外來種龍眼雞 (半翅目：蠟蟬科) 族群動態與防治建議

Abstract

龍眼雞 (Pyrops candelaria) 為 2018 年首次發現於臺灣本島的外來種，在中國是龍眼樹的害蟲，目前對臺灣農業危害程度尚未知，然外來種有對本土生態仍可能造成負面影響，故需進行防治。本研究藉由野外觀察與捕捉以及實驗室飼養，來瞭解龍眼雞的生活史、藏匿處、卵塊位置與若蟲棲地等生物學特性，分析其族群動態以及做出防治建議。同時以若蟲及卵塊形態與龍眼雞相近的渡邊氏東方蠟蟬 (P. watanabei) 以及近幾年入侵至多國造成嚴重危害的斑衣蠟蟬 (Lycorma delicatula) 之資料做為參考，找出可以有效防治龍眼雞的方法。野外觀察與捕捉包括直接觀察、草地掃網與人工移除，將參考往昔對龍眼雞生活史的研究，在不同月份至新北市進行，並針對不同蟲期而有不同觀察與捕捉方式。因為草本植物為若蟲的寄主，故針對龍眼樹周圍的草地進行掃網，確認草地是否為若蟲棲地。人工移除部分在新北市八里區進行為期三年的監測與捕捉，以廣義加成模型 (generalized additive model, GAM) 分析各個變數與龍眼雞成蟲數量的關係，並模擬「所有發現的成蟲皆不捕捉」與「所有發現的成蟲皆捕捉」的情境，分析人工移除的可行性。實驗室飼養將針對若蟲，以瞭解詳細的若蟲生活史。將若蟲與卵塊進行測量，與渡邊氏東方蠟蟬比較並找出可分辨兩者的特徵，避免防治時誤殺。目前在野外有發現卵塊與高齡若蟲，產於實驗室的卵塊孵化後，最高飼養至三齡若蟲。草地掃網無捕捉到龍眼雞，草地是否為若蟲的棲地需再確認。人工移除若每次捕捉超過 50 隻成蟲便可使下次觀察到的成蟲數量下降，故防治可以此為目標。情境模擬若完全不移除龍眼雞，則第一年即會族群大發生，故無法不進行防治。測量部分龍眼雞與渡邊氏東方蠟蟬的兩卵蓋間距、卵蓋長寬、一齡若蟲之頭長有顯著差異，未來若遇卵塊與一齡若蟲，可藉由測量以上部位鑑定，針對目標蠟蟬進行防治，加強移除效率。期望本研究可以提供未來移除外來種的作業參考。

Pyrops candelaria is a new invasion on the main island of Taiwan, first observed in northern Taiwan in 2018. P. candelaria is one of the pests of longan trees in China, while its impact on the agriculture of Taiwan is unclear. However, an alien species may pose a threat to native ecosystems and biodiversity, requiring prevention and control. Since the lack of information on nymphal stage of P. candelaria, this study focused on the nymph and the egg. In order to find effective methods to control P. candelaria, the biological data of P. watanabei whose nymphs and eggs are similar in appearance to P. candelaria, and the control measures of Lycorma delicatula, can be served as references. This study aims to investigate the population dynamics of P. candelaria and make suggestions on the control of it. The section of field observation and capturing includes direct observation, net-sweeping method, and manual removal. Based on the biological study of P. candelaria, the different observation and capturing methods were used in different life cycle stage. Since herbaceous plants are also host plants for nymph, net-sweeping method was used on the grassland to find nymphal habitat. Manual removal was conducted in Bali District, New Taipei City, with three years of monthly monitoring and capture. The generalized additive model (GAM) was used to analyze the association between explanative variables and the number of adult P. candelaria. In addition, two scenarios were simulated to consider the efficiency of removal of this alien species: “all observed P. candelaria were not captured” and “all observed P. candelaria were captured.” The laboratory rearing section focused on nymphs to know the life cycle of nymphs. Eggs and nymphs of P. candelaria were measured and then compared with P. watanabei, which are similar in appearance with P. candelaria, to determine whether there are differences between these two species, and thus the misidentification can be avoided. Egg masses and older nymphs were found in the field, and the nymphs in the laboratory grew to up to the third instar. No nymphs were captured by net sweeping, and whether the grassland was the nymphal habitat was needed to reconfirm. In GAM result, when the captured number exceeded 50 individuals, the more adults captured could result in the less adults observed in next monitoring. In the simulated scenario of “all observed P. candelaria were not captured,” the outbreaks were predicted to occur in the first year of monitoring, so control measures could not be avoided. P. candelaria and P. watanabei showed significantly different in the egg spacing, lid length, lid width of egg, and the head length of first instar nymph. Therefore, the target species can be distinguished to improve removal efficiency by measuring these parts. It is believed that this study can provide an important reference for the future removal of alien species.