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How does juvenile hormone affect an insect’s development?
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insect
An illustration of insect diversity.
Juvenile hormone, secreted by the corpora allata glands near the brain, is essential for regulating an insect's development and metamorphosis.123
Its primary functions include:
- Maintaining Juvenile Characters: During larval or nymphal stages, the presence of juvenile hormone in the hemolymph ensures that molting epidermal cells produce a larval cuticle rather than adult features. It is believed to function by suppressing the genes responsible for adult characteristics.432
- Triggering Metamorphosis: As an insect reaches its final larval stage, the production of juvenile hormone declines or ceases. This reduction allows the insect to undergo metamorphosis and emerge as an adult. In holometabolous insects, the pupa stage develops when only a very small amount of the hormone is present.43
- Adult Function: Beyond development, the hormone often remains active in adults, where it is frequently necessary for normal egg production in females.12
Because this hormone is critical for life-cycle transitions, synthetic compounds that mimic its effects are sometimes used as insecticides, as abnormal levels during development can be fatal to the insect.2