Large Herbivore Attack

Proton Transfer Reaction Mass Spectrometry 5.7.7.6 Large Herbivore Attack... 

Another facet of chemical ecology concerns communication between members of the same species. Recent discoveries have shown that certain plants of the African savanna communicate among themselves the arrival of large herbivores the first plant that suffers their attacks quickly emits a volatile bouquet perceived by neighbors of the same species, which then quickly synthesize protective tannins. In the time it takes an elephant or a giraffe to graze on several leaves, individuals of the same species in the vicinity have already become repulsive [WAR 02]. 

To summarize, specific toxins are effective deterrents to generalist herbivores, but polyphenols produced In relatively large quantities are the only effective deterrent to specialists. Since leaf toughness and lower nitrogen content also deter many herbivores, deciduous forest trees are especially vulnerable to attack during the period of canopy development, which occurs yearly at a predictable time. Gsnopy development Is heavily dependent on available reserves of carbohydrate and nitrogen, and the production of quantitative... 

Abstract The chapter discusses the interactions of relatively low molecular weight and largely lipophilic secondary plant metabolites with insects and some other invertebrates. This includes compounds stored within plant tissues that are toxic to insects by a range of mechanisms. It covers metabolites that are both constitutively produced and those that are induced in response to defence signalling stimuli including insect attack. Also included are volatile compounds released from plants that act as signals (semiochemicals) detected by herbivorous insects and those that interact with insects at higher trophic levels. Finally, plant to plant communication is described. 

Some of these endophytes are able to reinforce the tolerance of the host plant not only to environmental stresses (dryness, large temperature variations, high salinity, etc.), but also to attacks from herbivores and phytopathogenic fungi. For example, the presence of endophytes in the leaves of Theobroma cacao (cocoa) significantly reduces necrosis and mortality of leaves when the plant is infested by the oomycete Phytophthora sp. 

The first study was by Penuelas et al. [203]. This revealed that Euphydryas aurinia caterpillars feeding on Succisa pratensis leaves induced emissions of large amounts of methanol and other VOCs (including monoterpenes, sesquiterpenes and lipoxygenase-derived volatile compounds (e.g. (Z)-3hexenal and (Z)-3-hexenyl acetate)). VOC release was monitored immediately after leaf attack (within the first hour) and after 1 day of continuous herbivorous feeding. Some of the VOCs observed at the start of the... 

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