Gall wasp
Encyclopedia
Gall wasps 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.
, 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
.
, in which a male is completely unnecessary. With most species, however, there is 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 inquiline
s 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 are 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 bud
s, the branch
es, and the root
s. Other species of gall wasp live in eucalyptus trees
, 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.
provides the developing gall wasp with a safe refuge for the most vulnerable stage of its life-cycle, however, many other wasps have found a way to penetrate this defence and parasitise the larva(e) within. Some of these parasitoids use their long, hardened egg laying tube (ovipositor
) to bore into the gall and lay an egg on the helpless gall maker. Collect a Bedeguar
or robin's pincushions gall before the autumn and keep it somewhere cool. In the spring, you will see at least one species of parasitoid emerge instead of the gall maker. These wasps such as Eurytoma rosae are beautiful, metallic insects with long ovipositors. These parasitoids, may in turn, be preyed upon by other wasps, hyperparasitoids.
These turn reddish in the fall and are commonly known as oak apple
s. 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 pincushions. 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:
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
and are classified with the Apocrita
Apocrita
Apocrita is a suborder of insects in the order Hymenoptera.Apocrita includes wasps, bees and ants, and consists of many families. It includes the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" formed between the first two segments of the actual abdomen; the...
suborder of wasps in the superfamily Cynipoidea
Cynipoidea
Cynipoidea is a moderate-sized Hymenopteran superfamily that presently includes five modern families and three extinct families, though others have been recognized in the past. The most familiar members of the group are phytophagous, especially as gall-formers, though the actual majority of...
. 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 ApocritaApocrita
Apocrita is a suborder of insects in the order Hymenoptera.Apocrita includes wasps, bees and ants, and consists of many families. It includes the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" formed between the first two segments of the actual abdomen; the...
, gall wasps have a distinctive body shape, the so-called wasp waist
Wasp waist
Wasp waist refers to a woman's fashion silhouette, produced by a style of corset and girdle, that has experienced various periods of popularity in the 19th and 20th centuries. Its primary feature is the abrupt transition from a natural-width rib cage to an exceedingly small waist, with the hips...
. The first abdominal tergum
Tergum
A tergum is the dorsal portion of an arthropod segment other than the head. The anterior edge is called the base and posterior edge is called the apex or margin. A given tergum may be divided into hardened plates or sclerites commonly referred to as tergites...
(the propodeum
Propodeum
The propodeum is the first abdominal segment in Apocrita Hymenoptera . It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans...
) is conjoined with the thorax
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....
, while the second abdominal segment forms a sort of shaft, the petiole. The petiole connects with the gaster
Gaster
The gaster is the bulbous posterior portion of the metasoma found in Apocrita Hymenoptera . This begins with abdominal segment III on most ants, but some make a postpetiole out of segment III, in which case the gaster begins with abdominal segment IV....
, which is the functional abdomen
Abdomen
In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...
in apocritan wasps, starting with the third abdominal segment proper. Together, the petiole and the gaster
Gaster
The gaster is the bulbous posterior portion of the metasoma found in Apocrita Hymenoptera . This begins with abdominal segment III on most ants, but some make a postpetiole out of segment III, in which case the gaster begins with abdominal segment IV....
form the metasoma
Metasoma
The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circulatory system, and the apical segments are typically...
, while the thorax
Thorax (insect anatomy)
The thorax is the mid section of the insect body. It holds the head, legs, wings and abdomen. It is also called mesosoma in other arthropods....
and the propodeum
Propodeum
The propodeum is the first abdominal segment in Apocrita Hymenoptera . It is fused with the thorax to form the mesosoma. It is a single large sclerite, not subdivided, and bears a pair of spiracles. It is strongly constricted posteriorly to form the articulation of the petiole, and gives apocritans...
make up the mesosoma
Mesosoma
The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings....
. The antennae are straight and consist of 12 to 16 segments. In many varieties the backside of the mesosoma
Mesosoma
The mesosoma is the middle part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the metasoma. It bears the legs, and, in the case of winged insects, the wings....
appears longitudinally banded. The wings are typically simply structured. The female's egg-depositing ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
is often seen protruding from the tip of the metasoma
Metasoma
The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circulatory system, and the apical segments are typically...
.
Reproduction and development
The reproduction of the gall wasp is partly pure two-sex propagation, partly pure parthenogenesisParthenogenesis
Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occur without fertilization by a male...
, in which a male is completely unnecessary. With most species, however, there is an alternation of generations
Alternation of generations
Alternation of generations is a term primarily used in describing the life cycle of plants . A multicellular sporophyte, which is diploid with 2N paired chromosomes , alternates with a multicellular gametophyte, which is haploid with N unpaired chromosomes...
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
Gall
Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...
they induce.
The larvae of most gall wasps develop in characteristic plant galls they induce themselves, however many species are also inquiline
Inquiline
In zoology, an inquiline is an animal that lives commensally in the nest, burrow, or dwelling place of an animal of another species. For example, some organisms such as insects may live in the homes of gophers and feed on debris, fungi, roots, etc...
s 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 are 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
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
. One can find galls on nearly all parts of such trees, some on the leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
, the bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s, the branch
Branch
A branch or tree branch is a woody structural member connected to but not part of the central trunk of a tree...
es, and the root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s. Other species of gall wasp live in eucalyptus trees
Eucalyptus
Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...
, rose bushes
Rose
A rose is a woody perennial of the genus Rosa, within the family Rosaceae. There are over 100 species. They form a group of erect shrubs, and climbing or trailing plants, with stems that are often armed with sharp prickles. Flowers are large and showy, in colours ranging from white through yellows...
or maple trees
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
, 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.
Parasitism
A gallGall
Galls or cecidia are outgrowths on the surface of lifeforms caused by invasion by other lifeforms, such as parasites or bacterial infection. Plant galls are abnormal outgrowths of plant tissues and can be caused by various parasites, from fungi and bacteria, to insects and mites...
provides the developing gall wasp with a safe refuge for the most vulnerable stage of its life-cycle, however, many other wasps have found a way to penetrate this defence and parasitise the larva(e) within. Some of these parasitoids use their long, hardened egg laying tube (ovipositor
Ovipositor
The ovipositor is an organ used by some animals for oviposition, i.e., the laying of eggs. It consists of a maximum of three pairs of appendages formed to transmit the egg, to prepare a place for it, and to place it properly...
) to bore into the gall and lay an egg on the helpless gall maker. Collect a Bedeguar
Rose bedeguar gall
The 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...
or robin's pincushions gall before the autumn and keep it somewhere cool. In the spring, you will see at least one species of parasitoid emerge instead of the gall maker. These wasps such as Eurytoma rosae are beautiful, metallic insects with long ovipositors. These parasitoids, may in turn, be preyed upon by other wasps, hyperparasitoids.
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.These turn reddish in the fall and are commonly known as oak apple
Oak apple
Oak apple is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from 2-5cm. Oak apples are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae. The adult female wasp lays single...
s. 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 pincushions. 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:
- AndricusAndricusAndricus is a genus of gall wasps in the family Cynipidae, comprising the following species:* Andricus assarehi* Andricus atkinsonae* Andricus californicus* Andricus cecconii* Andricus chodjaii* Andricus conificus...
- Biorrhiza
- CynipsCynipsCynips is a genus of gall wasps. One of the best known of these oak gall wasps is the common oak gall wasp , which induces characteristic two-centimeter in diameter, spherical galls on the underside of oak leaves.-Species:...
- DiplolepisDiplolepis (wasp)Diplolepis is a gall wasp genus in the family Cynipidae....
- NeuroterusNeuroterusNeuroterus 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...
- Synergus
Additional information
- The galls of several species, especially Mediterranean variants, were once used as tanning agents.
- Before his work in human sexualityHuman sexualityHuman sexuality is the awareness of gender differences, and the capacity to have erotic experiences and responses. Human sexuality can also be described as the way someone is sexually attracted to another person whether it is to opposite sexes , to the same sex , to either sexes , or not being...
, Dr. Alfred KinseyAlfred KinseyAlfred Charles Kinsey was an American biologist and professor of entomology and zoology, who in 1947 founded the Institute for Sex Research at Indiana University, now known as the Kinsey Institute for Research in Sex, Gender, and Reproduction, as well as producing the Kinsey Reports and the Kinsey...
was known for his study of gall wasps. - Galls formed on oak trees are one of the main ingredients in Iron gall ink
See also
- Oak appleOak appleOak apple is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from 2-5cm. Oak apples are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae. The adult female wasp lays single...
- Oak Marble gallOak marble gallOak marble galls develop as a chemically induced distortion of leaf buds on pedunculate oak , or sessile oak trees, caused by the parthenogenetic gall wasp which lays eggs within leaf buds using their ovipositor...
- 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...
- 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...
- Common Spangle gall
Further reading
- 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.
External links
- Andricus quercusclavigera and A. quercuscornigera on the UFUniversity of FloridaThe University of Florida is an American public land-grant, sea-grant, and space-grant research university located on a campus in Gainesville, Florida. The university traces its historical origins to 1853, and has operated continuously on its present Gainesville campus since September 1906...
/ IFASInstitute of Food and Agricultural SciencesThe University of Florida’s Institute of Food and Agricultural Sciences is a federal-state-county partnership dedicated to developing knowledge in agriculture, human and natural resources, and the life sciences, and enhancing and sustaining the quality of human life by making that information...
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