日週相位對兩種蜚蠊(Blattella germanica and Blattella bisignata)生殖成功率及族群增長的影響

Circadian phase effects on reproductive success and population growth of two sibling species of cockroach, Blattella germanica and Blattella bisignata

吳杏惠(Hsin-Hue Wu)

指導教授 ： 李後晶

國立臺灣大學/生物資源暨農學院/昆蟲學研究所/博士(2008年)

https://doi.org/10.6342/NTU.2008.02701

摘要

本論文是以”生物時鐘對蜚蠊的生態意義”為主軸，探討生物時鐘對昆蟲繁殖的影響。具體研究方法是以雌雄兩性的日週相位不同步時，對兩種蜚蠊(Blattella germanica and B. bisignata)生殖成功率的影響。蜚蠊的繁殖行為可以細分為以下步驟：尋找配偶、雌雄相遇之後雄蟲求偶、雌蟲接受求偶、交尾及受精。針對這幾個步驟進行實驗，而以尋找配偶能力、交尾率、交尾時間的選擇、交尾時間的長短及子代數作為相位差影響的量化指標。以12L:12D光照條件設定雌雄蟲之日週相位，然後偵測10天連續活動週期，做為尋找配偶能力的估算。而後續的配偶接受度、交尾率、交尾時間長短及子代數的實驗，更以蜚蠊活動相位之同相或反相的雌雄蟲，估算尋找配偶能力。結果對德國蜚蠊而言，因為雌蟲活動行為具有掩蓋日週律動的效應，所以同相與反相並沒有顯著差異，但是在雙紋姬蠊中則有顯著差異。在交尾接受度的試驗中，同相22L♀-22L♂德國蜚蠊的成功交尾率顯著大於雌雄反相的兩種組合，然而雙紋姬蠊則四種組合都沒有顯著差異，但所有相位組合中，交尾成功都明顯地集中在雌蟲內在時鐘的夜晚相位。顯示交尾時間的選擇主要由雌蟲決定。而德國蜚蠊的交尾較集中且日齡提早，明顯地與雙紋姬蠊不同。然而子代數在各種處理間卻沒有顯著差異，顯示只要交尾成功了，其交尾過程中精子的製造與受精，並不會因為時間相位的不同有顯著影響。而綜括所有因素組合後，活動相位對兩種蜚蠊的影響是顯著的，只是作用的時間點不同。對德國蜚蠊雌蟲有掩蓋活動效應的情況下，相位的影響呈現在相遇後的交尾率上，這可能與其群聚生活的特性有關。而雙紋姬蠊因為具有野外獨居的特性，活動相位的影響則集中在尋找配偶上，至於在找到配偶後，相反的活動相位並未引起重大差異。但整體而言，德國蜚蠊的繁殖力大於雙紋姬蠊卻是不爭的事實。如果雙紋姬蠊入侵人類居所，與德國蜚蠊競爭，長期競爭下是否可能適應環境而勝出呢?首先建立齡期結構的族群模式，再以時間連續的模式和時間不連續的模式進行數十代族群生長的電腦模擬，探討了：(一)日週時鐘對族群動態的長期影響；(二)兩種蜚蠊競爭下，哪一種將是優勢的競爭者；(三) 人類對德國蜚蠊的防治策略必須嚴苛到什麼程度，才能克制德國蜚蠊的族群增長。試驗結論是(一)雌雄的生物時鐘會影響兩種蜚蠊的族群增長；(二)德國蜚蠊比雙紋姬蠊較具競爭力的；(三) 雖然在現實中是很難達到的，但是配合合理的實驗設計，利用電腦模擬進行族群增長的計算，提供了有效且有力的方法，是有機會消滅德國蜚蠊。

關鍵字

尋找配偶能力 ； 活動掩蓋效應 ； 活動行為 ； 日週時鐘 ； 德國蜚蠊 ； 雙紋姬蠊 ； 敏感度與可塑性分析

並列摘要

The goal of this study was to unveil the ecological significance of biological clock in cockroach. In particular, study demonstrated the differences of reproductive success in cockroach, Blattella germanica and B. bisignata, when the mate-finding locomotion was off-phased between sexes. In each step leading to a successful mating was investigated the significant effect by the locomotor circadian phase. The mate-finding rate, copulation rate and number of offspring in each major step were calculated when the pairs were grouped into four scenarios, of which 10L♀-10L♂ and 10L♀-10L♂ as on-phased scenarios and 22L♀-10L♂and 10L♀-22L♂ as the off-phased ones. The results indicated circadian phase significantly affected the success of mate-finding, timing of copulation, and number of offspring. In particular, the female’s circadian phase was the crucial factor to determine the success of reproduction. Since B. germanica is a domicile cockroach and B. bisignata is a feral species, the effect of circadian phase contributes significantly on reproductive success more in the former than the latter. Imagine the B. bisignata was able to establish in cockroach-free households, too. May the B. bisignata can win the competition with B. germanica? In this article, I develop a stage-structured population model of these two species and use two kinds of calculate methods (such as in time continuous and time discrete) to explore (i) whether their circadian clock impact their long-term population dynamics, (ii) which of these species is a superior competitor, and (iii) how stringent potential pest control strategies have to be to significantly impact established populations of the German cockroach. The results of the model are as follows. Firstly, variation in the circadian clock did not affect cockroach population dynamics unless males and females were out of phase and their mate finding abilities rather limited. Secondly, the German cockroach was the superior competitor: it was able to invade and drive out established populations of the double-striped cockroach and prevent any invasion of the latter. Finally, only a significant and simultaneous reduction in a number of most sensitive German cockroach parameters gave us a chance of species extirpation. Only careful and data-based models of German (and double-striped) cockroach population dynamics can become helpful tools in our quest to win the fight over this awkward yet very sturdy species.

並列關鍵字

Mate-finding rate ； masking effect ； locomotion ； circadian clock ； German cockroach ； double-striped cockroach ； sensitivity and elasticity analysis

參考文獻

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