In this first module, you’ll learn about the recent history of pesticides as debuted by the industrial revolution and World War II. There were 5 methods of pest control in wide use by the turn of the century:
- Biological Control
- Mechanical and Physical Control
- Cultural Control
- Chemical Control
- Resistant Varieties
In this module, we’ll first get some basics of what pesticides are and how the function, then look mainly at the history of chemical control of pesticides, using the now well-known story of DDT to illustrate how war-time chemicals so quickly made their way into a war in our farming systems.
Excerpt 1: What are pesticides?
by Pesticide Action Network | from Pesticides 101
RoundupInsecticides (bug killers), herbicides (weed killers), and fungicides (fungus killers) are all pesticides; so are rodenticides and antimicrobials. Pesticides come in spray cans and crop dusters, in household cleaners, hand soaps and swimming pools.
Insecticides are generally the most acutely (immediately) toxic. Many are designed to attack an insect’s brain and nervous system, which can mean they have neurotoxic effects in humans as well. Herbicides are more widely used (RoundUp and atrazine are the two most used pesticides in the world) and present chronic risks. This means ongoing, low-level exposures can increase the risk of diseases or disorders such as cancer, Parkinson’s disease or infertility and other reproductive harms. Fungicides are also used in large amounts; some are more benign, some are not.
Pesticides are also sometimes broken down into chemical classes and modes of action. For example, fumigants are pesticides applied as gases to “sterilize” soil, and systemics work their way through a plant’s tissue after being taken up at the root. Major chemical classes include: carbamates, organochlorines, organophosphates (mostly developed 70 or more years ago for chemical warfare) and triazines. Newer classes include pyrethroids and neonicotinoids, synthesized to mimic nature’s pest protection. For more details on specific pesticides, visit our online database at www.pesticideinfo.org.
Excerpt 2: Chemical Control
by John H Vandermeer | from The ecology of agroecosystems. Jones and Bartlett Publishers, 2011
DDT was developed in the late 1800s, and its insecticidal properties were discovered in the early 1900s. It was adopted by the armed forces in Britain and the United States. Tropical diseases, vectored by arthropods, killed more than the enemy during warfare. War research focused on finding effective solutions, and an arsenal of insect-fighting weapons were established as a part of war-preparedness. War was a watershed for the chemical industry, and during the war it built up an immensely productive capacity for both pesticides and herbicides.
Once the war was over, there was a chemical overproduction crisis. The industry had developed ingenious marketing strategies, and the public was susceptible to wartime rhetoric. The original argument that we needed chemicals to defeat the enemy in war was easily translated into the need for these chemicals to defeat the new enemy in agriculture.
The importance of this advertising blitz cannot be overemphasized. Throughout the times of new husbandry, pest management had taken on the generalized goal of maintaining a healthy ecosystem through the five major categories of activities (see above). Pests in agriculture were almost like germs in health, and the goal was to maintain a “disease-free” system. The dominant metaphor seems to have been a medical one, but with wartime and especially postwar propaganda, the pests came to be seen as enemies to be vanquished rather than germs to be controlled- the “war metaphor” replaced the medical metaphor.
The armaments in this new war were, of course, the new organic chemicals produced by the same corporations that produced them for the war effort. The new metaphor meant that farmers changed from stewards who maintained the health of their farms to warriors who vanquished their enemies. The consequences were massive spraying of biocides in the years after World War II and, effectively the maturation of what we now usually refer to as the “industrial” agricultural system. It is worth contemplating the proposition that this industrial system owes its origin not to the need for increased production or production efficiency, but rather to the needs of a distorted economic system, the crisis of overproduction in the postwar world.
Pesticides are usually targeted at a specific insect, or insect family. Instead of looking at insect populations holistically, as a complex part of a complex ecosystem, pesticides target specific parts of the system, attempting to eradicate them. “When you start spraying for a single pest, more pests come, and you have to spray more, which leads to more pests, meaning that you have to spray yet more- a treadmill.”
Applications of pesticides kills the target pests, but it also kills the non-target natural enemies. The target pest, free from normal predatory control, is able to “resurge” after pesticide use. What we soon learned, was that evolution can adapt quickly. When a pesticide is sprayed, it can immediately wipe out a great percentage of pests, but the pests that remain can have increased resistance to the pesticide. The survivors breed, and within a couple generations there can be a population of insect pests who are resistant to the pesticide a farmer is spraying. The farmer can respond by buying and spraying more pesticide, or buying a new, stronger pesticide. Either way, who benefits? You guessed it- the pesticide company. This same cycle can occur with weeds as well, but is known as the “Pesticide Treadmill.”