The life cycle of the gall wasp, Andricus quercuscalicis (Burgsdorf) (Cynipidae :
Hymenoptera) involves the alternation between a sexual generation on the male
inflorescences (catkins) of the Turkey oak, Quercus cerris L. in the spring and an
agamic generation on the acorns of the English oak, Quercus robur L. in the autumn.
This study concerns with only the sexual generation of the wasp and its guild of
parasitoids. The generation was followed from the appearance of galls on catkins
until the adult gall wasp emergence in May-June and its parasitoids emergence in late
June.
The density of galls was positively correlated with the density of catkins on the
trees. The distribution of gall was clumped over the catkins. The sex ratio of the wasp
was highly male biased (68% male and 32% female), and the males were protandrous.
The sexes were patchily distributed over the trees. The sexual generation suffered
21.7% mortality through pupal parasitism by four oak-gall generalist parasitoids,
such as Mesopolobus xanthocerus (Thompson), M. tibialis (Westwood), M. fuscipes
(Walker) and M. dubius (Walker) (Pteromalidae : Hymenoptera) and 27.8% through
non-emergence, the cause of which was unknown. The parasitoids emerged from the
sexual galls of A. quercuscalicis were extremely male biased being virtually all males.