萊氏綠僵菌(BCRC FU31706)對斜紋夜蛾的感染能力及對小白菜幼苗生長影響之研究

Abstract

本研究探討了昆蟲病原真菌萊氏綠僵菌(Metarhizium rileyi) 作為斜紋夜蛾(Spodoptera litura)生物防治手段的效力及其對小白菜(Brassica rapa var. chinensis)生長的影響。在臺灣國立臺灣大學實驗林鹿谷鄉鳳凰茶園自然教育中心收集的 M. rileyi (BCRC FU31706)菌株對 S. litura 幼蟲進行了感染實驗。結果顯示，在1 × 10⁵ 孢子/毫升的濃度下，M. rileyi 導致的死亡率為40%，受感染幼蟲在接種後12到13天之間死亡。透過PCR分子分析證實了受感染幼蟲中存在 M. rileyi。此外，通過生長實驗評估了 M. rileyi 對 B. rapa var. chinensis 生長的影響。發現與其他 Metarhizium 物種相反，M. rileyi 未能促進植物生長，反而可能抑制了根和莖的發展。本研究結果認為測試生物防治劑對非目標植物可能產生的不良影響是有其必要性，因此建議優化真菌應用方法以提高害蟲防治效果之外，同時也應將對作物的負面影響降至最低。

This study explores the efficacy of the entomopathogenic fungus Metarhizium rileyi for biological control of Spodoptera litura and its impact on the growth of Brassica rapa var. chinensis. Infection experiments were conducted on S. litura larvae using a M. rileyi strain (BCRC FU31706) collected from the Feng Huang Tea Garden Nature Education Center in Taiwan. Results indicated that at a concentration of 1 × 10⁵ spores/ml, M. rileyi caused a mortality rate of 40%, with infected larvae displaying mortality between 12 to 13 days post-infection. Molecular analysis via PCR validated the presence of M. rileyi in the infected larvae before and after. Additionally, an in vitro dual culture growth experiment was performed to assess the impact of M. rileyi on B. rapa var. chinensis. Contrary to other Metarhizium species, M. rileyi did not promote plant growth; instead, it may inhibited both root and shoot development. This study underscores the necessity of thoroughly testing biocontrol agents for potential adverse effects on non-target plants and advocates for optimizing fungal application methods to enhance pest control efficacy while minimizing negative impacts on crops.