Author: (Denis and Schiffermüller, 1775)
European pine shoot moth
Pine shoot moth
Species Overview:
Adult: 16-24 mm wingspan; thorax light orange-yellow, abdomen dark grey. Forewing ground colour silvery white, variably suffused with yellow-ochreous, strigulated with plumbeous and with poorly defined ferruginous-orange markings covering most of wing-surface. Pre-tornal marking triangular. Hindwing fuscous.
Egg: lenticular-ovate; deposited singly or in small groups of two or three, on the bark of the shoots, on the basis of the needles, on the bud scales or on the needles [Rhyacionia buoliana egg].
Larva: about 21 mm long; head brown, often mottled with darker brown, or wholly black; prothoracic plate brown or black, with a distinct light brown medial sulcus; abdomen shining reddish brown, paler ventrally; spinules of integument dense; pinacula minute, dark brown or black; setae very short, yellowish; anal plate weakly sclerotized, yellowish brown marked with blackish brown, rounded posteriorly; anal comb absent; thoracic legs dark brown. Abdominal legs with small sclerotized plate [Rhyacionia buoliana larva].
Pupa: 7-12.5 mm long; head, thorax and wings brown or dark brown, abdomen brown, paler ventrally. Anal segment with four hooked setae dorsally and four pairs of hooked setae ventrally; abdominal segments 2-8 without athwart excavation dorsally; frons with rounded process [details pupa R. buoliana ]. In a silken cocoon in the larval habitation [Rhyacionia buoliana pupa].
Taxonomic Description:
Male:
Rhyacionia buoliana adult
Rhyacionia buoliana adults
Rhyacionia buoliana male
External characters: 16-24 mm wingspan. Thorax light orange-yellow; abdomen dark grey. Forewing termen slightly convex; ground colour silvery white, variably suffused with yellow-ochreous and strigulated with plumbeous, forming thick, rather diffuse, irregular, anastomosing striae, usually less well-defined dorsally; markings ferruginous-orange, poorly defined; basal and sub-basal fasciae more or less confluent, obsolescent dorsally; median fascia broad, bifurcate on costa, obsolescent dorsally, confluent with a large, triangular pre-tornal marking; subterminal fascia occupying most of distal area, sometimes with a silvery stria subterminally; cilia white suffused with grey, with a black sub-basal line. Hindwing fuscous; cilia whitish, with a dark sub-basal line (Bradley et al., 1979).
male genitalia R. buoliana
Genitalia: Uncus rudimentary; gnathos not developed. Socii very small, attached to tegumen. Valva strong, with large basal excavation; cucullus very broad, without definite ventral lobe. Aedeagus with cluster of detachable cornuti in vesica.
Female:
External characters: Similar to male, but usually larger and with the silvery striae sharper and more pronounced.
female genitalia R. buoliana
Genitalia: Sterigma a double scobinate hairy patch; ostium cup-shaped; colliculum a sclerotized tube to which inner sclerites of ductus bursae may attach. Corpus bursae without signum.
Variation:
The fasciate markings and silvery striae of the forewing are extremely variable; the striae may be reduced and in extreme examples the ferruginous-orange markings are confluent and almost obliterate them. In both sexes the hindwing is sometimes very dark fuscous.
Biology:
infested bud whorl (Scots pine), showing exit hole and the resin tent constructed by a larva in the spring.
Rhyacionia buoliana is a univoltine species. The period of emergence starts at the earliest in May, but usually in June, and lasts 3-4 weeks until the middle of July. The males emerge 3-5 days before the females and fly from the late afternoon, when the light intensity starts to decrease until darkness sets in. A turbulent swarm flight, the direction of which is determined by the prevailing light intensity and wind direction, is followed by a search flight under the influence of the sex pheromone, towards the calling females situated on the top of needles. The females start to lay their eggs in the evening of the day following copulation. The oviposition period lasts on an average about 3 weeks. Eggs are laid singly, sometimes in small groups of two or three on the bark of the shoots, on the bases of the needles, on the bud scales or on the needles. Eggs hatch after 8-18 days. The young larva moves up the shoots. It attaches a tunnel-shaped web between a needle sheath and the shoot, from where it bores into the needle basis and starts to feed. The first moult takes place after about 1 week. The larva then leaves the first pair of needles in order to continue to feed on the next pair further on the shoot. After 1 or 2 weeks, several needles are excavated before the larva has reached the top of the shoot, where it starts to spin a tent-like web between a bud and neighbouring needles. From this tent, a circular hole is gnawed through the bud scales. Food particles are glued with resin to the web, which protects the larva against adverse weather conditions. One or more buds are partially or entirely excavated before the beginning of the winter rest, prior to which one or two further moults occur. Resumption of activity is clearly indicated by the formation of new webs, which are spun on hitherto undamaged buds. The first webs appear between March and the middle of April, depending on weather conditions. The larvae moult shortly after the start of feeding. They continue to feed on the extending pine shoots and reach the prepupal stage as sixth instar larvae in Central Europe between the end of April and the end of May, and in Southern Sweden and Northern Poland in the middle of June. The young larvae maintain their negatively geotactic and positively phototactic response during the crawling period in spring and also later on when they search for suitable food sources. The populations of the larvae become therefore more concentrated in the upper part of the tree crowns. The pupal cradle inside the basis of the excavated shoot is coated with a dense, white webbing and provided with a hole that is closed with silk threads and resin. The sixth instar larva then moults towards the prepupal stage, which after a few days develops into the pupa. The pupal stage lasts about 3 weeks, for females a little longer than for males. Before emergence of the adult, the pupa moves by rotations along its longitudinal axis out of the prepared hole until the first abdominal segment (Bogenschütz, 1991).
Host plants:
The larvae of Rhyacionia buoliana are oligophagous. The original host plants are Pinus sylvestris and Pinus nigra. The host plant spectrum has been expanded to more members of the genus Pinus after the introduction of North American pine species into Europe and after transport of Rhyacionia buoliana to North and South America. This species is also recorded from Abies alba.
Damage:
Rhyacionia buoliana damage
first stage in the development of a "posthorn" deformation on the leading shoot of a Scots pine.
posthorn deformation
Rhyacionia buoliana is primarily a pest of pine plantations and in nurseries and ornamentals. All open-grown young host trees below the height of 6-8 m are usually attacked and damaged. The most important damage is caused by spring killing of terminal and lateral buds resulting in dead tops. Loss of all buds of the terminal shoot causes a dense or bushy growth by activation of adventive buds, partial loss of buds and broken twigs lead to deformation of the stems. Forked growth, crooks or posthorns and sideways transposed stem axes (so-called bayonet) are often the result. Bush growth causes loss in growth length. The affected trees have no value as future components of the final stand unless the stem abnormalities can grow out (Bogenschütz, 1991; Scott, 1972).
In Europe, there is a definite sequence of host susceptibility descending in order from Lodgepole pine (Pinus contorta) , through Scots pine (Pinus sylvestris) and Austrian pine (Pinus nigra var. nigra), to Corsican pine (Pinus nigra var. maritima). Ponderosa pine (Pinus ponderosa), Monterey pine (Pinus radiata) and Maritime pine (Pinus pinaster) are also recorded hosts. Pinus strobus seems to be the least susceptible (Scott, 1972).
In the USA, Red pine (Pinus resinosa) is the most susceptible to damage. Scots pine (Pinus sylvestris), Austrian pine (Pinus nigra var. nigra), Ponderosa pine (Pinus ponderosa) and Lodgepole pine (Pinus contorta) are moderately susceptible, while Jack pine (Pinus banksiana), Pitch pine (Pinus rigida), Virginia pine (Pinus virginiana), and Eastern white pine (Pinus strobus) are relatively resistant. Ornamental pines such as Pinus mugo var. mughus, Scots and Lodgepole pine can also be attacked in urban areas (Otvos, 1991).
Distribution:
Europe to Eastern Russia and Japan; Madeira; North and South America (introduced). The species has, in the past, been recorded from Korea, but does not occur there (anymore) (Byun and Park, 1994; Byun et al., 1998).
In Europe, the southern border of the area of distribution of the nominate species runs through Spain, Italy, Yugoslavia, Greece and along the Black Sea coast towards the mouth of the Wolga in the Caspian Sea. South of the border, the subspecies Rhyacionia buoliana thurificana Lederer occurs.
Pheromone:
E 9-12Ac
(Smith et al., 1974)
or
E 9-12Ac : 10 *
E 9-12OH : 1 *
12Ac : 1
12OH : 0.2
Components marked with * are involved in attraction (Gray et al., 1984).
Parasitoids:
Europe
of egg:
Trichogramma
of larva:
Orgilus obscurator (Nees) (Braconidae)
Cremastus interrupter (Gravenhorst) (Ichneumonidae)
Pristomerus sp. (near orbitalis Holmgren) (Ichneumonidae)
Sinophorus rufifemur (Thomson) (Ichneumonidae)
Campoplex ramidulus Brischke (Ichneumonidae)
Ephialtes ruficollis (Gravenhorst) (Ichneumonidae)
Ephialtes roborator (Fabricius) (Ichneumonidae)
Ephialtes buolianae (Hartig) (Ichneumonidae)
Ephialtes sagax Hartig (Ichneumonidae)
Ephialtes longiseta Ratzeburg (Ichneumonidae)
of pupa:
Pimpla turionellae Linnaeus (Ichneumonidae)
Tetrastichus turionum (Hartig) (Eulophidae)
Actia nudibasis Stein (Tachinidae)
Lypha dubta (Fallén) (Tachinidae)
Pseudoperichaeta insidiosa (Robineau-Desvoidy) (Tachinidae)
Pseudoperichaeta nigrolineata (Walker) (Tachinidae)
The efficacy of the parasitoid complex of Rhyacionia buoliana is strongly diminished in some places by the hyperparasitoid Perilampus tristis Mayr (Perilampidae).
North America
of larva:
Orgilus obscurator (Nees) (Braconidae) (introduced)
Bracon gelechiae Ashm (Braconidae)
Elachterus spp. (Eulophidae)
Hyssopus thymus Grlt. (Eulophidae)
Eurytoma pini Bugbee (Eurytomidae)
Eupelmella vesicularis (Retz.) (Eupelmidae)
Atrometrus clapipes (Davis) (Ichneumonidae)
Calliephialtes comstockii (Cress.) (Ichneumonidae)
Campoplex sp. (Ichneumonidae)
Gelis sp. (Ichneumonidae)
Idemum sp. (Ichneumonidae)
Itoplectis conquisitor (Say) (Ichneumonidae)
Itoplectis evetriae Vier. (Ichneumonidae)
Pimpla aqualis Prov. (Ichneumonidae)
Pimpla turionellae (Ichneumonidae) (introduced)
Scambus hispae complex (Ichneumonidae)
Temelucha sp. (Ichneumonidae)
Oedemopsis scabricula (Grav.) (Ichneumonidae)
Temelucha minor (Cush.)
Habrocytus sp. (Pteromalini)
The braconid Orgilus obscurator (Nees) was introduced from Europe to control R. buoliana and is one of the most effective parasitoids in plantations where certain food is present, for example wild carrot, Daucus carota Linnaeus (considered a noxious weed in forestry).