Temperature effects on Chrysomya megacephala and Chrysomya rufifacies development: forensic application

• Main Authors: Hui-Hsuan Chang, 張蕙萱
• Other Authors: Chiou-Herr Yang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/7t3f65

碩士 === 中央警察大學 === 鑑識科學研究所 === 100 === The major application of forensic entomology in criminal investigation is to estimate the post-mortem interval (PMI) by means of the insect succession pattern and the age of blow fly larvae on a corpse. For the use of insect evidence to estimate PMI, we need to obtain the development curves at a range of temperatures. In this study developmental curves for Chrysomya megacephala and Chrysomya rufifacies were conducted at four and six different constant temperatures, respectively, using developmental landmarks and length as measures of age. We also incorporated previous research results (Ming-Hui Lin, master thesis, 2010) into this study to establish the duration of developmental times of the blow fly C. megacephala and C. rufifacies at eight different constant temperatures (17, 20, 23, 25, 28, 30, 33, and 35℃). These developmental data were also used to construct isomorphen and isomegalen diagram. The thermal summation constant (K) and developmental threshold (t0) of C. megacephala and C. rufifacies were calculated using reduced major axis regression method described previously by Ikemoto and Takai (2000). Results have shown that, for example, the thermal summation constant (K) of C. rufifacies for the development of egg hatching, first ecdysis, second ecdysis, peak-feeding and pupariation was 187.38, 288.75, 600.71, 1241 and 2127 degree-hours (ADH), respectively, and completing a life cycle required 3952 ADH. Comparison with the thermal constant (K) of C. megacephala to those of studies previously published by Richards et al. (2009) have indicated that our thermal constant values were smaller than Richards’s laboratory data. Reasons for this variation may be attributed to the populations in each study differed in geographic latitude. Therefore, regional studies may be still necessary to conduct to increase the precision of PMI estimates in local medico-legal investigations. In this thesis, C. rufifacies was chosen for pupal age study. Pupae were collected every 6 or 8 hours after the start of pupariation. The pupae was shell off and age estimation of pupae was carried out from external morphological observation under stereomicroscope. The pictures of different pupae age and morphological features for various temperatures were taken. Theses data were also used to construct isomorphen diagram of pupal age. These results would provide a basis for estimating the pupal age. The aim of the study was to model the development of C. megacephala and C. rufifacies and we hoped that these studies would facilitate more precise estimate of the post-mortem interval.