亞洲柑橘木蝨的行為在柑橘黃龍病媒介傳播之研究

Abstract

柑橘黃龍病目前尚無有效化學藥劑可供防治上使用，因此，在防治上首重預防。繼建立健康種苗制度後，此病透過嫁接傳播的途 徑已獲得有效控制；但健康種苗仍可能經由亞洲柑橘木蝨 (Diaphorina citri Kuwayama) 再感染，因此，以健康種苗進行防病同時，需兼顧防治媒介昆蟲，才能有效防治可經由媒介昆蟲傳播之植物病害。有效媒介昆蟲防治策略擬定仰賴對柑橘木蝨本身的特性充足了解。本研究將藉由人為釋放健康柑橘木蝨成蟲新進入原本不具柑橘木蝨族群之柑橘園內 (30.8 × 28 m2)，以估計新入侵的柑橘木蝨在田區內擴散情形的特性。兩次釋放結果顯示，第一次釋放染色柑橘木蝨擴散範圍在首週之後便不再擴大，第一週擴散平均距離約 7 m；第二次釋放染色木蝨擴散範圍在第4天亦不再擴大，擴散平均距離約 9 m，第二次釋放調查到染色柑橘木蝨數量，擴散距離及範圍均較第一次大。向外散佈的成蟲會尋找柑橘植株新芽進行產卵，並藉由後代繼續下一次的擴散。兩次釋放的柑橘木蝨擴散偏向東南方，且皆與首週的風向一致；由田區迎風面及逆風面同時釋放柑橘木蝨約 400 隻，迎風面釋放之柑橘木蝨擴散面積較逆風面大，擴散距離亦較遠，迎風面擴散平均距離約 46 cm；逆風面擴散平均距離約 7 cm。支持風向對柑橘木蝨擴散方向性之影響。前人研究指出柑橘木蝨在病株間具選擇偏好性，為確認擴散方向性非受對感染黃龍病植株之偏好導致，進行柑橘木蝨對病健株偏好性試驗，試驗結果顯示，柑橘木蝨對病健株之偏好性無統計上之顯著差異。田區風向為目前探討因子中與柑橘木蝨田間擴散方向最為相關。柑橘木蝨的累代擴散為田間黃龍病向外傳播之重要因子。藉由試驗所得之柑橘木蝨田間生態及行為資訊，以期修正現行之監測方式，及未來柑橘黃龍病防治策略擬定之參考依據。

Citrus Huanglongbing (HLB), a destructive disease of citrus without any efficient chemical cure, is mainly managed by reducing the initial infection instead of curing. Since 'the healthy seedling system' was promoted by Taiwan government, we successfully prevent the HLB transmission by using grafting. However, it is still very difficult to prevent the healthy plants from infection if we cannot control their insect vectors, Asian citrus psyllid (Diaphorina citri Kuwayama). As only a few studies have been focused on the dispersal behavior of Asian citrus psyllid, we here performed a weekly survey of 64 citrus trees in a 30.8 × 28 m2 orchard. After 10-week survey since May, 2014 and September, 2015, two artificial releases of 1000 marked D. citri revealed that the dispersal range of released adult D. citri was no longer expanded after the first week. The longest dispersion distance in average was about 7 m away from the origin and decreased in the following weeks at the first release, and was about 9 m away in the following days after day 4 at the second. The second artificial release had longer average dispersion distance. The offsprings of the released psyllids became adults at the 4th week and then further expanded their distribution. D. citri moved toward the southeast of the central origin, and was consistent with the wind direction in the first week. In order to examine whether the directional movement of psyllids was dependent on the wind direction or the preference between infected and healthy plants. About 400 D. citri were released at the northwest and southeast corners of the orchard. The directional movement of psyllids was mainly followed the wind direction and had larger dispersal distance. However, the preference of D. citri between HLB – infected and healthy plants was not found. With the field ecology and behavior information of D. citri obtained from this survey, we could further adjust the present monitoring methods, and provide further information for HLB control strategy.