Plant-insect interactions properties

Several lists of plant secondary compounds which are involved in plant-insect interactions have been compiled (1, ,1 3.17,, -46). In addition, lists of plants with insecticidal properties have been published (47,48). Many of these compounds are physically located on the outside of the plant, either in the epidermal... 

Most plants have trichomes on their aerial surfaces. The trichomes may be simple hairs or more specialized glandular trichomes, whose main function may be the production and accumulation of chemicals such as essential oils. The vast majority of these consists of monoterpenoids, sesquiterpenoids and diterpenoids with a high vapour pressure. They may be absorbed on the cuticular wax layer. The trichome secretions are closely related to plant-insect or plant-microbe interactions. Terpenoids can attract, rep>el or initiate defence reactions in insects. Apart from their ecological roles, plant terpenoids are widely used in the pharmaceutical and fragrance industries. The properties of essential oils are correlated with their qualitative and quantitative compositions. 

If herbivore attack can lead to reduced food quality of plants, then it seems reasonable that naturally attacked plants should exhibit decreased food quality compared to naturally unattacked ones. On the other hand, there is considerable evidence that herbivores preferentially attack plants or tissues of high food quality Q). In other words, plant food quality can probably act both as a dependent and an independent variable as far as degree of herblvory is concerned. Therefore, conclusions drawn from comparisons of foliage properties of naturally attacked versus naturally unattacked plants are likely to be confounded by the interaction of these two effects. To avoid this problem the following experiments were conducted by subjecting plants to attack by Insects placed on them by the Investigators. 

Numerous plant alkaloids with antiherbivore properties are classified according to their mode of action (e.g., toxins, antifeedants, antidigestive proteins, etc.) and have been used in agriculture to control insect pests. The pyridine alkaloid nicotine is one of the best-studied putative plant resistance traits. Because it can interact with the acetylcholine receptors in the nervous systems of animals, nicotine is extremely toxic to most herbivores and, consequently, was one of the first insecticides used to control pests in agriculture. Evidence for the resistance value of nicotine arises from... 

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