球孢白殭菌（Beauveria bassiana CHF 523）對荔枝椿象（Tessaratoma papillosa Drury）之生物防治應用潛力

本研究篩選對荔枝椿象（Tessaratoma papillosa Drury）具有高感染潛力之蟲生真菌菌株，2019年自田間採集疑似遭受蟲生真菌感染致死的蟲體，經分離純化獲得12株菌株，篩選部分菌株於室內設定的高相對濕度（＞90% RH）環境下接種於荔枝椿象成蟲進行致病性測試，其中以球孢白殭菌（Beauveria bassiana CHF 523）的防治效果為最佳。於室內25℃下，將CHF 523孢子懸浮液（1×10^8 conidia/mL）以蟲體浸液檢定法（submersion bioassay）進行接種。結果顯示一、三齡若蟲及成蟲於第9日之累積死亡率均可高達100%，半數致死時間（LT_(50)）分別為3.8、4.6及5.2天。若以1×10^9 conidia/mL接種五齡若蟲於第9日之平均累積死亡率為93.3±3.3%，LT_(50)為4.5天，顯示CHF 523對不同發育期的荔枝椿象均具高度致病性。於溫室較低相對濕度（67-78% RH）模擬田間環境下評估CHF 523之致病力，以噴霧法（spraying method）將CHF 523（1×10^8 conidia/mL）進行接種，結果顯示三齡若蟲於第10日之累積死亡率可高達100%，LT_(50)為6.0天，五齡若蟲及成蟲於第14日之平均累積死亡率分別可達93.3±3.3及86.7±3.3%，換算成蟲之半數致死濃度（LC_(50)）為3.2×10^6 conidia/mL，LT_(50)則分別為8.0及9.3天。另於龍眼園內進行田間試驗，以噴霧法（1×10^8 conidia/mL）進行越冬成蟲防治效果評估，接種後第8日開始發現罹病蟲體，至第21日平均累積死亡率為55.2±18.6%。將CHF 523以三種不同榖物作為載體，進行室內固態發酵（solid-state fermentation）培養試驗，結果顯示以白米載體最佳，在第5天產孢量即可達1.1×10^9 conidia/g，小麥及玉米等載體均需於第15天產孢量才能達9.1×10^8 conidia/g。CHF 523菌株對於荔枝椿象具有高防治潛力，以白米進行固態發酵具有最高產孢效率，可供未來菌種量產與田間應用參考。

關鍵字

荔枝椿象；球孢白殭菌；量產

並列摘要

This study aimed to screen entomogenous fungi with high infectious potential to litchi stink bug (Tessaratoma papillosa Drury). Twelve isolates of entomogenous fungi were isolated from infected litchi stink bugs in 2019. These isolates were selected to inoculate back to litchi stink bugs and incubated under a high relative humidity (＞ 90% RH) for their pathogenicity bioassay. Among these isolates, Beauveria bassiana CHF 523 showed the best biocontrol efficiency. The submersion bioassay was conducted by using the conidial suspension of CHF 523 (1×10^8 conidia/mL) as the inoculum. The cumulative mortality of 1^(st)- and 3^(rd) instar nymphs and adults were up to 100% at 9 days after inoculation, and LT_(50) values of CHF 523 against 1^(st)- and 3^(rd) instar nymphs and adults were 3.8, 4.6 and 5.2 days, respectively. In addition, the cumulative mortality of 5^(th) instar nymphs inoculated with CHF 523 (1×10^9 conidia/mL) was 93.3±3.3% at 9 days after inoculation, and the LT_(50) value of CHF 523 against 5^(th) instar nymph was 4.5 days. These results suggested that CHF 523 was highly pathogenic to litchi stink bugs at different developmental stages. To simulate the field environment, another pathogenicity test of CHF 523 was performed in a greenhouse with a low relative humidity (67-78% RH), and its conidial suspension at 1×10^8 conidia/mL was sprayed on litchi stink bugs. The cumulative mortality of 3^(rd) instar nymphs was up to 100% at 10 days after inoculation, and the LT_(50) value of CHF 523 against 3^(rd) instar nymphs was 6.0 days. The cumulative mortalities of 5^(th) instar nymphs and adults were 93.3±3.3% and 86.7±3.3%, respectively. Moreover, the LC_(50) value of CHF 523 against adults was 3.2×10^6 conidia/mL. The LT_(50) values of CHF 523 against 5^(th) instar nymphs and adults were 8.0 and 9.3 days, respectively. A field trial was conducted at a longan orchard sprayed with CHF 523 at 1×10^8 conidia/mL to determine the control efficacy on overwinter adults. Infected adults were observed at 8 days after inoculation, and the cumulative mortality was 55.2±18.6% at 21 days after inoculation. Three different kinds of grains were used for mass spore production of CHF 523 by solid-state fermentation. Rice grains was the best carrier to culture CHF 523 because the spore concentration reached 1.1×10^9 conidia/g at 5 days after cultivation, whereas the spore concentration reached 9.1×10^8 conidia/g at 15 days after cultivation for wheat and corn carriers. This study suggests that B. bassiana CHF 523 has a great biocontrol potential against T. papillosa and rice grains can be used for mass spore production of CHF 523.

並列關鍵字

Tessaratoma papillosa ； Beauveria bassiana ； mass production

國際替代計量

球孢白殭菌（Beauveria bassiana CHF 523）對荔枝椿象（Tessaratoma papillosa Drury）之生物防治應用潛力

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