ENTOMOLOGY A. Stojanovic and C. Markovic (2007) Phytoparasitica 35(3):239-243 The Hymenopteran Parasitoids of Some Elm Bark Beetles in Serbia Aleksandar Stojanovic 1 and Cedomir Markovic *,2 The parasitoids of the elm bark beetles Scolytus ensifer, S. kirschi, S. multistriatus, S. pygmaeus and Pteleobius vittatus were studied in ten localities in Serbia. Eleven species of parasitoids of S. ensifer, 10 of S. kirschi, 13 of S. multistriatus, 12 of S. pygmaeus, and four of P. vittatus were found. The most abundant were Ecphylus silesiacus, Dendrosoter protuberans, Cheiropachus quadrum and Rhaphitelus maculatus. Acrocormus semifasciatus, Cerocephala eccoptogastri, Mesopolobus typographi and Doryctes pomarius were found in some samples. KEY WORDS: Hymenoptera; parasitoids; Ulmus spp.; elm; Ophiostoma ulmi; Dutch elm disease; Serbia. INTRODUCTION Dutch elm disease, which is caused by the vascular fungus Ophiostoma ulmi (Schwarz) Nannfeldt, is a dangerous disease that has killed elm trees on a massive scale in Europe and North America. The vectors of Dutch elm disease in Europe are the bark beetles Scolytus scolytus (Fabricius), S. multistriatus (Marsham), S. pygmaeus (Fabricius), S. laevis Chapuis, S. kirschi Skalitzky and S. ensifer Eichhoff. In North America it is transmitted by S. multistriatus, which was introduced from Europe, and by the native elm bark beetle Hylurgopinus rufipes (Eichhoff). Following eclosion, adults of the mentioned species engage in maturation feeding in the crowns of healthy trees, gnawing the bark in the axils of slender branches. If the adults developed under the bark of infected trees, they carry spores of the fungus O. ulmi in the process. In the course of maturation feeding, the spores are transmitted to healthy trees, which are thereby infected (19). Parasitoids of elm bark beetles have been studied to date by a number of authors (1,2,4,15). Several investigators have established that the parasitoids of elm bark beetles can exert significant influence on their abundance (7,8,15,17). In Serbia, elm bark beetles have been studied by Maksimovic (6) and by Manojlovic et al. (9-12). Because the investigations of these authors were carried out in only one limited area of Serbia (Srem region), we decided to conduct a wider study of the spectrum of parasitoids of elm bark beetles in Serbia. MATERIALS AND METHODS Samples of branch and stem sections of elm trees Ulmus spp. inhabited by bark beetles and their parasitoids were collected during the period of 1994-1998 at ten localities in ReceivedFeb. 4, 2006;acceptedNov.9, 2006; http://www.phytoparasitica.org postingMay 4, 2007 1Natural HistoryMuseum,Belgrade,Serbia. 2Faculty of Forestry, Belgrade University, 11000 Belgrade, Serbia. *Corresponding author [e-mail: markovicc@ptt.yu]. Phytoparasitica 35:3, 2007 239