at 23:00, 03:00 and 07:00. These observations have potential use for estimating the postmortem interval in forensic entomology.