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This research on the occurrence of insects mining leaves of the English oak Quercus robur was performed between 2011–2012 in Bydgoszcz and in nine neighbouring sites: seven in forest areas and two in an urbanized environment. The analysis of the gathered material revealed the occurrence of insects from three different orders, Coleoptera, Hymenoptera and Lepidoptera, and 10 families: Curculionidae, Tenthredinidae, Bucculatricidae, Coleophoridae, Eriocraniidae, Gracillariidae, Heliozelidae, Incurvariidae, Nepticulidae and Tischeriidae. In total, 21 insect species were collected from Q. robur; most of them at forest sites. A slightly lower number of species was recorded at Janowo, where oaks were growing on the edge of the forest in the vicinity of a transport route with heavy traffic. Even fewer taxa were observed in the vicinity of urbanised areas; in the city park on the Bydgoszcz Canal and in Fordon. The most abundant species on the English oak were Tischeria ekebladella (Bjerk.) and Phyllonorycter heegeriella (Zell.).

Data on the parasitoid eulophid complexes reared from 6 species of leaf mining moths damaging the oak in the Middle Volga Area are reported. The reared eulophids belong to three subfamilies: Eulophinae (8 species from 6 genera): Cirrospilus diallus Walker, C. viticola (Rondani), Euplectrus liparidis Ferriere, Hyssopus geniculatus (Hartig), Sympiesis gordius (Walker), Pnigalio rotundiventris (Erdos), P. soemius (Walker), Rhicnopelte crassicornis (Nees); Entedoninae (11 species from 4 genera): Chrysocharis laomedon (Walker), Ch. prodice (Walker), Ch. pubens Delucchi, Ch. submutica Graham, Closterocerus formosus Westwood, Neochrysocharis aratus (Walker), Pediobius cassidae Erdos, P. flaviscapus (Thomson), P. metallicus (Nees), P. pyrgo Walker; and Tetrastichinae (3 species from 3 genera): Aprostocetus sp., Minotetrastichus frontalis (Nees), and Sigmophora brevicornis (Panzer). The most abundant of the moth parasitoids are M. frontalis and Ch. laomedon, while Tischeria ekebladella has the greatest number of parasitoids. The ectoparasitoids/endoparasitoids ratio in the number of species is 2: 1, and in the number of individuals reared, 1.76: 1. Thus, the host density is regulated primarily by the ectoparasitoids.

Moths and butterflies (Lepidoptera) represent the most diverse group of animals with heterogametic females. Although the vast majority of species has a WZ/ZZ (female/male) sex chromosome system, it is generally accepted that the ancestral system was Z/ZZ and the W chromosome has evolved in a common ancestor of Tischeriidae and Ditrysia. However, the lack of data on sex chromosomes in lower Lepidoptera has prevented a formal test of this hypothesis. Here, we performed a detailed analysis of sex chromosomes in Tischeria ekebladella (Tischeriidae) and 3 species representing lower Ditrysia, Cameraria ohridella (Gracillariidae), Plutella xylostella (Plutellidae), and Tineola bisselliella (Tineidae). Using comparative genomic hybridization we show that the first 3 species have well-differentiated W chromosomes, which vary considerably in their molecular composition, whereas T. bisselliella has no W chromosome. Furthermore, our results suggest the presence of neo-sex chromosomes in C. ohridella. For Z chromosomes, we selected 5 genes evenly distributed along the Z chromosome in ditrysian model species and tested their Z-linkage using qPCR. The tested genes (Henna, laminin A, Paramyosin, Tyrosine hydroxylase, and 6-Phosphogluconate dehydrogenase) proved to be Z-linked in all species examined. The conserved synteny of the Z chromosome across Tischeriidae and Ditrysia, along with the W chromosome absence in the lower ditrysian families Psychidae and Tineidae, suggests a possible independent origin of the W chromosomes in these 2 lineages.

1. Shared enemies may link the dynamics of their prey. Recently, quantitative food webs have been used to infer that herbivorous insect species attacked by the same major parasitoid species will affect each other negatively through apparent competition. Nonetheless, theoretical work predicts several alternative outcomes, including positive effects. 2. In this paper, we use an experimental approach to link food web patterns to realized population dynamics. First, we construct a quantitative food web for three dominant leaf miner species on the oak Quercus robur. We then measure short- and long-term indirect effects by increasing leaf miner densities on individual trees. Finally, we test whether experimental results are consistent with natural leaf miner dynamics on unmanipulated trees. 3. The quantitative food web shows that all leaf miner species share a minimum of four parasitoid species. While only a small fraction of the parasitoid pool is shared among Tischeria ekebladella and each of two Phyllonorycter species, the parasitoid communities of the congeneric Phyllonorycter species overlap substantially. 4. Based on the structure of the food web, we predict strong short- and long-term indirect interactions between the Phyllonorycter species, and limited interactions between them and T. ekebladella. As T. ekebladella is the main source of its own parasitoids, we expect to find intraspecific density-dependent parasitism in this species. 5. Consistent with these predictions, parasitism in T. ekebladella was high on trees with high densities of conspecifics in the previous generation. Among leaf miner species sharing more parasitoids, we found positive rather than negative interactions among years. No short-term indirect interactions (i.e. indirect interactions within a single generation) were detected. 6. Overall, this study is the first to experimentally demonstrate that herbivores with overlapping parasitoid communities may exhibit independent population dynamics - or even apparent mutualism. Hence, it proves the potential for versatile indirect interactions in nature, and suggests that the link between patterns in food web structure and realized population dynamics should be verified by rigorous experiments.

When examined at any moment in time, different parts of an individual oak tree exhibit almost as large differences in quality as different trees. But how consistent are such patterns in time? In this paper, we use intraclass correlations to assess the temporal consistency of host plant quality at several spatial scales. As measures of quality, we use both individual chemical attributes (phenolic contents) and the overall performance (larval survival) of the host-specific leaf-miner Tischeria ekebladella . Concentrations of 24 phenolic compounds were monitored on seven trees throughout a season. Variation in mine initiation and larval survival rates was assessed for individuals transplanted to another set of trees early versus later in the season, while year-to-year variation in larval survival was studied through stratified surveys of wild individuals during three years. At all time scales considered, measures of host quality were moderately consistent: a tree favourable in quality at one point in time often remained so, but there was abundant variation around this relationship (r /0.40.6). One hierarchical level deviated from this general pattern: on individual branches, larval survival rates varied randomly among years (r /0). Our study suggests that the quality of trees, and in particular of smaller units within trees, may be difficult to predict both in space and in time. To account for this, insects might benefit from adopting a bethedging strategy when selecting resources.

Optimal selection among host-units intended to support eggs-deposits is of paramount importance for those insects species with larval stage concealed within one and unique host-unit, such as leaf for leaf-miners. Selection is expected to be particularly severe (leaf acceptance ratio low) when insects specialise upon tough materials with efficient chemical defence, as is the case with oaks leaves. Yet, beyond egg-laying mothers selectivity, a complementary strategy to cope with such leaves opposing substantial deterrents, would consist in adopting more thoroughly a regime which escapes partially these defences such as sap-feeding instead of whole-tissue feeding. Then, mining species which tend to increase the sap contribution of their larval regime might perhaps, hypothetically, relax somewhat the selective exigency of mothers prior to egg-laying. This hypothesis was tested by comparing the leaf-acceptance ratio of Cameraria (larva more consistently sap-feeding) to other mining moth species (becoming more quickly tissue-feeding). Results conform fairly well to the proposed hypothesis but uncertainty remains as for the proper effect of leaves chemical variations among oak species, since we had not the possibility of making more relevant comparisons with mining species occurring on a same oak species. Regarding those results, this work is thus preliminary and in fact, addresses at first a methodological aspect of the question: the implementation of a new procedure allowing convenient quantitative inferences of both leaf-acceptance ratio and clutch-size, on the basis of easily recorded field-data collected a posteriori.

Since CO2 enrichment alters the composition of live plant tissues, the ongoing global increase of atmospheric CO2 concentration is expected to affect plant–animal interactions. Although this is a widely explored field, test systems studied so far have not included mature trees. Our study uses the Swiss Canopy Crane and the web-FACE CO2 enrichment system in a 35 m tall temperate deciduous forest. We studied the in situ abundance of dominant leaf-galls and leaf-miners on 13 mature oaks before the treatment started, and in two sub-groups, one of which received CO2 enrichment from 2001 to 2004. We expected that gall-inducing cynipids (Neuroterus quercusbaccarum and N. numismalis) would show similar loads with spangle-galls on the two tree groups, due to their capacity to manipulate their host plant and the quality of gall tissues. On the other hand, we expected that leaf-miners (Tischeria ekebladella) would show higher infestation on trees with high-quality (i.e. low C/N ratio, etc.) foliage leading to less mines on CO2 enriched oaks. Partially in line with our hypothesis, spangle-gall density showed only a positive short-term pulse effect (N. quercusbaccarum only) and did not differ across treatments after 4 years. In contrast to our hypothesis, the leaf-miner species did not respond persistently to CO2 enrichment either; it even showed higher infestation on CO2 enriched oaks in the 1st year after the onset of enrichment. In conclusion, CO2 enrichment had no lasting effect in all three taxa, despite the substantial and consistent change in leaf chemistry of oak due to growth in elevated CO2.

1. The distribution, abundance and population dynamics of herbivorous insects may be affected by trophic interactions, by abiotic influences, or by intra-specific processes. Relatively little is known about how trophic influences vary across space. Here, we investigate spatial variation in mortality in the oak-feeding leaf miner Tischeria ekebladella as attributable to individual causal agents. 2. Leaf miners were experimentally introduced on 67 trees on an island 5 km2 in area in south-western Finland. On each tree, some larvae were protected by a muslin bag, others by a glue barrier around the branch and some left exposed. 3. In the bagged transplants, 78.4% of larvae survived, compared with only 9.6% in the other two treatments. Most of the mortality was because of airborne agents: mortality on branches sheltered by a glue barrier was as high as on fully exposed branch tips. 4. We consider mortality caused by parasitoid wasps to be the main source of larval death and the primary factor driving general patterns of survival. The effects of bird predation and premature leaf abscission were negligible. 5. We detected spatial aggregation in larval survival and parasitism rates at the level of individual trees, but not across the landscape. 6. Spatial variation in overall leaf miner survival, parasitism and leaf abscission does not suffice to explain patterns of incidence and abundance of wild T. ekebladella on experimental trees. Rather, we identify metapopulation dynamics as a likely determinant of the spatial distribution of T. ekebladella in the landscape.

Prikazujemo sedem vrst metuljev, ki obžirajo hrastove liste: gobar (Lymantria dispar), zeleni hrastov zavijač (Tortrix viridana), mali zimski pedic (Operophthera brumata), veliki zimski pedic (Erannis defoliaria), hrastov sprevodni prelec (Thaumetopoea processionea), zlatoritka (Euproctis chrysorrhoea) in prstaničar (Malacosoma neustria). L. dispar in T. viridana sta se v submediteranskem in predpanonskem območju Slovenije pojavljala večkrat v močnejših gradacijah in povzročala škode. Naslednje dve vrsti pri nas povzročata manjše golobrste predvsem v naravnih sestojih doba v Prekmurju in Krakovskem gozdu ter v sestojih termofilnih hrastov v primorskem območju. T. processionea, E. chrysorrhoea ter M. neustria sporadično povzročajo poškodbe listja hrastov. Ugotavljajo, da se metulji defoliatorji pojavljajo v evropskih gozdovih vse pogosteje in začenjajo ponovno povzročati velike škode.Tudi pri nas ugotavljamo v zadnjih letih ponavljajoče se golobrste v hrastovih sestojih. Na kratko je prikazana morfologija, bionomija, opis poškodb, morebitne zamenjave, gostitelji, najpomembnejši naravni sovražniki inza nekatere omenjene vrste tudi vzroki za nastanek in nadaljevanje gradacij ter ogroženost sestojev. In the present contribution seven species of butterflies on oaks (Quercus spp.) are presented: gypsy moath (Lymantria dispar), European oak leaf roller (Tortrix viridana), winter moth (Operophthera brumata), mottled umber moth (Erannis defoliaria), oak processionary moth (Thaumetopoea processionea), browntail moth (Euproctis chrysorrhoea) and lackey moth (Malacosoma neustria).L. dispar and T. viridana have appeared several times in the sub-mediterranean and sub-pannonic areas of Slovenia and have caused damage. The next two species cause less significant defoliation mostly in natural pedunculate oak (Quercus robur) stands in Prekmurje and in the Krakovo forest as well as in thermophyllic oak stands in the coastal region. T. processionea, E. chrysorrhoea and M. neustria cause damage on oaks sporadically. Researchers state that butterflies which defoliate forests are appearing more frequently in Europe and are starting to cause extensive damagein forests again. Recently, in Slovenia the situation in oaks forests isthe same. A short description of the insects' morphology, bionomy, a description of damage, possible misidentifications, hosts, their most important natural enemies, causes of beginning or continuation of their outbreaks and their threat to forests are given.

From the perspective of a specialist herbivore, how homogenous are individual tree crowns as patches of habitat? We partitioned variation in physical and chemical host leaf traits and in the abundance and performance of a specialist oak leaf miner, Tischeria ekebladella, into variation at different hierarchical levels. For the phenolic contents of the leaves, we examined variation among oak stands, among trees within stands and among branches within trees. For leaf size and water content, we assessed variation among trees within a single stand, among shoots within trees, and among leaves within shoots. For moth abundance and performance, we examined variation across all levels: among oak stands, among trees within stands, among branches within trees, among shoots within branches and among leaves and insect individuals. For measures of phenolic contents, we found little variation among stands but substantial variation among individual trees. Yet, a tree particularly rich in a given compound was often comparatively poor in another. At a finer spatial scale, the phenolic composition of individual parts of a single tree was quite consistent, whereas leaf weight and water content varied widely within individual tree crowns. Moth abundances varied more among shoots within branches than at any other spatial level, whereas moth survival showed equal levels of variation within individual shoots as among separate oak stands. Likewise, for four other measures of larval performance (assessed at the level of trees and lower), we found more variation within than between trees. In conclusion, the large variation observed in the performance of a specialist moth and in the physical traits of the leaves among different parts of single tree crowns refutes the image of an oak tree as an ‘island’ of internally homogeneous quality. Hence, we may expect little evolutionary adaptation of T. ekebladella at the scale of individual trees. The moths may instead evolve to behaviourally select their resource at a very fine scale. Large variation within trees also calls for extensive replication within trees in ecological sampling designs and/or the sampling of maximally similar leaves.

New distribution data for Tischeria dodonaea Stt. – a species recently discovered in Lithuania – are provided, together with distribution maps for both currently known Lithuanian tischeriid species: Tischeria ekebladella (Bjerk.) and T. Dodonaea Stt. Genitalia drawings of T. Dodonaea and leafmine photos of T. Ekebladella (Bjerk.) and T. Dodonaea are also given.

Eleven representatives of the superorder Amphiesmenoptera (Trichoptera + Lepidoptera) were examined for sex chromatin status. Three species represent stenopsychoid, limnephiloid and leptoceroid branches of the Trichoptera; eight species belong to the primitive, so-called nonditrysian Lepidoptera and represent the infra-orders Zeugloptera, Dacnonypha, Exoporia, Incurvariina, Nepticulina and Tischeriina. The female-specific sex chromatin body was found in the interphase somatic nuclei of Tischeria ekebladella (Bjerkander 1795) (Lepidoptera, Tischeriina). The sex chromatin was absent in all investigated Trichoptera species as well as in all representatives of the nonditrysian Lepidoptera except Tischeria ekebladella. The sex chromosome mechanism of Limnephilus lunatus Curtis 1834 (Trichoptera, Limnephilidae) is Z/ZZ. The sex chromosome mechanism of Tischeria ekebladella (Lepidoptera, Tischeriina) is ZW/ZZ including the W chromosome as the largest element in the chromosome set. The data obtained support the hypothesis that the Z/ZZ sex chromosome system, the female heterogamety and the absence of the sex chromatin body in interphase nuclei are ancestral traits in the superorder Amphiesmenoptera. These ancestral characters are probably kept constant in all the Trichoptera and in the most primitive Lepidoptera. The W sex chromosome and the sex chromatin evolved later in the nonditrysian grade of the Lepidoptera. It is proposed that the sex chromatin is a synapomorphy of Tischeriina and Ditrysia.

A total of 78 insect species were recorded as damaging plant organs (galls, mines and eaten leaves) on nine Quercus species in south-western Slovakia during 1987–1992. The insects belong to five orders: 41 species of Hymenoptera, 16 species of Lepidoptera, 13 species of Diptera, two species of Coleoptera and five species of Homoptera. In addition, galls of Eriophyes cerreus (Eriophyidae, Acari) were found. The following species were abundant: Andricus kollari (Htg.), A. lignicola (Htg.), A. lucida (Htg.), Neuroterus quercusbaccarum (L.), Biorrhiza pallida (Oliv.) (Hym., Cynipidae) and Periclista lineolata (Klug) (Hym., Tenthredinidae); Tischeria ekebladella (Bjerk.) (Lep., Tischeriidae) and Phyllonorycter (Lithocolletis) roboris Zll. (Lepidoptera, Gracillariidae); Haltica quercetorum Foundr. (Col., Chrysomelidae). The number of insect species moderately oscillated and changed during 1987–1992. The lowest number (35 species) was found in 1991, the highest (48 species) in 1989. The highest number, 42 insect species, was associated with Quercus cerris, the lowest (25 species) with Q. pubescens. Insect species caused a total of 6356 galls, mines and other types of damage on nine Quercus species. Insect species were evaluated according to degree of harmfulness.

The native leafmining moth Tischeria ekebladella (Lepidoptera: Tischeriidae) feeds on oaks and recently has become a pest of silviculture and urban green areas in central Europe. The behavioral responses of male moths to hexane extracts of whole bodies of calling females or males were tested under laboratory conditions. Only extracts of females elicited responses from males. Analysis of extracts by coupled gas chromatography/electroantennographic detection revealed the presence of two electroantennogram-active peaks. Structure elucidation of these compounds, by gas-chromatography/mass spectrometry and independent synthesis revealed them to be (3Z,6Z,9Z)-tricosa-3,6,9-triene and (3Z,6Z,9Z,19Z)-tricosa-3,6,9,19-tetraene. While the triene was present in both sexes, the tetraene was female-specific. The latter is a new structure for a pheromone component of Lepidoptera and a novel natural product. Field trapping tests, carried out in a mixed oak forest near Budapest (Hungary), using synthetic compounds applied to rubber dispensers, showed that the tetraene per se elicited catches of males in large numbers. When the triene was added to the tetraene in a ratio of 1:1, there was no increase in trap catch; the triene alone did not elicit catches of males. For monitoring this insect, the tetraene, applied to rubber dispensers at a dose of 300 μg, is a potent sex attractant.

U ovome radu istraživana je prilagodba autohtonih parazitoidskih kompleksa na novo unesene strane i invazivne vrste lisnih minera u fauni Hrvatske. Istraživani su parazitoidski kompleksi domaćih vrsta lisnih minera: Phyllonorycter roboris, Phyllonorycter quercifoliella, Tischeria ekebladella i Phyllonorycter klemannella i stranih vrsta Phyllonorycter robiniella, Parectopa robinella, Phyllonorycter platani, Cameraria ohridella i Phyllonorycter leucographella. Za svaki parazitoidski kompleks izračunat je koeficijent dominacije D, Shannonov indeks diverziteta H i ujednačenosti vrsta E te klaster analiza za usporedbu sličnosti između parazitoidskih kompleksa domaćih i stranih vrsta lisnih minera. Domaći lisni mineri.P. roboris/P. quercifoliella i T. ekebladella imali su najraznolikije i naj­ujednačenije parazitoidske komplekse. P.kleemanella i P. platani su zbog dominacije monofagnih parazitoida imali znatno niže vrijednosti H i E. P. roboris/P. quercifoliella, P. robiniella, P. leucographella, Pa. robiniella i T. ekebladella imaju najsličnije parazitoidske komplekse. Između parazitoidskih kompleksa domaćih i stranih vrsta pokazane su sličnosti, što ukazuje na prilagodbu polifagnih parazitoida na novo unesene domaćine. Svi parazitoidi uzgojeni iz ovih uzoraka su generalisti, česte i brojne vrste na različitim vrstama lisnih minera reda Lepidoptera, kojima su domaćini drvenaste biljne vrste. Ovo istraživanje pokazalo je da će se nakon unašanja, domaće vrste polifagnih parazitoida relativno brzo prilagoditi na novog domaćina, što će zasigurno imati utjecaj na gustoću njihovih populacija i eventualne štete. Ovakav tip prilagodbe mogući je model koji će se ponoviti kod drugih stranih i invazivnih vrsta u Hrvatskoj., Leaf miners support rich parasitoid assemblages and majority of these parasitoid species are generalists. Alien and invasive species are global problem and pose direct and indirect threat to ecosystem stability. Leafminers are very successfull invaders and they build up their populations soon after establishment in an new area. Invaders escape from their native parasitoids and have competitive advantage over native species in new area. Native parasitoids adapt to new host and new parasitoid assemblages are established. Croatia has rich native leafminer fauna with recently added alien and invasive species. Phyllonorycter roboris, Phyllonorycter quercifoliella, Tischeria ekebladella on Quercus robur and Q. petraea, Phyllonorycter klemannella on Alnus glutinosa are native leafminers. Phyllonorycter robiniella, Parectopa robinella on Robinia pseudoacacia, Phyllonorycter platani on Platanus sp., Cameraria ohridella on Aesculus hippocastanum and Phyllonorycter leucographella on Pyracantha coccinea are recently introduced invasive species in Croatia. In this research we tested the following hypotheses: a) native parasitoids have adapted to new hosts, b) these parasitoid species are generalists, c) native and alien species of leafminers with similar bioecological characteristics have similar parasitoid assemblages. The sites of research were chosen according to the host plant sites, in forests and parks in Croatia. The research was carried out from 2004–2006. Leaves with mines were collected and kept in glass containers in outside insectary until emergence of parasitoids. For each parasitoid assemblage the diversity indices were calculated: Domination index (D), Shannon’s diversity index H and evenness of species E. Cluster analyses for comparison of similarities of parasitoid assemblages was done. In total, 28 taxa of parasitoids from the superfamily Chalcidoidea and 4 taxa from the superfamily of Ichneumonoidea have been found (Table 1). Table 1 shows domination index (D) for parasitoid species found for a host leaf miner. This research compares the parasitoid assemblages of different species of leafminers, the results have been obtained after mass rearings of parasitoids from different localities and different collection times and it does not give detailed insight into parasitism percentages and the seasonal distribution of parasitoid species within a parasitoid assemblage. Table 2 shows values of Shannon’s diversity index H and evenness of species E, and Figure 1 shows dendrogram from cluster analyses grouping leaf miner species according to the similarities of their parasitoid assemblages. The majority of parasitoid species found are generalist species found on other species of leaf miners from the order Lepidoptera. P. roboris/P. quercifoliella have the most diverse parasitoid assemblage (the highest H value) (Table 2) followed by T. ekebladella. Oaks support rich fauna of taxonomicaly and ecologicaly similar leaf miner species and free exchange of parasitoids is enabled among them. All the parasitoid species found on these leafminers are generalist. They also have the highest E value (Table 2) because they lack specific monophagous parasitoid species. P. klemannella has lower diversity indices H and E because of the dominance of specific parasitoids from Encyrtidae family. P. platani has two dominant parasitoid species Minotetrastichus platanellus and Pediobius saulius. Dendrogram shows that P. roboris/P. quercifoliella, P. robiniella, P. leucographella, Pa. robiniella i T. ekebladella have similar parasitoid assemblages. Very similar are T. ekebladella and Pa. robiniella, both host species grow on the same sites together (oak and black locust) and generalists can search for similar mines: white upper surface leaf mines. The greater linkage distance between P. klemannella i P. platani can be explained with the dominance of specific monophagous parasitoid species in the assemblage. The similarities between parasitoid assemblages of native (P. roboris/P. quercifoliella, T. ekebladella) and alien (P. leucographella, P. robiniella, Pa. robiniella, C. ohridella) leaf miner species show that the native generalist parasitoids have adapted to new hosts. Ten species of parasitoids have been found on C. ohridella, with Pediobius saulius and Minotetrastichus frontalis as two dominant species (Table 1). This research has shown that invasive leaf miner species in Croatia have recruited a parasitoid community similar to the native leaf miner species and that this process has occurred quite rapidly.

1. The spatial structure of natural populations may profoundly influence their dynamics. Depending on the frequency of movements among local populations and the consequent balance between local and regional population processes, earlier work has attempted to classify metapopulations into clear-cut categories, ranging from patchy populations to sets of remnant populations. In an alternative, dichotomous scheme, local populations have been classified as self-sustaining populations generating a surplus of individuals (sources) and those depending on immigration for persistence (sinks). 2. In this paper, we describe the spatial population structure of the leaf-mining moth Tischeria ekebladella, a specialist herbivore of the pedunculate oak Quercus robur. We relate moth dispersal to the distribution of oaks on Wattkast, a small island (5 km(2)) off the south-western coast of Finland. 3. We build a spatially realistic metapopulation model derived from assumptions concerning the behaviour of individual moths, and show that the model is able to explain part of the variation in observed patterns of occurrence and colonization. 4. While the species was always present on large trees, a considerable proportion of the local populations associated with small oaks showed extinction-recolonization dynamics. The vast majority of moth individuals occur on large trees. 5. According to model predictions, the dominance of local vs. regional processes in tree-specific moth dynamics varies drastically across the landscape. Most local populations may be defined broadly as 'sinks', as model simulations suggest that in the absence of immigration, only the largest oaks will sustain viable moth populations. Large trees in areas of high oak density will contribute most to the overall persistence of the metapopulation by acting as sources of moths colonizing other trees. 6. No single 'metapopulation type' will suffice to describe the oak-moth system. Instead, our study supports the notion that real populations are often a mix of earlier identified categories. The level to which local populations may persist after landscape modification will vary across the landscape, and sweeping classifications of metapopulations into single categories will contribute little to understanding how individual local populations contribute to the overall persistence of the system.

1. According to the preference-performance hypothesis, female insects select resources that maximize offspring performance. To achieve high fitness, leaf miner females should then adjust their oviposition behaviour in response to leaf attributes signalling high host quality. 2. Here we investigate resource selection in Tischeria ekebladella, a leaf-mining moth of the pedunculate oak (Quercus robur), in relation to two alternative hypotheses: (1) females select their resources with respect to their future quality for developing larvae; or (2) temporal changes in resource quality prevent females from selecting the best larval resources. 3. Specifically, we test whether females show the strongest selection at the levels at which quality varies the most (shoots and leaves); whether they respond to specific leaf attributes (leaf size, phenolic content and conspecific eggs); and whether female preference is reflected in offspring performance. 4. Female choice of leaves was found to be non-random. Within trees, the females preferred certain shoots, but when the shoots were on different trees the degree of discrimination was about four times larger than when they were on the same trees. 5. While females typically lay more eggs on large leaves, this is not a result of active selection of large leaves, but rather a result of females moving at random and ovipositing at regular intervals. 6. The females in our study did not adjust their oviposition behaviour in response to leaf phenolic contents (as measured by the time of larval feeding). Neither did they avoid leaves with conspecific eggs. 7. Female choice of oviposition sites did not match patterns of offspring performance: there was no positive association between offspring survival and counts of eggs. 8. We propose that temporal variation in resource quality may prevent female moths from evaluating resource quality reliably. To compensate for this, females may adopt a risk-spreading strategy when selecting their resources.