The structure of a leafminer-parasitoid community

1. Quantitative food webs were constructed describing the community of leafmining moths in the genus Phyllonorycter (Gracillariidae) and their parasitoids at a site in southern England. 2. Twelve species of Phyllonorycter were reared from four species of tree. The moths were attacked by 27 species of hymenopterous parasitoids. 3. Four webs were constructed for successive moth generations over 2 years. A summary web was built and a comparison made between webs expressed in terms of number of mines and number of females recruiting to the next generation. 4. All hosts and most parasitoids were recorded in the first year, but new host-parasitoid associations were discovered throughout the sampling period. The diversity of mines and parasitoids was similar across generations. 5. The structure of the parasitoid community was strongly influenced by the host plant. 6. The extent of potential indirect interactions between hosts was assessed by constructing quantitative parasitoid overlap diagrams. The measure of influence used was the importance of one species as a source of parasitoids attacking the other. The greatest potential for apparent competition was between species of host attacking the same species of plant.