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　　瓢虫喜欢吃蚜虫以及其它害虫。因此人们开始引进一种称作“小丑瓢虫”的亚洲物种，以此作为控制自然虫害的手段。但是在新环境中，小丑瓢虫却消灭了本地的瓢虫，这要归因于小丑瓢虫带来的寄生虫。这是根据《科学》杂志发表的文章得出的结论。

　　A parasite called microsporidia lies dormant in the circulatory systems of harlequin ladybirds.But when scientists injected microsporidia into a common European ladybug species, theinsects died within two weeks. When the ladybugs were injected with dead microsporidia or acontrol substance most survived.

　　这种叫做“微孢子虫”的寄生虫潜藏在小丑瓢虫的循环系统内。然而，当科学家向普通的欧洲瓢虫体内植入微孢子虫时，不出两个星期它们就死亡了。当植入死的微孢子虫或者对照物质时，大多数都存活了。

　　Harlequin ladybirds' immune systems, on the other hand, have learned to deal withmicrosporidia—which lets the insects use them as biological weapons. Because one wayladybugs compete is by consuming the eggs and larvae of rival species. When Europeanladybug species eat the harlequin ladybird eggs and larvae, they also consume themicrosporidia. And die.

　　另一方面，小丑瓢虫的免疫系统已经学会了如何处理微孢子虫，这让瓢虫把它们作为生化武器。因为瓢虫的一种竞争手段是吃对手的卵或者幼虫。当欧洲的瓢虫吃小丑瓢虫的卵和幼虫的同时，也吃掉了微孢子虫。然后它们就会死。

　　The discovery demonstrates an important role of immunity in evolutionary selection. And itshows that there are many ways to lose a food fight.

　　这项发现说明免疫系统在进化选择中扮演了重要的角色，也证实了在食物大战中被打败有许多因素作怪。

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