''Synergus japonicus'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

gall wasp Gall wasps, also traditionally called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1,300 species of this gene ...

in the family

Cynipidae Gall wasps, also wikt:gallfly#Usage notes, traditionally called gallflies, are hymenopterans of the family Cynipidae in the wasp superfamily Cynipoidea. Their common name comes from the galls they induce on plants for larval development. About 1 ...

. Whereas most gall wasps create the galls in which they live, ''Synergus japonicus'' is an

inquiline In zoology, an inquiline (from Latin ''inquilinus'', "lodger" or "tenant") 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 ...

species, living in the

gall Galls (from the Latin , 'oak-apple') or ''cecidia'' (from the Greek , anything gushing out) are a kind of swelling growth on the external tissues of plants. Plant galls are abnormal outgrowths of plant tissues, similar to benign tumors or war ...

created by another species of wasp. It is native to Japan, China and Russia.

Distribution

''Synergus japonicus'' was for a long time only known from Japan, but more recently it has been found in China, and also in eastern Russia where it was discovered living in the galls created by '' Andricus kashiwaphilus'', on the Japanese emperor oak, ''

Quercus dentata ''Quercus dentata'', also called Japanese emperor oak, daimyo oak, or Korean oak (, ''kashiwa''; ; , ''tteokgalnamu''), is a species of oak native to East Asia (Japan, Korea and China). The name of the tree is often translated as "sweet oak" in ...

''.

Ecology

About 1,400 species of gall wasps have been described, and of these about 180 develop inside the galls created by other species. These inquilines can be considered as kleptoparasites because the shared gall is an arrangement that is only to the advantage of the inquiline. Gall wasps have complex life cycles, often with an alternation of generations with one sexual generation of both males and females alternating with an all-female,

parthenogenetic Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

generation. In the sexual generation, male ''Synergus japonicus'' seek out females, but do not distinguish between them on the basis of age or reproductive status. Instead, the males take part in certain courtship behaviours and only proceed to mate with a female if she adopts an acceptance posture. At this stage the female is receptive to the male, and continues in this state for a time, whether the pair copulate or not. Once the acceptance posture is discontinued, it is never adopted again, irrespective of whether the pair have mated. In Japan, the burr-shaped galls of '' Andricus mukaigawae'' normally contain a single cell in which the larva of that gall wasp develops. However, larvae of ''Synergus japonicus'' are often also present in the gall, creating their own cells and consuming the gall tissues. The larvae of both species are often parasitised by chalcid wasps in the genus ''

Torymus ''Torymus'' is a genus of chalcid wasps from the family Torymidae, and there are more than 400 spp. worldwide. It was named by the Swedish naturalist Johan Wilhelm Dalman in 1820. Most species are ectoparasitoids of gall forming insects, usuall ...

''.

References

{{Taxonbar, from=Q21317314 Cynipoidea Hymenoptera of Asia Insects described in 1874 Taxa named by Francis Walker (entomologist)