Dark reaction:

6C02 + 12 NADPH

C6H1206 + 12NADP"

Figure 1.4 A summary of the reactions of photosynthesis in green plants chlorophyll, starch, cellulose, lignin, tannins, anthocyanins, flavones and triterpenes belong only to plants.

On the other hand, all the biosynthetic methods, in their broad sense, used by insects, discussed in this book, are available to plants. That is, the formation of fatty acids and their derivatives, such as hydrocarbons; the acetogenins; and especially the terpenes and aromatic compounds are all used by plants. Acetogenins are not as prominent among plant products as the others, except in the formation of anthocyanins and flavones. Only special areas are left to insects alone. It is surprising, as more information accumulates, how insects and plants seem often to have found similar or the same way to biosynthesize certain compounds. Some authors call this parallel evolution.

Plants and insects have been evolving together for about 300 million years. In that time plants have produced both physical (hairs, spines and thick waxy surfaces) and chemical (stinging trichomes, alkaloids, toxins and feeding deterrents) defences against insects, while insects have been evolving ways to overcome them. An interesting example of plant counter-attack are the phytoecdysteroids made by plants, which mimic the natural moulting hormone of insects and are stored in the leaves to disrupt normal development of the insect feeding on them (Chapter 7). There are plant anti-juvenile hormone compounds too. Nevertheless, there is probably not a single plant species without at least one insect that has found a way to overcome its defences.

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