Neuroterus quercusbaccarum
Encyclopedia
The common spangle gall on the underside of leaves and the currant gall on the male catkins or occasionally the leaves, develop as chemically induced distortions on pedunculate oak
(Quercus robur), or sessile oak
(Quercus petraea) trees, caused by the cynipid wasp Neuroterus quercusbaccarum which has both agamic and bisexual generations.
Previous names or synonyms for this species are Neuroterus
baccarum, N. lenticularis, N. malpighii, Cynips lenticularis, C. quercus-baccarum, Spathegaster baccarum, S. varius, S. interruptor.
The smooth surfaced currant gall generation appears in April and lay unfertilised eggs in the staminate catkins or occasionally the developing young leaves. The resulting spherical galls are around 4 mm in diameter, unilocular and unilarval, green at first, maturing through pink to red, therefore closely resembling redcurrants.
Several different spangle type galls are found on oak leaves so close inspection is required for proper identification.
The suckers at the base of older trees are often more heavily infested than the mature tree foliage. This may be due to the poor flying abilities of N. quercusbaccarum or it may relate to the physiological age of the leaves.
The spangle galls are sometimes mis-identified as scale insect
s.
The distribution and numbers of spangle galls on mature oak trees differs from that on young trees; the differences could be partly due to the earlier date of leaf opening on mature trees. No spatial zonation of spangle galls was apparent on the mature trees. Galls on catkins are less parasitised than those on leaves.
Pedunculate Oak
Quercus robur is commonly known as the Pedunculate Oak or English oak. It is native to most of Europe, and to Anatolia to the Caucasus, and also to parts of North Africa.-Taxonomy:Q...
(Quercus robur), or sessile oak
Sessile Oak
Quercus petraea , the Sessile Oak, also known as the Durmast Oak, is a species of oak native to most of Europe, and into Anatolia.-Description:...
(Quercus petraea) trees, caused by the cynipid wasp Neuroterus quercusbaccarum which has both agamic and bisexual generations.
Previous names or synonyms for this species are Neuroterus
Neuroterus
Neuroterus is a genus of gall wasps. Some species produce galls that fall off the host plant and jump along the ground due to the movement of the larvae within.Species include:*Neuroterus albipes*Neuroterus anthracinus*Neuroterus aprilinus...
baccarum, N. lenticularis, N. malpighii, Cynips lenticularis, C. quercus-baccarum, Spathegaster baccarum, S. varius, S. interruptor.
Galls
The spangle gall generation on the underside of the oak leaves are flat discs, with a distinct central elevation, slightly hairy, yellow-green at first and reddish later, attached by a short stalk. These galls are up to 6 mm in diameter, unilocular, unilarval with a whitish or yellow undersurface; they mature in September, detach and fall to the ground before the leaves themselves. The larva continue to develop in the fallen spangle and, protected by the leaf layer, they overwinter. Any Spangle galls that remain attached to the leaves dry up and die.The smooth surfaced currant gall generation appears in April and lay unfertilised eggs in the staminate catkins or occasionally the developing young leaves. The resulting spherical galls are around 4 mm in diameter, unilocular and unilarval, green at first, maturing through pink to red, therefore closely resembling redcurrants.
Several different spangle type galls are found on oak leaves so close inspection is required for proper identification.
The suckers at the base of older trees are often more heavily infested than the mature tree foliage. This may be due to the poor flying abilities of N. quercusbaccarum or it may relate to the physiological age of the leaves.
The spangle galls are sometimes mis-identified as scale insect
Scale insect
The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...
s.
Distribution on the leaves
Life cycle
The male and female of the bisexual generation emerge in June from the currant galls and after mating the fertilised eggs are laid in the lower epidermis of the oak leaves. The spangle galls develop over the winter and the insects emerge in April, laying their eggs in the catkins or lower epidermis. The cycle, an alternation of generation, then begins again.Predators, inquilines, and parasitoids
Spangles lying on the ground are often eaten by gamebirds and both of these galls are prone to being colonised by a variety of other organisms. Synergus spp. are inquilines which attack small galls, and the primary parasitoid Mesopolobus tibialis attacks medium size galls and Torymus auratus attacks large galls. The two parasitoids affect the final mature size of the spangle galls, highlighting the galling insects chemical influence upon the host plant.Infestations
From 80 to 100 spangle galls can develop on the underside of each leaf and therefore vast numbers fall onto the ground in September, sometimes completely colouring and covering the ground. Infestations do not have any serious effect upon galled trees.See also
- Knopper gallKnopper gallAndricus quercuscalicis is a gall wasp species inducing Knopper galls.Knopper galls develop as a chemically induced distortion of growing acorns on Pedunculate Oak trees, caused by gall wasps, which lay eggs in buds with their ovipositor...
- Oak artichoke gallOak artichoke gallOak artichoke galls, oak hop galls, larch-cone galls or hop strobiledevelop as a chemically induced distortion of leaf axillary or terminal buds on Pedunculate Oak or Sessile Oak trees, caused by the parthenogenetic gall wasp Andricus fecundator, which lays single eggs within leaf buds using...
- Rose bedeguar gallRose bedeguar gallThe Rose bedeguar gall, Robin's pincushion gall, or Moss galldevelops as a chemically induced distortion of an unopened leaf axillary or terminal buds mostly on Field Rose or Dog rose shrubs, caused by the parthenogenetic hymenopteran gall wasp , previous synonyms are D...
- Neuroterus albipesNeuroterus albipesNeuroterus albipes is a gall wasp that forms chemically induced leaf galls on oak trees which has both bisexual and agamic generations and therefore forms two distinct galls, the smooth spangle gall and Schenck's gall...
- Neuroterus anthracinusNeuroterus anthracinusNeuroterus anthracinus is a widely distributed gall wasp that forms chemically induced leaf galls on oak trees. N. anthracinus has both bisexual and agamic generations and in consequence forms two distinct galls, the oyster gall and April-bud gall. -Synonyms:Ameristus Förster 1869, Diplobius Kinsey...