S. Mahunka szerk.: Folia Entomologica Hungarica 57. (Budapest, 1996)

Gödöllő in the pure and in the mixed oak forests rather in August of all three years (1992-1994). A long series of its moth (mainly lymantriid, notodontid, noctuid and geometrid) caterpillar hosts living in the oak forests coincides well with its occurrence in the canopy as well as in the shrub layers. Leiophron apicalis: In the canopy a total of 25 specimens in seven samplings were trapped rather in June fairly equally in the pure and in the mixed oak forests in a conspicuously lower number at Csobánka (2 specimens on 1992) than at Gödöllő (23 specimens in 1992-1994). In the shrub layer rather in August a total of 11 specimens in four samplings were trapped in the pure and in the mixed oak forests only at Csobánka. Although the species was trapped in a higher quantity and more samplings in the canopy than in the shrub layer it seems equally to occur in the canopy and shrub layers which ecological claim is supported by a high number of its mirid bug hosts living in oak forests. The species richness or heterogeneity (H) was fairly equal in the canopies and shrub layers of the mixed and pure oak forests at Csobánka and Gödöllő except the canopy of Gödöllő pure oak forest where in 1992 and 1994 the numbers of the species (and the number of the specimens of the dominant species) were fairly significantly higher in the canopy than in the shrub layer (Fig. 2/A-FJ). Table 3. Species identity of the braconid assemblages between the old oak forests at Csobánka and Gödöllő 1992-1994 Locality Csobánka Csobánka Gödöllő Forest type pure oak forest mixed oak forest pure oak forest Csobánka, mixed oak forest 44.4% — Gödöllő, pure oak forest 37.1% 23.7% Gödöllő, mixed oak forest 46.9% 35.3% 53.6% 2. Comparing the compositions of the braconid species assemblages in the old (i.e. 70-100 years old) pure and mixed oak forest stands to the young (i.e. 12-15 years old) ones conspicuous differences are recognisable (see Table 3). At Csobánka in pure oak forest 29, in mixed oak forest 27 species were captured against the 13 species taken in the young forest. At this point it is worthy to note that Apanteles ater and Blacus ruficornis were trapped (2 and 7 specimens, respectively) only in the young oak forest. At Gödöllő in the same oak forests the species numbers figure 24, 22 versus 13. Also interesting is that Phanerotoma acuminata, a fairly frequent species in Hungary, was trapped in 28 specimens only in the young oak forest. In a detailed form the numbers of the species in the two layers of the old forest, shrub and canopy ones, as well as in the young oak forest stands at Csobánka and Gödöllő are demonstrated in Fig. 2. The species composition or heterogeneity (H) is significantly higher in the shrub + canopy layers than in the young stands at Gödöllő. The ecological establishment is somewhat in controversy to that of the Ichneumoninae in the pine forest of Poland (Sawoniewicz 1995) where the ichneumonine wasp species numbers were the greatest in the young stands and the H decreased parallel with the eldering of the pine forest stands. The similarity of the braconid species assemblages between the canopy as well as the shrub layer of the old forests versus the single layer of the young oak forests is fairly low. The Jaccard-index (Southwood 1978) in relation of the old mixed oak forest stand versus young one at Csobánka is 27.2%, that of the pure oak wood stand versus young one also at Csobánka is 30%,