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18 Cards in this Set
- Front
- Back
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How do alpha and beta ecdysones differ in terms of structure, activity, and step in the ecdysone pathway?
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alpha-ecdysone- has one less hydroxyl group in the side chain. less active metabolite- alpha is before beta in the ecdysone steps
beta-ecdysone- active form, has one more hydroxyl, most insect tissues and not ecdysial gland can carry out this reaction. Cholesterol is the precursor |
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What's the precursor for alpha ecdysone?
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cholesterol precursor for alpha and alpha is a precursor for beta
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What does the edysial gland produce?
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Alpha
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What about most insect tissues?
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Beta
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How do ecdysones interrupt insect growth and differentiation?
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High dose will cause insect to molt at any stage, inducing new cuticle before finishing old one so failure to secrete wax layer and larvae dessicates
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Why aren't ecdysones practical for use as an insect growth regulator?
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Does not penetrate the cuticle well and it usually takes injection
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What is an example of a synthetic ecdysone agonist and what does it target?
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FENOZIDES- bind to ecdysone receptor
TEBUFENOZIDE controls lepidopterous larvae |
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What is the natural purpose of juvenile hormone in insects?
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maturation hormone
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What are the sites of JH biodegradation by esterases and hydratases?
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p. 176
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How is the normal hormone in insects partially protected from degradation?
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by transport on a protein carrier
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What are the pros and cons of using JHs for insect control??
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Pros: tox, lower dose, synthetic analogs act like natural JH
Cons: growth stage intermediates, timing applications, resistance, larger larvae |
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What are some commercial juvenoids?
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Methoprene, hydroprene, kinoprene, fenoxycarb
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How do antiallatotropins or precocenes act?
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Interferes with production of JH (antagonist)
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How is radiation used to induce dominant lethals (type of ray and action)?
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Pros- avoids residues, if on isolated population very selective, impossible to be immune, high sterilization rate so very effective on small populations
X-rays, gamma rays, UV Rearrange DNA in genes, affect cell division, dominant lethal mutation progeny cannot survive, great penetrating power |
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What are some examples of eradication due to the release of dominant lethals?
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Screwworm, florida and southeastern states, Texas.Mexico with mosquitoes, fruit flies
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How do chemosterilants impede an insect's ability to reproduce?
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deprive the ability of the insect to reproduce
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Why must chemosterilants be used in a manner to avoid any exposure?
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High mammalian tox, carcinogen, mutagen, teratogen, sexual sterility in mammals
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What other way can you sterilize species?
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by crossing species or races of insects
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