探討臺灣疣胸琉璃蟻本土與入侵族群在形態、表皮碳氫化合物與行為上的變異

Abstract

疣胸琉璃蟻原本被認為是台灣的原生種，但近十年來在中部地區出現大量爆發情況，對農業生產和居住環境造成顯著影響。許博士等人在先前研究已確認台灣存在兩個遺傳上明顯分化的族群，本研究採用整合性方法分析這兩個族群的生物學特性差異。本研究探討台灣疣胸琉璃蟻（Dolichoderus thoracicus）的種內變異，特別聚焦於本土族群（C1）和入侵族群（C2）間在形態、行為及化學特性上的差異，以了解這一罕見隱性入侵事件的生態機制。 研究方法包括採集35個蟻巢（18個本土族群，17個入侵族群），進行形態測量（頭寬、頭長和胸長）、本土與入侵族群間的一對一攻擊性測試、群體競爭試驗以及表皮碳氫化合物分析。形態測量分析顯示兩族群間在平均體型上無顯著差異，然而入侵族群表現出較高的巢內形態變異性，特別是在頭長（C1 = 4.00%，C2 = 4.99%，p = 0.0272）和胸長（C1 = 4.43%，C2 = 6.03%，p = 0.0139）方面。行為實驗方面，在本土與入侵族群間的一對一攻擊性測試顯示兩族群間無顯著差異，群體競爭試驗在不同競爭情境下觀察到生存率差異模式。表皮碳氫化合物分析主要體現在特定化合物類別（尤其是烯烴類化合物）。 本研究發現兩族群間存在多個不同的特徵分化。形態差異最為顯著，行為層面未發現明確差異，而化學特徵儘管受實驗條件影響，仍顯示顯著的族群分化。這些發現揭示社會性昆蟲隱蔽入侵的成功可能透過多面向特徵差異實現，並強調了在入侵生物學研究中考慮種內變異的重要性。本研究為未來隱性入侵機制研究提供了基礎。

This study investigates intraspecific variation in the black cocoa ant (Dolichoderus thoracicus) in Taiwan, focusing on differences in morphology, behavior, and chemical characteristics between native (C1) and invasive (C2) populations to understand the ecological mechanisms underlying this rare cryptic invasion event. While originally considered native to Taiwan, D. thoracicus has experienced significant outbreaks in central regions over the past decade, substantially impacting agricultural production and residential environments. Previous research confirmed the existence of two genetically distinct populations in Taiwan, and this study employs an integrative approach to analyze biological trait differences between these populations. The methodology included collecting 35 colonies (18 native, 17 invasive), performing morphological measurements (head width, head length, and thorax length), conducting one-on-one aggression tests between native and invasive populations, group competition trials, and analyzing cuticular hydrocarbon compositions. Morphological analysis revealed no significant differences in mean body size between populations, however, the invasive population exhibited higher within-nest morphological variation, particularly in head length (C1 = 4.00%, C2 = 4.99%, p = 0.0272) and thorax length (C1 = 4.43%, C2 = 6.03%, p = 0.0139). Behavioral experiments showed no significant differences between populations in one-on-one aggression tests between native and invasive populations, while group competition trials revealed survival rate difference patterns under different competitive scenarios. Cuticular hydrocarbon analysis revealed differences primarily in specific compound classes, particularly alkenes. This study reveals multifaceted trait differentiation between the two populations. Morphological differences were most pronounced, while no clear differences were detected at the behavioral level, and chemical traits showed significant population differentiation. These findings provide important insights into the ecological mechanisms of cryptic invasions in social insects and highlight the importance of considering intraspecific variation in invasion biology research. This study establishes a foundation for future research on cryptic invasion mechanisms.