The Past ahd Present Status of the Vector Transmission of Citrus Likubin in Taiwan

柑橘立枯病之媒介昆蟲傳播試驗隨著病原觀念之改變，試驗方向亦因而改變。1940年以前，立枯病的研究係以探討病因為主，尚未真正進行媒介傳播試驗。1940~1970年間，由於立枯病被認為由tristeza病毒或tristeza病毒相似之病原所引起，媒介昆蟲傳播均以蚜蟲為試驗對象。1970年前後，由於擬菌質體(mycoplasm-like organism, MLO)被發現於立枯病組織體內，柑橘木蝨（Diaphorina ritri）則懷疑為其媒介昆蟲。由於木蝨傳病能力極低，因此至1982年才被證實。有關木蝨蟲體獲得病原所需時間或病原在蟲體之潛伏期等基本資料目前均未獲得。立枯病在田間之發生蔓延與木蝨族羣消長之關係，尚未有資料。但在溫室的情況下，柑橘萌芽影響木虱族羣之消長，萌芽期木虱之若蟲及成蟲密度均有顯著增加，立枯病發生率亦增加。一年當中，以春芽期木蝨族羣密度最高，立枯病發生率亦最高。 Studies on vector transmission of citrus likubin change mainly by the concepts of the causal agent of the disease at different stages during the past six decades. In 1913-1940, most work on likubin research were focused on identification of the causal agent. There was no report on insect transmission. During the years of 1940 to 1970, because likubin was considered to be caused by a virus which was closely related to tristeza, and therefore aphid was suspected to be the vector. Report of aphid transmission showed that likubin diseased citrus trees contained tristeza virus and one unknown component. In 1970’s, the finding of mycoplasma-like organism (MLO) in likubin-affected citrus trees and reports from other countries, scientists started to suspect psylla(Diaphorina citri)would be the vector of the disease. It was not proved until 1982 Huang et at. reported that likubin was transmitted by D. citri from diseased citrus plants to healthy citrus seedlings. Because the transmission efficiency by the vector was low, the acquisition feeding time and incubation period are still undetermined. At present, ecological studies on likubin and its vector, and evaluation of biological control of D. citri in fields are in progress