兩種Aleochara隱翅蟲 (鞘翅目：隱翅蟲科) 之蠅類擬寄生者生活史在法醫昆蟲學的意義

Abstract

在法醫昆蟲學中，估算死後間隔時間是很重要的一項議題，而以麗蠅為主的食屍性蠅類幼期的發育時間是目前估算死後間隔時間最主要的工具之一。許多寄生於雙翅目幼期的擬寄生者會影響寄主的發育，造成死後間隔時間估算的困難。在生活史已被了解的Aleochara屬隱翅蟲中，大部分種類的幼蟲皆為雙翅目環裂類蛹期的擬寄生者，成蟲則主要是蠅類卵及幼蟲的捕食者，其中寄生於食屍性雙翅目蛹期的種類則具備潛在的法醫重要性。我們以A. nigra 和 A. formosanorum這兩種分布於台灣的親屍性隱翅蟲為研究對象。於台灣北部進行之野外調查結果顯示此兩種隱翅蟲在台灣北部廣泛分布。兩種隱翅蟲皆有寄生受試的五種食屍性蠅類 (瘦葉帶綠蠅、銅綠蠅、大頭金蠅、紅顏金蠅、肉蠅的一種) 與一種非食屍性蠅類 (東方果實蠅) 的潛能，但在對不同寄主的接受度及適合度上有差異，顯示幼蟲可能有特定的合適寄主。我們記錄了這兩種隱翅蟲在三個不同溫度下的發育時間，以作為推估不同溫度下隱翅蟲發育時間的依據。這兩種隱翅蟲的幼蟲期加上蛹期的長度相較於數種寄主的蛹期皆較長，顯示它們具有延長可估算的死後間隔時間的潛力。而寄主重量與A. formosanorum 幼蟲期長度之間的正相關性，對於利用隱翅蟲又其發育時間來估算死後間隔時間，應具有其應用價值。

The estimation of postmortem interval (PMI) is one of the most important issues in forensic entomology, and estimating the developmental time of the immature stages of necrophagous flies, especially blow flies, has been the main tool to estimate PMI. Many parasitic insects may alter the development of immature stages of flies, and thus affecting the PMI estimation. For most species of the rove beetle genus Aleochara which have been studied, their larvae are ectoparasitoids of the pupae of cyclorrhapha flies. Among them, some species that parasitize necrophagous flies may have forensic importance. I studied two Aleochara species in Taiwan that visit carrion site, A. nigra and A. formosanorum. The results of field survey conducted in northern Taiwan show that they are commonly found in northern Taiwan. All the five necrophagous (Hemipyrellia ligurriens, Lucilia cuprina, Chrysomya megacephala, C. rufifacies, sarcophagid sp.) and one non-necrophagous fly species (Bactrocera dorsalis) I examined have the potential to be parasitized by some individuals of these two Aleochara species, but differences among the acceptance and suitability of the rove beetle larvae to these host species suggest that rove beetles may prefer specific hosts. Each stage of their life history under 3 different temperatures has been recorded for estimating the developmental time under different temperatures. The larval stage together with the pupal stage of both species are longer than the pupal stages of their hosts, implying their potential usage of elongating the PMI estimation in forensic investigation. In addition, the host weight and the duration of the larval stage of A. formosanorum are positively correlated, thus it should be considered while applying the parasitized fly pupae in PMI estimation.