Research for forensic entomological indicators that contribute to improving the accuracy of estimating postmortem intervals during warm-cold boundary periods and cold seasons

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K10529
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 58040:Forensics medicine-related
• Research Institution: Iwate Medical University
• Principal Investigator: SAIGUSA Kiyoshi 岩手医科大学, 教養教育センター, 准教授 (30398490)
• Co-Investigator(Kenkyū-buntansha): 高宮 正隆 岩手医科大学, 医学部, 教授 (30364334)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 法昆虫学 / 死後経過時間推定 / 寒暖境界期 / 寒冷期 / クロバエ科 / 低温耐性 / 休眠

Outline of Final Research Achievements

The temporal changes in gene expression related to cold tolerance and diapause in 4 species of Calliphoridae that are dominant during the cold seasons and investigated the utility as an indicator of the elapsed time. For genetic analysis, 4 blowfly species were reared in a controlled environment (photoperiod 12 hours, L/D: 20℃/10℃, 70% RH) from eggs to adult flies emergence observed them over time, and collected samples for gene expression analysis. However, insufficient samples were able to obtain. The cause for the difficulty in collecting matured females was thought to be insufficient information on their ecology, as well as environmental factors such as temperature differences between day and night and weather changes. To obtain the necessary number of samples for analysis, it is continuing our efforts to understand the activity (oviposition) conditions of the 4 blowfly species by placing pieces of sliced pork outdoors and recording them with a fixed-point device.

Free Research Field

法昆虫学

Academic Significance and Societal Importance of the Research Achievements

寒暖境界期および寒冷期にも死体が昆虫の蚕食を受けている例は散見されるが、法昆虫学的死後経過時間推定は温暖期に比し推定精度が低下する。その理由として、温暖期に優勢な昆虫は越冬のために休眠すること、寒冷期に優勢な昆虫は成長が緩徐で双翅目幼虫の体長のような形態学的変化を時間経過の指標として推定に利用することが難しいことなどが挙げられる。また、寒冷期の昆虫の活動（産卵）条件など生態学的知見が乏しいことに加え昼夜の気温差など環境要因も考慮しなければならない。遺伝子発現量を時間経過の指標として利用可能になれば、寒暖境界期・寒冷期の死後経過時間推定精度の向上が期待でき法昆虫学的解析の需要に応えるものである。