Phyto-ecdysones

Obviously, ecdysone or analogues that have similar or antagonistic modes of action could disturb the normal development of the insects and so can be used as insecticides. Inhibitors or inducers of the ecdysone biosynthesis may also be developed as insecticides. 

It is not too surprising that many plants produce ecdysteroids to defend themselves against potential insect pests. The so-called phyto-ecdysones have a potent molt-inducing effect, and some of them may be even more potent than p-ecdysone. Gymnosperms and ferns often contain much of phyto-ecdysones. Bracken (Pteridium aquilium) and the rhizomes of the well-known liquorice fern (Polypodium vulgare), for instance, have up to 1% of their dry weight of p-ecdysone, and the rhizomes of liquorice can be used as a commercial source of P-ecdysones. A Siberian medicinal plant (Leuzea carthamoides) was recently studied by Zeleny et al. (1997). The plant has as 

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Table 3. Comparison of phenoloxldase activity, protein, and ascorbic acid levels In the molt fluid and ascorbic acid levels In the hemoljanph approximately 36 hr following apolysls to the 5th Instar. B. moxn. larvae were Injected per os at 4th Instar 2nd day with 10 pi 30X aq/EtOH alone or with 10 jjl 30X aq/EtOH + phyto-ecdysone 25 larvae were used/treatment/parameter and analyzed.

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