No.~ 1991 SER. B VOL. 38 NO. 1 Norwegian Journal of Entomology PUBUSHEDBY NORSK ZOOLOGISK TIDSSKRlFfSENTRAL OSLO Fauna norvegica Ser. B Norwegian Journal of Entomology Norsk Entomologisk Forenings tidsskrift Appears with one volume (two issues) annually Ornitologisk Forening mottar tidsskriftet ved a Utkommer med to hefter pr. ar. ')etale kr. 65,-. Andre ma betale kr. 85,-. Disse nnbetalinger sendes til NZT, Zoologisk Museum, Editor-in-Chief (Ansvarlig redakter) 3arsgt. 1, N-0562 Oslo 5. Postgiro 0806 2348365. John O. Solem, University of Trondheim, The Museum, N-7004 Trondheim. FAUNA NORVEGICA B publishes original new Editorial Committee (Redaksjonskomite) information generally relevant to Norwegian ento­ Arne Nilssen Zoological Dept., Troms0 Museum, mology. The journal emphasizes papers which are N-9000 Troms0, Ole A. Srether, Museum of Zoo­ mainly faunistical or zoogeographical in scope or logy, Museplass 3, N-5007 Bergen, Albert Lille­ content, including checklists, faunallists, type ca­ hammer, Zoological Museum, Sars gt. 1, N-0562 talogues and regional keys. Submissions must not Oslo 5. have been previously published or copyrighted and must not be published subsequently except in abstract form or by written consent of the Editor­ Subscription in-Chief. Members ofNorw. Ent. Soc. will receive the jour­ nal free. Membership fee N.kr. 130,- should be paid to the Treasure of NEF: Preben Ottesen, NORSK ENTOMOLOGISK FORENING Gustav Vigelands vei 32, N-0274 Oslo 2. Postgiro ser sin oppgave i a fremme det entomologiske 0806 5440920. Questions about membership studiurn i Norge, og danne et bindeledd mellom de should be directed to the Secretary of NEF: Trond interesserte. Medlemskontingenten er for tiden kr. Hofsvang, P.O. Box 70, N-1432 As-NLH. Mem­ 130,- pr. ar. Henvendelse om medlemskap i NEF bers of NOF receive the journal by paying N.kr. sendes sekretreren: Trond Hofsvang, Postboks 70, 65,-, non-members by n.kr. 85,- to: NZT, Zoo­ 1432 As-NLH. Medlemmer far tidsskriftet fritt logical Museum, Sarsgt. 1, N-0562 Oslo 5, Post­ tilsendt og kan abonnere til redusert pris pa giro 0806 2348365. Outside Fennoscandia: addi­ FAUNA NORVEGICA serie A (generell zoologi, tional postage N.kr. 10,- per year (surface mail). 1 hefte pr. ar) for kr. 35,- og pa serie C (ornito­ logi, 2 hefter pr. ar) for kr. 65,-. Disse innbeta­ linger sendes til NZT, Zoologisk museum, Sarsgt. Abonnement 1, N-0562 Oslo 5. Medlemmer av Norsk Entomoligisk Forening far Postgiro 0806 2348365. tidsskriftet fritt tilsendt. Medlemskontingent kr. 130,- innbetales til kassereren i NEF: Preben Ottesen, Gustav Vigelands vei 32, 0274 Oslo 2. Trykket med bistand fra Norges almennviten­ Postgiro 0806 5440920. Medlemmer av Norsk skapelige forskningsrad. Opplag 700. Norsk zoologisk tidsskriftsentral (NZT) er et Managing Editor (Administrerende redakter) felles publiseringsorgan for NEF og NOF i samar­ Edvard K. Barth, Zoologisk museum, Sarsgt. 1, beid med de zoologiske avdelingene ved universi­ 0562 Oslo 5. tetsmuseene i Oslo, Bergen, Trondheim og Troms0. Adresse: Zoologisk museum, Sarsgt. 1, 0562 Oslo Editorial Board (Redaksjonsrad) 5. Postgiro 0806 2348365. Wim Vader, Troms0, Svein Haftorn and John O. Solem, Trondheim, Rolf Vik, Oslo. Kristiansen & W0ien, Oslo. ISSN 0332-7698 Fauna (Norsk Zoologisk Forening) har gatt ut av Norsk Zoologisk Tidsskriftsentral. Avtalen om gjensidig reduserte abonnementspriser pi foreningens tidsskrifter vii for fremtiden derfor bare gjelde mellom Norsk Entomologisk Forening og Norsk Ornitologisk Forening. Annual variation in abundance of phototactic Lepidoptera as indicated by light-trap catches SVERRE KOBRO Kobro, S. 1991. Annual variation in abundance of phototactic lepidoptera as indicated by light-trap catches. Fauna norv. Ser. B 38: 1-4. Annual variation in abundance of28 species ofphototactic lepidoptera common at one locality, is presented. A simplified light-trapping method was used to minimize the amount of work expended, and to reduce the influence of occasional weather condi­ tions on the catch data. O! the species, 19 ha~ abu~dance .max.ima in one of two years during the six years studIed. N10e ofthe specIes WIth maXIma m 1984 have larvae living on moss, lichens or grass, while six ofthe most abundant species in 1988 have Vaccinum, bushes and trees as hostplants. Sverre Kobro, Norwegian Plant Protection Institute, P. B. 70, N-1432 AS-NLH, Nor­ way. INTRODUCTION installed at the start ofevery season. The trap Annual variation in abundance of lepidop.. was situated in an edge habitat, between old tera is well known by most collectors, but coniferous 'forest, temperate deciduous fo­ variation for a long period of time is docu­ rest, open grassland and a garden. The site mented only for a limited number of species, was a shaded area and only to a small extent and mostly for larger ones. Reports are based exposed to direct moonlight. on either historical sources (e.g. Gigja 1961, The trap was usually operated the three Tenow 1972), on direct observations (e.g. first nights every week from late June to late Pollard 1988), or on light-trapping (e.g. Tay­ October in 1984-1989. Average number lor 1974). from nine nights (three nights in each of three The variations can be repeating events and consequtive weeks) is used as average of either random or cyclic in character. The bet­ abundance each year (see discussion). ter they are described and understood, the Most lepidoptera were identified, either by more they can be helpful for predictive and their genitalia, or by external characters. Geo­ preventive purposes. metrids (except the late flying species) were The intention of this study is to describe identified by Director emerit. J. Fjelddalen. I variations in abundance for a long period of identified the remainder of the material. The time for common, positive phototactic lepi­ nomenclature follows Schnack (1985). doptera, at one single locality, and thereafter It is an assumption in this work that photo­ to detect possible regularity ofthe variations. tactism and activity responses for each spe­ Light-trapping and treatment of catch data cies are constant from year to year. for this purpose are discussed, and prelimi­ nary results from the first six years are presen­ ted. RESULTS 603 species were identified with a total of 23000 specimens. Only a few species were MATERIALS AND METHODS regarded as common, based on light-trapping The light-trap used is of a simple funnel type during the six years. with 160 W mixed light bulb (Osram HWL 28 species were recorded with an average 160 W /235 V). The trap hung with the bulb abundance ofat least 5 specimens each night. one meter above the ground at precisely the The variation in abundance for these species same location each year. A new bulb was are shown in fig. 1 A, B. Fauna norv. Ser. B 38: 1-4. Oslo 1991. Two species show particularly high abun­ ciently high accuracy, without excessive dance and strong variation in this period. work. To minimize the amount ofwork, three Eudonia truncicolella (Stainton, 1849) had a simplifications were made: maximum level of 156.0 specimens each night in 1984 and a minimum level of 4.1 in 1987, and Rhopobota naevana (Hubner, 1817) had a maximum of 115.2 in 1985 while DlplMlrIna only one single specimen was caught in 1989. IMlu8trata Panmr The other species show more or less clear and 20 even variation in abundance. Xanthorhoe montanata DeIL& Schiff. 10 Eudonla Eullthla audetlea lal... populata L DISCUSSION 10 A. Methods In 1984 the light-trap was operated almost every night from early spring until late au­ tumn. A sampling method should give suffi­ ~~M~M~ ~~M~~~ ~~~~M~ ~~~~M~ Eplrrlta H5 chrl'tyl AlIen 16 Olethreutea Hydrlornena Per~ lacunana Den.' Sch. furcata Thunberg alohemlllata L PluteUa Croeaia Ypaolopha xyloateUa L. bergmanniana L. 10 Eplrrlta ~ 10 parantheaeUa L. autumnata Bork. ~~M~M~ ~~M~~~ ~~~~u~ ~~~~M~ ~~~~~~ ~~~~M~ ~~~~M~ ~~~~M~ Rualna ferruglnea Eaper 20 20 Hedya dlmldloalba Retzlua 16 16 Zeiraphera ParlJDma ratmburgiana Saxeoen dldymata L Caradrlna 10 EUema IIlOl'pMua Hufn. 10 Lathrcnympha lurldeola L Eplnotla atrigana Fabriclua maculana Fabrlciua ~~M~U~ ~~M~~~ ~~~~U~ ~~~~U~ ~~M~M~ ~~~~M~ ~~~~M~ ~~~~~~ Eudonla trunclcolella Stalnton lea AgrlphUa 140 ~ Rhopobota atramineUa Den.' Schiff. na_na Hubnet' Catoptria 120 H5 falaeUa Den.' Sciff. 1a Mythlmna 100 AgriphUa Impura Hubner trlatella Den.' Schiff. 80 10r Numonla 10~ DI.,,1a adVllnella Zlncken mendlea Flbrlolua ea 40 848686878889 848086878889 848086878889 848686878889 Fig. lA. Annual variation in abundace of 28 spe­ Fig. lB. Annual variation in abundance, conti­ cies of phototactic lepidoptera. Average catch nued. from 9 nights of light-trapping is used as a record of abundance. 2 1) The total catches were low in April and ria (Pollard 1988). When a trap is used one May, increasing in June, and highest in July should also make attempt to define the condi­ and August. Similar results are reported by tions. It is very difficult to define normal or Andersen (1982), Bakke (1974), and TaylOJ standard weather conditions when the total (1974). Therefore the trapping season wa: response of the insects to all conditions are started in late June. not known in detail. The difficulties can be overcome simply by leaving the decision to 2) The number of nights each week the light­ the insects themselves. When they react with trap was operated should give reasonably activity, the conditions are favourable. good data for abundance of each species. When conditions are optimal, the whole Calculations done for July, a period which population is likely to be on the wing. Be­ had by far the highest number ofboth species cause measurements of activity are used as a and specimens, showed that 75% of the spe­ record of abundance and an indicator of po­ cies recorded with more than 5% dominance pulation size, arithmetic means are used to in one week, were recorded with at least 3% give full value to the high activity records.