Ecologists frequently collect data on the patterns of association between adjacent trophic levels in the form of binary or quantitative food webs. Here, we develop statistical methods to estimate the roles of consumer and resource phylogenies in explaining patterns of consumer-resource association. We use these methods to ask whether closely related consumer species are more likely to attack the same resource species and whether closely related resource species are more likely to be attacked by the same consumer species. We then show how to use estimates of phylogenetic signals to predict novel consumer-resource associations solely from the phylogenetic position of species for which no other (or only partial) data are available. Finally, we show how to combine phylogenetic information with information about species' ecological characteristics and life-history traits to estimate the effects of species traits on consumer-resource associations while accounting for phylogenies. We illustrate these techniques using a food web comprising species of parasitoids, leaf-mining moths, and their host plants.

Phytophagous insects and their natural enemies make up one of the largest and most diverse groups of organisms on earth. Ecological processes, in particular negative indirect effects mediated by shared natural enemies (apparent competition), may be important in structuring phytophagous insect communities. The potential for indirect interactions can be assessed by analyzing the trophic structure of insect communities, and we claim that quantitative food webs are particularly well suited for this task. We review the experimental evidence for both short-term and long-term apparent competition in phytophagous insect communities and discuss the possible interactions between apparent competition and intraguild predation or shared mutualists. There is increasing evidence for the importance of trait-mediated as well as density-mediated indirect effects. We conclude that there is a need for large-scale experiments manipulating communities in their entirety and a greater integration of community and chemical ecology.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Animal Ecology. Summary 1. The reproductive behaviour of a small, gregarious, ectoparasitoid wasp (Goniozus nephantidis (Muesebeck)) in the family Bethylidae was studied in the laboratorv. The wasp lays a clutch of up to 20 eggs, with a very female-biased sex ratio, on the caterpillars of microlepidopterans. 2. Clutch size was strongly influenced by host size. 3. Clutches of different size were artificially created on hosts of approximately the same weight. The manipulations had little effect on juvenile survival, but adult female size decreased strongly with clutch size. Male size was also affected, although to a lesser extent. 4. In the laboratory, larger females lived longer and laid more eggs when provided with hosts. When deprived of hosts, smaller females lived slightly longer. 5. The possibility of using laboratory experiments to test clutch size models is discussed.

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