Gilpinia hercyniae
(spruce sawfly)

Pictures

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Identity

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Preferred Scientific Name

• Gilpinia hercyniae (Hartig, 1837)

Preferred Common Name

• spruce sawfly

Other Scientific Names

• Diprion hercyniae (Hartig)
• Diprion polytoma (Hartig)
• Diprion polytomum (Hartig)
• Diprion polytomus (Hartig)
• Gilpinia polytoma (Hartig)
• Gilpinia polytomus
• Lophyrus hercyniae Hartig
• Lophyrus polytoma Hartig
• Lophyrus polytomus Hartig
• Neodiprion polytoma

International Common Names

• English: European spruce sawfly
• French: diprion européen de l'épinette; tenthrède européen de l'épinette; tenthrede europeenne de l'épinette
• Russian: yelovyi obychnyi pililschik

Local Common Names

• Finland: hersykuusipistiäinen
• Germany: Fichtenblattwespe; Fichtenbuschhornblattwespe; Hornblattwespe, Fichtenbusch-
• Netherlands: ongelijke sparrebladwesp
• Poland: borecznik hercynski

EPPO code

• GILPPO (Gilpinia hercyniae)

Summary of Invasiveness

Top of page Gilpinia hercyniae is an invasive pest species; good examples are its introduction and rapid spread in Britain and North America.

The thelytokous parthenogenesis permits establishment of the insect from a single female provided it reaches a stand containing spruce.

Taxonomic Tree

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• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Arthropoda
•             Subphylum: Uniramia
•                 Class: Insecta
•                     Order: Hymenoptera
•                         Family: Diprionidae
•                             Genus: Gilpinia
•                                 Species: Gilpinia hercyniae

Notes on Taxonomy and Nomenclature

Top of page Diprionidae is a small family with about 125 species in 11 genera (Smith, 1993; Viitasaari, 2002). Gilpinia hercyniae (Hartig), the European spruce sawfly, was for a long time considered synonymous with the closely related spruce sawfly, Gilpinia polytoma (Hartig), until Reeks (1941) proved its validity.

Adams and Entwistle (1981) described the confused history of the taxonomy of these two species roughly as follows. Both species were described by Hartig, G. polytoma as Lophyrus polytomus (Hartig, 1834, 1837), and G. hercyniae as Lophyrus hercyniae (Hartig, 1837). Rohwer (1910) pointed out that Lophyrus is preoccupied and that the proper genus is Diprion. Enslin (1912) perpetuated the genus Lophyrus and relegated L. hercyniae as a synonym of L. polytomus. Escherich (1913) still recognized polytomus and hercyniae as distinct and continued to place them in Lophyrus. Smith (1938) discovered cytological and biological differences between Diprion polytomum in Canada and in Europe.

In the 1930s this spruce sawfly species had suddenly started to spread in northeastern North America and to cause serious damage in spruce forests. Benson (1939) proposed a new genus Gilpinia in which he placed polytoma, and apparently did not recognize hercyniae as distinct. Smith (1941) recognized two European forms, one of which was cytologically identical with the Canadian form of D. polytoma. The separate identities of Gilpinia polytoma and G. hercyniae were re-established by Reeks (1941), and confirmed by Forster (1949), and the latter species alone was shown to be present in North America (Balch et al., 1941). The two species had different chromosome numbers: 2n = 14 in G. hercyniae, and 2n = 12 in G. polytoma (Reeks, 1941; Smith, 1941).

In 1942 the name Gilpinia hercyniae began to come into use in the literature (e.g. Balch, 1942; Morris, 1942; Prebble, 1943). However, some authors persisted in the use of Diprion whilst others began to revert from Gilpinia to Diprion (c.f. Balch, 1942, 1958; Reeks, 1952, 1953, 1963). Smith (1974) published a checklist of Diprionidae of the world, in which he listed hercyniae and polytoma under Gilpinia. Nevertheless some authors in the 1970s continued to perpetuate Diprion hercyniae. Due to the taxonomic confusion, G. hercyniae was, prior to Reeks (1941), often erroneously referred to in the literature by the name Diprion polytomum. The occurrence of the three common European species of spruce sawflies, Gilpinia hercyniae (Hartig), G. polytoma (Hartig), and G. abieticola (Dalla Torre) has often been dealt with more or less collectively in the literature (Thalenhorst, 1955, 1960; Pschorn-Walcher, 1974, 1982).

See Adams and Entwistle (1981) for an annotated bibliography of Gilpinia hercyniae, covering the period 1834 to December 1979.

Description

Top of page Eggs

Eggs are pale green, elongate oval, about 1.9 mm long and 0.5 mm wide. Eggs are mainly laid singly into the edge of the one-year old needles. The female, using her saw-like ovipositor, makes a longitudinal slit, egg-pocket, in the middle or apical half of the needle and injects the egg. Freshly laid eggs are hard to detect, but a needle containing a viable, developing egg has a distinct bulge and the unhatched egg can often be seen protruding from the oviposition slit. Often the egg-pocket turns pale brown in colour (Scheidter, 1934; Billany, 1978).

Larvae

There are five feeding larval instars. The body colour of the first four instars is mostly green, but the fourth instar begins to show white stripes. L5 instar, 15-20 mm long, is green with five white stripes running the full length of the body; one mid-dorsal, one dorso-lateral, and one lateral; also a blackish dorso-lateral and a broken pedal stripe exist. The head capsule is mostly blackish in the first instar, becoming browner in second and succeeding instars. Spiracles are light brown. The fully grown larva moults to the final non-feeding prepupal or prespinning larva with a greenish brown head capsule and body without white stripes. It pupates by spinning a cocoon.

Green forms of larvae of G. hercyniae and G. polytoma are often regarded as indistinguishable (Reeks, 1941; Thalenhorst, 1955, 1960; Verzhutskii, 1973). Vehrke (1961) described characteristic differences in the dark frontal figures on the head capsules, which enable in most cases the separation of the larvae of these two species. Due to a considerable degree of variation in the pigmentation pattern of the head, especially in G. hercyniae, an exact identification is sometimes not possible (Thalenhorst, 1960; Pschorn-Walcher, 1974). Keys to larvae are given by Benes and Kristek (1979) and Wong and Szlabey (1986). Besides the green larval form, G. polytoma has a rarer form which is ventrally salmon-red (Reeks, 1941; Smith, 1941; Sellers, 1942).

The neuroendocrine organs of G. hercyniae larva were described by Hinks (1973).

Cocoon

The cocoon is cylindrical to spindle-shaped with rounded ends, tough, and finely textured. It is reddish brown, about 8-9 mm long and 4 mm wide (Billany, 1978, Plate 3), and has a weight of 70-75 mg (Otto, 1991). Cocoons are spun in the litter.

Adults

Reeks (1941) translated Hartig's original descriptions of G. polytoma (Lophyrus polytomus) and G. hercyniae (L. hercyniae), and he also redescribed both of the species. Only differences in genitalia of males and females allowed unambiguous separation of the species. A new character, maculation of the frons of adults, was presented by Benes and Kristek (1979), and Goulet (1981). In G. polytoma the surface ventrad to median ocellus with sharply outlined shallow fovea; fovea elongate, triangular, testaceous, and smooth; in G. hercyniae the surface ventrad to median ocellus without shallow fovea; fovea rugulose, sparsely punctate, and black or piceous.

Males: 4-8 mm, black, abdomen ventrally yellowish to ferruginous, darker on sides. Labrum and clypeus generally brownish or luteous, sometimes whitish. Angles of pronotum yellow. Antennae black with 24-28 segments, bipectinate. Penis valve pedate and strongly sclerotized at apex. In G. polytoma labrum and clypeus mostly whitish, and the penis valve spatulate with distal third membranous.

Females: 6-9 mm, black with yellow markings. Head mostly yellow; a blackish band between compound eyes enclosing ocelli and extending to antennal fovea. Labrum brownish, compound eyes black. Antennae with 21-22 segments, flagellum dark, serrate. Lancet with 11-12 annuli (in G. polytoma 9-10 annuli). Goulet (1981) has described characteristic differences between females of G. hercyniae and G. polytoma in the form of antennomere 3, in the distance between lateral ocellus and nearest inner margin of eye, and in the height of eye/ocellar-ocular distance.

Males of G. hercyniae are extremely rare (1 male to 1000-1200 females). A gynandromorphic adult, exhibiting characteristics of both sexes, has been described by Niklas (1962a).

Distribution

Top of page Due to the taxonomic confusion between G. hercyniae and G. polytoma, many records prior to 1941 cannot be reliably identified to the species (e.g. Sellers, 1942). G. hercyniae is native and widely distributed throughout central and northern Europe to Siberia, Mongolia, Korea and Japan (Smith, 1974; Pschorn-Walcher, 1982; Zhelochovtsev, 1988, 1994; Liston, 1995). It was established as an introduced pest species in Britain where it was first found in 1906 (Benson, 1933, 1951). It occurs in England and Scotland but not in Northern Ireland or the Republic of Ireland (Billany and Brown, 1977; Billany, 1978; Bevan, 1987, Liston, 1995).

Gilpinia polytoma is native and distributed in Central and Northern Europe, in Siberia to the Pacific coast, in Japan and in Pakistan. The species has not been recorded in Britain nor in America (Smith, 1971, 1974; Pschorn-Walcher, 1982; Mohyuddin et al., 1984; Zhelochovtsev, 1988, 1994; Liston, 1995).

Also see CABI/EPPO (1998).

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

Top of page G. hercyniae, the European spruce sawfly, was accidentally introduced into North America, and was first found in Ontario, Canada, in 1922 and in New Hampshire, USA, in 1929. The first massive outbreak started in the Gaspe Peninsula, Quebec, in 1930, and the dispersal rate in Canada was 30 miles per year (Balch, 1939; Reeks, 1963; Buckner, 1966). Prior to 1941, the species found in North America was referred to under the name Diprion polytomum (Hartig) (Reeks, 1941; Smith, 1979).

Risk of Introduction

Top of page The EEC Plant Health Directive, laying down measures to protect the European Economic Community from entry of foreign pests and diseases, was published for the first time in 1977 (Phillips, 1978). The "protected zones" (PZ) against G. hercyniae were Greece, Ireland, and Northern Ireland, the Isle of Man and Jersey. The same protected zones against G. hercyniae are also included in the Council Directive 2000/29/EC, of 8 May 2000, on protective measures against the introduction into the Community of organisms harmful to plants or plant products and against their spread within the Community.

Habitat List

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Category	Sub-Category	Habitat	Presence	Status
Terrestrial

Hosts/Species Affected

Top of page Gilpinia hercyniae attacks, to a varying degree, practically all species of spruce (Picea spp.). In Europe, Picea abies (P. excelsa) is the main host. According to Billany (1978), all age classes and species of spruce are susceptible to attack, and no significant host preference has been noticed with respect to provenance, aspect or elevation. All species of spruce native or grown in eastern North America are hosts but some preference is shown for P. glauca in oviposition and development (Balch, 1939; McGugan and Coppel, 1962).

Picea omorika is more resistant to G. hercyniae than P. abies (Dominik, 1989). In feeding experiments, larvae rejected P. omorika needles (Ohnesorge and Serafimovski, 1961). Feeding on Abies balsamea (Browne, 1968) and on A. alba (Schedl, 1982) has also been recorded, but evidently only in the absence of the natural host.

Host Plants and Other Plants Affected

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Growth Stages

Top of page Vegetative growing stage

Symptoms

Top of page Solitary larvae feed from June to September/October on fully developed, mainly 1-year-old or older, foliage of spruces. The small early stage larvae are difficult to spot owing to their colour, which closely matches the foliage, and their tendency to lie along the needles. Late stage larvae are more obvious, being bright green with white stripes running the full length of the body.

Larvae prefer the lower branches of trees and the edges of stands (Ohnesorge and Thalenhorst, 1956; Pschorn-Walcher, 1974). Even in light infestations, feeding is heavier in the lower part of the crown, and a severe outbreak gives a greyish-brown cast to the stand (MacAloney, 1936). The sawfly tends to kill the crown from the bottom upwards (Reeks and Barter, 1951). During heavy outbreaks, trees may gradually lose all of their old and part of their new foliage, with only a green tuft being left at the top. In Canada, heavily defoliated and dying trees were attacked by the eastern spruce barkbeetle (Dendroctonus piceaperda) and by secondary barkbeetles (Dryocoetes, Ips, Polygraphus) (Balch, 1941; Reeks and Barter, 1951).

According to Bevan and Davies (1971), the first signs of defoliation on Picea sitchensis appear in the upper part of the crown, and become noticeable when the current year's shoots show up as a reddish yellow colour. The early signs of rising population can be seen in the top four whorls of the crown (Billany, 1978).

Perhaps the best indication of the presence of larvae is the accumulation of large pellets of bright green frass approximately 2 x 1 mm diameter which lodge in the foliage or fall to the forest floor (Morris, 1942b; Billany, 1978). The green colour of the frass turns reddish brown after exposure to weather for a number of days. During heavy outbreaks, the frass may cover the ground to a depth of half an inch (1.25 cm) in some places (Dirks, 1944). A frass key for certain spruce defoliators, including G. hercyniae, has been published by Morris (1942b), and for certain defoliators of forest trees by Hodson and Brooks (1956).

List of Symptoms/Signs

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Biology and Ecology

Top of page The life history and habits of G. hercyniae were investigated intensively after the species was introduced and established as a major pest in North America. The literature has been reviewed by Smith (1979), Adams and Entwistle (1981) and Pschorn-Walcher (1982). G. hercyniae is obligatory parthenogenetic and thelytokous, i.e. females produce females and only very rarely males. Sex ratio is 1 male to 1000-1200 females. G. polytoma is facultatively parthenogenetic and arrhenotokous, i.e. unfertilized females produce males. Sex ratio is about 1:1. The number of generations of G. hercyniae per year varies, depending upon latitude and climatic conditions. In the most northerly latitudes there is only one generation per year, in the middle region two are possible, and in the southern extremity, three generations are produced. Adults of univoltine populations fly mainly in May-June (July), those of the bivoltine populations in May-June and July-August, and the flight periods in the south are in April-May, June-July and August-September, respectively. According to Billany (1978) adult sawflies may be found throughout the summer until late September. There is great temporal variation in the emergence and larval periods between years depending on weather conditions, and the generations may overlap. The eggs are laid singly in slits in old needles and hatch in about 10 days. Soft walled shade needles are best suited for oviposition (Bombosh and Ramakers, 1976), but Billany et al. (1978) found a preference for 1-year-old needles at the top of the crown of P. sitchensis. A single female may lay 30-60 eggs (Thalenhorst, 1968). The larvae live solitarily and in about 40 days, pass through five feeding stages, and one non-feeding stage. The effect of temperature on the development of the eggs and/or larvae has been studied by Thalenhorst (1973), and Otto (1991). Larvae prefer old foliage for feeding. Jensen (1988) reported 100% mortality of larvae when fed with newly-flushed foliage. The late season larvae can consume fully-matured new foliage (Balch, 1939). About 80 per cent of the feeding is done by the fifth larval instar (Reeks and Barter, 1951). The pre-spinning or prepupal larva spins a cocoon in the litter layer beneath the tree. G. polytoma spins cocoons mainly in the foliage or branches. The eonymphs in the cocoon may enter diapause or produce adults within a fortnight. The winter is passed in the eonymphal or pronymphal stage in the cocoon. A portion of the overwintering population may remain in diapause (prolonged) for two or more, sometimes even five, seasons. Diapause has a genetic base but temperature, day length (photoperiod), and moisture also regulate it (Prebble 1941; Niklas, 1962; Bombosch and Ramakers, 1976). The rearing of larvae under long day conditions (17 h) at 25°C inhibits the induction of eonymphal diapause, and even nine generations of certain strains have been reared annually in the laboratory (Bird, 1961). The life history and habits of G. hercyniae make it an ideal insect for laboratory research; it reproduces parthenogenetically, it is thelytokous, the eggs are deposited singly, larvae feed on old growth spruce foliage available throughout the year, and several generations may be reared annually. In the University of Göttingen, Germany, G. hercyniae has, since 1970, been the test insect for a long series of investigations on the nutritional quality of spruce needles for forest insect pests and on the interaction between the host tree and the pest (Bombosch, 1972; Lunderstädt and Claus, 1972; Lunderstädt, 1973, 1977, 1981a,b,c, 1983; Schwarz, 1973; Dinish, 1974; Lunderstädt and Hoppe, 1975; Lunderstädt et al., 1975, 1976/77; Dohrenbusch, 1978; Müller, 1979; Schopf, 1979, 1980; 1981, 1982, 1983a,b, 1986a,b,c, 1989; Lunderstädt and Reymers, 1980; Müller et al., 1981; Schopf et al., 1982; Lunderstädt and Ahlers, 1983, 1984, 1985; Kulcke, 1983; Lunderstädt and Küster, 1985; Spiller and Lunderstädt, 1988; Sabsch and Schopf, 1990; Schopf and Hartl, 1997). G. hercyniae is, despite of its wide distribution, a species that rarely occurs in outbreaks (Larsson et al., 1993). The main factors keeping the populations at endemic level are a nuclear polyhedrosis virus disease, parasitoids, and predators. The few economic level outbreaks known (Eastern North America, UK), have all occurred in cases where the sawfly has been introduced into new territories without its natural enemies. The taxonomic status, morphology, bionomics and ecology of G. hercyniae have been studied by Borowski (2004a,b,c).

Natural enemies

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Notes on Natural Enemies

Top of page G. hercyniae is attacked by several hymenopterous and dipterous parasitoids; many predators including ants, bugs, beetles, spiders, small mammals, birds; and a species-specific nuclear polyhedrosis virus (GhNPV).

G. hercyniae larvae possess a pair of esophageal diverticulae with resinous contents. In response to harrasment, larvae regurgitate a droplet of the resinous liquid. This behaviour, typical for the whole family of Diprionidae (Codella and Raffa, 1993), has been shown to repel predators and parasitoids. The liquid acts also as an oviposition deterrent for conspecific females (Weitzel and Hilker, 1993).

There are a large number of parasitoid records in the literature. For various reasons, however, a relatively high proportion of these records, particularly the older ones, are unreliable. The main sources of error have been the taxonomic confusion between G. hercyniae and G. polytoma prior to 1941, the mass-collection and mass-rearing of diprionid larvae and cocoons, inadequate sample-size and faulty timing of sampling, and false identification of the parasitoids or the hosts (see Morris et al., 1937; Reeks, 1952; Oehlke, 1965; Pschorn-Walcher, 1965, 1974). Morris et al. (1937) found 31 species of hymenopterous and dipterous parasitoids of Gilpinia polytoma (Diprion poytomum) in the material collected in 1932-1936 in Europe, and a total of 64 species of primary and secondary parasitoids were reared from this host in the material collected in 1935-1939 in Europe for shipment to Canada (Finlayson and Finlayson, 1958).


Egg parasitoids are not known from G. hercyniae. According to Vikberg (1985), a chalcid tetracampid, Dipriocampe elongata (Erdös), might be an egg parasitoid of G. hercyniae since he swept both of these species on the same Picea abies trees, and the parasitoid was known to be associated with P. abies in Hungary and Czechoslovakia.

The most important parasitoids of G. hercyniae in Europe are the larval parasitoids Olesicampe (Holocremnus) ratzeburgi (O. macellator), Lamachus marginatus (L. ophthalmicus, L. coalitorius), Exenterus tricolor, E. confusus, E. vellicatus, E. amictorius (Ichneumonidae), and Drino bohemica (Tachinidae), and the cocoon parasitoids Pleolophus basizonus, Agrothereutes spp. (Ichneumonidae) and Dahlbominus fuscipennis, Monodontomerus dentipes, Mesopolobus (Amblymerus) subfumatus (Chalcidoidea). Total parasitism usually varies over about 10-25% (Pschorn-Walcher, 1974).

When the massive outbreak of G. hercyniae in Canada in 1930 was detected, a virtual absence of attack by native parasitoids was found. Of the 276,000 cocoons and mature larvae, collected throughout the whole of the known range of the sawfly in Canada during 7 years, only less than 0.02% were successfully parasitized by native species (Balch, 1939). An extensive biological control programme was initiated in Europe in 1932 with a view to introduce natural enemies into Canada in order to bring the pest under control. The results of this successful programme are covered in the Control section. According to Finlayson (1960), 32 species are known in the literature as parasitoids of G. hercyniae in Canada.

Common insect predators preying on larvae and occasionally on adults of G. hercyniae are the pentatomid heteropterans, Podisus serieventris (Reeks, 1938) and P. maculiventris (MacAloney, 1936).

According to Balch and Bird (1944) some sawfly adults are destroyed by birds, but the number does not seem to be large. Entwistle et al. (1977a,b, 1978) reported that at least eight species of birds (wren, goldcrest, robin, redwing, song thrush, coal tit, blue tit, and starling) eat larvae of G. hercyniae in the field. They also found that 16 species of birds belonging to six families dispersed infective NPV in their faeces. In Saxony, Escherich and Baer (1913) found cocoons of Lophyrus hercyniae in the stomachs of sparrows and tits during winter, but the species was almost certainly Gilpinia polytoma.

Adults of coleopteran Carabidae readily attack sawfly cocoons in the litter (Morris, 1951). Larval Elateridae have been reported to destroy 1-2% (Morris, 1951) and 10-18% (Martineau, 1963) of the cocoons of G. hercyniae in the litter.

Small mammal predators, shrews, voles and mice (Soricidae, Microtidae), are very important factors affecting the spruce sawfly cocoons. In general, the portion of cocoons destroyed by small mammals has been reported to be 30-50% (Morris, 1942a, 1949a, 1951; Martineau, 1963; Neilson and Morris, 1964; Billany, 1978).

Larvae of G. hercyniae are infected by a lethal species-specific nuclear polyhedrosis virus disease (GhNPV). The disease is caused by Borrelinavirus hercyniae (B. gilpiniae), which belongs to baculoviruses (Tinsley et al., 1980; Cunningham and Entwistle, 1981). It occurs widely in nature and is one of the main factors keeping the populations of G. hercyniae at low level. The disease is not known from Gilpinia polytoma. The nature of the disease and symptoms of infection were described by Balch and Bird (1944). The literature on the disease and its role in regulating host populations have been reviewed by Adams and Entwistle (1981), and Cunningham and Entwistle (1981). Larvae become infected either by ingesting the polyhedral inclusion bodies (PIB) with the food, or via infected parent (Bird, 1961). The period of infection to death is 6-11 days. Parasitoids, predators and scavengers may act as transmission agents by straight contamination, or via their infectious faeces (Entwistle et al., 1977, 1978). GhNPV has been an effective factor in the biological control programmes against G. hercyniae, see Control section.

Means of Movement and Dispersal

Top of page Since the adults are strong fliers, and sometimes reach considerable altitudes, they must often travel many miles with the assistance of air currents. The thelytokous parthenogenesis permits establishment of the insect from a single female provided it reaches a stand containing spruce. Large numbers of adults have been observed on the tops of mountains above the timber line, and a great many adults drop into lakes and rivers (Balch, 1939).

G. hercyniae larvae normally pupate (spin cocoons) in the litter and soil, occasionally also in the foliage or branches. During outbreaks there is a risk that larvae accidentally pupate in containers, vehicles, camping equipment etc. in the forest, and thus get transported into new areas.

Pathway Vectors

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Plant Trade

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Plant parts not known to carry the pest in trade/transport
Bulbs/Tubers/Corms/Rhizomes
Flowers/Inflorescences/Cones/Calyx
Fruits (inc. pods)
Roots
Seedlings/Micropropagated plants
True seeds (inc. grain)
Wood

Wood Packaging

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Impact

Top of page Gilpinia hercyniae has no pest status in its native distribution range. In Central Europe some minor outbreaks have been caused by spruce sawfly species not exactly identified (Thalenhorst, 1960; Pschorn-Walcher 1974, 1982). Infestations of economic level damage have occurred only in territories and countries into which G. hercyniae was accidentally introduced and established without its natural enemies. Well known examples are the outbreaks in Britain and in northeastern North America.

In Britain, a minor outbreak, which declined within a few years, was noted on Picea omorika in 1950 (Billany, 1978). The outbreak history of G. hercyniae in Britain in 1970-1977 is well documented (Bevan and Davies, 1971, 1972; Brown, 1973; Brown and Billany, 1974; Bevan, 1975; Billany and Brown, 1975; Billany, 1976, 1977, 1978; Carter et al., 1976; Billany et al., 1977). Defoliation and damage to Picea sitchensis and P. abies were widespread and locally serious, but the trees were not killed. The effect of five years defoliation on the height increment of 16-year-old Sitka spruce brought about a 24% reduction. No reduction in radial increment was detectable. In many cases of top-kill of P. abies, side shoots took over and recovery was good though stem distortion through multiple leaders was not uncommon (Billany, 1978).

The huge literature on the introduction of G. hercyniae into North America in the 1930s and the large biological control programme initiated in 1932 to stop the destructive spread of the new pest in the northeastern parts of Canada and USA, have been thoroughly reviewed by McGugan and Coppel (1962), Neilson et al. (1971), Reeks and Cameron (1971), Clausen (1978), Adams and Entwistle (1981), Hulme and Green (1984), and Magasi and Syme (1984).

The outbreak started in the Gaspe Peninsula, Quebec, Canada, in 1930 and over 15 years spread westwards to Ontario, Canada and southwest to the New England states, USA (Balch and Simpson, 1932; Balch et al., 1934; MacAloney, 1936; Dowden, 1939; Balch, 1937, 1939, 1940, 1941; Balch and Bird, 1944). The most severely defoliated were Picea glauca, P. mariana and P. rubens. According to Reeks and Barter (1951) and Kulman (1971) loss of 20-50% of the old foliage caused measurable growth losses. Successive defoliations for 13, 7, and 4 years resulted in increment losses for 17, 12, and 10 years. In Picea glauca, 4-7 years of 90% old and 50% new foliage loss caused little mortality, but trees that lost 95% old and 75% new foliage frequently died. P. mariana died from lower rates of defoliation than did P. glauca.

Severe mortality was confined to Gaspe, where the outbreak lasted 8 to 15 years. By 1940 it was estimated that 66% of the spruce volume had been destroyed and the total mortality in the Gaspe was estimated at over 40 million m³ of spruce (Reeks and Barter, 1951). Additional loss resulted from reduced growth on surviving trees and associated windfall. According to Riley and Skolko (1942), spruces killed by sawfly deteriorate faster than bark-beetle killed trees, because the bark remains intact keeping moisture content high.

Reeks and Cameron (1971) have evaluated the economic losses caused by the outbreak in Canada, and the benefits produced by the biological control programme. The collapse of the outbreak by 1945 was mainly due to the effectively spread NPV disease and the action of introduced and native parasitoids. Populations have generally remained low since the early 1940s, and G. hercyniae could be relegated, at least in terms of economic importance, to the status of an unimportant insect (Neilson et al., 1971; Magasi and Syme, 1984).

Williams et al. (2003) demonstrated that the needle trace method (NTM) can be applied successfully to Sitka spruce (Picea sitchensis) to quantify defoliation caused by an outbreak of G. hercyniae that occurred many years previously, and that the technique can provide data on needle loss that is valuable for interpreting reductions in tree growth.

Environmental Impact

Top of page During heavy outbreaks of G. hercyniae the mortality of the more susceptible Picea species may lead to their decrease and substitution by less susceptible Abies species in the stands (Reeks and Barter, 1951; Reeks and Cameron, 1971).

Detection and Inspection

Top of page Eggs and the early stage larvae of G. hercyniae are difficult to detect. Larvae and the occasional adult female can be collected by beating the foliage with a stick over a beating tray (Thalenhorst, 1960; Neilson and Morris, 1964; Pschorn-Walcher, 1974). A good indication of the presence of larvae is the accumulation of pellets of bright green frass in the foliage or on the forest floor (Morris, 1942b; Billany, 1978). Frass drop measurements can be used also for determining population trends (Morris, 1949b).

G. hercyniae overwinter in a cocoon in the forest litter. In plantations on ploughed land, the sawfly shows a distinct preference for overwintering on the ploughed ridge, but despite this tendency to aggregate, cocoons are very difficult to find at low population levels (Billany, 1978). Various methods of cocoon sampling in population studies have been tested by Prebble (1943), and a non-destructive, wet technique to extract sawfly cocoons from a variety of soil and surface litter types has been described by Jukes (1977).
Quite considerable defoliation and increasing populations of the sawfly can go undetected for several seasons in dense stands of spruce. This is due to the solitary feeding and the preference of larvae for older needles. Spruces retain their needles for several years and the current year's growth also tends to mask defoliation in light to moderate attacks (Billany, 1978). So, the large and destructive outbreak in Canada, when first discovered in the Gaspe Peninsula in 1930, had been in progress for several years (Balch, 1939; Morris, 1958).

Similarities to Other Species/Conditions

Top of page Spruce sawfly species are morphologically so similar that an exact identification in the field is often difficult. Therefore samples of larvae, adults or cocoons should always be taken for later determination.

According to Pschorn-Walcher (1974), larvae of Nematinae are often difficult to separate from those of Gilpinia spp. without proper inspection under the microscope. Almost all the spruce Nematinae in Central Europe complete feeding in July or early August, so that in later collections (after mid-August) virtually only larvae of Gilpinia spp. are obtained. The sorting, handling and rearing of this rather "pure" material is then much easier and less time-consuming (Pschorn-Walcher, 1974). Keys to spruce sawfly larvae have been given by Lindquist and Miller (1971) and Benes and Kristek (1979).

Prevention and Control

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Biological Control

Larvae of G. hercyniae were not susceptible to Bacillus sotto toxin, probably because the toxin is not soluble in the gut due to the comparatively low pH of 8.5 (Angus, 1956). In laboratory tests Bacillus cereus was pathogenic (36-46% mortality) to larvae of G. hercyniae, but there was no suggestion that the bacterium could be used as a control agent (Heimpel, 1961). Smirnoff and Berlinguet (1966) found in some commercial preparations of Bacillus thuringiensis var. thuringiensis a labile exotoxin which caused a 100% mortality of larvae of G. hercyniae and many other sawfly species.

The most effective biological control agents against G. hercyniae are the nuclear polyhedrosis virus (GhNPV) and the parasitoids.

In 1932 an extensive biological control programme was initiated in Europe with a view to introduce natural enemies into Canada in order to bring the European spruce sawfly under control. This campaign was successful and by 1938 the sawfly population began to decline and continued to do so until, by about 1945, the outbreak in eastern North America had largely subsided (McGugan and Coppel, 1962; Neilson et al., 1971; Reeks and Cameron 1971; Pschorn-Walcher, 1982; Hulme and Green, 1984; Magasi and Syme, 1984).

In 1933-1951 over 890 million individuals of 27 parasitoid species, introduced and reared, were released against G. hercyniae in North America. Eight parasitoid species became established. Dahlbominus fuscipennis, Exenterus confusus and E. amictorius were effective mainly at high host densities whereas Exenterus vellicatus and Drino bohemica proved to be effective also at low host population levels. The main control agent, however, was the virus, which was accidentally introduced, most probably with parasitoid material, from Europe. In Canada the disease was discovered in larval laboratory cultures in 1936 and in the field populations in 1938. It spread rapidly and was also disseminated artificially, and by 1942 it was distributed throughout the greater part of the range of the sawfly (Dowden, 1940; Balch and Bird, 1944; Bird, 1961; Bird and Burk, 1961; Reeks, 1963). Biological control attempts against G. hercyniae using parasitoids and NPV virus in Canada were evaluated to have given good control for 1910-58, and complete control for 1958-68 and for 1969-80 (Hulme and Green, 1984). This control programme and the attendant studies must rank as one of the best documented and most successful attempts to control and regulate an insect pest in the history of biological control (Neilson et al., 1971).

The biological control programme for the importation of parasitoids from Europe to Britain, initiated in 1973, was less successful. Some recoveries of the released parasitoid species were made, but establishment of effective parasitoid populations were not recorded (Pschorn-Walcher, 1974; Greathead and Pschorn-Walcher, 1976; Billany, 1978; Billany et al., 1983). The virus arrived in Britain in 1972, probably carried by birds from Europe. It spread rapidly and controlled G. hercyniae more or less completely by 1977. The population of the pest has remained at a low level since then (Entwistle et al.,1977; Bevan, 1984, 1987).

G. hercyniae females lay their eggs singly and therefore are capable of starting many foci for virus infection. This might well account for the phenomenal spread of the GhNPV and for the very low population levels compared to the NsNPV of Neodiprion sertifer which lays eggs in clusters (Bird and Elgee, 1957; Bird, 1961; Bird and Burk, 1961). The patterns of spatial growth of small epicentres of GhNPV were studied in spruce forests in Wales by Entwistle et al. (1983). According to Dwyer (1994), the spatial spread of GhNPV can be explained with a very simple model of host movement, without recourse to complicated mechanisms of dispersal.

In the field, populations of G. hercyniae GhNPV maintained a very high virulence for over twenty years (Bird and Burk, 1961). Polyhedra of G. hercyniae lose virulence during storage, complete inactivation being reached after 12 years at 4.5°C (Neilson and Elgee, 1960).

Pheromonal Control

G. hercyniae reproduces parthenogenetically, and males are extremely rare. Mating instinct appears to be rudimentary, and only a few cases of attempted mating have been observed (Balch, 1939; Smith, 1941). Neilson and Morris (1964) state that mating has never been reported. The sexual pheromone of G. hercyniae has not been investigated (Anderbrant, 1999). So, monitoring and control methods based on sexual pheromones are not available.

Silvicultural Methods

G. hercyniae is a primary pest attacking quite healthy trees. Larsson and Björkman (1993) reported that larvae did not survive or grow any better on drought stressed trees (Picea abies) than on control trees. Bombosch and Lunderstädt (1976) studied the nutritional quality variations of spruce stands for G. hercyniae, and commented on the possible importance of this in forest management. Avtzis and Bombosch (1993) studied the effect of fertilizer application, pruning and thinning of P. abies on the quality of its foliage as food for the sawfly. Larvae developed better on vigorous trees with good needles, long crowns and little root competition than on untreated control trees with poor growth, small crowns and strong root competition. Applications of phosphate to the crops have been made in Britain because the heaviest outbreaks of G. hercyniae occurred on the phosphorus-deficient soils of mid-Wales (Bevan, 1987).

Chemical Control

Chemical insecticides have not been employed in control programmes against G. hercyniae. According to Balch et al. (1934) the sawfly is easily controlled by dusting, but economic conditions did not permit artificial control measures in Canada. Some small scale spraying of small decorative and shade trees was carried out by the landowners (Baldwin, 1939).

In Britain, a biological control programme against G. hercyniae was initiated in 1970s instead of chemical applications (Bevan and Davies, 1971; Brown and Billany, 1974; Pschorn-Walcher 1974; Billany, 1978).

References

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Adams PHW, Entwistle PF, 1981. An annotated bibliography of Gilpinia hercynip (Hartig), European spruce sawfly. Occasional Papers, Commonwealth Forestry Institute, No. 11:58 pp.

Anderbrant O, 1999. Sawflies and seed wasps. In: Hardie J, Minks AK, eds. Pheromones of non-lepidopteran insects associated with agricultural plants. Wallingford, UK: CAB International, 199-226.

Angus TA, 1956. The reaction of certain lepidopterous and hymenopterous larvae to Bacillus sotto toxin. Canadian Entomologist, 88:280-283.

Avtzis N, Bombosch S, 1993. Effects of various tending measures on the nutritional quality of Norway spruce for phytophagous insects. Allgemeine Forst- und Jagdzeitung, 164(2-3):21-22

Balch RE, 1937. The spruce sawfly outbreak in 1936. Pulp Pap. Mag. Can., 38:249-255.

Balch RE, 1939. The outbreak of the European spruce sawfly in Canada and some important features of its bionomics. J. Econ. Ent., 32:412-418.

Balch RE, 1940. The spruce sawfly outbreak in 1939. Pulp Pap. Mag. Can., 41:249-253.

Balch RE, 1941. The spruce sawfly outbreak in 1940. Pulp. Pap. Mag. Can., 42:219-222.

Balch RE, 1942. The spruce sawfly outbreak in 1941. Pulp. Pap. Mag. Can., 43:385-388.

Balch RE, 1958. Control of forest insects. Ann. Rev. Ent., 3:449-468.

Balch RE, Bird FT, 1944. A disease of the European spruce sawfly, Gilpinia hercyniae (Htg.), and its place in natural control. Sci. Agric., 25:65-80.

Balch RE, Reeks WA, Smith SG, 1941. Separation of the European spruce sawfly in America from Gilpinia polytoma (Htg.) (Diprionidae, Hymenoptera) and evidence of its introduction. Can. Ent., 73:198-203.

Balch RE, Simpson LJ, 1932. A European spruce sawfly, Diprion polytomum (Hartig) attacking spruce in the Gaspe Peninsula, Quebec. Can. Ent., 64:162-163.

Balch RE, Simpson LJ, Prebble ML, 1934. The European spruce sawfly outbreak in the Gaspe peninsula. Rep. Ent. Soc. Ont., 64:57-59.

Baldwin HI, 1939. The European spruce sawfly in New Hampshire 1938. J. For., 37:876-878.

Bejer-Petersen B, 1966. The sawfly fauna on Norway spruce in a Danish plantation, with a comparison to some other NW-European countries. Ent. Meddr., 34:221-232.

Benes K, 1975. Sawflies new to fauna of Czechoslovakia (Hymenoptera, Symphyta). Acta Entomologica Bohemoslovaca, 72(2):121-126

Benes K, Kristek J, 1979. Present state of taxonomy of European species of the families Pamphiliidae, Diprionidae, and Tenthredinidae (Hymenoptera, Symphyta) feeding on spruce. Acta Universitatis Agriculturae Brno, C (Facultas Silviculturae), 48(1-4):77-118

Benson RB, 1933. Diprion polytomum Htg., a sawfly not previously recorded from Britain. Ent. Mon. Mag., 69:153-154.

Benson RB, 1939. On the genera of the Diprionidae (Hymenoptera: Symphyta). Bull. Ent. Res., 30:339-342.

Benson RB, 1951. Hymenoptera, 2, Symphyta, Section (a). Handbooks for the Identification of British Insects, 6(2a):1-49.

Bevan D, 1975. Gilpinia hercyniae. Rep. For. Res., London, 1975:38.

Bevan D, 1984. Coping with infestations. Quarterly Journal of Forestry, 78(1):36-40

Bevan D, 1987. Forest insects: a guide to insects feeding on trees in Britain. Forestry Commission Handbook, UK, No. 1:153 pp.

Bevan D, Davies JM, 1971. A spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1971:89.

Bevan D, Davies JM, 1972. The spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1972:101.

Billany DJ, 1976. The European spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1976:36.

Billany DJ, 1977. The European spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1977:35.

Billany DJ, 1978. Gilpinia hercynip (Hertig): a pest of spruce. Forest Record, No. 117:11 pp.

Billany DJ, Borden JH, Brown RM, 1978. Distribution of Gilpinia hercynip (Hymenoptera Diprionidae) eggs within sitka spruce trees. Forestry, 51(1):67-72

Billany DJ, Brown RM, 1977. The geographical distribution of Gilpinia hercynip Hymenoptera: Diprionidae in the United Kindgom. Forestry, 50(2):155-160

Billany DJ, Carter CI, Fielding NJ, 1977. The European spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1977:36.

Billany DJ, Carter CI, Winter TG, Fielding NJ, 1983. The effects of climate and parasites on Gilpinia hercynip (Hartig) (Hymenoptera: Diprionidae) in Britain. Entomologist's Monthly Magazine, 119(1428/1431):117-120

Bird FT, 1961. Transmission of some insect viruses with particular reference to ovarial transmission and its importance in the development of epizootics. Journal of Insect Pathology, 3:352-380.

Bird FT, Burk JM, 1961. Artificially disseminated virus as a factor controlling the European spruce sawfly, Diprion hercyniae (Htg.) in the absence of introduced parasites. Can. Ent., 93:228-238.

Bird FT, Elgee DE, 1957. Virus disease and introduced parasites as factors controlling the European spruce sawfly, Diprion hercyniae (Htg.) in central New Brunswick. Can. Ent., 89:371-378.

Blank SM, Boevé J-L, Heitland W, Jänicke M, Jansen E, Koch F, Kopelke J-P, Kraus M, Liston AD, Ritzau C, Schmidt S, Taeger A, 1998. Checkliste der Pflanzenwespen Deutschlands (Hymenoptera: Symphyta). In: Taeger A, Blank SM, eds. Pflanzenwespen Deutschlands (Hymenoptera, Symphyta). Kommentierte Bestandsaufnahme. Keltern, Germany: Verlag Goecke & Evers, 14-34.

Bombosch S, 1972. The food-value of spruce needles for forest insect pests. 1. Problems of influencing insect populations by changing the quality of their food. Zeitschrift fur Angewandte Entomologie, 70(3):277-281

Bombosch S, Lunderstädt J, 1976. Investigations of the causes of site-induced differences in population increases of forest insect pests. Translation, Environment Canada, No. OOENV TR-1108. Transl. from Forstarchiv (1975), 46:153-155.

Bombosch S, Ramakers PMJ, 1976. The permanent rearing of Gilpinia hercyniae Htg. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz, 83(1/2/3):40-44

Borowski J, 2004. The taxonomic status of Gilpinia hercyniae (Hartig) - morphology, bionomics and ecology of Gilpinia polytoma (Hartig) (Hymenoptera, Diprionidae). Part I. (Status taksonomiczny borecznika hacynskiego - Gilpinia hercyniae (Hartig) oraz morfologia, bionomia i ekologia borecznika swierkowca - Gilpinia polytoma (Hartig) (Hymenoptera, Diprionidae). Czesc 1.) Sylwan, 148(9):55-59.

Borowski J, 2004. The taxonomic status of Gilpinia hercyniae (Hartig) - morphology, bionomics and ecology of Gilpinia polytoma (Hartig) (Hymenoptera, Diprionidae). Part II. (Status taksonomiczny borecznika harcynskiego - Gilpinia hercyniae (Hartig) oraz morfologia, bionomia i ekologia borecznika swierkowca - Gilpinia polytoma (Hartig) (Hymenoptera, Diprionidae). Czesc 2.) Sylwan, 148(10):23-29.

Borowski J, 2004. The taxonomic status of Gilpinia hercyniae (Hartig) - morphology, bionomics and ecology of Gilpinia polytoma (Hartig) (Hymenoptera, Diprionidae). Part III. (Status taksonomiczny borecznika harcynskiego - Gilpinia hercyniae (Hartig) oraz morfologia, bionomia i ekologia borecznika swierkowca - Gilpinia polytoma (Hartig) (Hymenoptera, Diprionidae). Czesc 3.) Sylwan, 148(11):3-8.

Borries H, 1895. Naaleträernes bladhvepse. Ent. Meddr., 5:247-250.

Brown RM, 1973. The spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1973:104.

Brown RM, Billany DJ, 1974. The European spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1974:39.

Browne FG, 1968. Pests and diseases of forest plantation trees: an annotated list of the principal species occurring in the British Commonwealth. Oxford, UK: Clarendon Press.

Buckner CH, 1966. The role of vertebrate predators in the biological control of forest insects. Annu. Rev. Entomol., 11:449-470.

Buckner CH, 1967. Avian and mammalian predators of forest insects. Entomophaga, 12:491-501.

CABI/EPPO, 1998. Distribution maps of quarantine pests for Europe (edited by Smith IM, Charles LMF). Wallingford, UK: CAB International, xviii + 768 pp.

Carter CI, Fielding N, Billany DJ, 1976. The European spruce sawfly, Gilpinia hercyniae. Rep. For. Res., London, 1976:38.

Clark RC, Clarke LJ, Pardy KE, 1973. Biological control of the European spruce sawfly in Newfoundland. Bi-monthly Research Notes, 29(1):2-3

Clausen CP ed., 1978. Introduced parasites and predators of arthropod pests and weeds: a world review. Agricultural Research Service, United States Department of Agriculture, Washington DC: USA, Agricultural Handbook No. 480.

Codella SG Jr, Raffa KF, 1993. Defense strategies of folivorous sawflies. In: Wagner MR, Raffa KF, eds. Sawfly life history adaptations to woody plants. San Diego, USA; Academic Press, Inc., 261-294

Cunningham JC, Entwistle PF, 1981. Control of sawflies by Baculovirus. In: Burges HD, ed. Microbial Control of Pests and Plant Diseases 1970-1980. London, UK: Academic Press, 379-407.

Dinish KN, 1974. The food value of spruce needles for forest insect pests. 5. Investigations on the starch-splitting enzyme (amylase) in larvae of Gilpinia hercyniae Htg. Zeitschrift fur Angewandte Entomologie, 77(2):113-121

Dirks CO, 1944. Population studies of the European spruce sawfly in Maine as affected by natural enemies. J. Econ. Ent., 37:238-242.

Dohrenbusch A, 1978. The food quality of spruce needles for forest damaging insects. 9. Influence of extracts of the needles of spruce (Picea abies Karst.) on the activity of glucose-6-phosphate dehydrogenase on larvae of Gilpinia hercynip (Hym., Diprionidae). Zeitschrift fur Angewandte Entomologie, 85(4):379-391

Dominik J, 1990. [Characteristics of damage to exotic spruce and fir species by insects and fungi based on observations in Poland]. Sylwan, 133:1-5.

Dowden PB, 1939. Present status of the European spruce sawfly, Diprion polytomum (Htg.) in the United States. J. Econ. Ent., 32:619-624.

Dowden PB, 1940. Larval disease prevalent in heavy infestations of the European spruce sawfly in southern New Hampshire and Vermont. J. Forestry, 38:970-972.

Dwyer G, 1994. Density dependence and spatial structure in the dynamics of insect pathogens. American Naturalist, 143(4):533-562

EC, 2000. Council Directive 2000/29/EC, on protective measures against the introduction into the Community of organisms harmful to plants or plant products and against their spread within the Community. Official Journal of the European Communities, L169, p. 36.

Enslin E, 1918. 1912-1918 Die Tenthredinoidea Mitteleuropas. Deutsche Entomologische Zeitschrift, Beihefte.

Entwistle PF, Adams PHW, Evans HF, 1977. Epizootiology of a nuclear-polyhedrosis virus in European spruce sawfly (Gilpinia hercynip): the status of birds as dispersal agents of the virus during the larval season. Journal of Invertebrate Pathology, 20(3):354-360

Entwistle PF, Adams PHW, Evans HF, 1978. Epizootiology of a nuclear polyhedrosis virus in European spruce sawfly (Gilpinia hercynip): the rate of passage of infective virus through the gut of birds during cage tests. Journal of Invertebrate Pathology, 31(3):307-312

Entwistle PF, Adams PHW, Evans HF, Rivers CF, 1983. Epizootiology of a nuclear polyhedrosis virus (Baculoviridae) in European spruce sawfly (Gilpinia hercynip): spread of disease from small epicentres in comparison with spread of baculovirus diseases in other hosts. Journal of Applied Ecology, 20(2):473-487

Entwistle PF, Adams PHW, Evans HF, Rivers CF, Bird FT, Burk JM, 1983. Epizootiology of a nuclear polyhedrosis virus (Baculoviridae) in European spruce sawfly (Gilpinia hercyniae): spread of disease from small epicentres in comparison with spread of baculovirus diseases in other hosts. J. Appl. Ecol., 20:473-487.

EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm

Ermolenko VM, 1975. Rogochvosti ta pilschtschiki [Tenthredinoidea (Blattwespen)]. Kiev, Akad. Nauk Ukr., Fauna Ukraini 10, 3.

Escherich K, Baer W, 1913. Tharandter zoologische Miszellen: II; Ein Frass von Lophyrus hercyniae Htg. Natw. f. Forst- u. Landwirtsch., 11:104-109.

Finlayson LR, Finlayson T, 1958. Notes on parasitism of a spruce sawfly, Diprion polytomum (Htg.) (Hymenoptera: Diprionidae), in Czechoslovakia and Scandinavia. Can. Ent., 90:584-589.

Finlayson T, 1960. Taxonomy of cocoons and puparia, and their contents, of Canadian parasites of Neodiprion sertifer (Geoff.) (Hymenoptera: Diprionidae). Canadian Entomologist, 92:20-47.

Forster EW, 1949. On the taxonomic status of the European spruce sawfly Gilpinia hercyniae (Htg.), (Hymenoptera: Diprionidae). Can. Ent., 81:112-113.

Goulet H, 1981. New external distinguishing characters for the sawflies Gilpinia hercynip and G. polytoma (Hymenoptera: Diprionidae). Canadian Entomologist, 113(8):769-771

Greathead DJ, Pschorn-Walcher H, 1976. Conifer sawflies (Tenthredinidae and Diprionidae, Hym.). In: Greathead DJ, ed. A review of biological control in Western and Southern Europe. Techn. Commun. No. 7, Commonw. Inst. Biol. Contr., Slough, 70-71.

Haack RA, Mattson WJ, 1993. Life history patterns of North American tree-feeding sawflies. Sawfly life history adaptations to woody plants [edited by Wagner, M. R.; Raffa, K. F.] San Diego, USA; Academic Press, Inc., 503-545

Hartig T, 1834. Forstliches und forstnaturwissenschaftliches Conversations-Lexikon. Berlin, Germany: Nauch, 990-991.

Hartig T, 1837. Die Aderflügler Deutschlands mit besonderer Berücksichtigung ihres Larvenzustandes und ihrens Wirkens in Wäldern und Gärten für Entomologen, Wald- und Gartenbesitzer. Die Familien der Blattwespen und Holzwespen nebst einer allgemeinen Einleitung zur Naturgeschichte der Hymenopteren, Berlin.

Heimpel AM, 1961. Pathogenicity of Bacillus cereus Frankland and Frankland and Bacillus thuringiensis Berliner varieties for several species of sawfly larvae. J. Insect Pathol., 3:271-273.

Hinks CF, 1973. The neuroendocrine organs of larvae of Neodiprion lecontei, N. swainei, and Diprion hercyniae (Hymenoptera: Diprionidae). Can. Ent., 105:725-731.

Hodson AC, Brooks MA, 1956. The frass of certain defoliators of forest trees in the North Central United States and Canada. Can. Ent., 88:62-68.

Hulme MA, Green GW, 1984. Biological control of forest insect pests in Canada 1969-1980: retrospect and prospect. In: Kelleher JS, Hulme MA, eds. Biological control programmes against insects and weeds in Canada 1969-1980. Slough, UK, Commonw. Agric. Bureaux, 215-225.

Ionaitis VP, 1969. [Biology of the spruce sawfly Gilpinia hercyniae (Hymenoptera, Diprionidae) in the Lithuanian SSR.]. Zool. Zhurn., 48:1185-1188.

Jensen TS, 1988. Variability of Norway spruce (Picea abies L.) needles; performance of spruce sawflies (Gilpinia hercynip Htg.). Oecologia, 77(3):313-320

Jukes MR, 1977. Extraction of sawfly cocoons from samples of soil and surface litter. Annals of Applied Biology, 85(3):399-401; [1 fig.].

Kristek J, 1973. [Ein Beitrag zur Verbreitung von Fichtenblattwespen und Fichtenbuschhornblattwespen in Mähren]. Acta Univ. Agric. (Brno), 42:47-60.

Kulcke J, 1983. On the food quality of spruce needles for insect pests of forests. 21. Comparison of larval development and evaluation of needle compounds of spruce (Picea abies Karst.) by larvae of Gilpinia hercynip (Hym., Diprion.), Lymantria monacha and Lymantria dispar (Lep., Lymantr.) placed simultaneously on identical plant material. Zeitschrift fur Angewandte Entomologie, 95(4):390-405

Larsson S, Bjorkman C, Kidd NAC, 1993. Outbreaks in diprionid sawflies: why some species and not others? In: Wagner MR, Raffa KF, eds. Sawfly life history adaptations to woody plants. San Diego, USA; Academic Press, Inc., 453-483

Larsson S, Björkman C, 1993. Performance of chewing and phloem-feeding insects on stressed trees. Scandinavian Journal of Forest Research, 8(4):550-559; 42 ref.

Lindquist OH, Miller WJ, 1971. A key to sawfly larvae feeding on the foliage of Spruce and Balsam Fir in Ontario. Proceedings of the Entomological Society of Ontario, 102:118-122

Liston AD, 1995. Compendium of European sawflies. Gottfrieding, Germany: Chalastos Forestry.

Lunderstadt J, 1983. Principles controlling the ecological-physiological relationship between forest trees and phytophagous insects. Zeitschrift fur Angewandte Entomologie, 96(2):157-165

Lunderstädt J, 1973. Zur Nahrungsqualität von Fichtennadeln für forstliche Schadinsekten. 3. Über physiologisch bedingte Veränderungen in Fichtennadeln. Z. Angew. Ent., 73:340-351.

Lunderstädt J, 1977. Zur Nahrungsqualität von Fichtennadeln für forstliche Schadinsekten. 8. Untersuchungen zum Abbau von Proteinen aus Fichtennadeln im Verdauungstrakt der Larven von Gilpinia hercyniae Htg. (Hym., Diprionidae). Z. Angew. Ent., 84:19-31.

Lunderstädt J, 1981. Ernährungsphysiologische Gesichtspunkte für die Systembindung von forstlich wichtigen Phytophagen. Z. Angew. Ent., 92:510-520.

Lunderstädt J, 1981. Methodische Überlegungen zur Bestimmung der Nahrung als Abundanzfaktor für phytophage Insekten am Beispiel der Wechselwirkung zwischen Fichte und Gilpinia hercyniae (Hym., Diprionidae). Z. Angew. Ent., 91:316-319.

Lunderstädt J, 1981. The role of food as a density-determining factor for phytophagous insects with reference to the relationship between Norway spruce (Picea abies Karst) and Gilpinia hercyniae Htg. (Hymenoptera, Diprionidae). For. Ecol. Manage., 3:335-353.

Lunderstädt J, 1983. Steuerungsprinzipien für die ökophysiologische Bindung zwischen Waldbäumen und phytophagen Insekten. Z. Angew. Ent., 96:157-165.

Lunderstädt J, Ahlers S, 1983. On the food quality of spruce needles for forest-damaging insects. 19. The annual cycle of spruce-needle contents in relation to the systemic bond between spruce (Picea abies Karst.) and Gilpinia hercynip (Hym., Diprionidae). Zeitschrift fur Angewandte Entomologie, 95(2):141-150

Lunderstädt J, Ahlers S, 1984. Towards the regulation of population density of phytophagous insects through their food-plant. 1. Physiological performance of insects. Zeitschrift fur Angewandte Entomologie, 98(5):448-462

Lunderstädt J, Ahlers S, 1985. The regulation of population density of phytophagous insects through their food-plant. 3. Regulation of the physiological performance of insects. Zeitschrift fur Angewandte Entomologie, 100(5):513-522

Lunderstädt J, Claus G, 1972. The food-value of spruce needles for forest insect pests. 2. Comparative biochemical analyses of spruce needles and the excreta of larvae of Gilpinia hercyniae Htg. Zeitschrift fur Angewandte Entomologie, 70(4):386 - 403

Lunderstädt J, Hoppe IM, 1975. The food value of spruce needles for forest insect pests. 6. The utilisation of nutrients by larvae of Gilpinia hercyniae Htg. (Hym., Diprionidae) when fed on needles of spruce (Picea abies Karst.) under standard conditions. Zeitschrift fur Angewandte Entomologie, 79(2):177-193

Lunderstädt J, Kuster E, 1985. Controlling the population density of phytophagous insects through their food-plant. 2. Regulation of the physiological performance of insects. Zeitschrift fur Angewandte Entomologie, 99(4):333-340

Lunderstädt J, Postel U, Reymers A, 1977. The food quality of spruce needles for insect pests of forests. 7. Studies on the body constituents of larvae of Gilpinia hercynip Htg. (Hym., Diprionidae). Zeitschrift fur Angewandte Entomologie, 82(4):380-394

Lunderstädt J, Reymers A, 1980. As to the food quality of spruce needles for forest damaging insects. 14. Interrelationships between proteins and phenols after feeding larvae of Gilpinia hercynip (Hym., Diprionidae) with spruce needles (Picea abies Karst.). Zeitschrift fur Angewandte Entomologie, 90(2):113-126

Lunderstädt J, Schwarz U, Dinish KN, 1975. Relations between the metabolism of saccharides in larvae of Gilpinia hercyniae (Hym., Diprionidae) and the carbohydrate content of their natural food, the needles of spruce (Picea abies Karst). Zeitschrift fur Angewandte Entomologie, 77(3):258-263

MacAloney HJ, 1936. The European spruce sawfly in the USA Journal of Forestry, 34:125-129.

Magasi LP, Syme PD, 1984. Gilpinia hercyniae (Hartig), European spruce sawfly (Hymenoptera: Diprionidae). In: Kelleher JS, Hulme MA, eds. Biological control programmes against insects and weeds in Canada 1969-1980. Slough, UK: Commonw. Agric. Bureaux, 295-297.

Martineau R, 1963. Facteurs naturels de régulation des populations de la tenthrède européenne de l'épinette, Diprion hercyniae (Htg.), dans le sud du Québec. Can. Ent., 95:317-326.

McGugan BM, Coppel HC, 1962. Biological control of forest insects, 1910-1958. In: A review of the biological control attempts against insects and weeds in Canada, Pt II. Techn. Commun. No. 2, Commonwealth Institute of Biological Control, Trinidad, 35-216.

McIntyre HL, 1939. Report on forest pest problems in New York. J. For., 37:879-883.

Mohyuddin AI, Attique MR, Arif MI, Mazhar RA, 1984. Notes on the biology, ecology and incidence of Gilpinia spp. (Tenthredinidae) attacking conifers in high altitude forests in Pakistan. Pakistan Journal of Forestry, 34(3):155-166

Morris KRS, Cameron E, Jepson WF, 1937. The insect parasites of the spruce sawfly (Diprion polytomum, Htg.) in Europe. Bull. Ent. Res., 28:341-393.

Morris RF, 1942. Preliminary notes on the natural control of the European spruce sawfly by small mammals. Can. Ent., 74:197-202.

Morris RF, 1942. The use of frass in the identification of forest insect damage. Can. Ent., 74:164-167.

Morris RF, 1949. Differentiation by small mammal predators between sound and empty cocoons of the European spruce sawfly. Can. Ent., 81:114-12o.

Morris RF, 1949. Frass drop measurement in studies of the European spruce sawfly. Bull. Mich. Sch. For., No. 12, 58 pp.

Morris RF, 1951. The larval Elateridae of eastern spruce forests and their role in the natural control of Gilpinia hercyniae (Htg.) (Hymenoptera: Diprionidae). Can. Ent., 83:133-147.

Morris RF, 1958. A review of the important insects affecting the spruce-fir forests in the Maritime Provinces. Forestry Chronicle, 34:159-189.

Müller W, 1979. On the food quality of spruce needles for forest-damaging insects. 10. Studies on 3 enzymes of amino acid metabolism in larvae of Gilpinia hercynip Htg. Zeitschrift fur Angewandte Entomologie, 87(2):160-170

Müller W, Reymers A, Lunderstadt J, 1981. On the food quality of spruce needles for forest-damaging insects. 15. Comparative studies of the development and protein utilisation of older larvae of Gilpinia hercynip (Hym., Diprionidae) feeding on the same needle material of spruce (Picea abies Karst.) under controlled and field conditions. Zeitschrift fur Angewandte Entomologie, 91(2):113-123

Neilson MM, Elgee DE, 1960. The effect of storage on the virulence of a polyhedrosis virus. J. Insect. Path., 2:165-171.

Neilson MM, Elgee DE, 1965. An unusual increase of spruce sawfly numbers in New Brunswick. Bi-mon. Progr. Rep. Dep. For. Can., 21:1.

Neilson MM, Martineau R, Rose AH, 1971. Diprion hercyniae (Hartig), European spruce sawfly (Hymenoptera: Diprionidae). In: Biological control programmes against insects and weeds in Canada 1959-1968. Commonw. Inst. Biol. Contr. Techn. Comm. 4, 136-143.

Neilson MM, Morris RF, 1964. The regulation of European spruce sawfly numbers in the Maritime Provinces of Canada from 1937 to 1963. Can. Ent., 96:773-784.

Nigitz HP, 1974. The Nematini (Hym., Tenthredinidae) of spruce in Styria. Zeitschrift fur Angewandte Entomologie, 75(3):264-284

Niklas OF, 1962. A gynandromorph of Gilpinia hercyniae (Hartig) (Hymenoptera: Diprionidae). Dtsch. Ent. Ztschr., 9:311-315.

Niklas OF, 1962. Beobachtungen über Diapause und Virose an Laboratoriumzuchten der Fichtenblattwespen Gilpinia polytoma (Hartig) und G. hercyniae (Hartig) (Hymenoptera: Diprionidae). Z. Angew. Zool., 49:111-122.

Oehlke J, 1965. Die in europSischen Kiefernbuschhornblattwespen (Diprionidae) parasitierenden Ichneumonidae. Beitrage zur Entomologie, 15:791-879.

Ohnesorge B, Serafimovski A, 1961. Die Disposition der Omorikafichte (Picea omorika Pancic) für nadelfressende und -saugende Arthropoden. Allg. Forst.- u. Jagdztg., 132:129-131.

Ohnesorge B, Thalenhorst W, 1956. Zur Kenntnis der Fichten-Blattwespen. IV. Die Dispersion. Z. Pfl.krankh. u. Pfl.schutz, 63:197-211.

Otto LF, 1991. Investigations on the influence of changing temperatures on larval development of Gilpinia hercyniae Htg. (Hym., Diprionidae) and on the possibilities for their mathematical description. Zeitschrift fur Angewandte Zoologie, 78(1):31-43

Phillips DH, 1978. The EEC Plant Health Directive and British forestry. Forest Record, No. 116:22 pp.

Prebble ML, 1941. The diapause and related phenomena in Gilpinia polytoma (Hartig), I-V. Can. J. Res. (D), 19:295-322, 323-346, 350-362, 417-436, 437-454.

Prebble ML, 1943. Sampling methods in population studies of the European spruce sawfly, Gilpinia hercyniae (Hartig), in Eastern Canada. Trans. R. Soc. Canada, 1943 V, 93-126.

Pschorn-Walcher H, 1965. The ecology of Neodiprion sertifer (Geoffr.)(Hym.: Diprionidae) and a review of its parasite complex in Europe. Technical Bulletin, Commonwealth Institute of Biological Control, 5:33-97.

Pschorn-Walcher H, 1974. European spruce sawflies (Gilpinia spp.): Work in central Europe in 1973 and a review of the project to introduce natural enemies into Britain. Report, Delemont, Switzerland: Commonwealth Inst. of Biol. Control.

Pschorn-Walcher H, 1982. Suborder Symphyta, sawflies. In: Schwenke W, ed. Die Forstschaedlinge Europas. 4. Hautflügler und Zweiflügler. Hamburg, Germany: Paul Parey, 66-129.

Reeks WA, 1938. Native insect parasites and predators attacking Diprion polytomum (Hartig) in Canada. Rep. Ent. Soc. Ont., 60:25-28.

Reeks WA, 1941. On the taxonomic status of Gilpinia polytoma (Htg.) and G. hercyniae (Htg.) (Hymenoptera, Diprionidae). Can. Ent., 73:177-188.

Reeks WA, 1952. Establishment of Exenterus spp. (Hymenoptera: Ichneumonidae), parasites of the European spruce sawfly, near points of introduction. Can. Ent., 84:76-86.

Reeks WA, 1953. The establishment of introduced parasites of the European spruce sawfly Diprion hercyniae (Htg.) (Hymenoptera: Diprionidae) in the Maritime provinces. Canad. J. Agric. Sci., 33:405-429.

Reeks WA, 1963. The European spruce sawfly (Diprion hercyniae) in Ontario 1936 to 1962. Bi-m. Progr. Rep. For. Ent. Path. Br. Dep. For. Can., 19:2-3.

Reeks WA, Barter GW, 1951. Growth reduction and mortality of spruce caused by the European spruce sawfly, Gilpinia hercyniae (Htg.) (Hymenoptera: Diprionidae). Forestry Chronicle, 27:140-156.

Reeks WA, Cameron JM, 1971. Current approach to biological control of forest insects. In: Biological control programmes against insects and weeds in Canada 1959-1968. Commonw. Inst. Biol. Contr. Techn. Comm., 4:105-113.

Riley CG, Skolko AJ, 1942. Rate of deterioration in spruce killed by the European spruce sawfly. Pulp. Pap. Mag. Can., 43:521-524.

Rohwer SA, 1910. Japanese sawflies in the collection of the United States National Museum. Proc. U.S. Natn. Mus., 39:99-120.

Sabsch R, Schopf R, 1990. Oviposition and egg development of Gilpinia hercynip Htg. (Hym., Diprionidae) on needles of diseased and apparently healthy Norway spruce (Picea abies (L.) Karst.). Journal of Applied Entomology, 109(3):274-282

Schaffner JV Jr, 1943. Sawflies injurious to conifers in the Northeastern States. J. For., 41:580-588.

Schedl W, 1975. Die Pflanzenwespen (Hymenoptera, Symphyta) des Landesmuseums Joanneum in Graz. Teil 3: Tenthredinoidea: Familie Diprionidae. Mitt. Abt. Zool. Landesmus. Joanneum, 4:203-210.

Schedl W, 1982. Catalogus Faunae Austriae. Teil XVIb: U.-Ordn.: Symphyta II. Wien, Österreich: Verlag der Österreichischen Akademie der Wissenschaften.

Scheidter F, 1934. Forstentomologische BeitrSge. 28. Bestimmungstabelle fnr die Raupen der Gattung Lophyrus (Diprion). Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz, 44:406-411.

Schopf R, 1979. The food quality of spruce needles for forest-damaging insects. 11. Intake and excretion of 14C-labelled compounds by larvae of Gilpinia hercynip (Hym., Diprionidae) after feeding on radioactive spruce needles. Zeitschrift fur Angewandte Entomologie, 87(3):262-276

Schopf R, 1980. On the food quality of spruce needles for forest insect pests. 13. Studies on the nitrogen balance of larvae of Gilpinia hercynip Htg. (Hym., Diprionidae) after feeding on needles of spruce (Picea abies Karst) of different origin. Zeitschrift fur Angewandte Entomologie, 89(1):3-12

Schopf R, 1981. As to the food quality of spruce needles for forest damaging insects. 16. Assimilation of spruce needle compounds by the sawfly Gilpinia hercynip (Hym., Diprionidae). Zeitschrift fur Angewandte Entomologie, 91(3):236-241

Schopf R, 1982. Die Bestimmung der Nahrungsqualität zur Beurteilung der Eignung von Waldbäumen für den Befall durch phytophage Insekten. Forstarchiv, 53:205-208.

Schopf R, 1983. The importance of the pattern of spruce-needle composition for the development of phytophagous insects. Zeitschrift für Angewandte Entomologie, 96(2):166-172; [2 fig.]; 28 ref.

Schopf R, 1983. Zur Nahrungsqualität von Fichtennadeln für forstliche Schadinsekten. 20. Korrelationen der Konzentrationen von Fichtennadelinhaltstoffen mit Entwicklungsparametern der Blattwespe Gilpinia hercyniae Htg. (Hym., Diprionidae). Z. Angew. Ent., 95:189-196.

Schopf R, 1986. Laboratory studies on the predisposition of spruces (Picea abies Karst.) damaged to varying degrees to infestation by Gilpinia hercynip Htg. (Hym., Diprionidae) and Lymantria monacha L. (Lep., Lymantriidae). Journal of Applied Entomology, 101(4):389-396

Schopf R, 1986. The effect of secondary needle compounds on the development of phytophagous insects. Forest Ecology and Management, 15(1):55-64

Schopf R, 1986c. Zur Kausalanalyse der Disposition von Nadelbäumen für den Befall durch nadelfressende Insekten am Beispiel Picea abies (L.) Karst. und Gilpinia hercyniae Htg. (Hym., Diprionidae). Schriften aus der Forstl. Fakultät der Universität Göttingen und der Niedersächs. Forstl. Versuchsanstalt, No. 87.

Schopf R, 1989. Spruce needle compounds and the susceptibility of Norway spruce (Picea abies Karst.) to attacks by the European sawfly, Gilpinia hercynip Htg. (Hym., Diprionidae). Journal of Applied Entomology, 107(5):435-445

Schopf R, Hartl FJ, 1997. The host tree as a nutrient source for herbivorous insects. Mitteilungen der Deutschen Gesellschaft fu^umlaut~r Allgemeine und Angewandte Entomologie, 11(1/6):633-638; 20 ref.

Schopf R, Mignat C, Hedden P, 1982. As to the food quality of spruce needles for forest damaging insects. 18. Resorption of secondary plant metabolites by the sawfly Gilpinia hercynip Htg. (Hym., Diprionidae). Zeitschrift fur Angewandte Entomologie, 93(3):244-257

Schwarz U, 1973. The food value of spruce needles for forest insect pests. 4. Investigations on four carbohydrate-reducing enzymes in larvae of Gilpinia hercyniae Htg. Zeitschrift fur Angewandte Entomologie, 74(1):94-105

Scobiola-Palade X, 1985. La liste des espèces d'Argidae, de Cimbicidae et de Diprionidae (Sous-Ord. Symphyta) de Roumanie. Trav. Mus. Hist. nat. "Grigore Antipa", 24:125-133.

Sellers WF, 1942. The distribution of the European spruce sawfly Diprion polytomum (Htg) in the Scandinavian and Eastern Baltic countries. Bull. Ent. Res., 33:149-152.

Smirnoff WA, Berlinguet L, 1966. A substance in some commercial preparations of Bacillus thuringiensis var. thuringiensis toxic to sawfly larvae. J. Invert. Pathol., 8:376-381.

Smith DR, 1971. Some sawflies from Pakistan (Hymenoptera: Diprionidae, Tenthredinidae). Proceedings of the Entomological Society of Washington, 73(4):401-408

Smith DR, 1974. Conifer sawflies, Diprionidae: key to North American genera, checklist of world species, and new species from Mexico (Hymenoptera). Proceedings of the Entomological Society of Washington, 76(4):409-418

Smith DR, 1979. Symphyta. In: Krombein KV, Hurd PD, Smith DR, Burks BD. Catalog of Hymenoptera in America north of Mexico, 1: 1-137.

Smith DR, 1993. Systematics, life history, and distribution of sawflies. In: Wagner MR, Raffa KF, eds. Sawfly life history adaptations to woody plants. San Diego, USA; Academic Press, Inc., 3-32

Smith SG, 1938. Cytology of spruce sawfly and its control in Eastern Canada. Nature, 141:121.

Smith SG, 1941. A new form of spruce sawfly identified by means of its cytology and parthenogenesis. Scient. Agric., 21:245-305.

Spiller R, Lunderstädt J, 1988. The effects of different rearing conditions on the population structure during larval development of Gilpinia hercynip Htg. (Hym., Diprionidae). Journal of Applied Entomology, 105(3):229-248

Thalenhorst W, 1955. Zur Kenntnis der Fichten-Blattwespen. III. Die Apparenzen der Diprionini. Z. Pfl.krankh. u. Pfl.schutz, 62:353-361.

Thalenhorst W, 1960. Zur Kenntnis der Fichten-Blattwespen. VI. Die Populationsdichte der Diprionidae: Niveau und Fluktuationen. Z. Pfl.krankh. u. Pfl.schutz, 67:513-524.

Thalenhorst W, 1966. Zur Kenntnis der Fichten-Blattwespen. VII. Das Geschlechterverhältnis. Z. Pfl.krankh. u. Pfl.schutz, 73:57-69.

Thalenhorst W, 1968. Zur Kenntnis der Fichten-Blattwespen. VIII. Eizahl und Eiablage. Z. Pfl.krankh. u. Pfl.schutz, 75:338-350.

Thalenhorst W, 1973. Contributions to knowledge of the spruce sawflies. IX. The temperature-development-function of egg and larva. Zeitschrift fur Pflanzenkrankheiten und Pflanzenschutz, 80(3/4):133-147

Tinsley TW, Entwistle PF, Robertson JS, 1980. Advances in insect pest control I. Insect pathogenic viruses. Commonwealth Forestry Review, 59(3):327-336

Vehrke H, 1961. Zur Unterscheidung der Larven von Gilpinia abieticola (D.T.), G. polytoma (Htg.) und G. hercyniae (Htg.) (Hymenoptera: Diprionidae) nach dem Zeichnungsmuster der Kopfkapseln. Z. angew. Ent. 48:176-185.

Verzhutskii BN, 1965. [On some sawfly pests of conifers new to Cisbaikalia]. Izv. Sib. Otdel., Akad. Nauk. SSSR, Ser. biol-med. Nauk, 1:100-104.

Verzhutskii BN, 1969. Sawflies of the Baikal region. Transl. Dep. Fish. For. Can. No. OOFF-81 [Transl. from Pililsciki Pribajkalja. Akademija Nauk SSSR, Moscow. 1966], 391 pp.

Verzhutskii BN, 1973. Keys to the larvae of the wood-wasps and sawflies of Siberia and the Soviet Far East. Opredelitel' lichinok rogokhvostov i pilil'shchikov Sibirii i Dal'nego Vostoka. Moscow, Izdatel'stvo Nauka. USSR, 140 pp.

Viitasaari M, Heidemaa M, Nuorteva M, Zinovjev A, 1998. An annotated checklist of the sawflies (Hymenoptera, Symphyta) of Estonia. Proceedings of the Estonian Academy of Sciences, Biology, Ecology, 47(2):126-147; 30 ref.

Viitasaari M, Varama M, 1987. SahapistiSiset 4. HavupistiSiset (Diprionidae). Summary: Sawflies 4. Conifer sawflies (Diprionidae). Univ. Helsinki, Dep. Agric. and For. Zool., Reports 10:1-79.

Vikberg V, 1985. Dipriocampe elongata (Erdös, 1951), an addition to the Finnish fauna (Chalcidoidea, Tetracampidae). Notulae Ent., 65:166.

Weitzel C, Hilker M, 1993. Oviposition deterrence in the sawflies Diprion pini (L.) and Gilpinia hercyniae Htg. (Hymenoptera: Diprionidae). Mitteilungen der Deutschen Gesellschaft fur Allgemeine und Angewandte Entomologie, 8(4-6):697-701

Williams DT, Straw NA, Day KR, 2003. Defoliation of Sitka spruce by the European spruce sawfly, Gilpinia hercyniae (Hartig): a retrospective analysis using the needle trace method. Agricultural and Forest Entomology, 5:235-245.

Wolf F, 1969. Sur les Hyménoptères Symphytes inféodés à l'épicéa en Belgique. Bull. Rech. agron. Gembloux, 4:586-593.

Wong HR, 1972. The spread of the European spruce sawfly, Diprion hercyniae (Hymenoptera: Diprionidae) in Manitoba. Can. Ent., 104:755-756.

Wong HR, Ives WGH, 1969. The European spruce sawfly in Manitoba. Bi-Monthly Research Notes, 25(6):47

Wong HR, Szlabey DL, 1986. larvae of the North American genera of Diprionidae (Hymenoptera: Symphyta). Canadian Entomologist, 118(6):577-587

Zhelochovtsev AN, 1988. Symphyta. In: Medvedjev GS, ed. Opredelitel nasekomykh Evropeiskoi Chasti SSSR. III. Pereponchatokrylye 6. Opredeliteli po faune SSSR 158. Leningrad: Nauka, 7-234.

Zhelochovtsev AN, 1994. 27. Order Hymenoptera. Suborder Symphyta (Chalastogastra). In: Medvedjev GS, ed. Keys to the insects of the European part of the USSR. Translation, New Delhi: Amerind. Publ. Co. Pvt. Ltd., 3:1-387.

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