Insect growth regulator
An insect growth regulator (IGR) is a substance (chemical) that inhibits the life cycle of an insect. IGRs are typically used as insecticides to control populations of harmful insect pests such as cockroaches and fleas.[1]
Advantages
Many IGRs are labeled "reduced risk" by the
Mechanism of action
This section is missing information about molting hormones.(October 2022) |
As an insect grows it
Hormonal IGRs
Hormonal IGRs typically work by mimicking or inhibiting the juvenile hormone (JH), one of the two major hormones involved in insect molting. IGRs can also inhibit the other hormone, ecdysone, large peaks of which trigger the insect to molt. If JH is present at the time of molting, the insect molts into a larger larval form; if absent, it molts into a pupa or adult.[4] IGRs that mimic JH can produce premature molting of young immature stages, disrupting larval development.[4] They can also act on eggs, causing sterility, disrupting behavior or disrupting diapause, the process that causes an insect to become dormant before winter.[3] IGRs that inhibit JH production can cause insects to prematurely molt into a nonfunctional adult.[3] IGRs that inhibit ecdysone can cause pupal mortality by interrupting the transformation of larval tissues into adult tissues during the pupal stage.[4]
Chitin synthesis inhibitors
Chitin synthesis inhibitors work by preventing the formation of chitin, a carbohydrate needed to form the insect's exoskeleton. With these inhibitors, an insect grows normally until it molts. The inhibitors prevent the new exoskeleton from forming properly, causing the insect to die. Death may be quick, or take up to several days depending on the insect. Chitin synthesis inhibitors can also kill eggs by disrupting normal embryonic development.[2][3] Chitin synthesis inhibitors affect insects for longer periods of time than hormonal IGRs. These are also quicker acting but can affect predaceous insects, arthropods and even fish.[2] Compounds include benzoylurea pesticides.
Examples
Chitin synthesis inhibitors
- Diflubenzuron (Vigilante), a benzoylurea
- Triflumuron (Starycide), another benzoylurea
Juvenoids
Juvenoids are juvenile hormone mimics, also known as juvenile hormone analogs:
- Fenoxycarb (Varikill, Insegar, Logic)
- Hydroprene (Gentrol)
- Methoprene (Precor)
- Pyriproxyfen (Nyguard, Nylar, Sumilarv)
Others
- Azadirachtin (AzaGuard) – 20E and JH antagonist, among other, non-growth-related actions[5]
References
- ^ a b "Insect Growth Regulators". Retrieved 20 November 2010.
- ^ a b c Harris, Su; Waindle, Marianne. "Insect Growth Regulators (IGRs)" (PDF). Retrieved 20 November 2010. [dead link]
- ^ a b c d e Krysan, James; Dunley, John. "Insect Growth Regulators". Archived from the original on 30 November 2021. Retrieved 20 November 2010.
- ^ a b c d e "IGRs -- A Growing, But Misunderstood Group". GPN: Greenhouse Product News. Archived from the original on 2011-07-11. Retrieved 20 November 2010.
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