Towards the bionomy of gall wasps Andricus quercuscalicis and A. hungaricus (Hymenoptera, Cynipidae)

2001

S. 193-211

25 Abb., 10 Tab., zahlr. Lit. Ang.

Unselbständiges Werk

200087153

The paper deals with the biology of gall wasps Andricus quercuscalicis (Burgsd.) and A. hungaricus (Htg.) which got overpopulated in oak stands and seed orchards of southern Moravia in 1995. The main investigation was made in a 10-year old orchard of Quercus robur f. slavonica in the Valtice Forest District (Forest Enterprise Zidlochovice). Galls of both cynipids were collected from the orchard on 23 October 1995 and placed into outdoor photoeclectors. The evaluation of 5-year rearings and gall analyses by sectioning provided information about development and size of galls. Some adults of A. quercuscalicis were leaving the galls after the 1st wintering (in April), other after the 2nd, 3rd or 4th wintering (in March). The first wintering included grown-up larvae, the second wintering included 33% of adults and 67% of larvae, the third wintering included 80% of adults and 20% of larvae, and the fourth wintering included only adults. Average fecundity was 1,126 (max. 1,555) eggs and was increasing with the increasing diapause duration from 925 eggs (in females after the 1st wintering) up to 1,297 eggs (in females after the fourth wintering). Outer galls were on average 20.8 mm wide 16.2 mm high. Inner galls were on average 4.9 mm long, 3.9 mm wide and 3.2 mm high. 19.3% of larvae and pupae died without any obvious reason, 4.3% of larvae were killed by the chalcid Ormyrus nitidulus (F.), 9.2% of adults died in the inner galls and 6.3% in enclosed outher galls. Some 80% of adults left the galls via natural emergence holes in the outher galls and 20% of them bit out through the thinned walls of gall bases. The adults of A. hungaricus were leaving the galls after the 2nd and the 3rd wintering (exeptionally after the 1st and the 4th wintering), usually in the 2nd half of February and at the beginning of March. Average fecundity was 1,447 (max. 1,870) eggs and was increasing with the increasing diapause duration. The size of outer galls ranged between 20 and 43 (av. 32) mm. Inner galls were on average 5.4 mm long, 4.6 mm wide and 4.2 mm high. 16.2% of larvae and pupae died without any obvious reason, 8,5% of larvae were killed by the chalcid Aulogymnus trilineatus (Mayr), 9,8% imagoes died inside the inner galls and 2.1% died in the outher galls.