Effects of Ketum extract on blowfly Chrysomya megacephala development and detection of mitragynine in larvae sample

摘要

Major application of entomology in forensic is in determination of post mortem interval (PMI) based on the age of immature insects that resides the corpse. Chrysomya megacephala is the most forensically significant blowfly in Malaysia. In some death cases due to intoxication, it has been reported that the presence of toxins interrupted the development of immature blowflies, known as larvae that utilizes the corpse's flesh and internal organ and thus disrupt the PMI estimation. Therefore, this study was performed to examine the effects of mitragynine on C.megacephala growth spurt. Mitragynine is an active alkaloid in Mitragyna speciosa Korth or also known as Ketum. This chemical constituent of Ketum accumulated in human liver when consumed. In this study, 110 of C. megacephala larvae were reared on series of cow's liver homogenized with 0, 20g, 40g and 60g of ketum extract. Development rate of C.megacephala was observed by recording larvae length, duration of each development stages and survival rate. Duration of development was recorded in every stages of larvae instar, pupae until the blowfly emerged into adult. Survival rate on the other hand, was recorded based on the number of larvae, pupae and adult that survived to the next cycle of development. All data were compared with control group (0g). Mitragynine from larvae that consumed the mixture were extracted using SPE and detected using HPLC. Calibration curve of mitragynine standard was plotted to obtain the amount of mitragynine concentration in larvae sample. Survival rate and development of larvae exposed to 20g extract were almost similar to control with growth rate delayed by 6 hours and 69 % in survival rate. C.megacephala exposed in 40g extract delayed its growth rate by 12 hours compared to control and only 41% of larvae managed to emerge into adult. The lifecycle of C. megacephala in 60g ketum extract delayed up to 24 hours than the control and has the lowest survival rate among all test groups. Fro- chemical analysis, Mitragynine was detected in all larvae samples exposed to Ketum extact. Blowfly C. megacephala was proven legit for Mitragynine detection in the absence of biological sample on the carrions.