''Urocerus japonicus'', commonly known as the Japanese horntail, is a species of

sawfly Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...

, native to southeastern Asia. Studies show that the dispersal distance of the female is higher than the male. The fungal species ''

Amylostereum laevigatum ''Amylostereum laevigatum'' is a species of crust fungus in the family Amylostereaceae. Originally named ''Thelephora laevigata'' by Elias Fries in 1828, it was given its current name when transferred to the genus ''Amylostereum'' by French mycol ...

'' had its first appearance in Japan via this sawfly.

Ecology

This horntail lays its eggs in the trunk or branches of the

Japanese cedar ''Cryptomeria'' (literally "hidden parts") is a Monotypic taxon, monotypic genus of Pinophyta, conifer in the cypress family (biology), family Cupressaceae, formerly belonging to the family Taxodiaceae. It includes only one species, ''Cryptomeri ...

(''Cryptomeria japonica'') or the

Japanese cypress ''Chamaecyparis obtusa'' (Japanese cypress, hinoki cypress or hinoki; ja, 檜 or , ) is a species of cypress native to central Japan in East Asia, and widely cultivated in the temperate northern hemisphere for its high-quality timber and orname ...

(''Chamaecyparis obtusa'') and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e feed on the sapwood. When

ovipositing The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

, the horntail introduces a

symbiont Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

fungus which either provides essential nutrients for the larvae, or which produces

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

s which help decompose the

lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

in the wood. The staining produced by the fungus reduces the commercial value of the timber. The horntail carries

arthrospore An oidium (plural: oidia) is an asexually produced fungal spore that (in contrast to conidia) is presumed not to constitute the main reproductive preoccupation of the fungus at that time. The hypha breaks up into component cells/ small pieces and ...

s of the fungus in a pair of small sacs on the abdomen known as "mycangia". A newly emerged adult female makes a short dispersal flight before drilling several holes in the bark of a suitable tree, depositing eggs and arthrospores from the mycangia in each hole.

References

{{Taxonbar, from=Q65042614 Siricidae Hymenoptera of Asia Insects described in 1874 Taxa named by Frederick Smith (entomologist)