Everything about Gall Wasp totally explained
Gall wasps (Cynipidae), also called
Gallflies, are a family of the order
Hymenoptera and are classified with the
Apocrita suborder of wasps in the superfamily
Cynipoidea. About 1300 species of this generally very small creature (1-8 millimeters) are known worldwide, with about 360 species of 36 different genera in Europe and some 800 species in North America.
Features
Like all representatives of
Apocrita, gall wasps have a distinctive body shape, the so-called
wasp waist. The first abdominal
tergum (the
propodeum) is conjoined with the
thorax, while the second abdominal segment forms a sort of shaft, the
petiole. The
petiole connects with the
gaster, which is the functional
abdomen in apocritan wasps, starting with the third abdominal segment proper. Together, the
petiole and the
gaster form the
metasoma, while the
thorax and the
propodeum make up the
mesosoma. The antennae are straight and consist of 12 to 16 segments. In many varieties the backside of the
mesosoma appears longitudinally banded. The wings are typically simply structured. The female's egg-depositing
ovipositor is often seen protruding from the tip of the
metasoma.
Reproduction and Development
The reproduction of the gall wasp is partly pure two-sex propagation, partly pure
parthenogenesis, in which a male is completely unnecessary. With most species, however, there's an
alternation of generations with one two-sex generation and one parthenogenic generation annually. This process differentiates the various generations primarily in their appearance and the form of the
plant galls they induce.
The larvae of most gall wasps develop in characteristic plant galls they induce themselves, however many species are also
inquilines of other gall wasps, such as those of the genus
Synergus.
The plant galls mostly develop directly after the female insect lays the eggs. The inducement for the gall formation is largely unknown; discussion speculates as to both chemical, mechanical and viral triggers. The hatching larvae nourish themselves with the nutritive tissue of the galls, in which they're otherwise well-protected from external environmental effects. The host plants and the size and shape of the galls are specific to the majority of gall wasps, whereas about 70% of the known species live in various types of
oak tree. One can find galls on nearly all parts of such trees, some on the
leaves, the
buds, the
branches, and the
roots. Other species of gall wasp live in
rose bushes or
maple trees, as well as many herbs. Frequently, the determination of the species is much easier through observation of the galls produced rather than the insect itself.
Types
Most species of gall wasp live as gall-formers on oaks. One of the most well-known of these oak gall wasps is the common oak gall wasp (
Cynips quercusfolii), which induces characteristic two-centimeter in diameter, spherical galls on the underside of oak leaves.
Image:Diplolepis-rosae.jpg|Rose bedeguar gall on a wild rose in summer.
Image:Diplolepis Quercus01.jpg|Andricus fecundator parthenogenetic generation Oak artichoke gall
Image:Gallwespe bedient sich Eichel2.jpg|Andricus quercuscalicis parthenogenetic generation gall
Image:Diplolepis Quercus02.jpg|Andricus quercuscalicis parthenogenetic generation gall
image:Eikengallen op mannelijke bloeiwijze.jpg|Neuroterus quercusbaccarum sexual generation gall
Image:Oak Gall.jpg|Andricus kollari oak marble gall.
These turn reddish in the fall and are commonly known as
oak apples. Light lentiform galls on the underside of the same leaves are induced by
Neuroterus quercusbaccarum; darker ones with bulging edges are formed by
Neuroterus numismalis. Also striking are the galls of
Cynips longiventris, which likewise can be found on the underside of leaves, and are recognizable for their spheroidal shape and irregular red streaks. The oak potato gall wasp (
Biorrhiza pallida) has round galls that grow to about four centimeters. These are known colloquially as
oak potatoes. The latter type of gall is induced by this type of wasp not on the leaves, but on the roots of the oak. On the buds of young oak twigs, one can often find the hard-shelled galls of
Andricus kollari and
Andricus quercustozae.
The galls of the rose gall wasp (
Diplolepis rosae) are also distinctive and are known as
bedeguars or robin's pincusions. These are found on the shoots of dog roses and have a length of up to five centimeters with red long-haired outgrowths. Inside the galls are several chambers, which may be occupied by larvae.
Genera include:
Additional information
The galls of several species, especially Mediterranean variants, were once used as tanning agents.
A rose gallnut with stem makes a long-lasting bouquet adornment.
Before his work in human sexuality, Dr. Alfred Kinsey was known for his study of gall wasps.
Gall wasps tend to hover near dead bodies.
Literature
Gauld, I.D., Bolton, B. (1988): The Hymenoptera, Oxford
Honomichl, K., Bellmann, H. (1994): Biologie und Ökologie der Insekten (In German)
Liljeblad, J. (2002): Phylogeny and evolution of gall wasps (Hymenoptera: Cynipidae). Department of Zoology, Stockholm University. 1-176. Doctoral thesis.Further Information
Get more info on 'Gall Wasp'.
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