Optimal clutch size of the gall wasp Diplolepis rosae (Hymenoptera: Cynipidae)

Clutch size of the gall wasp Diplolepis rosae was studied in galls on Rosa spp. in Eastern Hungary and Romania, Transylvania on four dry pastures. We hypothesised that there was an optimal clutch size, and it was controlled by the emerging rate of the gall inducer and the escaping failure of hatched adults. The most frequent clutch size was 25–30 chambers, and there was a second peak around 60 chambers in each frequency distribution. The most common clutch size did not produce the highest proportion of larval emergence to adulthood. Parasitism rate decreased with increasing clutch size, while the proportion of emerged gall wasps increased and the proportion of dead individuals remained constant. The frequency distribution of clutch sizes was independent of parasitism, emerging failure or survival rate of the gall inducer. The escaping failure rate was also independent from the clutch size

Ökológiai szemléletű gyeptelepítés elmélete és gyakorlata - második kiadás

A könyv második, bővített kiadása a művelés alól kivett területek ökológiai szemléletű gyepgazdálkodással történő hasznosítása esetén nyújt átfogó segítséget. Részletezi többek között az ökológiai gyeptelepítés szempontjait, gyakorlatát, a várható gép- és költségszükségletet

Secondary succession of overgrazed Pannonian sandy grasslands

We assessed vegetation changes on acidic sandy soils in permanent plots to follow secondary succession after cessation of intensive goose breeding in E Hungary.We also aimed to estimate the time required for vegetation regeneration and indicate differences in secondary succession patterns at different altitudes in sand dunes. Two sites in the low and two in the high parts of the dunes were chosen and sampled for twelve years. The initial stages are characterized by ruderal communities dominated by nitrophilous annual weeds. Ruderal vegetation was soon replaced by nutrient-poor communities dominated by short-lived pioneer dicotyledonous plants and grasses. In the last few years of the study, coinciding with a rainy period, the low sites were dominated by the perennial grasses, Poa angustifolia, P. pratensis and Cynodon dactylon. In contrast, in the high sites a less dense cover of perennials developed. The influence of initial composition on vegetation development decreased with time and the influence of altitude increased during succession. The altitude of the site had a significant effect on regeneration. Species richness and Shannon diversity of the high sites increased during vegetation development and that of the lowsites decreased. Most annuals persisted in the high sites but became extinct in the low sites. The mean species turnover rate, irrespective of altitude, decreased during the study