The Diversity of Insect Communities in Leafmines and Plant Galls

Abstract

(1) Indices of species diversity are applied to parasite communities associated with cynipid gall-wasps and Phyllonorycter leaf-miners, their performances are examined, and it is concluded that they provide a useful measure of community composition. (2) Communities include more polyphagous than specific parasite species and they are more diverse on trees than on shrubs or herbaceous plants. In the latter situation communities are usually dominated by specific parasites whilst polyphagous parasites achieve their highest representation in tree communities. (3) Community diversity is highest in situations where most species of primary hosts occur. This is on trees in the cases of both gall-wasps and Phyllonorycter. (4) The varied structure of oak galls provides a basis for a partitioning of resources between polyphagous parasites and may explain the co-existence of many cynipid species on oak trees. Polyphagous parasites in Phyllonorycter mines do not, in general, discriminate between primary hosts on the same plant species and numbers of co-existing species of Phyllonorycter are restricted.