蓬萊虎灰蝶的幼期生物學與喜蟻現象 對其生長表現之影響

Abstract

本研究顯示勤勉舉尾蟻（Crematogaster laboriosa）在蓬萊虎灰蝶（Spindasis kuyanianus）的幼蟲生長表現與雌蝶的產卵行為上扮演重要的角色。野外觀察發現雌蝶會將卵產在有勤勉舉尾蟻棲息的羅氏鹽膚木（Rhus chinensis var. roxburghiana）及野桐（Mallotus japonicus）枝葉上，實驗也顯示雌蝶只在寄主植物與共生蟻存在的環境下產卵。幼蟲具有四種喜蟻器官，包括背部蜜腺器官（DNO）、碟狀腺（DOs）、觸手器（TOs）與圓頂狀開口器官（PCOs）。DNO在三齡幼蟲始具有功能，是維繫幼蟲與共生蟻共生關係的關鍵。DOs於五齡幼蟲第二腹節背部開始出現，在終齡蟲於第一至第五腹節皆存在。TOs與PCOs存在於每個齡期，TOs位於第八腹節，可自由伸縮，PCOs則集中分布在氣孔或DNO周圍。當幼蟲有螞蟻照顧時，個體幼蟲期縮短25%，成蝶前翅長增加3%。此外，與勤勉舉尾蟻互動的幼蟲存活率顯著較與三斑虎灰蝶及虎灰蝶共生的阿美舉尾蟻和建築舉尾蟻高。本研究推論蓬萊虎灰蝶屬於絕對喜蟻性灰蝶，與共生蟻之間沒有取捨的現象。再者，根據共生蟻種、成蟲形態與幼蟲DOs的出現時間證明蓬萊虎灰蝶是獨立種，不符合五十嵐將蓬萊虎灰蝶與虎灰蝶視為同種的處理。This present study manifests life history of Spindasis kuyanianus (Matsumura) (Lepidoptera: Lycaenidae), especially on how its attendant ant Crematogaster laboriosa plays an important role on larval performance and female oviposition behavior. Field observations showed that the females laid eggs in a cluster on twigs or leaves of Rhus chinensis var. roxburghiana (Anacardiaceae) or Mallotus japonicus (Euphorbiaceae), on which always inhabitated by the attendant ants. Laboratory experiments also showed that females only laid eggs under the hostplant with the presence of C. laboriosa. For immature morphology, four types of myrmecophilous organs were recognized, including dorsal nectary organ (DNO), dish organs (DOs), eversible tentacle organs (TOs) and pore cupola organs (PCOs). The DNO plays a functional role in maintenance of interaction with the attendant ants from third instars. The DOs appear on segment A2 from the fifth instars and on segments A1 to A5 in the final instars. The TOs on segment A8 and PCOs surrounding by spiracles or DNO are present in all larval stages. When larvae reared with ants, the larval duration shortened by 25%, and forewing length of emerged adults increased by 3%. Moreover, the survival rate of larvae that interacted with C. laboriosa was significantly higher than the treatments of with C. amia and C. dohrni fabricans, which are mutualistic with S. syama and S. lohita formosana, respectively. I conclude that S. kuyanianus is an obligatory myrmecophilous lycaenid butterfly, and there have no trade-off between S. kuyanianus and its attendant ants. Furthermore, according to the attendant ant species, the morphology of adults, and the instars of appearance of DOs, S. kuyanianus is justified as a distinct species, not conformed to the idea treating S. kuyanianus and S. lohita formosana as a single species by Igarashi.