The proportion of occupied patches will stabilize over time to 1− (x/m) x is the extinction rate of populations in patches per unit time m is the rate of movement between patches

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Secondary metabolites arere divided into Three major groups

Terpenes, 

Phenolics, and

Nitrogen-containing compounds

Terpenes

Basic structural elements of terpenes are sometimes called isoprene units

Ten-carbon terpenes, which contain two C5 units, are called monoterpenes; 15-carbon terpenes (three C5 units) are sesquiterpenes; and 20-carbon terpenes (four C5 units) are diterpenes. Larger terpenes include triterpenes (30 carbons), tetraterpenes (40 carbons), and polyterpenoids ([C5]n carbons, where n > 8).

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Monoterpenes ester are called pyrethroids

occur in leaves and flower of chrysanthemum species show very striking insecticidal activity

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Many plants contain mixtures of volatile monoterpenes and sesquiterpenes, called essential oils examples- Peppermint, lemon, basil, and sage 

Chief monoterpene constituent of peppermint oil is menthol; that of lemon oil is limonene

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Essential oils have well-known insect repellent properties.

Essential oils can be extracted from plants by steam distillation and are important commercially in flavoring foods and making perfumes

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The nonvolatile terpene antiherbivore compounds are the limonoids, a group of triterpenes (C30) well known as bitter substances in citrus fruit.

The most powerful deterrent to insect feeding known is azadirachtin

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Saponins are steroid and triterpene glycosides, it has soap like properties.  

The toxicity of saponins is thought to be a result of their ability to form complexes with sterols. Saponins may interfere with sterol uptake from the digestive system or disrupt cell membranes after being absorbed into the bloodstream.