© Entomologica Fennica. 3l.V.l993 Attraction of Epuraea bickhardti St.-Claire Deville and E. boreella (Zetterstedt) (Coleoptera, Nitidulidae) to ethanol and a-pinene L. M. Schroeder Schroeder, L. M. 1993: Attraction of Epuraea bickhardti St.-Claire Deville and E. boreella (Zetterstedt) (Coleoptera, Nitidulidae) to ethanol and a-pinene. Entomol. Fennica 4:133-135. High numbers of Epuraea beetles (Coleoptera, Nitidulidae) were caught in flight barrier traps baited with ethanol and the conifer monoterpene a-pinene. Of the Epuraea beetles caught, 95% were E. bickhardti and 3% were E. boreella. E. bickhardti was strongly attracted by ethanol alone. Ethanol in combination with a-pinene attracted both E. bickhardti and E. boreella. No sex related differences between treatments were detected for either of the species. L. M. Schroeder, Swedish University of Agricultural Sciences, Division of Forest Entomology, S-75007 Uppsala, Sweden 1. Introduction The aim of this study was to find out which of the Epuraea species present in conifer forests The genus Epuraea (Coleoptera, Nitidulidae) are attracted in flight to ethanol and a-pinene. comprises 39 species in Fennoscandia (Lundberg 1986). Information about the biology of Epuraea species is scarce in the literature. One reason for 2. Materials and methods this may be that the adults of many of the species are morphologically very similar. Thus reliable The study presented here is based on Epuraea identifications generally have to be based on the material obtained in earlier field experiments appearance of the male genitalia. Epuraea species conducted in a mixed stand of Scots pine and have been demonstrated to breed in dead or dying Norway spruce in central Sweden (Schroeder trees attacked by bark beetles, in sap flows from 1988). The attraction of beetles to ethanol and a damaged trees, and in fungi (Nuorteva 1956, pinene was studied with flight barrier traps. Palm 1959, Freude et al. 1967). Many beetle In 1986 (May 2-May 4) attraction of beetles species inhabiting dead or dying trees are attracted to (-)-a-pinene (Fluka 97%) alone and in com by volatiles released from this kind of substrate. bination with four different release rates of 95% In earlier studies (Schroeder 1988, Schroeder & ethanol (5% water) was studied (Table 1). Release Linde low 1989) high numbers of Epuraea beetles rates were estimated in the laboratory by meas were caught in traps baited with the degradation uring the weight loss of the dispensers (vials product ethanol and the conifer monoterpene a with differently sized openings) over time when pinene. However, no detailed analysis of the placed in a wind tunnel at 0.5 m/s and + 15 °C. species of Epuraea caught in those studies was Unbaited control traps were included in the ex made. periment. The six treatments were arranged in 15 134 Schroeder: Epuraea attracted to ethanol and a-pinene • ENTOMOL. FENNICA Vol. 4 randomized blocks. The distance between traps E. boreella were caught in the traps baited with in each block was at least 6 m and the distance a-pinene alone. between blocks at least 10 m. After this experi The female proportion of the E. bickhardti ment the same experimental setup was used to catch in the experiment with ethanol alone was assess attraction to ethanol alone (May 5-May 45%, while in the experiment with combinations 6). The release rates employed in this experiment of ethanol and a-pinene it was 51%. Fifty percent were the same as those used in the previous of the E. boreella caught were females. No dif experiment. For further experimental details, see ference in sex ratio between treatments was de Schroeder 1988. tected for any of the species (X2-test, P < 0.05). Sex determinations were made by dissection for E. boreella (Zetterstedt) and by examining the middle tibia for E. bickhardti St.-Claire 4. Discussion Deville. Both E. bickhardti and E. boreella inhabit Scots pine and Norway spruce in Scandinavia (Saalas 3. Results 1917, Nuorteva 1956). The adults and their progeny are found under the bark of dead trees, Ninety-five percent of the total number of often in bark beetle galleries. This type of decayed Epuraea beetles caught in the two experiments breeding material may release high amounts of were E. bickhardti and 3% were E. boreella. ethanol (cf. Cade et al. 1970, Moeck 1970), in These were the only Epuraea species caught in combination with monoterpenes. a-pinene is one sufficiently high numbers to permit differences of the major monoterpene constituents of both in numbers of beetles caught among the various Scots pine and Norway spruce (Heemann & treatments to be analysed statistically. E. pygmaea Francke 1977, Yazdani & Nilsson 1986, Strom (Gyllenhahl), E. angustula (Sturm), E. unicolor vall & Petersson 1991). Detailed information (Olivier), and E. biguttata (Thunberg), were most numerous among the other Epuraea species caught. Table 1. Total numbers of E. bickhardti and E. boreella Seven E. bickhardti were caught in the caught in flight barrier traps baited with ethanol alone unbaited traps in the two experiments, while 395 (E) or a-pinene alone (P) and in combination with were caught in the traps baited with ethanol alone ethanol (P+E). Unbaited traps were included in both and 3285 in the traps baited with combinations experiments. Release rates in mg/hr.-Values within of ethanol and a-pinene (Table 1). In both ex a species and experiment followed by the same letter periments the number of E. bickhardti caught are not significantly different at P = 0.05 level (nonparametric multiple comparison of Tukey-type). increased with increasing ethanol release rates. The differences in catch between unbaited and Release rate (mg/hr) E.bickh. E.boreella baited traps were statistically significant at the P a-pinene ethanol = 0.05 level at the two highest release rates for the traps baited with ethanol alone and for all Experiment 1 Unbaited 1a four combinations of ethanol and a-pinene. Traps E 1.5 18ab baited with a-pinene alone caught about eight E 13 17ab times as many E. bickhardti as unbaited traps but E 128 111b the difference was not statistically significant. E 2116 249c Not a single E. boreella was caught in the Experiment 2 unbaited traps, whereas 98 were caught in the Unbaited 6a oa traps baited with combinations of ethanol and a p 10 46ab 3a pinene. Most of these were caught at the two P+E 10 1.5 111b sa highest ethanol release rates, which were also the P+E 10 13 182bc 3a only treatments that differed significantly in E. P+E 10 128 837cd 26b P+E 10 2116 2155d 64b boreella catch from unbaited traps. Only a few ENTOMOL. FENNICA Vol. 4 • Schroeder: Epuraea attracted to ethanol and a-pinene 135 about the feeding habits of E. bickhardti and E. Ikeda, T., Enda, N., Yamane, A., Oda, K. & Toyoda, T. boreella is not available. In the laboratory E. 1980: Attractants for the Japanese pine sawyer, Mono chamus altematus Hope (Coleoptera: Cerambycidae). bickhardti is able to develop successfully on a - Appl. Entomol. Zoo!. 15:358-361. diet of bark beetle eggs (Nuorteva 1956), sug Lundberg, S. 1986: Catalogus Co1eopterorum Sueciae. gesting that this species may be predatory. Entomologiska Foreningen i Stockholm och Natur Ethanol is absent or present in only small historiska Riksmuseet, Stockholm. 155 pp. amounts in newly felled conifers unsuitable as Moeck, H. A. 1970: Ethanol as the primary attractant for breeding material for Epuraea species, while large the ambrosia beetle, Trypodendron lineatum (Coleo ptera: Scolytidae).-Can. Entomol. 102:985-995. quantities of monoterpenes are released from this Nuorteva, M. 1956: Uber den Fichtenstamm-Bastkiifer, kind of trees (Ikeda et a!. 1980, Stri:imvall & Hylurgops palliatus Gyll., und seine Insektenfeinde. Pettersson 1991). This may explain the observed -Acta Entomol. Fennica 13:1-118. weak attraction of E. bickhardti to a-pinene alone Palm, T. 1959: Die Holz- und Rinden-Kafer der Slid-und compared with the attraction to combinations of Mittelschwedischen Laubbiiume. - Opuscula Ento ethanol and a-pinene. mol., Suppl. 16. 374 pp. Saalas, U. 1917: Die Fichtenkiifer Finnlands. I.-Ann. Acknowledgements. I wish to thank H. H. Eidmann for Acad. Scient. Fenn. (Ser. A)8(1). 547 pp. comments on the manuscript. Financial support from the Schroeder, L. M. 1988: Attraction of the bark beetle SJFR Research Council is gratefully acknowledged. Tomicus piniperda and some other bark- and wood living beetles to the host volatiles a-pinene and ethanol. -Entomol. Exp. Appl. 46:203-210. Schroeder, L. M. & Lindelow, A. 1989: Attraction of References scolytids and associated beetles by different absolute amounts and proportions of a-pinene and ethanol. - Cade, S.C., Hrutfiord, B. F. & Gara, R.I. 1970: Identifi J. Chern. Ecol. 15:807-817. cation of a primary attractant for Gnathotrichus sulcatus Stromvall, A.-M. & Petersson, G. 1991: Conifer mono isolated from western hemlock logs. - J. Econ. terpenes emitted to air by logging operations.- Scand. Entomol. 63:1014-1015. J. Forest Res. 6:253-258. Freude, H., Harde, K. W. & Lohse, G. A. 1967: Die Kafer Yazdani, R. & Nilsson, J.-E. 1986: Cortical monoterpene Mitteleuropas, 6.-Goecke & Evers, Krefeld. 310 pp. variation in natural populations of Pinus sylvestris in Heemann, V. & Francke, W. 1977: Gaschromatographisch Sweden.-Scand. J. Forest Res. 1:85-93. Massenspektmmetrische Untersuchungen der fliich tigen Rindeninhaltsstoffe von Picea abies (L.) Karst. - Planta Medica 32:342-346. Received 26.II.l992