Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy

<i>Chrysomya nigripes</i> Aubertin, 1932, is a species of Calliphoridae widely distributed in Southeast Asia, with studies and case reports confirming the value of this species in estimating the minimum postmortem interval (PMI<sub>min</sub>). However, data on the growth and...

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Main Authors: Yi Guo, Yundi Gao, Na Chen, Xin Tang, Liangliang Li, Gengwang Hu, Jiangfeng Wang, Yu Wang
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Insects
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Online Access:https://www.mdpi.com/2075-4450/16/5/480
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author Yi Guo
Yundi Gao
Na Chen
Xin Tang
Liangliang Li
Gengwang Hu
Jiangfeng Wang
Yu Wang
author_facet Yi Guo
Yundi Gao
Na Chen
Xin Tang
Liangliang Li
Gengwang Hu
Jiangfeng Wang
Yu Wang
author_sort Yi Guo
collection DOAJ
description <i>Chrysomya nigripes</i> Aubertin, 1932, is a species of Calliphoridae widely distributed in Southeast Asia, with studies and case reports confirming the value of this species in estimating the minimum postmortem interval (PMI<sub>min</sub>). However, data on the growth and development of this species’ intra-puparial age are not yet complete. Here, we investigated the intra-puparial morphological changes of <i>C. nigripes</i> at seven temperatures, ranging from 16 °C to 34 °C. We also investigated the potential value of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) coupled with chemometric methods for the intra-puparial age estimation of <i>C. nigripes</i> at 19 °C, 25 °C, and 31 °C. The spectral data within the wavenumber range of 1800–900 cm<sup>−1</sup>, collected from the second thoracic segment of all puparia, were processed. Through this procedure, the mean values of ATR-FTIR spectra of <i>C. nigripes</i> of puparia at each intra-puparial age under various constant temperature conditions were obtained. The results showed that at 16 °C, <i>C. nigripes</i> could not complete its developmental process, while it could do so at the remaining six constant temperatures. With an increase in temperature, the average duration of the intra-puparial period was reduced from the longest at 19 °C of 192 ± 0 h to 77.3 ± 4.6 h at 34 °C. The intra-puparial morphological changes were divided into 12 sub-stages, and the development of the compound eyes, mouthparts, antennae, thorax, legs, wings, and abdomen were divided into 6–8 sub-stages. The Partial Least Squares Discriminant Analysis (PLS-DA) classification model predicted better results compared to the Random Forest (RF) classification model, with an accuracy of 58.3%, 77.8%, and 100% at 19 °C, 25 °C, and 31 °C, respectively. In this study, each sub-stage of the <i>C. nigripes</i> pupa and the time range of structure emergence were recorded, and it was concluded that the spectral trends were time-dependent. Thus, ATR-FTIR combined with chemometrics could also be used as a tool to assist in estimating the intra-puparial stage of <i>C. nigripes</i> and provide a reference value for PMI<sub>min</sub>.
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spelling doaj-art-4e0763def1384f1eb6774977ae6dea602025-08-20T03:14:41ZengMDPI AGInsects2075-44502025-05-0116548010.3390/insects16050480Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) SpectroscopyYi Guo0Yundi Gao1Na Chen2Xin Tang3Liangliang Li4Gengwang Hu5Jiangfeng Wang6Yu Wang7Department of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, ChinaDepartment of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, ChinaDepartment of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, ChinaDepartment of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, ChinaShandong University of Political Science and Law, Jiefang East Road, Jinan 250014, ChinaDepartment of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, ChinaDepartment of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, ChinaDepartment of Forensic Medicine, Soochow University, Ganjiang East Road, Suzhou 215000, China<i>Chrysomya nigripes</i> Aubertin, 1932, is a species of Calliphoridae widely distributed in Southeast Asia, with studies and case reports confirming the value of this species in estimating the minimum postmortem interval (PMI<sub>min</sub>). However, data on the growth and development of this species’ intra-puparial age are not yet complete. Here, we investigated the intra-puparial morphological changes of <i>C. nigripes</i> at seven temperatures, ranging from 16 °C to 34 °C. We also investigated the potential value of Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) coupled with chemometric methods for the intra-puparial age estimation of <i>C. nigripes</i> at 19 °C, 25 °C, and 31 °C. The spectral data within the wavenumber range of 1800–900 cm<sup>−1</sup>, collected from the second thoracic segment of all puparia, were processed. Through this procedure, the mean values of ATR-FTIR spectra of <i>C. nigripes</i> of puparia at each intra-puparial age under various constant temperature conditions were obtained. The results showed that at 16 °C, <i>C. nigripes</i> could not complete its developmental process, while it could do so at the remaining six constant temperatures. With an increase in temperature, the average duration of the intra-puparial period was reduced from the longest at 19 °C of 192 ± 0 h to 77.3 ± 4.6 h at 34 °C. The intra-puparial morphological changes were divided into 12 sub-stages, and the development of the compound eyes, mouthparts, antennae, thorax, legs, wings, and abdomen were divided into 6–8 sub-stages. The Partial Least Squares Discriminant Analysis (PLS-DA) classification model predicted better results compared to the Random Forest (RF) classification model, with an accuracy of 58.3%, 77.8%, and 100% at 19 °C, 25 °C, and 31 °C, respectively. In this study, each sub-stage of the <i>C. nigripes</i> pupa and the time range of structure emergence were recorded, and it was concluded that the spectral trends were time-dependent. Thus, ATR-FTIR combined with chemometrics could also be used as a tool to assist in estimating the intra-puparial stage of <i>C. nigripes</i> and provide a reference value for PMI<sub>min</sub>.https://www.mdpi.com/2075-4450/16/5/480forensic entomologypupariaintra-puparial periodspectroscopypostmortem interval<i>Chrysomya nigripes</i>
spellingShingle Yi Guo
Yundi Gao
Na Chen
Xin Tang
Liangliang Li
Gengwang Hu
Jiangfeng Wang
Yu Wang
Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy
Insects
forensic entomology
puparia
intra-puparial period
spectroscopy
postmortem interval
<i>Chrysomya nigripes</i>
title Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy
title_full Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy
title_fullStr Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy
title_full_unstemmed Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy
title_short Estimating the Intra-Puparial Period of <i>Chrysomya nigripes</i> Aubertin Using Morphology and Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) Spectroscopy
title_sort estimating the intra puparial period of i chrysomya nigripes i aubertin using morphology and attenuated total reflection fourier transform infrared atr ftir spectroscopy
topic forensic entomology
puparia
intra-puparial period
spectroscopy
postmortem interval
<i>Chrysomya nigripes</i>
url https://www.mdpi.com/2075-4450/16/5/480
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