Effects of Temperatures on Development of a Forensically Important Fly Chrysomya villeneuvi Patton (Diptera: Calliphoridae)

Forensic entomology is a field of knowledge that uses insects as evidence to estimate the duration after death or post mortem interval (PMI). The PMI determination is based on the developmental size and stage of the insects found on the dead body. Chrysomya villeneuvi is one of the important species of flies that can serve as an indicator for estimating the PMI. This study aimed to develop a database on the developmental progress of Ch. villeneuvi at different temperatures. The data are also used to develop accumulated degree hours (ADH) tables. Justification of this study is because the developmental data of Ch. villeneuvi have not been developed in Malaysia. PMI determinations were made by referring to Ch. megacephala developmental data. This will cause calculation of PMI becomes less precise. Earlier studies also involve a relating morphology and behavior of this species. Observations on the development of eggs, larvae and pupae of Ch. villeneuvi were carried out at 25, 27C, 30, 33 and 37°C inside an insect growth chamber. Adult flies were obtained by placing dead rats at the University of Malaya Research Center, 16th Mile, Gombak. These adult flies were reared in the laboratory as a source for the colony. Approximately 150 eggs were placed in a container with 200 g of beef liver as a food source for newly hatched larvae. The lengths of five larvae were measured every 3 h to get an average value for size at each temperature. Photographs and slides were also processed to ascertain the larval development. Ch. villeneuvi needed 9:40 ± 0.02 days at 25°C, 9:34 ± 0.04 days (27°C), 9.00 ± 0.07 days (30°C), 7.95 ± 0.02 days (33°C) and 7:51 ± 0.02 days (37°C) to complete its life cycle. There is a significant difference (p 0.001) on the duration of the life cycle of Ch. villeneuvi at different temperatures. The higher the temperature and the ADH, the shorter of the life cycle of flies Ch. villeneuvi. Knowledge about the duration of stages in a temperature-dependent life cycle facilitates the development of ADH data. Forensic investigators in Malaysia can calculate PMI based on developmental graft and ADH data obtained from this study when Ch. villeneuvi is found on corpses.