摘要或動機

大安水蓑衣（Hygrophila pogonocalyx）為局限分佈於臺中縣沿海溼地之稀有植物。大量境外復育栽殖後，造成近年來黑擬蛺蝶(Junonia iphita iphita)利用此種新寄主植物的比例增加。本實驗比較黑擬蛺蝶在原寄主植物臺灣馬藍(Strobilanthes formosanus)及新寄主植物大安水蓑衣上之生長環境遮蔽度、幼蟲生長發育、雌蝶產卵偏好的差異，探討大安水蓑衣復育對黑擬蛺蝶族群可能造成的影響。實驗結果發現利用大安水蓑衣之幼蟲生長發育較佳、羽化後成蟲體型較大、有效積溫常數較低。雌蝶產卵行為可能存在兩種偏好性，且子代雌蝶對寄主植物的偏好性與親代一致，不受幼蟲期取食植物影響。偏好新寄主植物之雌蝶其子代的生長發育，利用新寄主植物者顯著較利用原寄主植物者佳，顯示其對原寄主植物的適應顯著下降。本研究認為大安水蓑衣的復育結果，造成黑擬蛺蝶族群在可能共域的情況下，因為利用新的寄主植物可能已產生初步分化的現象。Hypgrophila pogonocalyx is a rare plant species which is distributed in wetlands along seashore of Taichung County. Recently, I found that the common butterfly Junonia iphita iphita recognized H. pogonocalyx as a new hostplant because of the restoration practices of H. pogonocalyx. We compared the differences of forest overstory coverage, larval growth performance and female oviposition preference between J. iphita iphita individuals exploiting the H. pogonocalyx and those utilizing the original hostplant Strobilanthes formosanus. Possible effects on J. iphita iphita by restoration of H. pogonocalyx are analyzed and discussed. It turns out that better growing performance and longer adult forewing length were found on the larvae feeding on H. pogonocalyx than those on the S. formosanus. Besides, the larvae feeding on H. pogonocalyx demonstrated lower constant value of effective accumulated temperature, suggesting that the new host may provide more energy to the larvae than the original host does. Two types of female oviposition preference seem to exist. No matter which hostplant the larvae fed on, the female adults still maintained the oviposition preference of the parental generation. Offspring of H. pogonocalyx-preferring female had better performance on this new hostplant. Our studies showed that the restoration of H. pogonocalyx might have caused primary differentiation of J. iphita iphita by using new hostplant in sympatry with the original hostplant.