J Pest Sci (2004) 77: 179–182 DOI 10.1007/s10340-004-0053-6
O R I GI N A L A R T IC L E
G. Georgiev Æ M. Raikova Æ T. Ljubomirov Æ K. Ivanov
New parasitoids of Saperda populnea (L.) (Col. Cerambycidae) in Bulgaria
Received: 24 February 2004 / Published online: 17 April 2004 Springer-Verlag 2004
Abstract The parasitoid complex of Saperda populnea (L.) (Col., Cerambycidae) was studied during the period 2002–2003 at different sites in Bulgaria. Galls containing cerambycid larvae were collected on branches of aspen (Populus tremula L.), goat willow (Salix caprea L.) and hybrid poplars and were studied under laboratory conditions. As a result, four new species for the parasitoid complex of S. populnea in Bulgaria were recorded: Dolichomitus tuberculatus (Geoffroy), Xylophrurus lancifer (Gravenhorst), Gelis ornatulus (Thomson) (Hym., Ichneumonidae) and Dendrocerus serricornis (Boheman) (Hym., Megaspilidae). D. serricornis and G. ornatulus are new species for Bulgarian fauna. D. tuberculatus and X. lancifer were found as primary parasitoids, and G. ornatulus and D. serricornis as hyperparasitoids. The primary parasitoids developed solitarily in the host larvae. D. serricornis was reared gregariously from a puparium of Billaea irrorata (Meig.) (Dipt., Tachinidae). The host of G. ornatulus was not identified, but the hyperparasitid could be connected with Iphiaulax impostor (Scop.) (Hym., Braconidae). The mortality of S. populnea caused by the parasitoids was 2.0–6.3%. Keywords Saperda populnea Æ Parasitoids Æ Ichneumonidae Æ Megaspilidae Æ Bulgaria
Introduction The small poplar longhorn beetle, Saperda populnea (L.) (Col., Cerambycidae), is a xylophagous insect that feed on poplars (Populus spp.) and some willows (Salix spp.). It develops in young stems and branches causing extensive damage to the host plants. Attacked trees produce galls at the points of infection. S. populnea is also a vector of fungal and bacterial diseases of the host plants (Grechkin and Vorontsov 1962). In Bulgaria, S. populnea is one of the most destructive pests in young poplar plantations (Daskalova 1968; Keremidchiev 1968; Georgiev 1996), poplar ornamentals (Georgiev and Delkov 1997) and aspen stands (Georgiev 2001). The population density of S. populnea is limited by the number of entomophagous insects (e.g. Pulkkinen and Yang 1884; Postner 1954; Hellrigl 1974). In Bulgaria, four parasitoid species—Iphiaulax impostor (Scop.) (Hym., Braconidae), Dolichomitus populneus (Ratz.), Schreineria populnea (Gir.) (Hym., Ichneumonidae) and Billaea irrorata (Meig.) (Dip., Tachinidae)—were established to kill an average of 13–33% of the pest larvae (Tsankov and Georgiev 1991; Georgiev 2001). This paper reports new hymenopteran parasitoids of S. populnea found in Bulgaria.
Materials and methods
G. Georgiev (&) Forest Research Institute, 132 St. Kliment Ohridski Blvd, 1756 Sofia, Bulgaria E-mail:
[email protected] M. Raikova Forest Protection Station, 82 Slavyanska St., 4000 Plovdiv, Bulgaria T. Ljubomirov Æ K. Ivanov Institute of Zoology, 1 Tsar Osvoboditel Blvd., 1000 Sofia, Bulgaria
The studies were conducted during the period 2002–2003 at different sites in Bulgaria. The parasitoids were reared under laboratory conditions from galls with S. populnea larvae collected from branches of aspen (Populus tremula L.), goat willow (Salix caprea L.) and hybrid poplar clones, Populus · euramericana (Dode) Guinier. Some characteristics of the studied areas and biological materials are given in Table 1. The laboratory methods used in this study are described in other publications (Tsankov and Georgiev 1991; Georgiev 2001).
180 Table 1 Main characteristics of the studied areas and biological materials Species
PrImary parasitoids Dolichomitus tuberculatus (Geoffroy) Xylophrurus lancifer (Gravenhorst)
Secondary parasitoids Gelis ornatulus (Thomson)a Dendrocerus serricornis (Boheman)a a
Locality
Altitude (m)
Host plant
Dates of sample collection
Parasitoid number ##
$$
Emergence date
Parasitism (%)
Gorni Lom
700
Populus tremula L.
30.03.2002
-
1
03.04.2002
4.8
Manole Lozen Simeonovgrad Ognjanovo Plovdiv
130 230 120 190 150
Populus Populus Populus Populus Populus
· · · · ·
euramericana euramericana euramericana euramericana euramericana
28.02.2003 26.02.2003 12.03.2003 13.03.2003 27.03.2003
4 1 1 -
4 1 1 2 1
17–31.03.2003 18.03.2003 19–22.03.2003 31.03.2003 12.04.2003
3.2 2.0 6.3 2.7 4.5
Plovdiv
150
Populus · euramericana
18.04.2002
-
1
27.05.2002
-
Gorni Lom
950
Salix caprea L.
30.03.2002
2
5
15–16.04.2002
-
A new species for Bulgarian fauna
The emerged parasitoids are kept in the collections of the Forest Research Institute and Institute of Zoology in Sofia.
Fig. 1 Location of the parasitoid collection sites in Bulgaria
Results Four new hymenopteran parasitoids of S. populnea were recorded in Bulgaria: Dolichomitus tuberculatus (Geoffroy), Xylophrurus lancifer (Gravenhorst), Gelis ornatulus (Thomson) (Hym., Ichneumonidae) and Dendrocerus (Macrostigma) serricornis (Boheman) (Hym., Megasp-
181
ilidae) (Table 1). D. serricornis and G. ornatulus are new species for Bulgarian fauna. Whereas X. lancifer was established at five sites, the remaining species were only found at single sites (Table 1). The collection sites of the parasitoids are indicated in Fig. 1. D. tuberculatus and X. lancifer were established as primary parasitoids. They developed solitarily on S. populnea larvae. G. ornatulus and D. serricornis were observed as hyperparasitoids of S. populnea for the first time in this study. D. serricornis parasitized gregariously on Billaea irrorata (Meig.) (Dipt., Tachinidae), a primary parasitoid of S. populnea. All hyperparasitoid specimens were reared from single puparia of the tachinid. The host of G. ornatulus was not identified, but the hyperparasitoid could be connected with the primary parasitoid Iphiaulax impostor (Scop.) (Hym., Braconidae), which emerged from the same samples. The mortality of S. populnea caused by the primary parasitoids was low and ranged between 2.0–6.3% (Table 1). In this study, only single cases of hyperparasitism were recorded and, therefore, the observed impacts of the secondary parasitoids on the primary ones are not reliable.
Discussion The ichneumonids D. tuberculatus and X. lancifer are well known as larval parasitoids of S. populnea (Postner 1954). D. tuberculatus is distributed in the Holarctic region and is connected with many coleopteran and lepidopteran hosts (Medvedev 1981). In Bulgaria, it was found in a faunistic study in The Rhodopes (Kolarov 1997). The European species X. lancifer is connected with Saperda carcharias (L.) and S. populnea (Medvedev 1981). It is also reported as a parasitoid of Paranthrene tabaniformis (Rott.) (Lep., Sesiidae) (Szontagh 1965, 1971). The larvae of the sesiid bore into the xylem and cause similar galls on poplar shoots. It must be noted, however, that large numbers of P. tabaniformis larvae have been studied in Bulgaria, but X. lancifer has never been reared from this host (Georgiev 2000a, 2000b). In Bulgaria, only one specimen of the parasitoid (syn. X. dispar Thunberg) was found in a faunistic study in The Rhodopes (Kolarov 1983). G. ornatulus occurs in northern Europe (Medvedev 1981). No data about its hosts have been found in the entomological literature. D. serricornis is widespread in Russia and Moldova (Alekseev 1978). According to the author, it has been reared from larvae of Cremifania nigrocellulata Czerny (Dipt., Cremifaniidae), Leucopis griseola (Falle´n) (Dipt., Camaemyidae) and Leucomyia obscura Haliday (Dipt., Sarcophagidae), which are entomophages of different
adelgids (Hom., Adelgidae). The tachinid host of D. serricornis in this study, B. irrorata, is one of the most important parasitoids of S. populnea in Bulgaria (Tsankov and Georgiev 1991; Georgiev 2001). The life cycle of B. irrorata is well synchronised with host development and this synchrony is reflected in high levels of parasitism, which in some cases reach over 20– 50% (Georgiev 1998). In conclusion it should be noted that the new records enhance the parasitoid complex of S. populnea and increase the species strength of Bulgarian fauna. Acknowledgements We are very grateful to Ms. S. Kitanova, Forest Research Institute, Sofia, for her kind assistance in preparing the English language version of the manuscript.
References Alekseev VN (1978) Megaspilidae. In: Medvedev GS (ed) Keys to the insects of the European part of the USSR (in Russian). Hymenoptera, vol 3, part 2. Nauka, Leningrad, pp 677–681 Daskalova I (1968) Ausmaß einiger Scha¨den auf verschiedenen Pappelhybriden (in Bulgarian, German summary). Wissensch Arb Forsttechn Hochschule Sofia (Serie Forstwesen) 16, pp 95– 102 Georgiev G (1996) Biological and ecological peculiarities of Saperda populnea L., (Coleoptera: Cerambycidae) in Bulgaria (in Bulgarian, English summary). For Sci 2:51–58 Georgiev G (1998) Bioecological peculiarities of Billaea irrorata (Meig.) (Diptera, Tachinidae)—a parasitoid of Saperda populnea (L.) (Coleoptera, Cerambycidae) in Bulgaria (in Bulgarian, English summary). For Sci 4:72–81 Georgiev G (2000a) Studies on larval parasitoids of Paranthrene tabaniformis (Rott.) (Lepidoptera: Sesiidae) on urban poplars (Populus spp.) in Sofia, Bulgaria. Ann For Sci 57(2):181–186 Georgiev G (2000b) Parasitoids of Paranthrene tabaniformis (Rott.) (Lepidoptera: Sesiidae) in Bulgaria (in Bulgarian, English summary). Book 2: Zoology. Annu Sofia Univ ‘‘St. Kliment Ohridski’’, Fac Biol 92:121–126 Georgiev G (2001) Parasitoids of Saperda populnea (L.) (Coleoptera: Cerambycidae) on aspen (Populus tremula L.) in Bulgaria. J Pest Sci 74(6):155–158 Georgiev G, Delkov A (1997) Phytophagous insects and their parasitoids on poplar trees in Sofia (in Bulgarian, English summary). Acta Entomol Bulg 1–2:61–65 Grechkin VP, Vorontzov AI (1962) Insect pests and diseases of the poplars and their control (in Russian). Goslesbumizdat, Moscow, pp 149 Hellrigl K (1974) Cerambycidae. In: Schwenke W (ed) Die Forstscha¨dlinge Europas. Band 2, Ka¨fer. Parey, Hamburg, pp 130– 202 Keremidchiev M (1968) Entomo-characteristics of the poplar plantations and sanitary measures (in Bulgarian). Forestry 9:66–69 Kolarov J (1983) New and rare species from subfamily Gelinae (Hymenoptera: Ichneumonidae) for the fauna of Bulgaria (in Bulgarian, English summary). Acta Zool Bulg 23:70–77 Kolarov J (1997) Fauna Bulgarica, 25. Hymenoptera, Ichneumonidae. Part 1: Pimplinae, Xoridinae, Acaenitinae, Collyrinae (in Bulgarian, English summary). In Aedibus Academiae Scientiarum Bulgaricae Pensoft, Sofia , p 326 Medvedev GS (1981) Keys to the insects of the European part of the USSR (in Russian). Hymenoptera, vol. 3, part 3. Nauka, Leningrad, 687 pp Postner M (1954) Zur Biologie und Beka¨mpfung des kleinen Pappelbockes Saperda populnea L. (Cerambycidae). Z Angew Entomol 36:156–177
182 Pulkkinen M, Yang ZQ (1884) The parasitoids and predators of Saperda populnea (Linnaeus) (Coleoptera, Cerambycidae) in Finland. Ann Entomol Fenn 50:7–12 Szontagh P (1965) A Paranthrene tabaniformis Rott. hazai eletmodja es karositasa (in Hungarian). Allattani Ko¨zlemenyek 52(1–4):135–142
Szontagh P (1971) Adatok a Paranthrene tabaniformis Rott. (Lepidoptera) fejlodesi es parazitaltsagi viszonyaihoz (in Hungarian). Folia Entomol Hung 24(7):99–108 Tsankov G, Georgiev G (1991) Records on parasitoids on smaller poplar borer, Saperda populnea (Coleoptera, Cerambycidae) along the Danube in Bulgaria. Entomophaga 36(4):48–53
