The Role of Terpenoids in Nature

Terpenoids are produced by a wide variety of plants, animals and microorganisms. As for all metabolites, the synthesis of terpenoids places a metabolic load on the organism which produces them and so, almost invariably, there is a role which the material plays and for which it is synthesised. The roles which the terpenoids play in living organisms can be grouped into three classes functional, defence and communication. 

There are a number of ways in which plants and animals use terpenoid chemicals to protect themselves. Probably the two commonest methods are the production of resins by plants which have been damaged and the production of materials which will render a plant or animal unattractive to predators. 

Many plants, when damaged, exude resinous materials as a defence mechanism. Rosin is produced as a physical barrier to infectious organisms, by pine trees when the bark is damaged. Similarly, rubber is 

Chemicals that carry signals from one organism to another are known as semiochemicals. These can be grouped into two main classes. If the signal is between two members of the same species, the messenger is called a pheromone. Pheromones carry different types of information. Not all species use pheromones. In those which do, some may use only one or two pheromones while others, in particular the social insects such as bees, ants and termites, use an array of chemical signals to organise most aspects of their lives. 

Chemicals which carry messages between members of different species are known as allelochemicals. Within this group, allomones benefit the 

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