2019年经济学人 害虫防治:弦理论(1)（在线收听）

Few pests wreak more havoc on coffee plantations than the berry-borer beetle.

咖啡浆果甲虫能对咖啡种植园造成很大破坏，很少有害虫能比它们更厉害。

In Brazil alone its depredations are reckoned to cost $300m a year,

仅在巴西，预计其造成的损失为每年三亿美元，

so keeping the insects under control is a priority for plantation owners around the world.

因此对全世界的种植园主而言，控制这些昆虫成为头等大事。

That is easier said than done. Berry borers spend most of their lives inside the berries.

说比做要容易。浆果蛀虫一生大部分时间都呆在浆果中。

Their eggs hatch there. Their larvae feed, grow and pupate there. And their adults mate there.

它们在那里孵卵。它们的幼虫在那里进食、生长和化蛹。成年后也在那里交配。

Only pregnant females seeking another berry to lay their eggs actually see the light of day. This makes attacking the beetles with insecticides tricky.

仅有怀孕的雌性会出来寻找另一颗浆果产卵，那时它们才真正见到了阳光。因此难以用杀虫剂对付它们。

Researchers have, however, known for some time that a species of Central American ant called Azteca sericeasur is adept at keeping berry-borer populations at bay.

但研究人员知道一种被称为Azteca sericeasur的中美洲蚂蚁很擅长牵制这种咖啡浆果蛀虫的数量。

These ants live in trees grown alongside coffee bushes to provide shade—for coffee bushes do not thrive in direct sunlight.

这些蚂蚁住在树上，而这些树和咖啡灌木共同生长并为它们提供树荫，因为在阳光直射的地方咖啡灌木无法茁壮成长。

In particular, the ants prefer to nest in a tree called the cuaniquil.

这些蚂蚁尤其喜欢在一种被称为cuaniquil的树上筑巢。

The question is how to encourage Azteca's foraging workers down from their cuaniquil eyries

问题是如何能鼓励Azteca的觅食工从它们位于cuaniquil树上的巢穴中出来

and into coffee bushes in large enough numbers to keep berry borers under control.

并大批进入咖啡灌木中抑制这些浆果蛀虫。

And, as they report in Biotropica, Esteli Jimenez-Soto of the University of California, Santa Cruz,

并且正如他们在《Biotropica》期刊中所述，圣克鲁兹加利福尼亚大学的Esteli Jimenez-Soto

and Jonathan Morris of the University of Michigan think they have an answer: build bridges.

以及密歇根大学的Jonathan Morris认为他们有了一个答案：建立桥梁。

Working with a team of colleagues, Dr Jimenez-Soto and Dr Morris studied a coffee plantation in Chiapas, Mexico.

通过和同事合作，Jimenez-Soto博士和Morris博士对墨西哥恰帕斯的一个咖啡种植园进行了研究。

All of the coffee bushes there were growing under a canopy of shade trees, and some of these trees were cuaniquil.

所有咖啡灌木都在能遮荫的树下生长，并且其中一些树就是cuaniquil树。

The researchers selected 20 sites, each separated from the others by at least ten metres, for their experiment.

研究人员选择了20个地方用于实验，且每处相隔至少10米。

All included a cuaniquil that hosted an active ant colony and six coffee bushes that were not touching one another.

每一处都有一棵蚁群寄居的cuaniquil树以及六个互不干涉的咖啡灌木。

To the trunks of three of these bushes, selected at random, they tied strings that led to branches of the ant-bearing cuaniquil.

他们随机从这些灌木中选择了三支，并绑上了线以连接cuaniquil树的树干。