People have spent great amounts of energy and resources to mold nature to their own satisfaction. It seems that this endeavor will be for nothing. Insects are adapting to insecticides to the extent that they have often become impervious to the poisons. One biologist remarked that no one knows enough about insects. As they study insects, they're always astounded that the impossible often happens. Insects are undergoing a process of natural selection so that they are becoming resistant to insecticides. Moreover, the use of chemical poisons weakens the natural enemies of insects. At the end of decades of chemical controls of problem insects, people are finding the return of the same insects that they thought were gone for good. Insects that had once been regarded as only minor threats are becoming strong enough in number to become serious pests. Chemical controls are by nature self-defeating. They don't take into account the complex biological structure of their targeted insects. They are tested against a few individuals, not against living communities.
Chemical control proponents often dismiss the ideal of not upsetting the balance of nature. They say the balance of nature has long since been upset and so it's a moot point. What they don't realize is that the balance of nature is in a constant state of adjustment. There is no such thing as the status quo of nature. People are part of this balance as well as insects, plants, and animals. Chemical control proponents overlook two important facts of nature: one, nature applies the most effective control of insects, and two, insects have an explosive capacity to reproduce once they have adapted to chemical control methods. Normally, nature controls this explosive population of insects and other forms of life. We see this happen over and over in the natural world. Cod, for instance, spawn millions of eggs, but the sea doesn't become a solid mass of cod; only enough cod develop from those eggs to replace the parent fish.
When people interfere in nature's control process, they upset the balance of nature. When people have tried to exterminate coyote, they've been surprised by a tremendous upsurge in field mice. When they've tried to kill off the predators of deer, they've seen deer populations skyrocket resulting in starvation and environmental destruction. Predator insects play the same role as the coyotes and the wolves above. If they're killed off, the population of the prey insect surges.
We don't even know how many insects inhabit the earth. Scientists say that 70 to 80 per cent of the earth's creatures are insects. Most of them are held in check by natural predators. The problem arises when we aren't aware of the natural population controls exerted by predator insects until they fail. Predator insects are many and varied. Wasps kill insects to feed their young. A particular kind of fly lays its eggs on aphid-infested plants and when the eggs hatch, they eat huge numbers of aphids. Ladybugs also kill huge numbers of aphids. Parasitic insects are even more extraordinary. They don't kill their prey outright, but use them as a slow feeding method to kill their young. Dragonflies fly over the water-eating mosquitoes while their young, the dragonfly nymphs are underwater eating mosquito larvae. All the predator and parasitic insects have been our allies in keeping nature's balance steady. Even so, people have conducted a mass killing of these insects with their chemical control methods. The threat is real that these controls will be killed off and we will have an overwhelming explosion of insects dangerous to humans.
Every year, scientists find more insects that have been involved in violent dislocations of nature's balance. Sometimes, chemical spraying even causes an upsurge in the targeted insect. At other times, they are effective against the targeted insect, but produce an upsurge in the population of insects hitherto considered harmless. Such was the case with the spider mite. DDT killed off its enemies and it became to kills massive amounts of vegetation. Whole forests were affected and some were even wiped out altogether. Spider mites even seem to thrive on insecticides. They do so because they are insensitive to them, but their enemies are not. Once the insecticide kills their enemies, they spread out and take over.
In an apple growing region of Virginia, one insect, the red-banded leaf roller became dominant after a spraying of DDT. Before this point, it had never been considered a dangerous insect. It killed 50 percent of the crop in one year. This kind of scenario is repeated from Nova Scotia to Sudan. In the U.S., farmers have often traded one insect for a worse one with their use of chemical solutions to insect problems. In Louisiana, farmers were encouraged to apply Heptachlor. The program increased the population of the sugarcane borer, an insect that killed sugarcane in such huge amounts that the farmers tied to sue the government for not warning them of this eventuality.
In some places, the situation is painfully ironic when farmers or growers once found success with natural predator insects and then turned to chemical solutions only to wipe out the earlier successes and incur more losses than they had ever dreamed of. Such happened with Florida citrus growers. In the 1880s, growers had experimented with great success with biological control of the scale insect. They introduced an insect called the Vedalia, which took only two years to control the entire citrus-growing region. In the 1940s, for no good reason, the growers switched to chemical controls. They spent millions of dollars, wiped out the beneficial insect, the Vedalia, and lost huge numbers of trees.
People are also concerned about insects that carry disease. Here, the determination of the best solution to insect problems carries more immediate threats to human life. On Nissan Island in the South Pacific, the U.S. carried on a spraying operation all during World War II, but stopped the spraying when the war ended. Swarms of malarial mosquitoes invaded and had free sway because the chemicals had effectively killed all their predators. Sometimes spraying works in a different way. For instance, snail-like mollusks are seemingly immune to insecticides. The problem comes when their population explodes, not because the snails are dangerous, but because they carry in their bodies dangerous parasitic worms. In the water, these parasites get loose in the water and enter the bodies of people and they also get loose in the air and enter the bodies of livestock and wildlife. The worms infest the host animals' livers and make them unfit for sale.
With a problem so huge, it would seem that we would want to put all our resources into the study of natural controls of insects. Instead, only 2 per cent of entomologists are studying in this area. The majority are attracted by the high dollars offered by chemical companies for research that forwards their aims. It's not surprising, then, that we so often hear learned entomologists dismissing claims that insecticides are dangerous. They're paid by insecticide companies and their research has been nurtured by those dollars from the beginning of their careers. The few entomologists who aren't supported by the chemical companies try to warn their colleagues against their arrogance toward nature. One entomologists wrote: "We must abandon our attitude of human superiority and admit that in many cases in natural environments we find ways and means of limiting populations of organisms in a more economical way than we can do it ourselves."
At the end of this chapter, Carson returns to the basic ethical appeal of the book: the idea that people have acted dangerously arrogantly toward nature and that if they would just study nature, they would find that it is self-regulating and that when it isn't, as people we can nurture its already built-in regulations to solve the problems we have. She uses this ethical appeal to combat the opponent--the large chemical companies and the scientists who are in their employ directly or indirectly through university research grants.
Clapsaddle, Diane. "TheBestNotes on A Long Way Gone".
TheBestNotes.com.
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