Observations on the developmental biology and occurrence of Victrix umovii (Lepidoptera, Noctuidae) in Sweden

4 Pages·1993·0.42 MB·

by  Hydén, N

Observations on the developmental biology and occurrence of
Victrix umovii (Lepidoptera, Noctuidae) in Sweden
NILS HYDEN
Hyd6n, N.: Observations on the developmental biology and occurrence of Victrix umovii
(Eversmann 1846) (Lepidoptera, Noctuidae) in Sweden. IIakttagelser av utvecklingsbiologi
och upptriidande hos barrskogslavflyet, Victrix umovii (Lepidoptera, Noctuidae) i Sverige.]
- Ent. Tidskr. 1 14 (3): 97-100. Uppsala, Sweden 1993. ISSN 0013-886x.
The developmental biology of. Victrix (Poliobrya) umovii (Eversmann, 1846) is discussed.
Eggs were obtained from caught females and the emerged larvae observed. The eggs and
early larval stages are briefly described. The larvae were observed to feed only on Alectoria
sarmentosa of four species of lichens and two mosses offered. The occurrence of the species
in Sweden and Northern Europe is discussed.
N. Hydin, Herkulesviigen 27, 5-745 42 Enkbping, Sweden.
Introduction
The developmental stages of. Victrix (Poliobrya) green-greyish eggs under and between lichens on
umovii (Eversmann 18a6) (Fig. 1) have remained dry twigs. After 20-25 days, the larvae emerged.
completely unknown and very little is known They were offered the lichens Bryoria capillaris,
about its ecology. Alectoria sarmentosa, Platismatia glauca and
In Sweden. Victrix umovii is associated with old Hypogymnia physodes together with the mosses
forest stands, rich in pendant lichens such as Pleurozium schreberi and Hylocomium splen-
IJsnea spp., Alectoria sarmentosa, Bryoria capilla- dens. To promote eating, the food was lightly
rls and Platismatia glauca. The species' taxono- moistened regularly. The larvae, which were rela-
mic relationship to the gents Cryphia and recent tively active, could only be observed to feed upon
integration in Victrix (Varga & Ronkay 1989, Alectoria sarmentosa, feeding mainly on the outer
Fibiger & Hacker 1991) has contributed to the parts of its twigs and not eating completely
assumption that lichens are the species' main through the twigs. Gnaw traces could clearly be
food. Statements that the food could be mosses observed in a magnifler. As the gnaw traces were
have been made (for instance, Skou 1991). So far small at these early larval stages, it can not be sta-
though, no report to confirm either of these ted with absolute certainty that the larvae neglec-
assumptions has been published. ted the other lichens offered. The behaviour of
The species is classified as vulnerable in the the larvae, however, supports the observation
Swedish Red Data List and is considered to be that they fed exclusively on Alectoria sarmentosa
threatened by the large scale rational forestry and used the other lichens merely as shelter and
(Ehnstrom & Wald6n 1986, Ehnstrom et al. camouflage. The mosses were completely omitted
1993). and almost never visited.
The biology of V. umovii is partly studied wit- The larvae were uniformly grey-greenish in
hin a project commenced in 1989 concerning Xes- colour and somewhat stout. When not feeding,
tia sincera (Hyddn & Sj6kvist 1993). they where effectively hiding among lichens. At
the time of the first hibernation they reached
Observations made approximately 5 mm in length, representing the
Females that were caught in the province Dalar- 2nd-3rd instar. They seemed to hibernate on the
na produced eggs in captivity and the larvae were branches, sheltered by lichens, and not on the
raised to the flrst hibernation. The females used a ground. They died during the early phase of
relatively long ovipositor to place the single hibernation.
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Nils Hyd€n Ent. Tidskr. 114 (1993)
indicate that V. umovii is not solely dependent on
stands dominated by spruce. This is further sup-
ported by the fact tbat Alectoria sarmentosa also
occurs in forests dominated by pines.
From the size of the larvae at the time of the
first hibernation and the growth rate it is assumed
that the species has a 2-year life cycle rather than
a 1-year cycle. It is also suggested that the larva
hibernates on the twigs aod not on the ground.
The behaviour of the imagines at mercury
vapor lamps leads to the assumption that the
moths reside among the upper parts of the trees.
This has also been indicated by other Swedish
Fig. 1. Victrix (Poliobrya) umovii, msle. Dr, Boda, lepidopterists (eg. B. Wickholm pers. comm.
4.7.1989. Wingspan:29 mm. Photo: N. Hydin. 1992). These assumptions together with the
Hane av barrskogslavfly, Victrix (Poliobrya) umovii. observations of the behaviour of the larvae gives
Vingbredd:29 mm. support to the hypothesis that the preferred habi-
tat of the species is the tree crowns.
Discussion The transitory population on Houtskar in Fin-
An almost complete list of all findings of Victrix land has been thorougly followed since its appea-
umovii made in Sweden up to 1992 has been esta- rance in 1961 and to its disappearance after 1978
blished (Hyddn unpubl.). The list covers all fin- (Bruun 1978, 1982 & 1992). Only one specimen
ding places and nearly all findings in the Nordic was captured in an even numbered year (the last
countries as well as in the rest of the Palaearctic. specimen found 1978), supporting the hypothesis
In Norway one female has been found (Bakke that the species indeed has a 2-year developmen-
1972) and in Finland a total of 34 specimens (of tal cycle (cf. Bruun 1978).
which two are not verified as of today). In Swe- In Sweden, the imagines could be found every
den. Victrix umovii has been found on a total of year with no clear relation to odd or even numbe-
14 places, 11 of them in the province Dalarna. red years. The appearance though varies greatly
Approximately 260 findings have been made in between different years. Based on the authors
Sweden representing nearly 80% of all findings of observations in two localities near Boda in Dalar-
the species. Of the Swedish specimens, findings na (cf. Hyd6n & Sjdkvist 1993) the observed year
have been made on one occasion in the province to year fluctuation in appearance is. as it seems,
Viirmland (two males) (Palmqvist 1982) (Fig2), dependent on climatic or other environmental
once in Gtistrikland (one male) (Palmqvist 1988) factors. During a few nights in early June 1990
and once in Uppland (one male), the latter repre- the temperature went down to approx. -15"C.
senting the first Swedish finding (Svensson 1977). This cold weather situation apparently shifted the
Based on present knowledge it is likely that the main flight years of V. umovii: before the event it
species has populations in Dalarna, Viirmland appeared predominantly in odd years but from
and Giistrikland. 1990 and onwards it has appeared only in even
It is suggested that y. umovii at least in the years. These observations gives support to the
Nordic countries prefers dry forest stands. This hypothesis tbal V. umovii has a two-year deve-
has also been proposed by other authors (Ehn- lopmental life cycle. Seemingly, the period of
strdm & Walddn 1986). Several known habitats in extreme weather did not severely affect the popu-
Sweden are located on well drained ground. A lation of imagines that emerged about two weeks
few localities though, are on or closely surroun- later. but instead affected the overwintered lar-
ded by more humid ground. This is also in agree- vae that presumably would have given moths in
ment with the observations in Estonia where fin- odd years.
dings have been made in a pine stand and in a After this event a very clear shifting to predo-
coniferous stand on sandy ground (Skvortsov & minantly even year appearance was observed also
Thomson 1973, Skvortsov pers. comm. 1992). for Xestia sincera in the same studv areas.
In Sweden, findings have been made also in
forest stands dominated by pine (Hyd6n and Acknowledgements
other lepidopterists unpubl.). These observations The project has been kindly supported by the World
98
Ent. Tidskr. 114 (1993) On the biology of Victrix umovii
7
T
Fig.2. The author (to the right) and Per Ahgren, The nature conservotion bureau in the province of Viirmland, at the
only finding ptace in Viirmland of Victrix umovii. Older, light opened coniferous stand on W-sloping sandy ground
in the River Klartilven valley. The locality is, however, not rich in the pendant lichen Alectoria sarmentosa, lhe hil'
herto only known food oJ the larvae of V. umovii. Xestia sincera has also been collected here. Vr, Stdllet, Kyrkebol,
2l/9 1991. Photo: Sven-Ake Berglind.
Artikelfdrfattaren (till hdger) i samsprfrk med Per Ahgren, liinsstyrelsens naturvfrrdsenhet i Viirmlands liin, vid den
hittills enda vtirmliindska fyndplatsen fr)r V. umovii (tvd fynd frfin 1981). Ojamn\ iildre granblandbestdnd pd en san'
dig viistsluttning mot Klariilven S om Stdllet. Lokalen iir emellertitl inte rik pd garnlav, den hittills enda kiinda vdrd-
viixten fbr V. umovii. Aven barrskogsfjiillflyet, Xestia sincera, har pdtriiffats hdr.
Wildlife Fund (WWF). My appreciations to my good Bruun, H. 1982. Aland och SkiirgArdshavet som bro och
friend Per Sjdkvist, who is participating in the project, hinder f6r Lepidopterologisk artspridning. - Bap-
for all his interest. sometimes hard work. discussions trial (l):9-23.
and friendship during many days and nights by now. Bruun, H. 1992. Changes in Species Composition of the
Many thanks also to an anonymous referee, to my fat- Moth and Butterfly Fauna on Houtskar in the Archi-
her for linguistic advise and to the new and devoted edi- pelago of SW Finland during the years of 1954 -
tor in charge, Sven-Ake Berglind, Uppsala (and Viirm- 1989 (Lepidoptera: Hesperiidae - Noctuidae). Abo
landl) for valuable comments and ideas on the manu- (Abo Academy Press.1.
scnpt. Ehnstr6m, B. & Wald6n, H. 1986. Faunavflrd i skogs-
bruket, Del 2 - den lZigre faunan. Jdnkdping (Skogs-
References styrelsen ).
Bakke, A. 1912. Ostlig nattfly, Poliobrya umovii Ev. Ehnitrdm, B., Giirdenfors, U. & Lindelow, A. 1993.
funnet i Norge. - Norsk ent. Tidskr. 19 (2):173-114. R6dlistade evertebrater i Sverige 1993. Uppsala
Bruun, H. 1978. Fynd av Poliobrya umovii i norra Euro- (Databanken f6r hotade arter).
pa. - Baptria 3 (1): 22-23. Fibiger, M. & Hacker, H. 1991. Systematic List of the
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Nils Hyd€n Ent. Tidskr. 114 (1993)
Noctuidae of Europe. Esperiana, Bd. 2. Schwanfeld Som foder provades naverlav (Platismatia glau-
(Delta Druck u. Verlag). ca), garnlav (Alectoria sarmentosa), blAslav
Hyd6n, N. & Sjokvist,P. 1993. Barrskogsfjallflyet (Xes- (Hypogymnia physodes) och gra lagellav (Bryo-
tia sincera) (Lepidoptera, Noctuidae) och det moder- ria capillaris). Larverna konstaterades iita endast
na storskaliga skogsbruket. - Ent. Tidskr. ll4 (l-2): garnlav (Alectoria sarmentosa). Niir de inte et
1-11. g<imde de sig synnerligen effektivt mellan och
Palmqvist, G. 1982. Intressanta fynd av Macrolepidop-
under lavarna. Ingen tendens kunde iakttas hos
Patlemrqav ii sSt,v eGri.g e1 918988.1 I. n-tr esEsnat.n tTai dfsyknrd. 1a0v3 M (2a)c: r8o9le-9p5id.op- dem att vilja s6ka sig ner till "markniv6" infcir
tera i Sverige 1987. - Ent. Tidskr. lO9 (2):59-64. overvintringen, tvArtom syntes de frirbereda sig
Skou, P. 1991. Nordens ugler. Danmarks Dyreliv, Bd. 5. pA att <ivervintra mellan lavarna pA kvistar. Troli-
Stenstrup (Apollo Books). gen civervintrar larverna av V. umovii uppe i trAd-
Skvortsov, V. & Thomson. E. 19'13. Poliobrya umovi skiktet, vilket betyder att artens egentliga biotop
(Lep., Noctuidae) in Esttand. - Ent. Zeitschr. 83 (4): formodligen helt ar i de <ivre skikten av liimpliga
45-48. skogsbestAnd. FrAn ndra nog kompletta fyndlistor
Svensson, I. 1977. F6riindringar i Sveriges storfjiirilfau- over V. umovii kan preliminiira slutsatser gdras
na en tredje tioArsperiod (Lepidoptera). Ent.
YaTrgidas,k Zr., 9&8 (R$:o1n1k3a-1y,2 2L.. 1989. Taxonomical n-o tes on ssotinmd inpdi iktoerrraarr ea totc ahr tmeenr fvcAirleddririaner rbaadrers kmoagrskbeer,-
the genus Victrix Staudinger, 1879 (Lepidoptera: giirna blandbestand med tall. Victrix umovii har i
Noctuidae). I. The description of a new subgenus, Sverige till och med 7992 petreffats pe totalt L4
two new species and a new subspecies. - Nota platser, varav 11 i Dalarna, en i Viirmland (2 han-
Lepid. 12 (1): 65-82. nar), en i Uppland (1 hane) och en i Gdstrikland
(1 hane). Arten har troligen en 2-hrig utveckling
Sammanfattning men upptriider varje ar i Sverige till skillnad mot i
Honor av Victrix (Poliobrya) umovii (Eversmann Finland. En viiderkatastrof med extrem kyla river
1846) har formfltts att liigga iigg i bur. Med hjAlp stora delar av Mellansverige i b<irjan av juni 1990
av en relativt l6ng ovipositor placerades aggen p6verkade troligen lokala populationer av y.
enstaka under grenlavar pe torra kvistar. De livli- umovii sd att deras huvudsakliga upptriidandeir
ga larverna <iverlevde till forsta <ivervintringen indrades frin udda Ar (studerat under 1987 och
och var d6 ca 5 mm lflnga och enfargat grongrA. 1989) till enbart jiimna flr dArefter.
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