THE RECRUITMENT OF PARASITOID SPECIES TO 2 INVADING HERBIVORES

1. Two small species of leaf-mining moth, Phyllonorycter leucographella and P. platani, colonized the British Isles during the 1980s. The parasitoid assemblage on the invading species is described and compared with assemblages on native Phyllonorycter species. 2. Sixteen species of parasitoid were recorded from each invading host. Against initial predictions, the size of the assemblages were indistinguishable from those on native species. 3. The equitability of the distribution of individuals among parasitoid species was relatively low for assemblages on the two introduced hosts in comparison with native hosts. 4. It was predicted that the parasitoids attacking novel hosts should have a wider host range than those attacking native hosts. This was not found to be the case. 5. Cluster analysis revealed the assemblages on introduced species to be relatively dissimilar to those on native hosts. There was no particular similarity with native hosts on related host plants. 6. The most important parasitoid on P. platani was a specialist that invaded the British Isles at the same time as its host. The most important species on P. leucographella attacked hosts that had ecological features in common with the invader.