Plant Architecture and the Diversity of Phytophagous Insects

Abstract

In general, trees have richer insect faunas than herbs. This familiar observa­ tion is but one of several ways in which and insect species diversity are correlated. In this review I explore the nature of these correlations and ask how they are produced. To keep within reasonable bounds I have restricted attention to herbivorous insects that consume living, green plant material (93, 102). Pollinators, scavengers, predators and travellers on plants (60) are willfully ignored. For the same reason, single species of plants and their associated insects receive most attention. Ex­ trapolations to entire plant communities are made cautiously in the final section. Architecture in everyday English means the structure and design of things; I have used it as shorthand for a variety of plant attributes, particu­ larly size and growth form and the seasonal development, persistence, and variety of above-ground parts (48, 52). It will be convenient, first, to estab­ lish the broad effects of plant architecture on herbivore diversity before moving to more detailed studies in the second half of the review. Studies of many kinds of ecological systems reveal effects of habitat complexity (architecture) on species diversity (54). Hence, their discovery among plant-feeding insects is neither novel nor surprising.