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fie id s) hosted larvat hibernacula. li follows that we regard practi catly ali patches of S. Scilicibolia in the area os interest as utili sed by Ν. rivularis. This cloes not iiDplythat there are weli defined adult colonies at ali patches: in total. 24 stray butterni eswere recorded over 500 meters away fiona the smod plant patches in l996 suggest-ing relative ly good dispersal abili ty of the species Fig. l).
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Hibernating larvae of V rivuliariS sui vived submerge iace in laboratory for upto three Jays without detectabie decline in sui vivat. Longer submergence caused substanties mortali ty, and no larva sui vived the longe si period teste l. i. e. 2l days. In constant f PC temperature, there was no differe iace in mortali ty between theg roups submerged in aerated as oppo sed to an Oxic water. Thus. Very shon inundation periods would probab ly not influence larvat sui vivat in the fiet d. under et therrunning or still water. but a prolonged flood may cause substantial reduction os population Si ZC. The nature of the injury causing moriali ty in the larvae was not clearly determined in this study. However we expect that the mortali ty was not caused by an Oxia - an impossibility of respiration os aerial oxygen . This assumption is supported by two observationso mortali ty did not differ belween aerated and ano xi csubmerged conditions , and it was not increased under nitrogen atmosphere notsubmerge l) in comparison to the uiati eated controi and air control. The Volume of the experimental jars was big enough to dilute possibi e waste metabo lites, so that the larvae were not pol soned by them. The only plausibi e explanation we suggest is a fallure of os motic balance, in other woriis, uncontroited intake of large amotant of water in to the body through the cuticle. Our resulis confirm previ ous observation by HI ASE K and HLASER l99J).who vlewed floods as a serious moriali ty factor. Ν. rivialiaris is considerably lesstolerant to floo ling than one of the other two European buttersites studi ed so far the Large copper si iacena dimar Diam Pu v), which would sui Vive without substan
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sponiis to floo ling by an active escape reaction. whicli is uia likely in larvae of Vrivulcaris encased in their hibernacula. Also, at least sonae individuals of C. tullia may sui vive for as long as 28 days of submergeiace JOY 9 PULLIN l99J); but nostich case was detected in Ν. rivulcaris. Finalty, we did not finit - unlike of C. tullint, ut similarly to L. divia r hiata PuS - an eviden ce sor a delayed mortality at acti Vating conditions os previ ous ly submerged larvae, suggesting that larvae that sui vivea stood may normalty reach their maturi ty. N. rivulariS is thus, with respect to winter inoo ling. intermediary between the two other specieS. The differen ces in sui vivat among the three welland- inhabiting species corresponit relati vely welt with character of their habitat s. In the lowland fens of Brit-ain and Netherland s. prolonged winter inoods are a rule and the populations os L. nimia r hiata Pus that occupy such sites are likely to be adapted to them. On the other hanci, winter l4oods are not regular phenomena at Brit isti habitats of C. tullia. i. e.
buttersites of different geographical origin may be disserent ly adapted to flood ing NICHOLS L PULLlN 2000). we expect that populations of V ri VuliariS si om
It should be noted that the larvat mortali ty observed in otir experiment cloeson ly weal ly reflect the real siluation in the Geld. Since the smod plant of V rivuliariSmay reach considerable height sup to 3 metres) at sonae localities, a natural anti-inoo ling defence for the larvae would be to hibernate in ille tipper paris of Diriaecishoots. On the other hand, hibernat ing too hi gh on Di mea branches would exposethe larvae to increased predation by insectivorous biriis. HI ASEM and HLA SEM l99 P) mentioned feed ing speciali sation os ovet wintering local blue tits on VrivuliariS hibernacula. While collecting our experimental material February2000). we noted that abolit βοδ os hibernacula were attacked by birils and the content was eaten oui. The abili ty of hirtis to orientate them solves according to the leasdam age caused by lepidoptet an larvae is well known se. g. HEINRICH 9 COLLINSl 983. MURA KAMI l 999) and is expectabie in Ν. rivulariX, whicli offers eas ity accessit, te anil detectabie morseis for foraging biriis. Predation pressure might eventia crease during floods, when only non- submerged mod is avat labie for hird s. Dur ing a major 1 ood in April l 996 we observed flocks of warblers foraging on the tops
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of Diraeia branches, which were in these days Only a few centi meters topping water sui face. These circumstantiat eviden ces suggest that larvae of V rivularis hibernat ing at flooded si tes have to see k a balance bet ween two risks, predation and prolonged submergetace. Is we take into account that the floods vary among years in duration and intensity, it would follow that the larvae hibernat ing in intermediate heights should have the highest sui vivat when averaged among years. This hypothesis should be testable by manipulative fiet d experiments. At ille floodplain sites of the Trebon Basin. the early spring floods do not occur every year, and both ex te nil and duration os inoo ling varies among sites an d
jud ged frona the records of stray individuals considerable dispersal abili ty. These facis, and relative ly close 'clustering of V rivuliaris habitat s. should assure that major hostplant sites are eas ity recoloni sed is a major flood transitionalty destroysso me locat colonies. Our resulis poliat to possit, ly large diversi ty of anti-floo lingadaptations of wetland inhabiting buttersites, i anging frona inundation tolerance in sedentary, clo sed populations of Lycaenia di Uar Dialia VI S. io a low tolerance, hut considerable dispersat anil recoloni sation abili ty in Ν tiX rivuliaris.
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Actia Mologica Academiae Scientiarum Hungaricae ψS 2); im. 8 99, 2002
OBSERVATIONS ON THE OVIPOSITING STRATEGY OFGORTYNA BORELII PIERRET. l83J LEPIDOPTER A. NOCTU IDAE) IN A BRITISH POPULATION
localities: the norit, Essex coast around the walton Hackwaters area and the norit,
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The majority of the Britisti population os G. Dorelli occurs on constat grass- lanci, at c2 ira above mean sea levet. In continental Europe, however, the species is
United K in gilom; the habitat of G. borelli is particularly vulnerable to inundationby the sea as a result of rising sea levet s. Sea leveis are predicted to rise around the coasis of Brita in by about 5 cm per decade as a result of climate change CLIMATECHANGE IMPACT REVIEw GROUP l 996). PETHICK sl 993) also suggesis that lectonic subsidence is accounting for a further relative sea levet rise of 4-β nam per year on the coasi os Essex. The extinction os a G. horetii population in a river area Necker Valley) in Germany is thought to be a result os prolonged inoo ling STE INER l 985). To secure the long terna suture of G. horetii in Britalia it has been proposed to estabiisti colonies fui ther in land GIBSON 2000). away frona the dan-gers of sea levet rise. There are. however, stili many aspects of the life history and habitat requirements of this species that need to he undet stood hes ore new coloni escata be established. One of the most fundamental aspecis is to determine theovi position requirements and preferences of the species.
ovi positing was observe l. the actuat location of eggs on the plani or delatis of the proces s of Ovi position were not. howe ver recorded by these authors. Other species
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ceptance in Lepido plera can be reliant on a number of Sens Ory Cues, such AS colour, texture, si ape, and chemicat stimulants. Furthei more, is the species lays eggs onplanis, they generat ly have a preserence sor laying at a certain height HINTONl98 l). Also, factors Such as temperature, relative humidity, wind and the time os the Jay a re important sor ovi position in many in secis. In pre Vi Ous papers, RiNGwOOD et a l. 2000, 2002) and HILL et til. 2002)have examine d habitat characteristi cs of G. horetii and iis larvat si od plant P. ici acile) in the Uni ted Kingilom and Germany. The objectives of the studies reported in iliis paper were to determine the preferred host planis for ovi position theen Viron mental requirements for ovi positing and the he havio ur of G. Dorelli bes ore. during and aster ovi position. The studies also investigat ed the position ofovi position on preferred host planis and the distance of ovi positing frona the ne ar- est larval smod plani. The resulis are discus sed in ternas of the conservation and management of the G. horetii population in the Uni ted K ing dona.
To determine tho incideiace and locution os ovi position in relation to habitat and vegetationalstructure, a transect route was set out in the arca os study. The transect rolite incorporated ali the mainstands os P. officinale and other habitats found with in the study arca. The transect was dividod intocle vela sections os dissering vegetational structui c. habitat or densi ty of P. Dissicintile. A vegetationsurvey was carried out in cach os these sections using a visual estimation os couer sor cach of the species present BULLOCK l 996). The transcct was waiked twice a wee k during the stight period bcgin- ning of September to enit os October). At the stari and sinisti of each transect furvoy detatis os the weather conditions. including air temperature, wind speed and cloud coVer. were recorde l. The transect was waiked hetween l9 00 and 03 00 houi s. and fit tered torchlight whi te light) was used tosight G. horolii. When ovi positing was observed. the plant species on whicli the moth was deposit inglier eggs, the height scin) si om ground . the distance isto in the nearest larvat 1 ood plant scin) the timeos the observation and the transect section were recorded. Selecti vi ty os host plant sor ovi positing was assessed by of observed and expected ovi positing evenis calculated si ona the incideiace os potentialliost species for egg laying Bellavio urat observations were to e Valuate the seque iace os evenis prece ling. during and Subsequent to ovi position and also the tength of Ovi positing bouis. These observations were made twice a weck during the ldight period. Each bellavi ourat observation period was approximate ly 2 hours in duration and performed hetween l9 00 and 06 00 houi s. The bellavi our was observed using Gille red whi te light) torchlight. At the stari and cnd of each period. delatis os the weather conditions were recorded. The bellavi ourat observation perio is involved recording the time at the stari and finisti os
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Eighty-four observations of ovi positing were made over ille three years of monitoring. fifty- sive during transeci sui Veys and twenty-nine during the bellavio urat observation sessions. The species of plant on which G. Dorelli was observed laying eggs are shown in Fig. l. Six ovi position host planis were recorded, sive of hich were grass species: Elytrigia citheri , E. r EMS, Arrheric Itherum EliatiuS, DactyliS glomerata and Holci S lianiati S. Two ovi position Observations were madeon P. officinale, the larval smod plant. The most frequently observed host plant foro vi position was E. america; with 52 δ of the total observations and Elytrigia spp. made up J I of the observations. The majori ty J3I) of ovi position bellavio urwas made on dead infloresce iaces and pseudostems of grasses. Gortynia Dorellis howed strong selectivi ty in iis host plant for ovi post ling. There was an under representation of ovi positing on Festuca rubra and P. officinale in relation to the dis
Fig. 1. The species on whicli Gortynia horetii was observed ovi positing
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tributiori of the two species of plant. Positive selecti Vlty in ovi positing was observed sor Elytrigiti and Arrhenatherum as the inciden ce of ovi positing on these species was significantly greater than that expected χ' 6 d. 0 6 l. 3: PQ0. Ool). The requirements of G. horetii for a suitabie species of grass for ovi positionc an be related to the vegetational structure of the areas where the most ovi position observations were made. The distribution of ovi positing was most frequent 66 Rof observations) in relative ly sparse densities of P. Gicincile Q2 π ground cover)with dense s Jβδ) ground cover os long coarse grasses, characteri sed by Elytriglia sp p. No ovi position observations were made with in areas of scrub sal tmarsh, or grassiand areas that supported a dense stand in ground cover) os P. Dociniale. Behavi ourat observations found that the semale laid the eggs by probing withher ovi positor bene ath ille outer leas si eath of the grass and depositing the eggs in anumber of rows belween the stem and the outer leas sileath Fig. 3). The eggs laidon P. Os iciniale were deposited wii hin a crevice in the stem axit of the plant. The OVa are covered in mucus and are Stuck to each other as weli as to the stem. Overtwo hundred eggs were observed being laid in one batch. A typical ovi positing be-havi ourat observation session is represented in Fig. 2. The period immediately be- fore ovi positing is characteri sed by crawling, wing movement and resting bouis. The majori ty of the bellavi our bovis observed both preceding dita) and subsequent 68 R) to ovi position were crawling. When the female is cra ling, probingos sultable sites for egg laying is observe d. howe ver the cve for eg g deposition is