「クレイジーアント」というアリが、2002年に米テキサス州のヒューストンで初めて発見されて以来、フロリダ州、ルイジアナ州、ミシシッピ州へとその分布を広げている（リンク先によると、ブラジルやアルゼンチンからの「侵入種」）。
「ABC News」の記事によれば、「ラズベリークレイジーアント（raspberry crazy ant）」や「黄褐色クレイジーアント（tawny crazy ant）」という名称でも知られるこのアリは、「家畜から電気機器にいたるまで何でも好む」とされ、住宅や変圧器だけでなく、ノートパソコンやスマートフォンの中にまで侵入することが報告されている。
近縁種の「ファイアーアント」（Fire Ant。カミアリ／ヒアリ。アルカロイド系の毒をもつ）とは違い、クレイジーアントの行動は極めて侵略的だ。いくつかの地域では、ファイアーアントが住み家を奪われているという。
クレイジーアントは、ほかの種のアリの生息地に侵入すると、攻撃的に資源を競って優位性を確立する。ファイアーアントは「毒入りのエサ」で駆除も可能だが、クレイジーアントはこうしたエサには見向きもしない。
「クレイジーアントに侵入された地域の住民たちは、ファイアーアントに戻って来てほしいと話している」と語るのは、テキサス大学オースティン校自然科学学部で侵入種の研究を行うエド・ルブラン教授だ。「ファイアーアントは、あらゆる面で礼儀正しいアリだった。庭に小さな山を作って住み、その山を踏みさえしなければ攻撃してくることはなかった」
ルブラン教授は、テキサス州の生態系でクレイジーアントがファイアーアントを駆逐していることに関する最新の研究の共著者だ。同教授は、クレイジーアントがどこでも巣を作るという習性が生物学的な優位につながる大きな要因であると説明する。ファイアーアントのほうも外来種だが、テキサス州の生態系は過去40年間にわたって、ファイアーアントに対応するよう形成されてきた。しかしクレイジーアントによって、生態系が大きく変化する可能性がある。
クレイジーアントは雑食性だが、実際には電気製品を「食べる」わけではない。電気装置に被害が及ぶのは、アリが電線を喰い破り、回路をショートさせるからだ（さらに、感電したアリが放出する化学物質で、ほかのアリが「攻撃者」を探して集結するため、アリが大量に入り込んで過熱等が生じるという）。
「クレイジーアントのテリトリー内にパソコンを置くのをやめたとしても、それで十分とは言えない。このアリは、固定設備や屋内配線、キャンピングカーにまで侵入する傾向がある」と、「CNET」は伝えている。
[Andres Jauregui (English) 日本語版：兵藤説子、合原弘子／ガリレオ]
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Invasive Species Of North America
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