沖縄島の農耕地とくに施設圃場におけるアリ相とその季節消長

摘要

As a first step for the biological control of pest insects using ants we surveyed the ant fauna and its seasonality on seven farm lands, six of which were greenhouses, in the southern part of Okinawa Island. Cultivated plants were dragon fruits, eggplants, bitter gourds, green peppers and sugarcanes. Ants were collected using pitfall traps every 2 month (with some exception) throughout 2006. Regardless of inside or outside the greenhouses ants were less active and less abundant in the low temperature period from January to March, whereas they were abundant and seemingly active in the high temperature period from May to October. The ant species composition did not differ very much by cultivated plant species. Four species (Tetramorium bicarinatum, Monomorium chinense, Pheidole fervens and P. parva) were most common in those fields, which implies that these four species can have the highest potential as the biological-control agents in the warm season in Okinawa, on one hand. On the other hand, a large portion of those dominant ants consists of exotic tramps species, therefore their risk of biological invasion should be also carefully estimated before using them as control agents.%沖縄におけるアリの生物的害虫防除への利用に向けた第一歩rnとして，沖縄島の7ケ所の圃場（そのうち6つはハウス）におけrnるアリ相と個体数の季節変動を約1年間調べた．ピットフォールrnトラップ法を用いて圃場の中とすぐ外の屋外環境で調査を行った．rn栽培作物はラン，ドラゴンフルーツ，ナス，ゴーヤ，サトウキビ，rnピーマンであった．屋外，ハウスに限らずアリ類は気温が低い1rn月から3月は採取個体数・種数ともに少なく，気温が高い5月rn～10月にかけて採取個体数・種数ともに多かった．栽培作物にrnよるアリ相に大きな違いはみられず，オオシワァリ，クロヒメアリ，rnブギオオズアリ，ミナミオオズアリの遍在性が高く個体数も多かっrnた．沖縄島の圃場でアリを害虫防除資材として利用する場合，rnこれらの種が高温期に利用できる可能性があると考えられる．そrnの→方で優占種の多くは外来の放浪種であり，利用時にはそのrn侵略性のリスクの検討も必要である．