In agriculture and in forestry industries, it's very common to use chemical pesticides to get rid of unwanted insects/bugs/weeds. Most of the times, they are only partly effective at best. After every application, even if a number of those insects die, a few still remain. And the next generation that emerge from these tough ones are usually immuned to the earlier pesticide application. So again the whole process of applying pesticide starts, only this time even stronger.
Pesticides are poisons. Not just for the unwanted 'pests', for the beneficial ones as well, such as bees and flies that help pollination. It's even poisonous to humans, many times even lethal. And they have this terrifying ability to 'bioaccumulate' and 'biomagnify', making them even more dangerous to humans in the long run.
Nature is incredibly complex, more than even our wildest imagination. But it still has a way of balancing itself. What seems like the end of an ecosystem, can as well be the beginning of a new ecosystem.
Nature can bounce back on its own. It can take frost and fire, drought and flood. But what it cannot take is uncontrolled meddling by ignorant humans for generations, using and abusing it without the slightest knowledge or consideration of the long term impact. It cannot take those man made chemicals, those poisons that are totally alien to nature. The pests that we are getting rid of using pesticides, are perhaps way less harmful than these chemicals in the long run.
But tell that to the induatrialists!!