CBSE Class 9 Answered

It would be better to use preventive measures for protecting crops rather than allow the crops to be infested by pests and then control them using toxic chemicals. Use of such toxic chemicals causes environmental pollution. Also these chemicals can cause harm to the other animals and humans consuming such plants in the ecosystem.

Biological control methods involves the use of some organism to destroy specifically the weeds or insects attacking the crop plants. So there is no harm caused to the crop plant or any other organism except the pests. In addition there is no use of chemicals here, which prevents any environmental pollution.

So preventive measures and biological control methods help in protecting the crops without use of toxic chemicals which can cause huge environmental pollution. Use of such chemicals can also give rise to tolerant or resistant pests.