Diprion pini

Diprion pini. Britain. A, Larva; B, ventral aspect of pupa; C, imago, male. (After Vollenhoven.)

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Hexapoda
Classis: Insecta
Cladus: Dicondylia
Subclassis: Pterygota
Cladus: Metapterygota
Infraclassis: Neoptera
Cladus: Eumetabola
Cladus: Endopterygota
Superordo: Hymenopterida
Ordo: Hymenoptera
Subordo: Symphyta
Superfamilia: Tenthredinoidea

Familia: Diprionidae
Genus: Diprion

Diprion pini, the common pine sawfly, is a sawfly species in the family Diprionidae.[1] It is a serious pest of economic forestry, capable of defoliating large areas of pine forest. It occurs throughout Europe and Russia.
Description

Diprion pini is an insect with complete metamorphosis, changing from a caterpillar larva via a pupal stage to a winged adult. Last-stage larvae can be up to 25 millimetres (0.98 in) long; the head is brown, while the body is light green with black spots. The adult (imago) is brown and is around 10 millimetres (0.39 in) long. The larvae feed on pine needles.[3][4]

Eggs are laid in rows in springtime, on pine needles from the previous year. Young caterpillars start feeding on the old needles near where they hatched, leaving the vascular bundles uneaten. Older caterpillars feed more widely, moving to other branches and eating whole needles except for the leaf sheath; late in the season they also consume the current year's needles. The caterpillars live in groups of some 60 to 100 individuals. The pupa is attached to a pine twig.[2]

Last instar larva with exuviae
Larva forming cocoon in pine tree

Opened cocoon
Male imago

Female imago

Distribution and ecology

The species is widely distributed across Europe and Russia, and is present in Algeria, Siberia, and Turkey.[1][2] Its host plants are species of pine including Pinus banksiana (jack pine), P. cembra (arolla pine), P. contorta (lodgepole pine), P. mugo (mountain pine), P. nigra (black pine), P. pinaster (maritime pine), P. radiata (radiata pine), P. strobus (eastern white pine), P. sylvestris (Scots pine), P. uncinata (mountain pine), and P. wallichiana (blue pine).[2]

Mass of larvae on pine tree

Deimatic behaviour: group of larvae waving their heads simultaneously

Pest of forestry

Outbreaks of D. pini are eruptive, rising rapidly to large infestations after long latent periods; this makes monitoring difficult.[2] Scots pines are not generally killed by a single defoliation, but weakened trees may suffer increased attack by bark beetles, buprestid beetles, and pine weevils, which can kill trees, as can repeated defoliation. During high rates of defoliation, the growth rate of pines decreases significantly.[2] Climate change appears to be allowing the pest to damage forests increasingly far north, such as in Scandinavia. Since it feeds until late in the autumn, affected trees are weakened and often die in the subsequent winter.[5] The presence of D. pini can be monitored with pheromone traps.[6] Serious infestations are treated by aerial spraying with insecticides such as diflubenzuron or pyrethroids.[2] Biological control with the parasitoid of sawfly pupae Dahlbominus fuscipennis has been used effectively.[2] The planting of mixtures of species of tree has been proposed to reduce pest damage.[2][7]

Larval damage to pine

Pine sawfly pupa killed by sawfly parasitoid wasp, Dahlbominus fuscipennis, with adult wasps

See also

Neodiprion sertifer, another common European pine sawfly pest, also called red pine sawfly and fox-coloured sawfly

References

"Diprion pini (Linnaeus, 1758)". Fauna Europaea. Fauna Europaea Secretariat, Museum für Naturkunde, Berlin. Retrieved 27 June 2022.
"Diprion pini (common pine sawfly)". PlantwisePlus Knowledge Bank. 10 December 2020. Retrieved 6 September 2023.
"Pine sawflies". Royal Horticultural Society. Retrieved 6 September 2023.
Diprion pini (common pine sawfly), CABI Publishing, 2022-01-07, doi:10.1079/cabicompendium.19194
Krokene, Paal (6 December 2014). "The common pine sawfly – a troublesome relative". Science Nordic. Archived from the original on 29 November 2016. Retrieved 28 November 2016.
Anderbrant, O. "Monitoring pine sawflies with pheromone traps." Methodology of forest insect and disease survey in Central Europe. Proceedings, First Workshop of the IUFRO WP 7.03. 10, Ustroń-Jaszowiec, Poland, 21–24 April 1998. Instytut Badawczy Leśnictwa (Forest Research Institute), 1998.
Herz, Annette, 1997. Zur Effektivität und Struktur der Parasitoidengemeinschaft von Diprion pini (L.) (Hym.: Diprionidae) bei latenten Dichten des Wirtes. PhD thesis. Ludwig Maximilians University, Munich.