AGRICULTURE REPORT - Biological Controls, Part 1

AGRICULTURE REPORT - Biological Controls, Part 1
By Mario Ritter

Broadcast: Tuesday, April 13, 2004

This is Steve Ember with the VOA Special English Agriculture Report.

Biological controls are living things that eat organisms harmful to crops. They offer new ways for farmers to grow organic crops and protect the environment.

In modern times, farmers have depended on chemicals to kill harmful insects, plants and other organisms. But, many scientists and farmers are looking for ways to grow crops without using poisons. Limiting chemicals can save farmers money as well. One way to avoid using poisons is to release helpful insects that are natural enemies of harmful insects, or pests.

Some insects eat pests. The lady beetle¹, or ladybug, is well known. Round, colorful lady beetles² eat many kinds of harmful insects including aphids. Aphids develop colonies and eat plant fluids.

An adult lady beetle can eat fifty or more aphids a day. Aphids attack many different kinds of crops. This makes lady beetles a good defense³ against aphids for growers of fruit, grains, beans, strawberries and other crops. Lady beetles live in Asia, Europe and the Americas. Farmers can buy them from suppliers.

Some insects inject their eggs inside the bodies of pests. These are called parasitoids. Young parasitoids come out of their eggs and eat the pests. Some parasitoids can be very effective. They keep the pests from reproducing. After they become adults, they lay many eggs on other pests.

A tiny wasp⁴ with a big name is a good example. Encarsia formosa is used all over the world for vegetables and flowers grown indoors.

The Encarsia formosa wasp injects eggs into the bodies of young white flies. There are many different kinds of white fly pests and E formosa likes to eat at least fifteen of them. Some of these wasps⁵ can lay enough eggs to kill ninety-five young white flies in twelve days. E. formosa is most popular in Russia and Europe.

The United States Department of Agriculture has been studying a fly that attacks another pest - the fire ant. The phorid fly attacks fire ants in the same way as E. formosa. Phorid flies kill only about three percent of the ants in a colony. But they greatly damage the colony's ability to collect food. The U.S.D.A. has released phorid flies in an effort to control fire ants in the southeastern United States.

Next week, we tell about two kinds of biological controls that attack pests in new ways.

This VOA Special English Agriculture Report was written by Mario Ritter. This is Steve Ember.

1 beetle   

n.甲虫，近视眼的人

参考例句：

• A firefly is a type of beetle.萤火虫是一种甲虫。
• He saw a shiny green beetle on a leaf.我看见树叶上有一只闪闪发光的绿色甲虫。

2 beetles   

n.甲虫( beetle的名词复数 )

参考例句：

• Beetles bury pellets of dung and lay their eggs within them. 甲壳虫把粪粒埋起来，然后在里面产卵。 来自《简明英汉词典》
• This kind of beetles have hard shell. 这类甲虫有坚硬的外壳。 来自《现代汉英综合大词典》

3 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

4 wasp   

n.黄蜂，蚂蜂

参考例句：

• A wasp stung me on the arm.黄蜂蜇了我的手臂。
• Through the glass we can see the wasp.透过玻璃我们可以看到黄蜂。

5 wasps   

黄蜂( wasp的名词复数 )； 胡蜂； 易动怒的人； 刻毒的人

参考例句：

• There's a wasps' nest in that old tree. 那棵老树上有一个黄蜂巢。
• We live in dread not only of unpleasant insects like spiders or wasps, but of quite harmless ones like moths. 我们不仅生活在对象蜘蛛或黄蜂这样的小虫的惧怕中，而且生活在对诸如飞蛾这样无害昆虫的惧怕中