Research Article |
Corresponding author: Jaroslav Holusa ( holusaj@seznam.cz ) Academic editor: Marko Prous
© 2016 Emanuel Kula, Jaroslav Holusa, Ladislav Roller, Miroslav Úradník.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Kula E, Holuša J, Roller L, Úradník M (2016) Allochthonous blue spruce in Central Europe serves as a host for many native species of sawflies (Hymenoptera, Symphyta). Journal of Hymenoptera Research 51: 159-169. https://doi.org/10.3897/jhr.51.9219
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In air-polluted mountain areas of the Czech Republic, including the Ore Mountains, pure forest stands of introduced blue spruce (Picea pungens) were established in the 1980’s. We studied the Symphyta (Hymenoptera) fauna in the canopies of these trees at four sites and in the canopies of adjacent Picea abies trees at one of these sites by beating tree branches. For the first time, Nearctic blue spruce is reported as a host for 17 European species of Symphyta (sawflies). Diprionids in the genus Gilpinia were the most abundant sawflies on P. pungens and were more abundant on P. pungens than on the native Picea abies. Spruce pamphiliids in the genus Cephalcia were also more abundant on P. pungens than on P. abies, while the abundances of representatives of the tenthredinid genera Pikonema, Pachynematus, and Pristiphora were similar on P. pungens and P. abies. Our results indicate that many species of European spruce Symphyta are able to use the allochthonous species P. pungens as a host.
Picea pungens , Picea abies , Symphyta , Diprionidae , Tenthredinidae , Pamphiliidae , larvae
In Central Europe, P. abies (L.) Karst is the only native species of spruce (
Many forest pests including many defoliators feed on spruce (
At least 34 species belonging to three families of Symphyta (32 species in Central Europe) feed on needles of native spruce in Europe. These feeders include Pamphiliidae with at least nine species of Cephalcia (
Although the blue spruce P. pungens is planted in the extensive, air-polluted areas of the Czech Republic, the Symphyta fauna developing on this allochthonous plant have not been thoroughly studied. One reason is that serious outbreaks of pests have not occurred during the 25- to 30-year period following the establishment of pure stands of P. pungens in the Ore Mountains (
The host status of P. pungens for European native Symphyta is unknown. The goals of this study were (i) to identify the sawflies that feed on P. pungens in the Czech Republic and (ii) to compare the abundances of these sawflies on the native P. abies and on the introduced P. pungens.
Sawflies were studied in three localities in the Ore Mountains (NW Czech Republic) (Table
Locality | Tree species | Geographic characteristics | Altitude (m asl) | Stand density | Age of stand [years] | Area/percentage of spruce forest in district | Native forest type | Annual mean temperature and total precipitation |
---|---|---|---|---|---|---|---|---|
[%] | ||||||||
Jirkov | P. pungens | 50°33'11"N, 13°22'59"E | 875 | 90 | 25–36 | 14.43 km2/ | Fageto - Piceetum acidophilum | 4–4.5 °C |
15.4% | 1050–1200 mm | |||||||
Dlouhá louka | P. pungens | 50°39'00"N, 13°38'04"E | 865 | 70 | 34 | 29.37 km2/ | Fageto - Piceetum acidophilum | 4–4.5 °C |
22% | 1050–1200 mm | |||||||
Sněžník | P. pungens | 50°47'28"N, 14°04'33"E | 576 | 70 | 27–31 | 4.87 km2/ | Piceeto - Fagetum acidophilum | 4.5–5.5 °C |
4.5% | 900–1050 mm | |||||||
Sněžník | P. abies | 50°47'30"N, 14°04'15"E | 576 | 70 | 19 | 28.76 km2/ 26.6% | Piceeto - Fagetum acidophilum | 4.5–5.5 °C |
900–1050 mm |
Sawfly larvae and adults were sampled by beating tree branches and collecting the falling insects on a sheet stretched on a 0.5 × 1 m metal frame. On each sampling date, 10 samples were collected at each of the four stands. For each sample, two branches were selected at random in the crowns of 10 trees, the branches were located from 0.7 to 2.5 m above the ground, and the sampled trees were in a line with 10 m between adjacent trees. Trees were sampled on 17 May, 15 June, 14 July, 15 August, 15 September, and 15 October 2007. Thus, one sample consisted of insects collected from one stand (a total of 20 branches on 10 trees) across all six sampling dates.
The collected insects were stored in 75% ethanol. Larvae were identified using the keys of
The data of larvae per locality were not normally distributed. When the abundance of a sawfly species was > 10 on both P. abies and P. pungens at Sněžník, the values were compared with a Wilcoxon pair test in Statistica 12.0.
In total, 748 larvae and 79 adults of 36 species of sawflies were collected (Table
Total numbers of sawflies (Hymenoptera: Symphyta) collected on P. abies and P. pungens in the Czech Republic (plus information on known host plants for each species of sawfly). The sawflies were collected from 20 branches per stand (two branches on each of 10 trees) in three P. pungens stands (at Jirkov, Dlouhá louka, and Sněžník) and in one P. abies stand (at Sněžník) on six sampling dates from spring to fall in of 2007. Sawfly species feeding on spruce are in bold. When the abundance of a sawfly species (larvae + adults) was > 10 on both P. abies and P. pungens at Sněžník, the values were compared with a Wilcoxon pair test (an asterisk indicates a significant difference, and n.s. indicates a non-significant difference). The information on known host plants is from
Number of larvae | Number of adults | Known hosts | ||||
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Sawfly species | On P. abies at Sněžník | On P. pungens at all three stands (and at Sněžník in brackets) | Wilcoxon pair test | On P. abies at Sněžník | On P. pungens at all three stands | |
Arge fuscipes (Fallén, 1808) | 1 | 1 | Salix, Betula | |||
Cephalcia sp. | 5 | 17(4) | ||||
Cephalcia abietis (Linné, 1758) | 11(1) | 6 | P. abies, P. obovata, P. koraiensis | |||
Cephalcia alpina (Klug, 1808) | 2 | 16(2) | P. abies, P. obovata, P. koraiensis, P. jezoensis | |||
Cephalcia arvensis Panzer, 1805 | 16(7) | 4 | 11 | P. abies, P. obovata, P. koraiensis, P. jezoensis | ||
Cephalcia erythrogaster (Hartig, 1837) | 1(0) | 1 | P. abies, P. koraiensis | |||
Cephalcia fulva Battisti & Zanocco, 1994 | 1 | 6(2) | P. abies, P. koraiensis | |||
Dineura virididorsata (Retzius, 1783) | 1 | Betula | ||||
Dolerus gonager (Fabricius, 1781) | 1 | Poaceae | ||||
Dolerus nigratus (O.F.Müller, 1776) | 2 | Poaceae | ||||
Gilpinia sp. | 17 | 84 (42) | 2.36* | |||
Gilpinia abieticola (Dalla Torre, 1894) | 19 | 98 (19) | 0.00 n.s. | 2 | P. abies, P. obovata, Pinus pumila (probably missidentification, Karel Beneš pers. comm.) | |
Gilpinia hercyniae (Hartig, 1837) | 2 | 134 (4) | 0.80 n.s. | P. abies, P. obovata (In N. America P. glauca, P. sitchensis, P. pungens, P. mariana, P. rubens, P. pungens (Quarantine PEST data Sheet)) | ||
Gilpinia polytoma (Hartig, 1834) | 7 | 19 (19) | 1.85 n.s. |
P. abies, P. obovata, and P. smithiana ( |
||
Macrophya sanguinoleta (Gmelin, 1790) | 1 | Veronica, Galeopsis, Senecio | ||||
Pachynematus lichtwardti Konow, 1903 | 2 | unknown | ||||
Pachynematus (Epicenematus) sp. | 21 | 95(17) | 0.65 n.s. | |||
Pachynematus montanus (Zaddach, 1883) | 1 |
P. abies, and P. obovata ( |
||||
Pachynematus styx (Benson, 1958) | 1 | P. abies | ||||
Pachyprotasis rapae (Linné, 1767) | 7 | oligophagous | ||||
Pamphilius hortorum (Klug, 1808) | 1 | Rubus | ||||
Pikonema insigne (Hartig, 1840) | 1(1) |
P. abies, and P. obovata ( |
||||
Pikonema scutellatum (Hartig, 1840) | 11 | 11(1) | 1.94 n.s. | 1 | 1 | P. abies, P. obovata |
Pristiphora sp. | 17 | 39(12) | 1.40 n.s. | |||
Pristiphora abietina (Christ, 1791) | 2 | 6(4) |
P. abies, P. obovata ( |
|||
Pristiphora compressa (Hartig, 1837) | 8 | 41 (12) | 0.92 n.s. | 2 |
P. abies, and P. obovata ( |
|
Pristiphora decipiens (Enslin, 1916) | 4 | 15(6) | 1 | P. abies | ||
Pristiphora gerula (Konow, 1904) | 1 | 2(0) | P. abies | |||
Pristiphora leucopodia (Hartig, 1837) | 2 | 2(0) | P. abies | |||
Pristiphora pallida (Konow, 1904) | 1 | P. abies | ||||
Pristiphora pseudodecipiens Beneš & Křístek, 1976 | 6 | 6(0) | 1 | 1 | P. abies | |
Pristiphora robusta (Konow, 1895) | 1(0) |
P. abies, and P. obovata ( |
||||
Pristiphora saxesenii (Hartig, 1837) | 7(0) | P. abies | ||||
Pristiphora (Sharliphora) sp. | 2 | 9(2) | ||||
Pristiphora nigella (Förster, 1854) | 2 | P. abies | ||||
Pristiphora parva (Hartig, 1837) | 1 | P. abies | ||||
Tenthredo atra Linné, 1758 | 1 | oligophagous | ||||
Tenthredo mesomela Linné, 1758 | 3 | oligophagous | ||||
Tenthredo olivacea Klug, 1817 | 2 | oligophagous | ||||
Tenthredopsis ornata (Serville, 1823) | 3 | Brachypodium | ||||
Tenthredopsis scutellaris (Fabricius, 1804) | 1 | 15 | Festuca, Poa, Dactylis, Elytrigia | |||
Total | 127 | 621 | 10 | 69 |
Five species in the genus Cephalcia were only found in small numbers and on several specimens of P. pungens, and two of these five species were found on P. abies (Table
Diprionids of the genus Gilpinia were the most abundant sawflies in the samples and represented 51.8% and 35.4% of the specimens collected from P. pungens and P. abies, respectively. Gilpinia abieticola and G. hercyniae were the most numerous species, while G. polytoma was recorded exclusively in the P. abies and P. pungens stands at Sněžník. Although the Gilpinia abundancy did not differ between P. abies and P. pungens stands, more first and second instar larvae of Gilpinia were found on P. pungens than on P. abies at Sněžník (Table
Almost identical species (both larvae and adults) of spruce tenthredinids (Pristiphora, Pachynematus, and Pikonema) were found in the P. abies and the P. pungens samples, and the abundance of larvae of each species did not differ on P. abies vs. P. pungens. Based on larvae, Pachynematus (Epicenematus) sp. followed by Pristiphora compressa were the most abundant species in P. pungens samples (Table
Across all species, sawfly abundance did not statistically differ on P. abies vs. P. pungens at Sněžník (z=0.59, p>0.05).
In the current study, a total of 18 sawfly species were collected from P. pungens in the Ore Mountains of the Czech Republic. This represents 56% of the species of needle-feeding spruce sawflies in Central Europe (N=32) (
In Central Europe, eight species of Pamphiliidae are associated with P. abies (
The most abundant larvae collected from P. pungens were species of Gilpinia. All three spruce diprionids (G. abieticola, G. hercyniae, and G. polytoma) are common in spruce stands in Central Europe (
The numbers of spruce tenthredinids in the genera Pikonema, Pristiphora, and Pachynematus were similar on P. pungens vs. P. abies. We suspect that the L1 and L2 larvae identified as Pachynematus (Epicenematus) sp. are P. montanus, although Pachynematus (Epicenematus) pallescens (Hartig, 1837) and the extremely rare P. styx may also be present in the studied stands. The former species has the ability to rapidly increase (
The larvae of eight Pristiphora species plus adults of P. (Sharliphora) pallida and P. (Sharliphora) parva were collected on P. pungens, but it is very probable that larvae of Pristiphora (Sharliphora) sp. were represented mainly by the larvae of Pristiphora nigella. P. abietina is a pest of Norway spruce in Central Europe (
In the investigated air-polluted areas the native P. abies stands are almost completely absent because this tree was not used for forest regeneration in the 1980’s (
The spruce-feeding sawflies in Central Europe are not strictly monophagous on P. abies. Most of these species have been observed to feed on other Palaearctic spruces like Picea obovata (Ledeb.), Picea koraiensis Nakai, and Picea jezoensis (Sieb. & Zucc.) (
Because the abundance of sawfly larvae and adults was low in the current study (compare with
Our results demonstrate that European spruce sawflies are able to use the diverse allochtonous spruce species as hosts and may show stronger preferences for the new host, here especially P. pungens, than for the native host, P. abies.
This study was supported by grants VZ MSM 6215648902 “Forest and Wood: the support of functionally integrated forest management and use of wood as a renewable raw material“, and EHP-CZ02-OV-1-044-01-2014 “Frameworks and possibilities of forest adaptation measures and strategies connected with climate change“. The study was also sponsored by the following companies and organizations: Netex Co. (Děčín), Nadace ČEZ Co. (Prague), Lafarge cement (Čížkovice). The authors thank Dr. Bruce Jaffee (USA) for critically reading the manuscript.