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The forensic availability of a simple and time-saving method for the identification of dipteran species to estimate postmortem interval using entomological evidence
Legal Medicine 8 (2006) 253–254 www.elsevier.com/locate/legalmed
Letter to the Editor The forensic availability of a simple and time-saving method for the identification of dipteran species to estimate postmortem interval using entomological evidence We had recognized the methods of species identification from the egg, larvae and pupal stage of dipteran specimens [1]. Nonetheless, we stated that “it is generally impossible to morphologically distinguish the species of immature diptera at egg to pupal stage” in the introduction of our article [2], meaning “generally speaking, it is impossible, although this is not strictly the case for everyone”. Dr Hiromu Kurahashi, one of the coauthors of the letter [3], and Dr Satoshi Shinonaga, who takes charge of species identification of specimens in research [4], are both expert entomologists regarding the identification of dipteran species. The contribution of such experts should make identification of the species of immature diptera possible, and we also utilized their published data for morphological identification of the adult flies [1,2,5,6]. However, species identification from the larval specimens requires, for example, a sophisticated technique to dissect the larval mouthpart under a stereomicroscope and vast knowledge of the morphological characters of the cephalopharyngeal skeleton [1]. Therefore, accurate identification of the dipteran species based on the morphological keys at the immature stages cannot help but rely on detailed examinations of which only a few expert entomologists are capable, but which are extremely difficult for almost all forensic scientists within their routine work. Moreover, consultation with the specialists by sending the collected samples is time consuming and not always suitable for the purpose of prompt estimation of the postmortem interval (PMI). If the expression ‘generally impossible’ is felt to be an exaggeration, alternatively it should be expressed more accurately as ‘it is practically impossible’ or ‘without great assistance from an expert entomologist, it is generally impossible’. Although their letter contained little concrete description of the availability of entomological evidence, we agree with the suggestion that it is very important for PMI estimation to carefully examine immature diptera. However, the entomological evidence for PMI estimation is not only available during the period when the immature 1344-6223/$ - see front matter q 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.legalmed.2006.04.004
diptera are feeding on a corpse. After the insect faunal succession associated with postmortem change of the corpse has occurred, and there are only emerging traces of adult flies such as puparium and larval or adult shells on and around the victim, accurate identification of the insect species attracted to the carrion provides seasonal and environmental information surrounding the corpse based on the ecological behavior of the identified species [2,7–9]. Therefore, we believe that simple and time-saving species identification based on mitochondrial DNA sequences was shown to be a practically useful and important forensic entomological approach.
References [1] Greenberg B. Key to the eggs, larvae, pupae and adults of some forensically important flies. In: Greenberg B, Kunich JC, editors. Entomology and the law flies as forensic indicator. Cambridge, UK: Cambridge University Press; 2002. p. 54–153. [2] Saigusa K, Takamiya M, Aoki Y. Species identification of the forensically important flies in Iwate prefecture, Japan based on mitochondrial cytochrome oxidase gene subunit I (COI) sequences. Legal Med 2005;7:175–8. [3] Chigusa Y, Hitoguchi M, Kurahashi H, Tokudome S, Matsuda H. Species and instars of dipteran larvae could be identified. Legal Med 2006;8:62–3. [4] Chigusa Y, Shinonaga S, Koyama Y, Terano A, Kirinoki M, Matsuda H. Suspected intestinal myiasis due to Dryomyza formosa in a Japanese schizophrenic patient with symptoms of delusional parasitosis. Med Vet Entomol 2000;14:453–7. [5] Kano R, Shinonaga S. Genus Calliphora Robineau-Desvoidy, genus Lucilia Robineau-Desvoidy, genus Phaenicia RobineauDesvoidy, genus Chrysomiya Robineau-Desvoidy. In: Kano R, Shinonaga S, editors. Fauna Japonica: Calliphoridae (Insecta: Diptera). Tokyo: Sanko Printing; 1968. p. 9–21 [see also p. 73–91, 91–8, 101–10]. [6] Kano R, Field G, Sinnonaga S. Genus Parasarcophaga Johnston et tiegs. In: Kano R, Field G, Shinonaga S, editors. Fauna Japonica: Sarcophagidae (Insecta: Diptera). Tokyo: Sanko Printing; 1967. p. 39–78. [7] Saigusa K, Takamiya M, Kanetake J, Aoki Y. The forensic entomological survey of the sarcosaprophagous insects ranging over Iwate prefecture [in Japanese with English abstract]. Res Pract Forensic Med 2003;46:67–72. [8] Anderson GS. Insect succession on carrion and its relationship to determining time of death. In: Byrd JH, Castner JL, editors. Forensic entomology. Boca Raton, FL: CRC Press; 2001. p. 143–75.
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Letter to the Editor / Legal Medicine 8 (2006) 253–254
[9] Haskell NH, Hall RD, Cervenka VJ, Clark MA. On the body: insect’s life stage presence, their postmortem artifacts. In: Haglund WD, Sorg MH, editors.Forensictaphonomy.BocaRaton,FL:CRCPress;1997.p.415–41.
Kiyoshi Saigusaa,* Masataka Takamiyab Masatoshi Matsumasaa Yasuhiro Aokib a Department of Biology, Iwate Medical University, School of Liberal Arts and Sciences,
* Corresponding author. Tel.: C81 19 651 5111x5033; fax: C81 19 629 2627.
3-16-1 Honcho-dori, Morioka, Iwate 020-0015, Japan b Department of Legal Medicine, Iwate Medical University, School of Medicine, Morioka, Iwate, Japan *E-mail address: [email protected] Received 3 April 2006; Accepted 11 April 2006 Available online 27 June 2006
Letter to the Editor The forensic availability of a simple and time-saving method for the identification of dipteran species to estimate postmortem interval using entomological evidence We had recognized the methods of species identification from the egg, larvae and pupal stage of dipteran specimens [1]. Nonetheless, we stated that “it is generally impossible to morphologically distinguish the species of immature diptera at egg to pupal stage” in the introduction of our article [2], meaning “generally speaking, it is impossible, although this is not strictly the case for everyone”. Dr Hiromu Kurahashi, one of the coauthors of the letter [3], and Dr Satoshi Shinonaga, who takes charge of species identification of specimens in research [4], are both expert entomologists regarding the identification of dipteran species. The contribution of such experts should make identification of the species of immature diptera possible, and we also utilized their published data for morphological identification of the adult flies [1,2,5,6]. However, species identification from the larval specimens requires, for example, a sophisticated technique to dissect the larval mouthpart under a stereomicroscope and vast knowledge of the morphological characters of the cephalopharyngeal skeleton [1]. Therefore, accurate identification of the dipteran species based on the morphological keys at the immature stages cannot help but rely on detailed examinations of which only a few expert entomologists are capable, but which are extremely difficult for almost all forensic scientists within their routine work. Moreover, consultation with the specialists by sending the collected samples is time consuming and not always suitable for the purpose of prompt estimation of the postmortem interval (PMI). If the expression ‘generally impossible’ is felt to be an exaggeration, alternatively it should be expressed more accurately as ‘it is practically impossible’ or ‘without great assistance from an expert entomologist, it is generally impossible’. Although their letter contained little concrete description of the availability of entomological evidence, we agree with the suggestion that it is very important for PMI estimation to carefully examine immature diptera. However, the entomological evidence for PMI estimation is not only available during the period when the immature 1344-6223/$ - see front matter q 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.legalmed.2006.04.004
diptera are feeding on a corpse. After the insect faunal succession associated with postmortem change of the corpse has occurred, and there are only emerging traces of adult flies such as puparium and larval or adult shells on and around the victim, accurate identification of the insect species attracted to the carrion provides seasonal and environmental information surrounding the corpse based on the ecological behavior of the identified species [2,7–9]. Therefore, we believe that simple and time-saving species identification based on mitochondrial DNA sequences was shown to be a practically useful and important forensic entomological approach.
References [1] Greenberg B. Key to the eggs, larvae, pupae and adults of some forensically important flies. In: Greenberg B, Kunich JC, editors. Entomology and the law flies as forensic indicator. Cambridge, UK: Cambridge University Press; 2002. p. 54–153. [2] Saigusa K, Takamiya M, Aoki Y. Species identification of the forensically important flies in Iwate prefecture, Japan based on mitochondrial cytochrome oxidase gene subunit I (COI) sequences. Legal Med 2005;7:175–8. [3] Chigusa Y, Hitoguchi M, Kurahashi H, Tokudome S, Matsuda H. Species and instars of dipteran larvae could be identified. Legal Med 2006;8:62–3. [4] Chigusa Y, Shinonaga S, Koyama Y, Terano A, Kirinoki M, Matsuda H. Suspected intestinal myiasis due to Dryomyza formosa in a Japanese schizophrenic patient with symptoms of delusional parasitosis. Med Vet Entomol 2000;14:453–7. [5] Kano R, Shinonaga S. Genus Calliphora Robineau-Desvoidy, genus Lucilia Robineau-Desvoidy, genus Phaenicia RobineauDesvoidy, genus Chrysomiya Robineau-Desvoidy. In: Kano R, Shinonaga S, editors. Fauna Japonica: Calliphoridae (Insecta: Diptera). Tokyo: Sanko Printing; 1968. p. 9–21 [see also p. 73–91, 91–8, 101–10]. [6] Kano R, Field G, Sinnonaga S. Genus Parasarcophaga Johnston et tiegs. In: Kano R, Field G, Shinonaga S, editors. Fauna Japonica: Sarcophagidae (Insecta: Diptera). Tokyo: Sanko Printing; 1967. p. 39–78. [7] Saigusa K, Takamiya M, Kanetake J, Aoki Y. The forensic entomological survey of the sarcosaprophagous insects ranging over Iwate prefecture [in Japanese with English abstract]. Res Pract Forensic Med 2003;46:67–72. [8] Anderson GS. Insect succession on carrion and its relationship to determining time of death. In: Byrd JH, Castner JL, editors. Forensic entomology. Boca Raton, FL: CRC Press; 2001. p. 143–75.
254
Letter to the Editor / Legal Medicine 8 (2006) 253–254
[9] Haskell NH, Hall RD, Cervenka VJ, Clark MA. On the body: insect’s life stage presence, their postmortem artifacts. In: Haglund WD, Sorg MH, editors.Forensictaphonomy.BocaRaton,FL:CRCPress;1997.p.415–41.
Kiyoshi Saigusaa,* Masataka Takamiyab Masatoshi Matsumasaa Yasuhiro Aokib a Department of Biology, Iwate Medical University, School of Liberal Arts and Sciences,
* Corresponding author. Tel.: C81 19 651 5111x5033; fax: C81 19 629 2627.
3-16-1 Honcho-dori, Morioka, Iwate 020-0015, Japan b Department of Legal Medicine, Iwate Medical University, School of Medicine, Morioka, Iwate, Japan *E-mail address: [email protected] Received 3 April 2006; Accepted 11 April 2006 Available online 27 June 2006