Just add water: The garden insect that can turn into a plague - Jeffrey A. Lockwood

翻译人员: Lexi Ding 校对人员: Helen Chang

The ravenous swarm stretches as far as the eye can see.

肆虐的蝗虫成群结队， 蔓延至天际。

It has no commanding general or strategic plan;

蝗群没有将帅， 也无策略指导；

its only goals are to eat, breed, and move on—

它们的目标只有蚕食、 繁衍，然后继续向前——

a relentless advance that transforms pastures and farms into barren wastelands.

残酷无情的蝗虫过境之后， 牧场、农场全都沦为不毛之地。

These are desert locusts— infamous among their locust cousins

这是沙漠蝗虫—— 在蝗虫家族中臭名昭著

for their massive swarms and capacity for destruction.

因为它们数量庞大 且破坏力惊人。

But these insects aren't always so insatiable.

但这类昆虫并非总是如此贪得无厌。

In fact, most of the time desert locusts are no more dangerous

事实是，大多数时间， 沙漠蝗虫并不比花园中的蚱蜢们

than garden-variety grasshoppers.

危险多少。

So what does it take to turn these harmless insects

那么，是什么驱使这些 无害的昆虫们

into a crop-consuming plague?

酿成一场毁坏庄稼的蝗灾呢？

Desert locust eggs are laid in the damp depths of desert soil,

在干燥的北非到南亚一带，

in arid regions stretching from North Africa to South Asia.

沙漠蝗虫将卵产在 潮湿的沙漠土壤深处。

During the dry weather typical in these ecosystems,

在这些生态系统中 典型的干燥天气里，

desert locusts live a solitary lifestyle.

沙漠蝗虫过着孤独的生活。

Adolescent hoppers will spend a few lonely weeks foraging for plants,

幼蝗虫会独自生活几周， 孤单地寻觅植物，

before growing wings, reproducing, and dying.

然后会长出翅膀， 繁衍后代，最后死去。

But when a region receives an abundance of rain,

但如果某个地区经历了 一场充沛的降雨，

the scene is set for a startling transformation.

这个场景则将迎来惊人的转变。

Increased moisture supports more vegetation

增长的水汽滋养了更多植被，

for newly hatched hoppers to eat,

新生的蝗虫有了更多的食物，

leading large groups to feed in close proximity.

导致大群蝗虫 在邻近区域觅食。

The frequent contact stimulates their leg hairs,

频繁的接触刺激了 它们腿毛的生长，

triggering the release of a hormone

引发一种激素的释放，

that causes them to actively cluster even closer.

这种激素会导致它们 主动聚集地更加紧密。

Gluttonous crowds of locusts produce huge amounts of poop,

贪吃的蝗虫们 排出大量粪便，

which carries a pheromone that furthers their transformation.

其中所含的一种信息素 进一步促进它们的变化。

The hopper’s diet shifts to include plants with toxic alkaloids.

幼蝗虫的饮食发生转变， 它们开始吃含有有毒生物碱的植物。

Soon, the locusts take on a striking pattern that warns predators

不久后，蝗虫的外表变得鲜艳 这一变化警告捕食者们

of their newly poisonous nature.

它们身上开始带有毒性。

Smaller groups merge into bands of millions,

小蝗群融合成 上百万只的大部队，

which mow down virtually all plant life in a kilometer-wide swath.

像一把长达千米的镰刀， 几乎将所经之处的植物收割殆尽。

Roughly every week they shed and expand their exoskeletons,

它们几乎每周都会褪一次壳， 其外骨骼将会变大，

growing to roughly 50 times their hatching weight in just one month.

短短一个月时间， 就能长到约出生时的50倍重。

Finally, the metamorphosis is complete.

最终，变形完成。

The adults beat their translucent wings and take flight

成年蝗虫们扇动 半透明的翅膀，

随进化完全的蝗虫群一起飞去。

as a full-fledged locust swarm.

In this gregarious phase, these long-winged, brightly colored creatures

在这一群居阶段， 这群长翅、色彩明亮的生物

appear so different from their solitary counterparts

与独居时期的蝗虫 差异显著，

that they were long thought to be a separate species.

以至于人们一直以为 它们是两种物种。

A typical swarm contains more locusts than there are humans on the planet,

一个蝗群内的蝗虫数量 一般比世界人口数量还多，

covering hundreds of square kilometers in a dense cloud.

面积可达上百平方公里， 如乌云般遮天蔽日。

At these numbers, desert locusts easily overwhelm their predators.

数量如此巨大，沙漠蝗虫 轻易便压制了其捕食者。

A large swarm can match the daily food intake of a city of millions,

一个大蝗群每日消耗的食物 抵得上数百万人口的城市所需，

and flying with the wind,

顺着风向，

the insect invasion can travel up to 150 kilometers a day.

蝗群每日可飞行高达150公里。

This living tornado can also cross large bodies of water.

这群活飓风还能飞越 广阔的河流海洋。

In 1988, a swarm even managed to traverse the Atlantic Ocean.

1988年，一个蝗群 甚至成功横穿大西洋。

The locusts likely formed rafts to rest at night,

蝗虫们晚上大概会 排成筏子一样来休息，

before fueling up in the morning with a nourishing breakfast of their dead kin.

早上它们会将亲属的尸体当作早餐， 饱餐一顿补充能量。

While flying over land, they seek out moist soil to lay eggs.

飞越陆地时，他们会 寻找潮湿的土壤产卵。

Swarming mothers transfer their gregarious condition to their offspring,

蝗群中的蝗虫妈妈们 将群居的生活习惯传给后代，

making it likely that the next generation will form another swarm.

这样很可能它们的下一代 又会组成下一个蝗群。

This means that while an individual desert locust lives only three months,

这就意味着，尽管一只 沙漠蝗虫的寿命只有三个月，

a plague can last up to a decade.

一场蝗灾却可能持续十年。

The potential for a years-long plague isn’t unique to desert locusts,

并非只有沙漠蝗虫 有酿成数年蝗灾的可能，

but the region they inhabit makes the prospect particularly deadly.

但它们生活的地区， 使得蝗灾的影响尤其致命。

Their habitat spans some of the world’s poorest countries,

它们生活的区域贯穿了 若干世界上最贫困的国家，

largely populated by people who grow their own food.

那里居住着大量 种植庄稼自给自足的人。

By consuming crops and pastures,

通过啃食农作物和牧草，

these insects directly endanger 10% of humanity.

这些蝗虫直接导致 全球10%的人口面临死亡风险。

Fortunately, a desert locust plague doesn't last forever.

幸运的是，沙漠蝗虫蝗灾 并不会一直持续下去。

When a wet period ends,

当雨季结束，

vegetation becomes scarce and egg laying conditions decline.

植被减少， 产卵条件恶化。

As existing swarms die off, new hatchlings spread out in search of food,

随着现有的蝗群逐渐消亡， 新生蝗虫四散开来寻找食物，

creating enough distance to prevent solitary locusts from transforming.

创造出足够大的距离， 阻止这些独居的蝗虫们变化习性。

Human intervention can also help.

人类干预也能起到作用。

Researchers use satellite imagery to identify regions at risk

研究人员使用卫星影像 来识别蝗灾风险区域，

of becoming locust hotspots and alert local governments.

并向当地政府发出警告。

While most countries fight back with chemical insecticides,

在大多数国家使用 化学杀虫剂对抗蝗灾时，

some regions have found success using fungal diseases that are lethal to locusts

一些地区使用能够杀死蝗虫的 真菌病害成功地消灭了蝗灾，

but safe for people and the environment.

但其对人和环境无害。

Unfortunately, other modern practices are exacerbating the threat.

不幸地是，现代社会的一些做法 加剧了蝗灾威胁。

Fields densely packed with a single crop are like a table set for locusts.

稠密地种植着单一作物的田野， 就像给蝗虫摆放的餐桌。

And erratic weather caused by climate change makes swarms harder to predict.

气候变化导致的多变天气， 也使蝗灾更难预测。

If we plan to discourage lonely locusts from becoming catastrophic crowds,

如果想要阻止散居的蝗虫 演变成灾难性的蝗群，

humans need to cut carbon emissions, rethink our agriculture,

人类需要减少碳排放， 重新考虑农业布局，

and generally reconsider our own ravenous appetites.

以及再反思一下我们自己 贪婪的口腹之欲。