History of Pesticide UseHistory of Pesticide Use |
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John Unsworth 10th May 2010
The practice of agriculture first began about 10,000 years ago in the Fertile Crescent of Mesopotamia (part of present day Iraq, Turkey, Syria and Jordan) where edible seeds were initially gathered by a population of hunter/gatherers1. Cultivation of wheat, barley, peas, lentils, chickpeas, bitter vetch and flax then followed as the population became more settled and farming became the way of life. Similarly, in China rice and millet were domesticated, whilst about 7,500 years ago rice and sorghum were farmed in the Sahel region of Africa. Local crops were domesticated independently in West Africa and possibly in New Guinea and Ethiopia. Three regions of the Americas independently domesticated corn, squashes, potato and sunflowers2. It is clear that the farmed crops would suffer from pests and diseases causing a large loss in yield with the ever present possibility of famine for the population. Even today with advances in agricultural sciences losses due to pests and diseases range from 10-90%, with an average of 35 to 40%, for all potential food and fibre crops3. There was thus a great incentive to find ways of overcoming the problems caused by pests and diseases. The first recorded use of insecticides is about 4500 years ago by Sumerians who used sulphur compounds to control insects and mites, whilst about 3200 years ago the Chinese were using mercury and arsenical compounds for controlling body lice4. Writings from ancient Greece and Rome show that religion, folk magic and the use of what may be termed chemical methods were tried for the control of plant diseases, weeds, insects and animal pests. As there was no chemical industry, any products used had to be either of plant or animal derivation or, if of mineral nature, easily obtainable or available. Thus, for example, smokes are recorded as being used against mildew and blights. The principle was to burn some material such as straw, chaff, hedge clippings, crabs, fish, dung, ox or other animal horn to windward so that the smoke, preferably malodorous, would spread throughout the orchard, crop or vineyard. It was generally held that such smoke would dispel the blight or mildew. Smokes were also used against insects, as were various plant extracts such as bitter lupin or wild cucumber. Tar was also used on tree trunks to trap crawling insects. Weeds were controlled mainly by hand weeding but various “chemical” methods are also described such as the use of salt or sea water5,6. Pyrethrum, which is derived from the dried flowers of Chrysanthemum cinerariaefolium “Pyrethrum daisies”, has been used as an insecticide for over 2000 years. Persians used the powder to protect stored grain and later, Crusaders brought information back to Europe that dried round daisies controlled head lice7. Many inorganic chemicals have been used since ancient times as pesticides8, indeed Bordeaux Mixture, based on copper sulphate and lime, is still used against various fungal diseases. Up until the 1940s inorganic substances, such as sodium chlorate and sulphuric acid, or organic chemicals derived from natural sources were still widely used in pest control. However, some pesticides were by-products of coal gas production or other industrial processes. Thus early organics such as nitrophenols, chlorophenols, creosote, naphthalene and petroleum oils were used for fungal and insect pests, whilst ammonium sulphate and sodium arsenate were used as herbicides. The drawback for many of these products was their high rates of application, lack of selectivity and phytotoxicity9. The growth in synthetic pesticides accelerated in the 1940s with the discovery of the effects of DDT, BHC, aldrin, dieldrin, endrin, chlordane, parathion, captan and 2,4-D. These products were effective and inexpensive with DDT being the most popular, because of its broad-spectrum activity4 ,10. DDT was widely used, appeared to have low toxicity to mammals, and reduced insect-born diseases, like malaria, yellow fever and typhus; consequently, in 1949, Dr. Paul Muller won the Nobel Prize in Medicine for discovering its insecticidal properties. However, in 1946 resistance to DDT by house flies was reported and, because of its widespread use, there were reports of harm to non-target plants and animals and problems with residues4,10.
Throughout most of the 1950s, consumers and most policy makers were not overly concerned about the potential health risks in using pesticides. Food was cheaper because of the new chemical formulations and with the new pesticides there were no documented cases of people dying or being seriously hurt by their "normal" use11. There were some cases of harm from misuse of the chemicals. But the new pesticides seemed rather safe, especially compared to the forms of arsenic that had killed people in the 1920s and 1930s12. However, problems could arise through the indiscriminate use and in 1962 these were highlighted by Rachel Carson in her book Silent Spring13. This brought home the problems that could be associated with indiscriminate use of pesticides and paved the way for safer and more environmentally friendly products.
Research into pesticides continued and the 1970s and 1980s saw the introduction of the world’s greatest selling herbicide, glyphosate, the low use rate sulfonylurea and imidazolinone (imi) herbicides, as well as dinitroanilines and the aryloxyphenoxypropionate (fop) and cyclohexanediones (dim) families. For insecticides there was the synthesis of a 3rd generation of pyrethroids, the introduction of avermectins, benzoylureas and Bt (Bacillus thuringiensis) as a spray treatment. This period also saw the introduction of the triazole, morpholine, imidazole, pyrimidine and dicarboxamide families of fungicides. As many of the agrochemicals introduced at this time had a single mode of action, thus making them more selective, problems with resistance occurred and management strategies were introduced to combat this negative effect.
In the 1990s research activities concentrated on finding new members of existing families which have greater selectivity and better environmental and toxicological profiles. In addition new families of agrochemicals have been introduced to the market such as the triazolopyrimidine, triketone and isoxazole herbicides, the strobilurin and azolone fungicides and chloronicotinyl, spinosyn, fiprole and diacylhydrazine insectides. Many of the new agrochemicals can be used at grams rather than the kilograms per hectare.
New insecticide14 and fungicide15 chemistry has allowed better resistance management and improved selectivity This period also saw the refinement of mature products in terms of use patterns with the introduction of newer and more user-friendly and environmentally safe formulations9. Integrated pest management systems, which use all available pest control techniques in order to discourage the development of pest populations and reduce the use of pesticides and other interventions to levels that are economically justified, have also contributed to reducing pesticide use16.
Today the pest management toolbox has expanded to include use of genetically engineered crops designed to produce their own insecticides or exhibit resistance to broad spectrum herbicide products or pests. These include herbicide tolerant crops like soybeans, corn, canola and cotton and varieties of corn and cotton resistant to corn borer and bollworm respectively9. In addition the use of Integrated Pest Management (IPM) systems which discourage the development of pest populations and reduce the use of agrochemicals have also become more widespread. These changes have altered the nature of pest control and have the potential to reduce and/or change the nature of agrochemicals used.
REFERENCES
1. Impetus for sowing and the beginning of agriculture: Ground collecting of wild cereals; M.E. Kislev, E. Weiss and A. Hartmann, Proceedings of the National Academy of Sciences, 101 (9) 2692-2694 (2004)
http://www.weizmann.ac.il/kimmel-arch/pdf/17_Kislev2004.pdf
2. Primal Seeds, Origin of Agriculture
http://www.primalseeds.org/agricult.htm
3. Economic Benefits of Pest Management; R. Peshin, Encyclopedia of Pest Management, pages 224-227, Pub. Marcel Dekker, 2002
4. The History of Pesticides, Organic Pesticides, September 19th 2008
http://blog.ecosmart.com/index.php/2008/09/19/the-history-of-pesticides/
5. History of Horticulture, Roman Agricultural History; J. Janek, Purdue University
http://www.hort.purdue.edu/newcrop/Hort_306/text/lec18.pdf
6. Forerunners of Pesticides in Classical Greece and Rome; A.E. Smith and D.M. Secoy,
J. Ag. Food Chem. 23 (6) 1050 (1975)
See http://www.hort.purdue.edu/newcrop/history/lecture18/r_18-1.html
7. Pyrethrum, The Natural Insecticide; Equatorial Health Services
http://www.equatorialhealth.com/pyrethrum.html
8. A Compendium of Inorganic Substances Used in European Pest Control before 1850; A.E. Smith and D.M.
.Secoy, J. Ag. Food Chem. 24 (6) 1180 (1976)
See http://www.hort.purdue.edu/newcrop/history/lecture31/r_31-1.html
9. A History of Crop Protection and Pest Control in our Society; CropLife Canada (2002)
http://www.croplife.ca/english/pdf/Analyzing2003/T1History.pdf
10. Pesticide Usage in the United States: History, Benefits, Risks, and Trends; Bulletin 1121, November 2000, K.S. Delaplane, Cooperative Extension Service, The University of Georgia College of Agricultural and Environmental Sciences
http://pubs.caes.uga.edu/caespubs/pubs/PDF/B1121.pdf
11. Wessels Living History Farm, York, Nebraska; Farming in the 1950s & 60s
http://www.livinghistoryfarm.org/farminginthe50s/pests_08.html
12. Wessels Living History Farm, York, Nebraska; Farming in the 1930s
http://www.livinghistoryfarm.org/farminginthe30s/pests_04.html
13. Silent Spring, 40th Anniversary Edition, Rachel Carson, Houghton Mifflin Harcourt, 2002
ISBN 0618249060, 9780618249060
14 . New Insecticide Modes of Action: Whence Selectivity? J. Coats, Iowa State University, Ames, Iowa, USA
15. A Short History of Fungicides, V. Morton and T. Staub, APSnet, March 2008
http://www.apsnet.org/online/feature/fungi/
16. OECD SERIES ON PESTICIDES, Number 8, Report of the OECD/FAO Workshop on Integrated Pest Management and Pesticide Risk Reduction, April 1999
Last modified 10th May 2010
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Date added: 2010-05-08 00:58:32
Last Updated 2010-05-10 04:43:01 |
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