2004-4-19
This is Steve Ember with the VOA Special English Agriculture
Report.
Biocontrols are the way nature seeks balance. Consider the
example of insects that attack crops. Other creatures eat these
pests, unless natural controls are missing.
Biocontrols can also include organisms like worms and fungi. And
they come in the form of bacteria and viruses. These are called
pathogens. A good example is a disease that affects Japanese
beetles.
These beetles were accidentally brought to the United States
almost one-hundred-years ago. They ate crops and spread out of
control.
But in the nineteen-thirties, researchers discovered some young
beetles infected with a condition known as milky disease. The
researchers found the bacteria that caused this infection. They put
it on the soil for other beetles to eat.
The government used hundreds of tons of the bacteria, called
Bacillus popilliae (ba-SI-lus po-PILL-ee-eye). It controlled the
Japanese beetles. But today it seems less effective. Another control
may be needed.
Plants may also find themselves in a new home where they can
reproduce quickly. The alligator weed native to South America is one
such plant. It came to the United States and took over wetlands and
rivers in several states in the South.
In nineteen-sixty-four, researchers released flea beetles in
Florida. Flea beetles are also from South America. They like to eat
alligator weed. The beetle solved the weed problem in central
Florida. There was no need for further use of plant poisons. This
case serves as a model of biological weed control.
There are three methods for biocontrol. One is conservation.
Experts say this is probably the most important. Natural enemies of
pests must be protected. This means to avoid treating crops with
chemicals that will harm any helpful insects.
A second method is often called classical biological control.
This means a helpful biocontrol is released to fight a pest problem.
The release of ladybeetles to fight aphids on plants is another such
example.
Finally, there is the method of biocontrol that experts call
augmentation. Helpful organisms are added to fields to improve
environmental balance.
Cornell University in Ithaca, New York, has a full Web site on
biocontrol. You can find a link at our site,
voaspecialenglish-dot-com. Or enter the words "Cornell" and
"biocontrol" into a search engine on the Internet.
This VOA Special English Agriculture Report was written by Mario
Ritter. This is Steve Ember.