2009年3月6日 星期五

黃蛺蝶的幼蟲經驗對於成蟲寄主偏好沒有影響

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No effect of larval experience on adult host preferences in Polygonia c-album (Lepidoptera: Nymphalidae): on the persistence of Hopkins’ host selection principle
Ecological Entomology (2009), 34, 50–57 | Full Text: HTML, PDF (Size: 112K) |

NIKLAS JAN Z , LINA SÖDERLIND and SÖREN NYL I N Department of Zoology, Stockholm University, Stockholm, Sweden

幼期的印痕或是「化學遺產」對其後產卵行為的可能影響常被稱為「霍普金斯寄主選擇原則」,這是一個有爭議性卻又一再在寄主植物選擇研究中出現的主題。既然被稱作是原則,這個假說的實驗支持其實是有歧義的。近期研究指出應該考量其理論上的暗示以及假設此原則成立、又是在怎麼樣的情形下受到天擇的偏好。本研究假設多食性的蝴蝶Polygonia c-album L. (Lepidoptera, Nymphalidae) 的寄主偏好並不會受到幼蟲環境的影響,幼蟲分別以三種天然寄主植物飼養:蕁麻科的Urtica dioica、柳科的Salix cinerea以及虎耳草科的Ribes uva-crispa,化蛹以後秤重依照性別分開,羽化後的母蝶在交配之後放入設有兩種植物的產卵室,每隻母蝶會被放入共計三種組合中測試(C3取2),其測試順序隨機。結果顯示以蕁麻科U. dioica 飼育的個體發育最快,取食柳科的S. cinerea 者次之;而幼蟲取食的植物對其選擇產卵植物沒有顯著影響;整體而言,P. c-album U. dioica 的偏好顯著高於其他兩種植物,對S. cinereaR. uva-crispa 的選擇則沒有顯著差異。雖然「霍普金斯寄主選擇原則」不適用於此例中,作者認為基於近期關於環境與遺傳資訊的精確性如何影響發育上轉換之控制的洞悉,幼蟲期的線索對產卵選擇有何影響仍値得討論,並認為植食性昆蟲在寄主選擇的適應上所需的條件太過特殊,以至於無法以單一普遍的假說來說明。

Abstract
1. The possible effect of juvenile imprinting or ‘chemical legacy’ on the subsequent oviposition – often called the ‘Hopkins’ host selection principle’ – has been a controversial but recurrent theme in the literature on host-plant preference. While it appears possible in principle, experimental support for the hypothesis is equivocal. The present study points out that it is also important to consider its theoretical implications, and asks under what circumstances, if any, it should be favoured by natural selection.
2. Following this reasoning, it is predicted that host preference in the polyphagous butterfly Polygonia c-album L. (Lepidoptera, Nymphalidae) should not be influenced by larval environment. This was tested by rearing larvae on three natural host plants: the high-ranked Urtica dioica and the medium-ranked Salix cinerea and Ribes uva-crispa , and exposing the naive females to oviposition choices involving the same set of plants.
3. It was found that larval host plant had no effect on oviposition decisions of the adult female. Hence, the Hopkins’ host selection principle does not seem to be applicable in this species.
4. Based on recent insights on how accuracy of environmental versus genetic information should affect the control of developmental switches, the conditions that could favour the use of juvenile cues in oviposition decisions are discussed. Although the Hopkins’ host selection hypothesis cannot be completely ruled out, we argue that the circumstances required for it to be adaptive are so specific that it should not be invoked as a general hypothesis for host selection in plant-feeding insects.

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