Pesticide resistance

Pesticide application can artificially select for resistant pests. In this diagram, the first generation happens to have an insect with a heightened resistance to a pesticide (red) After pesticide application, its descendants represent a larger proportion of the population, because sensitive pests (white) have been selectively killed. After repeated applications, resistant pests may comprise the majority of the population.

Pesticide resistance describes the decreased susceptibility of a pest population to a pesticide that was previously effective at controlling the pest. Pest species evolve pesticide resistance via natural selection: the most resistant specimens survive and pass on their acquired heritable changes traits to their offspring.[1] If a pest has resistance then that will reduce the pesticide's efficacy – efficacy and resistance are inversely related.[2]

Cases of resistance have been reported in all classes of pests (i.e. crop diseases, weeds, rodents, etc.), with 'crises' in insect control occurring early-on after the introduction of pesticide use in the 20th century. The Insecticide Resistance Action Committee (IRAC) definition of insecticide resistance is 'a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species'.[3]

Pesticide resistance is increasing. Farmers in the US lost 7% of their crops to pests in the 1940s; over the 1980s and 1990s, the loss was 13%, even though more pesticides were being used.[1] Over 500 species of pests have evolved a resistance to a pesticide.[4] Other sources estimate the number to be around 1,000 species since 1945.[5]

Although the evolution of pesticide resistance is usually discussed as a result of pesticide use, it is important to keep in mind that pest populations can also adapt to non-chemical methods of control. For example, the northern corn rootworm (Diabrotica barberi) became adapted to a corn-soybean crop rotation by spending the year when the field is planted with soybeans in a diapause.[6]

As of 2014, few new weed killers are near commercialization, and none with a novel, resistance-free mode of action.[7] Similarly, as of January 2019 discovery of new insecticides is more expensive and difficult than ever.[8]

  1. ^ a b PBS (2001), Pesticide resistance. Retrieved on September 15, 2007.
  2. ^ Guedes, R.N.C.; Smagghe, G.; Stark, J.D.; Desneux, N. (2016-03-11). "Pesticide-Induced Stress in Arthropod Pests for Optimized Integrated Pest Management Programs". Annual Review of Entomology. 61 (1). Annual Reviews: 43–62. doi:10.1146/annurev-ento-010715-023646. ISSN 0066-4170. PMID 26473315. S2CID 207747295.
  3. ^ "Resistance Definition". Insecticide Resistance Action Committee. 2007.
  4. ^ Grapes at Missouri State University (MSU) How pesticide resistance develops Archived 2007-08-17 at the Wayback Machine. Excerpt from: Larry Gut, Annemiek Schilder, Rufus Isaacs and Patricia McManus. Fruit Crop Ecology and Management, Chapter 2: "Managing the Community of Pests and Beneficials." Retrieved on September 15, 2007.
  5. ^ Miller GT (2004), Sustaining the Earth, 6th edition. Thompson Learning, Inc. Pacific Grove, California. Chapter 9, Pages 211-216.
  6. ^ Levine, E; Oloumi-Sadeghi, H; Fisher, JR (1992). "Discovery of multiyear diapause in Illinois and South Dakota Northern corn rootworm (Coleoptera: Cerambycidae) eggs and incidence of the prolonged diapause trait in Illinois". Journal of Economic Entomology. 85: 262–267. doi:10.1093/jee/85.1.262.
  7. ^ Service, Robert F. (20 September 2013). "What Happens When Weed Killers Stop Killing?". Science. 341 (6152): 1329. doi:10.1126/science.341.6152.1329. PMID 24052282.
  8. ^ Guedes, R. N. C.; Roditakis, E.; Campos, M. R.; Haddi, K.; Bielza, P.; Siqueira, H. A. A.; Tsagkarakou, A.; Vontas, J.; Nauen, R. (2019-01-31). "Insecticide resistance in the tomato pinworm Tuta absoluta: patterns, spread, mechanisms, management and outlook". Journal of Pest Science. 92 (4). Springer: 1329–1342. doi:10.1007/s10340-019-01086-9. ISSN 1612-4758. S2CID 59524736.