110
The Essex species of gall-inducing Cynipids (Hymenoptera; Cynipidae :
Aulacideini and Rhoditini) on host plants other than Quercus
JERRY BOWDREY
Colchester Museums, 14 Ryegate Road, Colchester CO1 1YG
Abstract
The distribution and status in Essex of the distribution maps are provided for some
Cynipid wasps that induce galls in host plants species. There are notes to help distinguish
other than Quercus is reviewed. Tetrad genera and species.
Introduction
The gall wasps belong to the Cynipinae, a subfamily of the hymenopteran family Cynipidae.
There are estimated to be around 1800 species worldwide, over 250 in Europe (Nieves-Aldrey,
1994) with just under 100 occurring in Britain (Gould & Bolton, 1988).
The majority of the Cynipinae have the ability to induce gall formation in plants. A gall is
defined as an abnormal growth produced by a plant under the influence of another organism and
involves enlargement and proliferation of plant cells which provide shelter and food for the gall
maker (modified from Redfern and Askew, 1992). Cynipid galls show a complex structure with
a nutritive layer upon which the larval gall wasps feed. In many cases the form of the gall is
sufficiently constant to enable it to be used in species determination, there are, however,
exceptions and confirmatory rearing of the adult is to be recommended.
Six tribes are currently recognised within the Cynipinae (Nieves-Aldrey, 1994). All except one,
the Eschatocerini occurring in north-west Europe. Another, the Pediaspidini is not represented in
Britain. Of the remainder, the Cynipini represent 75% of the European fauna and are gall
inducers on oak (Quercus spp.). For accounts of the Essex Cynipini see Bowdrey (1985, 1987);
Fitch (1882). Lewis (1902), Niblett(1957 ).
The Rhoditini comprises two genera of which only one, Diplolepis, occurs in Britain attacking
the plant genus Rosa and with 6 native species. The Synergini are inquilines in galls on
Quercus and Rosa, usually not forming galls themselves. The remainder comprise the
Aulacideini (Aylacini), considered to be the most structurally primitive Cynipids and attacking
the widest range of host plants from several different families.
The Rhoditini and Aulacideini of the County have hitherto received little attention in the
literature. The present paper attempts to redress the balance by listing, with annotations and
maps were appropriate, the species currently known from the County
Historical
The first published county records traced are those of Fitch (1882) who listed nine species (3
Rhoditini ; 6 Aulacideini). The next significant account was that of Niblett (1957) wliich
covered only the west of Essex and listed only six species (4 Rhodium; 2 Aulacideini) for this
area. In addition, there are a number of papers refering to single species, these are mentioned
under the relevant species account.
Essex Naturalist (New Series) 16 (1999)