Plant-herbivore-community relationships

Our approach is to focus on one group of compounds in one system. We believe this can help identify key gaps in both our knowledge of underlying mechanisms and our ability to construct relevant linkages. This will hopefully facilitate studies of other plant-herbivore-community relationships. Our efforts are at synthesis, not comprehensive review, as thousands of primary papers and many outstanding reviews have been written on this model. Any synthesis suffers from the need to resort to apples-to-oranges comparisons, so we have tried to provide examples from a few common systems. This necessarily emphasizes our own work. 

Food web—The feeding relationships within an ecological community, including the interactions of plants, herbivores, predators, and scavengers. 

Trophic levels — A functional classification of taxa within a community that is based on feeding relationships (e.g., aquatic and terrestrial green plants comprise the first trophic level and herbivores comprise the second). 

The great diversity of parasitoids and the complexity of parasitoid-host relationships is probably influenced by attempts of potential host insects to escape their predators, parasites and parasitoids. There is considerable speculation on the role that parasites (parasitoids) play in herbivore evolution. There are many examples where a host on different plants is attacked by different parasitoid species (see Vinson, 1981). As discussed by Zwolfer and Kraus (1957), and Vinson (1981), plants play an important role in the host selection process, probably by providing cues to the location of a potential host community. Theoretically, a host could escape a particular parasitoid by attacking a plant lacking those stimuli used by the parasitoid to locate the potential host community. This idea is supported by the observation that there is less tendency for parasitoids to select phylogenetically related hosts than to favor a range of hosts on a particular plant (Askew and Shaw, 1978 Cross and Chesnut, 1971). 

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