The problem of exotic species is a worldwide one, and those nations which take it seriously approach it as if confronting a formidable enemy, not only stepping up their monitoring of farm products, but also imposing ever stricter limits on the introduction of all kinds of organisms.
外來種是世界問題，慎重其事的國家如臨大敵，不僅在農牧產品上的查緝步步加強，對引進各種生物的限制條件也愈趨嚴格。