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

ROVARTANI KÖZLEMÉNYEK LVII 1996 pp. 157-169 Compositions and structures of the Braconid communities in two oak forests of Hungary (Hymenoptera: Braconidae) J. Papp and T. Kisbenedek Compositions and structures of the Braconid communities in two oak forests of Hungary (Hymenoptera: Braconidae) — The braconid species composition of the canopy and the shrub layers as well as the phenology of the braconid species have been investigated in two oak forests at Csobánka and Gödöllő near Budapest. The braconids were collected with tangle traps for two weeks each in June and August 1992-1994. In the two areas a total of 1793 specimens representing 50 braconid species were collected, of which 38 species (896 specimens) share Csobánka and 31 species (897 specimens) share Gödöllő (Table 1). Vegetation layer preference showed the following braconid species: 1) preference to the canopy seven species (Diospilus capito, Earinus elator, Glyptapanteles fulvipes, Macrocentrus pallipes, Meteorits gyrator, Microchelonus contractus, Zele albiditarsus); 2) preference to the shrub layer four species (Ascogaster varipes, Cotesia tibialis, Macrocentrus collaris, Microplitis mandibulator). A considerable difference was observed between the old (or mature) and young oak wood stands, at Csobánka in the mixed oak forest 27, in the pure oak forest 29 versus in the young oak forest 13 braconid species were captured; at Gödöllő in the same forest the species numbers figure 22, 24 versus 13. From among the 49 braconid species 19 were taken in both forests, i.e. 38.8% expressed in the Jaccard-index, albeit and supposedly the difference between the two forests is not so expressive. The species identity between the mixed and pure oak forests at the same area is higher than between the mixed as well as between the pure oak forests in the two areas (Table 3). Concerning the phenology of the braconid species they may be separated in two groups: 1) ten species were trapped sufficiently regularly in 1992-1994, they are permanent members of the oak forest having at least two generations annually; 2) the rest, 39, of the species are temporary (or seasonal) members of the braconid assemblages in the oak forest being present for a definite time-period only. With 4 figures and 3 tables. INTRODUCTION The faunistic exploration of the braconid wasps of the oak forests of Hungary is at a fairly high level. The number of the braconid species in our country amounts to about one thousand and two hundreds and out of it at least three hundred braconid species occur also in the oak forest vegetation. In the oak forests we can differentiate the canopy (or tree crown), shrub, herbaceous and soil vegetation layers. The entomophagous braconid wasps as well-flying insects are active mainly in the canopy and shrub + herb layers. This ecological peculiarity, coincident with the parasitoid bionomy of the braconids, motivated the present research project to answer the following questions: 1. Which braconid species prefer the canopy (or crown) as well as the shrub layers? 2. Do the braconid species exhibit heterogeneity (i.e. species richness, species composition) in the oak wood stands of different ages, i.e. between the elderly or mature (70-100 years old) and the young (12-15 years old) oak forest stands? The elaboration of this material was supported by the Hungarian National Scientific Research Fund (OTKA) No. T-3180.