Chemical defense

This article is about the concept in biology. For military applications, see Chemical warfare.
Monarch butterfly caterpillar on milkweed plant. Milkweeds use three primary defenses to limit damage caused by caterpillars: hairs on the leaves, cardenolide toxins, and latex fluids, but Monarchs have evolved to remain unaffected by these defenses. Cardenolide toxins sequestered during the Monarch's larval stage from feeding on the plant remains in the adult, making it unpalatable to predators.

Chemical defense is a strategy employed by many organisms to avoid consumption by producing toxic or repellent metabolites or chemical warnings which incite defensive behavioral changes.[1][2] The production of defensive chemicals occurs in plants, fungi, and bacteria, as well as invertebrate and vertebrate animals.[3][4] The class of chemicals produced by organisms that are considered defensive may be considered in a strict sense to only apply to those aiding an organism in escaping herbivory or predation.[1] However, the distinction between types of chemical interaction is subjective and defensive chemicals may also be considered to protect against reduced fitness by pests, parasites, and competitors.[5][6][7] Repellent rather than toxic metabolites are allomones, a sub category signaling metabolites known as semiochemicals. Many chemicals used for defensive purposes are secondary metabolites derived from primary metabolites which serve a physiological purpose in the organism.[1] Secondary metabolites produced by plants are consumed and sequestered by a variety of arthropods and, in turn, toxins found in some amphibians, snakes, and even birds can be traced back to arthropod prey.[8][9] There are a variety of special cases for considering mammalian antipredatory adaptations as chemical defenses as well.[10]

  1. ^ a b c Berenbaum MR (January 1995). "The chemistry of defense: theory and practice". Proceedings of the National Academy of Sciences of the United States of America. 92 (1): 2–8. Bibcode:1995PNAS...92....2B. doi:10.1073/pnas.92.1.2. PMC 42807. PMID 7816816.
  2. ^ Cite error: The named reference Dicke-2001 was invoked but never defined (see the help page).
  3. ^ Clucas B (2010). "Defensive Chemicals". In Breed MD, Moore J (eds.). Encyclopedia of Animal Behavior. Oxford: Academic Press. pp. 481–486. doi:10.1016/B978-0-08-045337-8.00293-X. ISBN 9780080453378.
  4. ^ Keller NP, Turner G, Bennett JW (December 2005). "Fungal secondary metabolism - from biochemistry to genomics". Nature Reviews. Microbiology. 3 (12): 937–47. doi:10.1038/nrmicro1286. PMID 16322742. S2CID 23537608.
  5. ^ Walters D (2011). Plant defense: warding off attack by pathogens, herbivores and parasitic plants. John Wiley & Sons.
  6. ^ Whittaker RH, Feeny PP (February 1971). "Allelochemics: chemical interactions between species". Science. 171 (3973). New York, N.Y.: 757–70. Bibcode:1971Sci...171..757W. doi:10.1126/science.171.3973.757. JSTOR 1730763. PMID 5541160.
  7. ^ Gloer JB (1995). "The chemistry of fungal antagonism and defense". Canadian Journal of Botany. 73 (S1): 1265–1274. doi:10.1139/b95-387.
  8. ^ Lasley EN (1999). "Having Their Toxins and Eating Them Too: Study of the natural sources of many animals' chemical defenses is providing new insights into nature's medicine chest". BioScience. 49 (12): 945–950. doi:10.1525/bisi.1999.49.12.945.
  9. ^ Savitzky AH, Mori A, Hutchinson DA, Saporito RA, Burghardt GM, Lillywhite HB, Meinwald J (September 2012). "Sequestered defensive toxins in tetrapod vertebrates: principles, patterns, and prospects for future studies". Chemoecology. 22 (3): 141–158. Bibcode:2012Checo..22..141S. doi:10.1007/s00049-012-0112-z. PMC 3418492. PMID 22904605.
  10. ^ Hettyey A, Üveges B, Móricz ÁM, Drahos L, Capon RJ, Van Buskirk J, et al. (December 2019). "Predator-induced changes in the chemical defence of a vertebrate". The Journal of Animal Ecology. 88 (12): 1925–1935. Bibcode:2019JAnEc..88.1925H. doi:10.1111/1365-2656.13083. PMID 31408536.