臺灣麗蠅科分類與大頭金蠅之繁殖行為

Abstract

法醫昆蟲學主要研究範疇為利用昆蟲等節肢動物證據來解決法律問題。其中最重要的議題為利用昆蟲來估算人或動物之最短死後間隔時間 (minimum post-mortem interval, mPMI)。雙翅目麗蠅科 (Diptera: Calliphoridae) 中某些食屍性的種類，會於屍體上產卵，幼蟲在屍體上發育；是最常被用作此類估算的工具之一。藉由數學模型等方式估算該麗蠅幼蟲之年齡，可得 mPMI 之估計值。以麗蠅估算 mPMI 最重要的前提是物種之正確鑑定，並確實了解該物種之生態行為，以便依此校正估算模型，而達到較為準確的估計。本研究中，第二章針對台灣產麗蠅科種類進行外部形態分類，描述一個新種，並附檢索及名錄。根據結果，台灣目前記錄麗蠅科種類共計 9 亞科、28 屬、76 種。其中麗蠅亞科 (Calliphorinae)、金蠅亞科 (Chrysomyinae)、綠蠅亞科 (Luciliinae) 中大多為食屍性種類，具有高度法醫重要性。其中金蠅亞科的大頭金蠅 (Chrysomya megacephala (Fabricius))、肥軀金蠅 (Chrysomya pinguis (Walker)) 分別為台灣低海拔及中高海拔地區最常見之食屍性麗蠅種類，本研究關於行為表現之部分主要即以此二種麗蠅作為模型物種。麗蠅成蟲之行為影響 mPMI 估算最甚者當為其產卵行為。本研究第三章以定性及定量方法進行試驗，結果顯示麗蠅具有聚集產卵行為。單隻雌蟲甚少出現產卵行為，而當同伴數量增加，雌蟲產卵量亦在一定範圍內隨之上升。此行為可能由雌蟲以視覺偵測其他同伴存在而誘發，同伴之大小、顏色可能皆為麗蠅視覺判斷之依據；同伴之種類對聚集產卵之誘發與否則依不同種類有相異的結果。其次，麗蠅夜間產卵與否一直是法醫昆蟲學科中一個具有爭議性的問題，各種研究結果莫衷一是。本研究第四章以麗蠅之運動－－包括飛行與爬行－－作為夜間產卵發生之可能性指標，探究可能誘發麗蠅夜間產卵之因素。結果顯示，懷卵雌蟲異於雄蟲與處女雌蟲，其夜間運動程度會受光照影響而提高。因此可得知懷卵可能改變麗蠅在夜間光照刺激下之反應，進而出現夜間產卵之現象。本研究最末章綜合麗蠅成蟲之產卵行為、運動行為及幼蟲之存活等表現，探討大頭金蠅及肥軀金蠅此二種於行為及形態方面皆高度相似之麗蠅，棲地分化之可能原因。肥軀金蠅成蟲在低溫環境之運動行為表現優於大頭金蠅，反之大頭金蠅之幼期表現則於高溫時優於肥軀金蠅。此現象可能為物種為避開競爭所演化形成的行為差異，可能因此形成或強化棲地及生態棲位之區隔。

Using insect and other arthropod evidences to solve all kinds of legal problems is the main purpose of forensic entomology. The most important issue in this field is estimating minimum post-mortem interval (mPMI) of victims or animals. Some of necrophagous blow fly (Diptera: Calliphoridae) species reproduce on corpse, and their larvae also develop on corpse. These flies are often used to help to estimate mPMI. By calculating the age of larva through some methmatic models, estimation of mPMI can be learned. To use flies to estimate mPMI, correct species identification and knowledge of its binomics and behaviors are necessary. These knowledge can help to modify the estimation. In this study, the second chapter is about taxonomy of Taiwanese calliphorid species, including morphological keys to all taxa, name lists, and description of one new species. According to results, there are 76 species of 28 genera of nine subfamilies in Taiwanese Calliphoridae. Most species in subfamilies Calliphorinae, Chrysomyinae, and Luciliinae are necrophagous species, show forensic importance. Chrysomya megacephala (Fabricius) and C. pinguis (Walker) of Chrysomyinae is one of the most common necrophagous species in lowland and in higher elevations respectively. In behavior study parts, these two species are mainly used as model species. The most important behavior of blow flies that may affect the accuracy of mPMI estimation is oviposition behavior. In the third chapter, qualitative and quantitative tests were used to verify gregarious oviposition behavior of blow flies. Results suggested that single female showed no egg-laying behavior, and fecundity of a female increased when numbers of companions raised. Vision may be one of the possible factors that females used to recognize the presence of companions, and thus induced gregarious oviposition. Size, and color may be factors that influenced visual cue. Different species show different effects to gregarious oviposition. On the other hand, nocturnal oviposition of blow flies has long been a controversial issue. In chapter 4, locomotor including flying and crawling were used as an index for testing the possibility of nocturnal oviposition. According to the results, locomotor activity of gravid females, but not that of males nor virgin females, will be increased by illumination at night time. In the last chapter, the possible reasons that the two morphologically and behaviorally similar species show habitat differenciation were verified by testing the adult and larval performance of their fitness under different temperature conditions. Locomotor activity of adult C. pinguis is significantly higher than that of C. megacephala under lower temperature condition, and larval performance of C. megacephala is significantly higher than that of C. pinguis when at higher temperature. Different strategies of these two species may be evolved to prevent interspecific competition and thus showed habitat differenciation.