Host-plant influeces on insect diversity: the effects of space and time

Oxford

1978

S. 105-125

13 Abb., zahlr. Lit. Ang.

Bandaufführung

162699

This paper is concerned with predicting the numbers of kinds of insects on individual species of plants in temperate regions. In it I wand to show the communities of phytophagous insects which are found on particular species of plants are not random assemblages, chewing away independently of one another; rather they have a structure which can be unravelle by a consideration of space and time. We will be concerned with space in three ways. First on a large scale, by examining the relationship between the number of species of insects associated with various species of plants, and the geographical ranges of these plants. Then on a local scale by looking at small clumps of plants (islands). Finally in a totally different way by considering the physical structure of the plants themselves, the "architecture" which forms the insects' living-space. Time enters the story in several ways. What I have to say the existence of relatively stable assemblages of species over periods of time measured in hundreds, if not relatively stable assemblages of species over periods of time measured in hundreds, if not thousends of years; I do not propose to discuss the voxing question of whether ecological communities in general, and communities of plant-feeding insects in particular "saturate" in evolutionary time (Gilbert, 1978; Southwood, 1973, 1977; Strong, 174a, b; Whittaker, 1969). The main consideration of the effects of time will be with very short periods; that is with seasonal effects. The paper is organised as follow. It starts by counting insects on plants that have different size geographical ranges, and then asks how many of these species will occur at any one locality within that total range. Next, seasonal changes in insect diversity are considered, together with associated changes in plant architecture and chemistry. I then use the idea that plant architecture plays a key role in determining insect diversity to make some preliminary suggestions about the ways in which insects exploit plants.