Population fluctuation of Diaphorina citri Kuwayama and incidence of citrus likubin in citrus orchards in Chlayi area

柑橘木蝨在田間的族群消長，成蟲一年分別於春芽、夏芽期出現兩個高峰，其中以春芽期蟲數最多。以聚集度值作為成蟲在空間分布變化之參考依據，當新芽長出時，成蟲逐漸聚集產卵，聚集度指標往上攀升，當若蟲大量羽化尚未分散之際，聚集度達最高值，隨著成蟲的分散，聚集度值往下降。由田間黃色枯板誘蟲結果得知，成蟲飛翔最活躍的時期發生在柑橘新芽出現後；羽化後的分散則以植株內的爬行為主，並在老葉下停留吸食汁液，不太活躍。柑橘園中木蝨較大量的遷移以三月中旬至四月下旬較多，木蝨侵入柑橘園後可迅速繁殖，於三個月內建立其族群，並在果園四處分散。於田間定值6個月的椪柑植株在不施藥情況下，當73％的植株發現有木蝨成蟲或若蟲時，以核酸探針偵測，結果有89% (82/92)的植株感染立枯病，其中70% (62/92)有病徵。立枯病在田間發生是由病株向鄰株漸進的擴散，受感染的植株須經六個月才會表現病徵。有些外表健康的植株其實已帶有病原，甚至一年以後才會出現病徵。 Investigation on population dynamics of the psyllid in citrus orchards showed that the population of adults had two peaks per year which were coincided with the periods of citrus flushing at spring and summer. The number of adults was most adundance in the first population peak. As the space distribution of the adults in the field was referring to the Relative Degree of Aggregation (RDA), the index of RDA went up during the flushing period when the adults aggregated on the new shoots to lay eggs. The index went up to the highest when the adult emerged completly, then it fell down with the dispersion of adults. Newly emerging adults was not so active, most of them dispersed by climbing within the same trees and sucked juice from down surface of leaves. Migration of adults around citrus orchard was mostly form March to the end of April. While the adults immigrated into a new citrus orchard, they multiplicated and set up population rapidly within three moths, then spread to other trees all over the year. About 73 % of citrus plants could be recorded to be infested by the psyll.id, 89 % of them could be detected by using dot hybridization(DH) test with DNA probe that had been infected by Likubin, only 70 % show symptom. The dissemination of likubin in the field from the primarily infected plants to the surrounding plants, which might be infected but not show any symptom within one year