入侵紅火蟻與餌劑處理對於當地螞蟻多樣性的影響 －以台北大學三峽校區為例

Abstract

本研究採用台灣入侵紅火蟻撲滅計畫的前導試驗所蒐集的資料進行分析，試驗地為台北大學三峽校區。以掉落式陷阱定量估計當地螞蟻覓食活動量，每間隔2-4個月進行一次調查，每次調查後使用藥劑進行入侵紅火蟻防治。到本研究結束為止，總共累積14次調查記錄，從中挑選四次調查，定義為防治前期（Bef.)、防治中期（Mid.）、防治後期（Lat.）以及防治末期（Ter.）進行研究；此外另選擇A2和D4兩個小區，分析14次調查的結果，作為群落變動的參考。於防治開始後，入侵紅火蟻的族群數量大幅下降並且受到壓制，直至本研究結束時仍沒有回升。其他本土螞蟻物種中，總共採集到蟻科（Formicidae）內4個亞科、19屬、33種本土螞蟻物種，並且在各區間有群落組成上的差異。由於這種區域性的差異，使得各區域內的優勢物種（dominat）與亞優勢物種（sub-dominat）組成也不同，但整體來說，優勢與亞優勢物種都由家蟻亞科（Myrmicinae）與山蟻亞科（Formicinae）組成。在使用藥劑防治入侵紅火蟻之後，台北大學整體的物種豐度（richness）與個體豐量（abundance）並沒有受到顯著的衝擊，但以多樣性指數而言，發現防治後當地螞蟻群落多樣性明顯降低，但卻具有逐漸回升的趨勢，不過直到研究結束為止仍沒有達到研究初期的水準。此外，檢視本土螞蟻物種於防治歷程的族群變動曲線，可發現當入侵紅火蟻受到藥劑控制後，其他蟻種可能會因火蟻減少而開始受到藥劑影響，因此認為目前台灣的防治策略仍有調整的空間，以減少對本土物種的衝擊。再者，這些族群變動曲線也顯示的確有某些蟻種具有資源上的競爭潛力（例如、熱帶大頭家蟻Pheidole megacephala），可進一步探討其防治上之利用價值。尤其於防治末期，為了降低再入侵率、減少防治成本以及緩和藥劑對本土物種的衝擊，若能配合這些具競爭潛力的螞蟻物種，應可達到更好的防治效果。

The data of this study were generated from the pilot study of the eradication program of the red imported fire ant (Solenopsis invicta, RIFA) carried out in Sanshia campus, National Taipei University. The numbers of RIFA and local ants were monitored by pitfall traps with 2-4 months interval followed by bait broadcasting. Data from four given periods among totally 14 monitoring courses were chosen and defined as initial stage (Ini.), middle stage (Mid.), late stage (Lat.) and terminal stage (Ter.) of control. Two small plots, A2 and D4, were selected to investigate the detailed changes in the numbers of ants over the 14 monitoring courses. Overall patterns suggest that the population of RIFA declined rapidly after control taking place and has been suppressed until the end of this study. All captured local ants comprised of 33 species, 19 genera, and 4 subfamilies in Formicidae. The compositions of ant fauna are different in study areas, which give raise the diverse make-up of dominate and sub-dominate species. In general, however, the dominate and sub-dominate species in distinct areas were composed of Myrmicinae and Formicinae. The overall richness and abundance of local ants in the campus seem not to be affected after RIFA was controlled by bait. Considering three different diversity indices, the diversity of the local ant populations significantly decreased after treatment and then increased gradually and slowly. However, it did not reach the level as found in the initial stage of invasion. The dynamic relationships among ants found in the campus suggest that not only the interspecific competition did exist under the pressure of RIFA and bait but also native ant species may be impacted by bait that RIFA can not occupy because of low population density. Based on the results obtained from this study, the control strategy might be modified to protect the local ant species by decreasing the amount of bait applied in the field and integrating the ants characterized by better competition ability as potential management agents. In this way the eradication program may gain additional benefits, particularly during the late stage of control, the likelihood of recolonization of RIFA could be minimized by the integration of chemical and biological controls.