title: Age-dependent changes in cuticular hydrocarbons of larvae in Aldrichina grahami (Aldrich) (Diptera: Calliphoridae).
abstract: Necrophagous flies, comprising the first wave of insects present in a cadaver, provide a great potential for more accurate determination of the late postmortem interval (PMI) based on their age. Cuticular hydrocarbons (CHs) are a promising age indicator in some insect species, especially for the larvae of necrophagous flies. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to characterize the age-dependent, quantitative changes in CHs of larval Aldrichina grahami (Aldrich) (Diptera: Calliphoridae) at 24°C. The majority of low-molecular-weight alkanes (≤C25) and almost all of the alkenes decreased in abundance with larval development. By contrast, the abundance of high-molecular-weight alkanes of chain length greater than C25 gradually increased with age. For several peaks, including peak 28 (pentacosene a), peak 31 (n-C25), peak 43 (n-C27) and peak 68 (n-C31), a highly significant correlation was found between peak ratio (n-C29 divided by each chromatographic peak) and chronological age of the larvae. A mathematical model, derived from multivariate linear regression analysis, was developed for determining age of the larvae based on age-dependent changes in CHs. The estimated larval age based on the CHs had a good linear correlation with the chronological age (R(2)>0.9). These results indicate that CHs has a great potential for determining the age of fly larvae, and concomitantly for the PMI in forensic investigation.
authors.affiliation: Department of Forensic Medicine, Shantou University Medical College, Shantou 515031, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
authors.affiliation: Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
authors.forename: Gong-Yin
authors.initials: GY
authors.lastname: Ye
authors.affiliation: The MOE Key Laboratory for Standardization of Chinese Medicines and the SATCM Key Laboratory for New Resources and Quality Evaluation of Chinese Medicines, Institute of Chinese Materia Medica, Shanghai University of Traditional Chinese Medicine, Shanghai 201210, China; Shanghai R&D Center for Standardization of Chinese Medicines, Shanghai 201210, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China.
authors.forename: Cui
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Forensic Medicine, Shantou University Medical College, Shantou 515031, China; Institute of Insect Sciences, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China. Electronic address: ghzhu@126.com.
authors.forename: Guang-Hui
authors.initials: GH
authors.lastname: Zhu
mesh_terms: D000818:Animals; D002849:Chromatography, Gas; D004175:Diptera / Q000737:chemistry* / Q000254:growth & development*; D016002:Discriminant Analysis; D006838:Hydrocarbons / Q000032:analysis*; D007814:Larva / Q000737:chemistry / Q000254:growth & development; D016014:Linear Models; D013058:Mass Spectrometry
chemical_list: D006838:Hydrocarbons
keywords: Aldrichina grahami; Cuticular hydrocarbons; Forensic entomology; Larval age; Postmortem interval