ABUNDANCE PATTERNS AND SPECIES RICHNESS OF THE PARASITOIDS AND INQUILINES OF THE ALIEN GALL-FORMER ANDRICUS-QUERCUSCALICIS (HYMENOPTERA, CYNIPIDAE)

1) Four parasitoid species attack the gall-maker in the agamic galls o f the invading cynipid Andricus quercuscalicis and further two parasit oid species attack inquiline larvae developing in the parenchymatic wa ll of the gall. The abundance of the parasitoids and inquilines are co rrelated with: 1) gall morphology) 2) the geographical location within Europe where the samples were collected; and 3) the abundance of othe r members of the species complex. 2) The invading gall wasp has been p resent for different periods of time at different sites, and this is l ikely to affect the geographic distribution of attack by parasitoid an d inquiline species. One of the parasitoid species was restricted to t he native range in south-eastern Europe (Aulogymnus trilineatus), whil e another species (Cecidostiba hilaris), a parasitoid of the inquiline s, was present throughout continental Europe but is not yet recorded f rom the British Isles. Species richness of the parasitoid complex asso ciated with the galls of A. quercuscalicis declined with increasing di stance away from the native range. Within the native range, however, s pecies richness was negatively correlated with the total number of cyn ipid species (alternative hosts for the parasitoid species) recorded a t the same sample site. 3) The size of mature knopper galls declined w estwards and northwards away from the native range of the gall wasp. I nquiline abundance was higher in larger galls, and so was the occurren ce of one of the parasitoid species, Megastigmus stigmatizans. The occ urrence of two other parasitoid species was negatively correlated with gall size while one species, Mesopolobus jucundus, was not affected b y gall size. 4) Neither the abundance of inquilines nor of parasitoids attacking the inquilines show any significant geographical trend asso ciated with the invasion history of the gall-maker. Attack rates by C. hilaris, the dominant parasitoid species in continental Europe, showe d a slight positive density dependence to the number of inquilines per gall, while those by M. jucundus, the dominant parasitoid of inquilin e in Britain, showed no such trend.