大頭金蠅（雙翅目：麗蠅科）幼蟲於巴拉刈影響下之發育變化及異速生長

Allometric growth and developmental changes of Chrysomya megacephala (Diptera: Calliphoridae) larvae under paraquat ingestion treatment

郭羿宏(Yi-Hung Kuo)

指導教授 ： 蕭旭峰

國立臺灣大學/生物資源暨農學院/昆蟲學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.00295

摘要

最小死後間隔時間 (minimum post-mortem interval) 是犯罪調查中重要的線索之一，通常可透過驗屍來估算，如：測量屍溫 (algor mortis) 及檢驗屍斑 (livor mortis)。法醫昆蟲學也是常被用作最小死後間隔時間估算的工具之一，一般我們使用節肢動物的發育及消長作為判定的指標。然而，不論驗屍或使用法醫昆蟲做估算，結果時常會受到許多不同因子的影響。舉凡溫度、濕度或屍體狀態都有可能造成不同。眾多因子當中，藥毒物對估算是頗具影響力的因子之一。我們在許多狀況下必須針對藥毒物進行校正，因此我們需要有可信的校正方法。現階段的化學分析常有再現性低落以及變異性高的問題，導致發生無法準確預測及校正的狀況。為解決此問題，本研究旨在發展一新的校正方法。此新校正方法為利用大頭金蠅 (Chrysomya megacephala)蛆蟲後氣孔 (posterior spiracle) 的異速生長 (allometric growth) 對受到不同巴拉刈濃度影響的蛆蟲進行區分。此新的方法可解決舊有校正方法中存在的可能問題。本實驗使用混合巴拉刈 (paraquat) 的人工飼料餵養大頭金蠅之幼蟲。每日將切下幼蟲之腹部末節進行形態變化的觀察，並使用線性判別分析來檢測判定準確度。根據實驗結果，本方法的判定準確率於二齡蟲中可達 75%，三齡蟲則為 43.48% (隨機猜測為 33.33%)。結果可證實此一新的概念具有前瞻性，並可被用作替代性的校正方案。然目前三齡蟲後氣孔於齡期內的不穩定度較高，使得我們在三齡的判定正確率低落，故往後仍需持續改良此方法，找出其他更為穩定的特徵。在此之前我們建議本方法只針對二齡幼蟲進行校正。

關鍵字

大頭金蠅 ； 異速生長 ； 後氣孔 ； 死後間隔時間 ； 法醫昆蟲毒理學 ； 法醫昆蟲學

並列摘要

Minimum post-mortem interval (mPMI) is an important information in crime scene investigation. It can be estimated through autopsy, such as examining algor mortis or livor mortis. Forensic entomology is also one of our candidates of estimation tool. We usually estimate mPMI by examining the development or succession of arthropods in forensic entomology. However, no matter autopsy or forensic entomology, the estimation is often affected by many factors such as temperature, humidity, or the condition of carcass. Among these factors, drug and toxin are two most influential factors, which may have high impacts on our estimation. Maggots grow slowly (or faster) with drug made the under-estimation (or over-estimation) of mPMI. As the consequence, a reliable calibration for drug and toxin’s impact is necessary. Chemical analysis is currently applied to detect the drug in maggots, but it is unreliable due to the low reproducibility and high variation. In this research, we introduce a new method which is calibrating the bias by checking the allometric growth of Chrysomya megacephala’s posterior spiracles. This new concept may solve the difficulties which exist in the current methods. Maggots of Chrysomya megacephala were reared on the artificial medium mixed with three different concentrations (0, 500, 1000 ppm) of paraquat to inspect daily change of characters on its posterior spiracle. The results analyzed by linear discriminant analysis showed the 75.00% and 43.48% maggots of 2nd and 3rd instar, respectively, were accurately predicted the concentration of paraquat provided during their developments. The accuracy, especially the estimation of 2nd instar larvae, is higher than 33.33% under randomly guessing. Despite it is not so high that can be directly applied, it is worth to pay more attention in the advantage of considering allometric growth in mPMI estimation, as well as its ecological significance of maggot's developmental response to the drug.

並列關鍵字

Chrysomya megacephala ； allometry ； post spiracle ； post-mortem interval ； forensic entomotoxicology ； forensic entomology

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