Shang Yanjie, Feng Yakai, Ren Lipin, Zhang Xiangyan, Yang Fengqin, Zhang Changquan, Guo Yadong
Department of Forensic Science, School of Basic Medical Sciences, Central South University, Changsha 410013, China.
Department of Forensic Medicine, School of Basic Medical Sciences, Xinjiang Medical University, Urumqi 830017, China.
Insects. 2023 Jan 31;14(2):143. doi: 10.3390/insects14020143.
(Robineau-Desvoidy, 1830) (Diptera: Sarcophagidae) is a forensically important flesh fly that has potential value in estimating the PMImin. The precise pupal age estimation has great implications for PMImin estimation. During larval development, the age determination is straightforward by the morphological changes and variation of length and weight, however, the pupal age estimation is more difficult due to anatomical and morphological changes not being visible. Thus, it is necessary to find new techniques and methods that can be implemented by standard experiments for accurate pupal age estimation. In this study, we first investigated the potential of attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and cuticular hydrocarbons (CHCs) for the age estimations of pupae at different constant temperatures (20 °C, 25 °C, and 30 °C). The orthogonal projections latent structure discrimination analysis (OPLS-DA) classification model was used to distinguish the pupae samples of different developmental ages. Then, a multivariate statistical regression model, partial least squares (PLS), was established with the spectroscopic and hydrocarbon data for pupal age estimations. We identified 37 CHCs with a carbon chain length between 11 and 35 in the pupae of . The results of the OPLS-DA model show a significant separation between different developmental ages of pupae (R2X > 0.928, R2Y > 0.899, Q2 > 0.863). The PLS model had a satisfactory prediction with a good fit between the actual and predicted ages of the pupae (R2 > 0.927, RMSECV < 1.268). The results demonstrate that the variation tendencies of spectroscopy and hydrocarbons were time-dependent, and ATR-FTIR and CHCs may be optimal for the age estimations of pupae of forensically important flies with implications for PMImin estimation in forensic practice.
(罗比诺 - 德沃伊迪,1830年)(双翅目:麻蝇科)是一种在法医学上具有重要意义的肉蝇,在估计最短死后间隔时间方面具有潜在价值。精确的蛹龄估计对最短死后间隔时间的估计具有重要意义。在幼虫发育过程中,通过形态变化以及长度和重量的变化来确定年龄很直接,然而,由于解剖学和形态学变化不可见,蛹龄估计更加困难。因此,有必要找到可通过标准实验实施的新技术和方法来准确估计蛹龄。在本研究中,我们首先研究了衰减全反射傅里叶变换红外(ATR - FTIR)光谱和表皮碳氢化合物(CHCs)在不同恒温(20℃、25℃和30℃)下对蛹龄估计的潜力。使用正交投影潜结构判别分析(OPLS - DA)分类模型来区分不同发育年龄的蛹样本。然后,利用光谱和碳氢化合物数据建立了多元统计回归模型——偏最小二乘法(PLS)用于蛹龄估计。我们在[某种肉蝇]的蛹中鉴定出37种碳链长度在11至35之间的表皮碳氢化合物。OPLS - DA模型的结果表明不同发育年龄的蛹之间有显著分离(R2X > 0.928,R2Y > 0.899,Q2 > 0.863)。PLS模型具有令人满意的预测效果,蛹的实际年龄和预测年龄之间拟合良好(R2 > 0.927,RMSECV < 1.268)。结果表明光谱和碳氢化合物的变化趋势与时间相关,ATR - FTIR和CHCs可能是法医学上重要苍蝇蛹龄估计的最佳方法,对法医实践中最短死后间隔时间的估计具有重要意义。