As Charles Darwin predicted with his theory of evolution, the fittest have survived: pests are getting stronger and more resistant with incredible speed. Many of the insects developing immunity to pesticides carry infectious diseases. Awareness of this problem has been slow to spread, but resistance among insect populations has not. Dr. Charles Elton called this issue “the early rumblings of what may become an avalanche…”
This chapter outlines a new aspect of Carson’s argument against pesticides: the rapid development of immunity to the pesticides among insects. Nature has trumped man’s reckless attempts at control, so that the ‘new era’ in which man can influence his environment has developed almost into a war, as Carson will demonstrate here.
Organizations combating disease-carrying insects are acutely aware of the problem. Carson lists cases of resistance among mosquitoes, ticks, houseflies, rat fleas, lice, and many more, each of which can carry a different infectious disease. This issue must be dealt with, but it seems questionable to choose a solution that seems to be rapidly worsening the problem instead of a more natural option.
In areas where control is necessary because of disease, the use of pesticides has backfired as insects gain immunity to more and more chemicals. Underestimating the power of nature to adapt has led man into a situation where escalation of the ‘war’, that is, the development of more and more dangerous chemicals, seems necessary.
Cases everywhere from Egypt to the United States demonstrate that pesticides are in nearly every case only a temporary solution to a serious problem. Perhaps the first medical use of pesticides occurred in Italy in 1943, when DDT dusting was used to control against typhus carrying mosquitoes. Within one year, mosquitoes of a particular genus had begun to show resistance to DDT. In 1948, Chlordane was added to the chemical cocktail, and achieved good results - until flies and mosquitoes developed resistance to it two years later.
Since the very early days of pesticide use, the development of immunity in targeted insects has been observable. But rather than stopping to question how this cycle will end, scientists and controllers have created and used increasingly toxic chemicals in an attempt to overcome the immunities – only to see nature respond with more resistance. Caution, rather than automatic escalation, is required.
This pattern is repeated around the world. In Korea, and many other countries, lice have become completely resistant to DDT. In fact, individuals tested in Korea actually had more lice after the application of DDT. The rate at which insects develop resistance is also remarkable. In 1956, the number of mosquito species displaying resistance was only 5 – by 1960 this number had increased to 28, including carriers of malaria in West Africa, the Middle East, Central America, Indonesia, and Eastern Europe.
As Carson demonstrates, the problem of immunity is a difficult one to address. If the public knew about this wave of resistance – and once Carson’s book has been published the public will know – perhaps they would be more cautious in developing ever-stronger chemicals. Instead, currently caution has been thrown to the wind in the pursuit of control over “pests” and nature.
In dealing with upsurges of cockroaches, ticks, mosquitoes, and more, in regions from Central Park West to Indonesia to Iran, control agencies are currently cycling through pesticides as insects develop resistances. The same story is seen in insects that threaten agricultural crops – spraying only strengthens pests. The chemical industry wishes to ignore resistance, but mounting costs betray the increased difficulty.
This escalation of pesticide toxicity is like an arms race, in which two opposing sides continue to one up each other until something gives and destruction follows. The problem is that the increasingly deadly weapons that we are deploying are not targeting only the insects, but also disrupting the natural system and, in the end, causing illness in humans.
It is the process of natural selection, in which only the strongest (or most resistant) members of a sprayed population survive, that leads to this problem. These resistant individuals then reproduce, and their genetic material becomes dominant. The short life spans of insects allow these adaptations to take effect quickly across a broad population. The development of more and more toxic pesticides is accelerating as older models become ineffective against resistant insects.
While insects can adapt quickly to new poisons in their environment, and have, humans have longer life spans and are therefore less genetically flexible – as we have seen, evolution may no longer be a safety net for the human race. In the pesticide arms race, humans lose out while insects continue to become stronger.
This endless escalation resembles an arms race, in which two sides compete to develop more advanced weaponry, and end up with an arsenal of destructive forces that cause more harm than good – it is difficult to see a positive conclusion to this competition. More officials like Dr. Briejer, Holland’s Director of Plant Protection Service, are now calling for a reduction in spraying as a result of these dangerous dynamics. Life is a miracle beyond our understanding, writes Carson, and requires reverence and humility rather than scientific arrogance or pride.
Here Carson makes clear her comparison of the dynamic between insects and pesticide manufacturers to an arms race. This arms race will lead to an extremely fraught future, as man struggles to keep up with the pace of his own development with dangerous consequences for the fragile balance of the natural environment, as we have already seen. This is as much a moral question as it is a scientific one.