利用球孢白殭菌防治香蕉假莖象鼻蟲：有效菌株篩選與香蕉假莖注射法之應用

Abstract

香蕉經常受到香蕉假莖象鼻蟲（Odoiporus longicollis Oliver）的危害，使植株內部組織結構破壞甚至整株倒伏，造成嚴重經濟損失。本研究從田間收集了五個受白殭菌感染之昆蟲（香蕉象鼻蟲為主）樣本進行有效菌株分離篩選，並加入唯一市售白殭菌僵僵好（A1）作為參考進行比較。根據 ITS、nrLSU、tef1-α、rpb1、rpb2 等五段基因序列建立親緣關係樹，可以確定本研究於野外所採集之樣本分離株皆為球孢白殭菌（Beauveria bassiana）。於實驗室內進行試驗，菌株 SF404、SF303、SF124 與 A1 於 3 × 10^8 conidia/mL 濃度下對香蕉假莖象鼻蟲成蟲之致死率在 12 天後分別可達 93.3、90.0、90.0 與 53.3%。在 24℃ 定溫下以 PDA 培養環境下，各菌株之孢子萌發率在 24 hrs 皆可達到 90% 以上。在 15 天培養後之菌落直徑於菌株 SF124、SF303 與 SF404 分別為 5.38、5.25 與 4.83 公分。於 24℃ 定溫下 SF124、SF303 與 SF404 三菌株之單位面積產孢量分別為 2.39 × 10^8、2.18 × 10^8 與 2.05 × 10^8 conidia/cm2。於香蕉假莖注射 1 × 10^7、1 × 10^8 與 1 × 10^9 conidia/mL 濃度之 SF124 孢子懸浮液，兩週後幼蟲之死亡率分別為 45.0、65.0 與 95.0%。注射 1 × 10^8 conidia/mL 濃度之 SF124 孢子懸浮液並放置 0、14、28 天後接種幼蟲，兩週後之死亡率分別為65.0%、35.0% 與 25.0%。基於上述等試驗結果，本研究所篩選之菌株與香蕉假莖注射法頗具潛力開發為防治香蕉假莖象鼻蟲之新選擇。

Banana plants were often attacked by the stem borer, banana pseudostem weevil, Odoiporus longicollis Oliver, causing severe stem damage and economic loss. In this study we collected five infected insects from the field and screened for effective strains compared with the only commercial product Beauveria bassiana (strain A1) in Taiwan. By using ITS, nrLSU, tef1-α, rpb1, and rpb2 sequences, the species of Beauveria isolates collected from field are confirmed as B. bassiana. The fatality rate of strain SF404, SF303, SF124, and A1 were respectively 93.3, 90.0, 90.0, and 53.3% at 3 × 10^9 conidia/mL concentration on adult banana pseudostem weevil after 12 days’ infection. The spore germination rate of strains SF124, SF303, and SF404 can all reach over 90% after 24 hours incubation on PDA medium at 24℃. The colony diameter of strains SF124, SF303, and SF404 were 5.38, 5.25, and 4.83 cm after 15 days incubation on PDA medium at 24℃. The spore production rate at 24℃ incubation for strain SF124, SF303, and SF404 were followed by 2.39 × 10^8, 2.18 × 10^8, and 2.05 × 10^8 conidia/cm2. The mortality of banana pseudostem weevil by applying pseudostem injection in 1 × 10^7, 1 × 10^8, and 1 × 10^9 conidia/mL concentration of strain SF124 spore suspension were 45.0, 65.0, and 95.0 respectively. After stand for 0, 14, and 28 days of 1 × 10^8 conidia/mL SF124 spore suspensions pseudostem injection and inoculate with banana pseudostem weevil larva, the mortality were 65.0, 35.0, and 25.0% respectively. Based on the experiment data, these new strains of B. bassiana and pseudostem injection provide a potential microbial agent and new ways to control banana pseudostem weevil.