Juvenile Hormone

juvenile hormone

[′jü·vən·əl ′hȯr‚mōn] (biochemistry) neotenin

Juvenile Hormone

an insect hormone that regulates the stage-by-stage development of insects. Chemically an isoprenoid, juvenile hormone is a colorless, optically active viscous oil that is insoluble in water.

It was discovered in 1956 by the American entomologist C. Williams in the abdomen of the male Hyalophora cecropia, a butterfly. Its isolation, structural determination, and chemical synthesis were first accomplished by a group of American scientists in the period 1967–69. The hormone occurs in insects with complete as well as incomplete metamorphosis. Its amount in the insect organism is very small, of the order of 10^–1 to 10^–2 μg/g.

Juvenile hormone is synthesized and secreted by the corpora allatum under the influence of the protein-activating hormone produced by the neurosecretory cells of the brain from the moment the larvae hatch from the ovum. During the larval period, it inhibits the activity of another hormone, ecdysone, which stimulates larval growth and hastens the molting of larva, thus contributing to the normal development of the larva to complete maturity. Inhibition is apparently effected through repression of the genes. With successive moltings, the secretion of juvenile hormone gradually decreases and is drastically reduced in the final larval stage, as a result of which the larva is transformed into a pupa under the influence of ecdysone. Thus, a balanced interaction of juvenile hormone and ecdysone ensures normal development in insects. Juvenile hormone also manifests gonadotrophic activity, influences diapause, and in some insects stimulates production of the sexual pheromones. Other isoprenoids, in particular juvabione, as well as many synthetic analogs, also possess the capability of juvenile hormone.

The use of juvenile hormone and its analogs as insecticides that disrupt the normal developing of insects has proved successful in controlling the larva of the cotton bollworm (Heliothis armígera) and other dangerous pests of agricultural and timber crops. The disadvantage of the insecticides is that their maximum effectiveness is only during the short period of the transformation of an immature individual into a mature one. Antagonists of juvenile hormone, called precocenes (from the English “precocious,” meaning early maturing), which cause premature metamorphosis of larvae, sterility, and anomalous diapause in insects, have been discovered in certain higher plants. Precocenes appear to be promising as “antihormonal” insecticides.

REFERENCES

Pridantseva, E. A., A. A. Drabkina, and Iu. S. Tsizin. “luvenil’nyi gormon nasekomykh.” Uspekhi sovremennoi biologii, 1971, vol. 71, issue 2.
Krimer, M. Z., and A. A. Shamshurin. Khimiia iuvenil’nogo gormona i ego analogov. Kishinev, 1972.
Röller, H., and K. H. Dahm. “The Chemistry and Biology of Juvenile Hormone.” In Recent Progress in Hormone Research, vol. 24. New York-London, 1968.
Naturally Occurring Insecticides. Edited by M. Jacobson and D.Crosby. New York, 1971.
Bowers, W. S., et al. “Discovery of Insect Anti-juvenile Hormones in Plants.” Science, 1976, vol. 193, no. 4253.

E. P. SEREBRIAKOV

单词	juvenile hormone
释义	juvenile hormone juvenile hormone n. Any of several hormones in insects that regulate various physiological processes, especially larval development and reproduction. juvenile hormone n (Biochemistry) a hormone, secreted by insects from a pair of glands behind the brain, that promotes the growth of larval characteristics and inhibits metamorphosis ju′venile hor′mone n. any of a class of insect hormones acting to inhibit the molting of an immature insect into its adult form. Juvenile Hormone juvenile hormone [′jü·vən·əl ′hȯr‚mōn] (biochemistry) neotenin Juvenile Hormone an insect hormone that regulates the stage-by-stage development of insects. Chemically an isoprenoid, juvenile hormone is a colorless, optically active viscous oil that is insoluble in water. It was discovered in 1956 by the American entomologist C. Williams in the abdomen of the male Hyalophora cecropia, a butterfly. Its isolation, structural determination, and chemical synthesis were first accomplished by a group of American scientists in the period 1967–69. The hormone occurs in insects with complete as well as incomplete metamorphosis. Its amount in the insect organism is very small, of the order of 10^–1 to 10^–2 μg/g. Juvenile hormone is synthesized and secreted by the corpora allatum under the influence of the protein-activating hormone produced by the neurosecretory cells of the brain from the moment the larvae hatch from the ovum. During the larval period, it inhibits the activity of another hormone, ecdysone, which stimulates larval growth and hastens the molting of larva, thus contributing to the normal development of the larva to complete maturity. Inhibition is apparently effected through repression of the genes. With successive moltings, the secretion of juvenile hormone gradually decreases and is drastically reduced in the final larval stage, as a result of which the larva is transformed into a pupa under the influence of ecdysone. Thus, a balanced interaction of juvenile hormone and ecdysone ensures normal development in insects. Juvenile hormone also manifests gonadotrophic activity, influences diapause, and in some insects stimulates production of the sexual pheromones. Other isoprenoids, in particular juvabione, as well as many synthetic analogs, also possess the capability of juvenile hormone. The use of juvenile hormone and its analogs as insecticides that disrupt the normal developing of insects has proved successful in controlling the larva of the cotton bollworm (Heliothis armígera) and other dangerous pests of agricultural and timber crops. The disadvantage of the insecticides is that their maximum effectiveness is only during the short period of the transformation of an immature individual into a mature one. Antagonists of juvenile hormone, called precocenes (from the English “precocious,” meaning early maturing), which cause premature metamorphosis of larvae, sterility, and anomalous diapause in insects, have been discovered in certain higher plants. Precocenes appear to be promising as “antihormonal” insecticides. REFERENCES Pridantseva, E. A., A. A. Drabkina, and Iu. S. Tsizin. “luvenil’nyi gormon nasekomykh.” Uspekhi sovremennoi biologii, 1971, vol. 71, issue 2. Krimer, M. Z., and A. A. Shamshurin. Khimiia iuvenil’nogo gormona i ego analogov. Kishinev, 1972. Röller, H., and K. H. Dahm. “The Chemistry and Biology of Juvenile Hormone.” In Recent Progress in Hormone Research, vol. 24. New York-London, 1968. Naturally Occurring Insecticides. Edited by M. Jacobson and D.Crosby. New York, 1971. Bowers, W. S., et al. “Discovery of Insect Anti-juvenile Hormones in Plants.” Science, 1976, vol. 193, no. 4253. E. P. SEREBRIAKOV juvenile hormone juvenile hormone n. Any of several hormones in insects that regulate various physiological processes, especially larval development and reproduction. juvenile hormone a hormone present in juvenile insects and secreted by the CORPUS ALLATUM of the brain. So long as it is produced, the cuticle maintains the characteristics of the nymphal or larval form at each moult. Only when it ceases to be present or the level falls below a threshold value does the insect moult to the adult form. Juvenile hormones have been used as an effective means of controlling insects, for example, in preventing the development of adult ants during hospital infestations. AcronymsSeeJHThesaurusSeejuvenile
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juvenile hormone