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.