Phenol insects

Lee, K., 1991. Glutathione S-transferase activities in phytophagous insects induction and inhibition by plant phototoxins and phenols. Insect Biochem. 21, 353-361. 

This example belongs to chemotaxonomy, a discipline that tries to classify and identify organisms (usually plants, but also bacteria, and even insects) by the chemical or biochemical composition (e.g., fingerprint of concentrations of terpenes, phenolic compounds, fatty acids, peptides, or pyrolysis products) (Harbome and Turner 1984 Reynolds 2007 Waterman 2007). Data evaluation in this field is often performed by multivariate techniques. 

More complex, second order interactions may be imagined, involving more than one natural enemy. For example, consider insects to which tannins are important deterrents and digestion inhibitors. As mentioned above, elevated gut pH appears to be a way of dealing with tannins, since tannin-protein complexes are dissociated or inhibited at alkaline pH (16,32). Indeed, using a model in vitro system in which hemoglobin is employed as a protein substrate, we found that several natural tannins and phenolic extracts do not precipitate this protein when the pH exceeds about... 

Lignin is a phenolic polymer. It is the second most abundant bio-polymer on Earth (after cellulose), and plays an important role in providing structural support to plants. Its hydrophobicity also facilitates water transport through the vascular tissue. Finally, the chemical complexity and apparent lack of regularity in its structure make lignin extremely suitable as a physical barrier against insects and fungi. 

Simple phenolics and flavonoids are often key determinants of the outcome of interactions with other organisms, including serving as allelopathic agents in interspecies plant-plant competition [Bais et al., 2004], acting as insect and herbivore deterrants [Feeny, 1970 Forkner et al., 2004 McAllister et al.,... 

---