Apollo Butterfly Research Articles

Conserving apollo butterflies: habitat characteristics and conservation implications in Southwest Finland

The conservation of insects, particularly endangered species such as the Apollo butterfly, is a pressing global concern. Understanding the habitat requirements and factors influencing species occupancy is crucial for designing effective conservation strategies. We focused on investigating the habitat characteristics expected to affect the occupancy of the nationally endangered Apollo butterfly in Southwest Finland. We conducted field surveys and GIS analysis to assess the impact of larval host plant and adult nectar resources, habitat encroachment, elevation, connectivity, and spatial variation on Apollo larval occupancy in rocky outcrop habitats. We found that rocky outcrops with abundant host plants and those less isolated from nectar patches play a significant role in supporting Apollo reproduction, whereas encroachment, specifically increased tree volume, negatively affected occupancy. We additionally observed spatial variation in occupancy across different blocks within the study area. Our findings emphasise the importance of resource availability for Apollo butterflies and highlight the dynamic nature of their habitat requirements. Maintaining a network of intact rocky outcrops with suitable resources is essential for the long-term persistence of the Apollo butterfly population in the region.Implications for insect conservation: Our research underscores the critical need to protect and restore habitats for the Apollo butterfly, particularly by addressing threats such as habitat encroachment and construction projects that pose risks to their breeding sites.

From 20 to 2? Landmark-based geometric morphometrics reveal negligible wing-shape divergence between 20 subspecies of the Apollo butterfly, Parnassius apollo (Lepidoptera, Papilionidae), in the Carpatho-Pannonian region

For effective conservation management of endangered taxa, it is important to define operational units for conservation. In the absence of detailed genetic analyses, morphology-based taxonomy is often used as a surrogate. The Apollo butterfly, Parnassius apollo, is one of the most endangered butterfly species in Europe (considered as a flagship species) with 26 subspecies rank taxa described from the Carpatho-Pannonian region (Central Europe), often based on old, one-by-one descriptions. We applied landmark-based geometric morphometrics on wing shape to determine the number of morphologically distinguishable groups in the region, based on 949 males and 477 females from 20 Carpatho-Pannonian putative subspecies (both extant and potentially extinct). We found a single division between the Eastern Carpathian populations (described as two subspecies: ssp. transsylvanicus and ssp. rosenius) and the rest of the populations (including our outgroup from the Swiss Alps). Since P. apollo was not observed in the Eastern Carpathians in the last two decades, and the currently known extant populations in the Carpatho-Pannonian region are all located in the Northern Carpathians, our results support a single conservation unit in the region. We suggest that (i) extensive monitoring is needed to reveal whether the unique Eastern Carpathian populations have really gone extinct and (ii) more taxonomical/phylogenetic studies on Central European P. apollo are needed for establishing the taxonomy of the species and efficient conservation strategies. We emphasize that modern integrative taxonomy is not only important for clarifying taxonomical issues, but also for providing basis for sound conservation management.

A Chromosome-Level Genome Assembly and Annotation for the Clouded Apollo Butterfly (Parnassius mnemosyne): A Species of Global Conservation Concern.

The clouded apollo (Parnassius mnemosyne) is a palearctic butterfly distributed over a large part of western Eurasia, but population declines and fragmentation have been observed in many parts of the range. The development of genomic tools can help to shed light on the genetic consequences of the decline and to make informed decisions about direct conservation actions. Here, we present a high-contiguity, chromosome-level genome assembly of a female clouded apollo butterfly and provide detailed annotations of genes and transposable elements. We find that the large genome (1.5 Gb) of the clouded apollo is extraordinarily repeat rich (73%). Despite that, the combination of sequencing techniques allowed us to assemble all chromosomes (nc = 29) to a high degree of completeness. The annotation resulted in a relatively high number of protein-coding genes (22,854) compared with other Lepidoptera, of which a large proportion (21,635) could be assigned functions based on homology with other species. A comparative analysis indicates that overall genome structure has been largely conserved, both within the genus and compared with the ancestral lepidopteran karyotype. The high-quality genome assembly and detailed annotation presented here will constitute an important tool for forthcoming efforts aimed at understanding the genetic consequences of fragmentation and decline, as well as for assessments of genetic diversity, population structure, inbreeding, and genetic load in the clouded apollo butterfly.

Phenotypic senescence in a natural insect population.

Senescence seems to be universal in living organisms and plays a major role in life-history strategies. Phenotypic senescence, the decline of body condition and/or performance with age, is a largely understudied component of senescence in natural insect populations, although it would be important to understand how and why insects age under natural conditions. We aimed (i) to investigate how body mass and thorax width change with age in a natural population of the univoltine Clouded Apollo butterfly (Parnassius mnemosyne, Lepidoptera: Papilionidae) and (ii) to assess the relationship of this change with sex and wing length. We studied a population between 2014 and 2020 using mark-recapture during the whole flight period each year. Repeated measurements of body mass and thorax width and single measurements of wing length were performed on marked individuals. We analyzed body mass and thorax width change with age (days since marking), wing length, and the date of the first capture. Both body mass and thorax width declined nonlinearly with age. Individuals appearing earlier in the flight period had significantly higher initial body mass and thorax width and their body mass declined faster than later ones. Initial body sizes of females were higher, but males' body sizes decreased slower. Initial thorax width showed higher annual variation than body mass. To our best knowledge, this is the first study that revealed phenotypic senescence in a natural butterfly population, using in vivo measurements. We found sexual differences in the rate of phenotypic senescence. Despite the annual variation of initial body sizes, the rate of senescence did not vary considerably across the years.

Catch Effectiveness Revealed by Site-Related Differences in Capture-Mark-Recapture Methods: A Butterfly Metapopulation Study.

Understanding metapopulation structures is very important in the context of ecological studies and conservation. Crucial in this respect are the abundances of both the whole metapopulation and its constituent subpopulations. In recent decades, capture-mark-recapture studies have been considered the most reliable means of calculating such abundances. In butterfly studies, individual insects are usually caught with an entomological net. But the effectiveness of this method can vary for a number of reasons: differences between fieldworkers, in time, between sites etc. This article analyses catch effectiveness data with respect to two subpopulations of the Apollo butterfly (Parnassius apollo) metapopulation in the Pieniny National Park (Polish Carpathians). The results show that this parameter varied significantly between sites, probably because of differences in microrelief and plant cover. In addition, a method is proposed that will include information on catch effectiveness for estimating the sizes of particular subpopulations and will help to elucidate the structure of the entire metapopulation.

A strong decline of the endangered Apollo butterfly over 20 years in the archipelago of southern Finland

Insect groups are declining worldwide; Lepidoptera are among the taxa most affected in terrestrial ecosystems. The main drivers of these declines are a diverse set of factors relating to environmental change including habitat loss, pollution, and climate change. In 2019 and 2020, we surveyed 118 and 90 islands, respectively, in southern Finland’s archipelago for occupancy of Parnassius apollo larvae and counted the abundance of their host plant Hylotelephium telephium. Compared with historical data (1997–2003), the occupancy of Apollo butterfly larvae has decreased remarkably from about 75% to about 20% of islands and abundance declined as well. However, the abundance of their host plant has not changed. Occupancy models showed that the present occupancy probability is not affected by host plant numbers, and shows substantial colonization-extinction dynamics making the population vulnerable to stochastic extinction.Implications for insect conservationOur results show that this Apollo butterfly population is declining, and conservation actions are needed.

The relevance of transition habitats for butterfly conservation

Biodiversity is declining across the globe. Main drivers causing the vanishing of species are habitat destruction and the transformation of former heterogeneous landscapes into homogeneous and intensively used landscapes. Modern land management focuses on the creation of landscape configuration with sharp boundaries between ecosystems. In consequence, transition zones between two ecosystems such as between forest and open grassland are rare, as it counteracts the efficient and commercial use of space. However, there are many species relying on such transition zones between habitats, as the Clouded Apollo butterfly Parnassius mnemosyne. This highly endangered butterfly species occurs in light deciduous forests, interspersed with extensively used grasslands. In our study, we analysed habitat requirements of this butterfly species. We recorded larvae and feeding marks at its primary larval food plant, Corydalis cava, and assessed microhabitat characteristics, including microclimatic conditions. We captured high-resolution multispectral aerial imagery with an unmanned aerial vehicle. We subsequently combined ground-truthing data with information from high resolution aerial pictures to calculate habitat suitability models. We found that P. mnemosyne larvae mainly occur in the transition zone between deciduous light forest and extensively used grasslands with C. cava. Caterpillars of P. mnemosyne are particularly found around trees, basking on foliage and grass to rapidly reach high operation temperatures. Results from Species Distribution Models underline the relevance of transition zones between habitats for P. mnemosyne, and for biodiversity in general. The Clouded Apollo may serve as excellent indicator species for light deciduous forests, and as flagship to promote the conservation and restoration of transition zones between habitats in nature conservation.

Lack of genetic structure suggests high connectivity of Parnassius phoebus between nearby valleys in the Alps

The spatial scale of intraspecific genetic connectivity and population structure are important aspects of conservation genetics. However, for many species these properties are unknown. Here we used genomic data to assess the genetic structure of the small Apollo butterfly (Parnassius phoebus Fabricius, 1793; Lepidoptera: Papilionidae) across three nearby valleys in the Central Swiss Alps. One of the valleys is currently used for hydropower production with future plans to raise the existing dam wall further. We found no significant genetic structure, suggesting a currently high connectivity of this species in our studied region.

The long-term effect of over-supplementation on recovered populations: why restraint is a virtue

AbstractWe present a long-term analysis of the results of the Apollo butterflyParnassius apollorecovery project in the Pieniny National Park, southern Poland, using a classical population ecology model. Six possible theoretical models of changes in population abundance were constructed and their predictions compared with current data. Models that did not take into account supplementation with captive-reared individuals provided the best fit to the population growth pattern during recovery. This was probably because of the introduction of captive-reared specimens to sites while habitat reconstruction was taking place. In addition, we provide data supporting the hypothesis that a significant reduction in the habitat's carrying capacity occurred during the restoration project, probably as a result of the population being over-supplemented with captive-reared individuals. Our analysis shows that for a recovery project to be successful, captive breeding and habitat restoration should be properly coordinated.

Demographic inferences and climatic niche modelling shed light on the evolutionary history of the emblematic cold-adapted Apollo butterfly at regional scale.

Cold-adapted species escape climate warming by latitudinal and/or altitudinal range shifts, and currently occur in Southern Europe in isolated mountain ranges within "sky islands". Here, we studied the genetic structure of the Apollo butterfly in five such sky islands (above 1,000m) in France, and infer its demographic history since the last interglacial, using single nucleotide polymorphisms (ddRADseq SNPs). The Auvergne and Alps populations show strong genetic differentiation but not alpine massifs, although separated by deep valleys. Combining three complementary demographic inference methods and species distribution models (SDMs) we show that the LIG period was highly unfavourable for Apollo that probably survived in small population in the highest summits of Auvergne. The population shifted downslope and expanded eastward between LIG and LGM throughout the large climatically suitable Rhône valley between the glaciated summits of Auvergne and Alps. The Auvergne and Alps populations started diverging before the LGM but remained largely connected till the mid-Holocene. Population decline in Auvergne was more gradual but started before (~7kya vs. 800 ya), and was much stronger with current population size ten times lower than in the Alps. In the Alps, the low genetic structure and limited evidence for isolation by distance suggest a nonequilibrium metapopulation functioning. The core Apollo population experienced cycles of contraction-expansion with climate fluctuations with largely interconnected populations overtime according to a "metapopulation-pulsar" functioning. This study demonstrates the power of combining demographic inferences and SDMs to determine past and future evolutionary trajectories of an endangered species at a regional scale.

The Genome Assembly and Annotation of the Apollo Butterfly Parnassius apollo, a Flagship Species for Conservation Biology.

Conservation genomics has made dramatic improvements over the past decade, leveraging the power of genomes to infer diverse parameters central to conservation management questions. However, much of this effort has focused upon vertebrate species, despite insects providing similar flagship status with the added benefit of smaller genomes, shorter generation times and extensive historical collections in museums. Here we present the genome of the Apollo butterfly (Parnassius apollo, Papilionidae), an iconic endangered butterfly, which like many species in this genus, needs conservation genomic attention yet lacks a genome. Using 68.7 Gb of long-read data (N50 = 15.2 kb) we assembled a 1.4 Gb genome for the Apollo butterfly, making this the largest sequenced Lepidopteran genome to date. The assembly was highly contiguous (N50 = 7.1 Mb) and complete (97% of Lepidopteran BUSCOs were single-copy and complete) and consisted of 1,707 contigs. Using RNAseq data and Arthropoda proteins, we annotated 28.3K genes. Alignment with the closest-related chromosome-level assembly, Papilio bianor, reveals a highly conserved chromosomal organization, albeit genome size is highly expanded in the Apollo butterfly, due primarily to a dramatic increase in repetitive element content. Using this alignment for superscaffolding places the P. apollo genome in to 31 chromosomal scaffolds, and together with our functional annotation, provides an essential resource for advancing conservation genomics in a flagship species for insect conservation.

Utilizing Red Spotted Apollo Butterfly Transcriptome to Identify Antimicrobial Peptide Candidates against Porphyromonas gingivalis.

Simple SummaryInfections caused by bacteria, fungi, or viruses possess serious threat to human health and life. This is well realized in the current COVID-19 pandemic scenario. Antimicrobial peptides (AMPs) are a natural line of defense in many organisms, especially insects which survive in extreme niches. Here we identified AMPs from red spotted apollo butterflies found at high altitudes in Russia, China, and Korea. The larval development stage occurs on the months of December to April, when there are very low temperatures. The insects natural defense mechanism might contribute to withstand this condition, which is our point of interest, and we utilized the genomic information to identify AMPs from red spotted butterflies. The obtained AMPs were tested against a list of pathogenic bacteria and fungi. Finally, we obtained one promising candidate active against Porphyromonas gingivalis, a causative organism for periodontitis. With further validations, this could be a lead antimicrobial agent in future.Classical antibiotics are the foremost treatment strategy against microbial infections. Overuse of this has led to the evolution of antimicrobial resistance. Antimicrobial peptides (AMPs) are natural defense elements present across many species including humans, insects, bacteria, and plants. Insect AMPs are our area of interest, because of their stronger abilities in host defense. We have deciphered AMPs from an endangered species Parnassius bremeri, commonly known as the red spotted apollo butterfly. It belongs to the second largest insect order Lepidoptera, comprised of butterflies and moths, and lives in the high altitudes of Russia, China, and Korea. We aimed at identifying the AMPs from the larvae stages. The rationale of choosing this stage is that the P. bremeri larvae development occurs at extremely low temperature conditions, which might serve as external stimuli for AMP production. RNA was isolated from larvae (L1 to L5) instar stages and subjected to next generation sequencing. The transcriptomes obtained were curated in in-silico pipelines. The peptides obtained were screened for requisite AMP physicochemical properties and in vitro antimicrobial activity. With the sequential screening and validation, we obtained fifteen candidate AMPs. One peptide TPS–032 showed promising antimicrobial activity against Porphyromonas gingivalis, a primary causative organism of periodontitis.

Parnassius nebrodensis: A threatened but neglected Apollo butterfly species from Southern Europe (Lepidoptera: Papilionidae)

Recent multi-locus phylogenetic studies repeatedly showed that what was thought to be the Clouded Apollo butterfly Parnassius mnemosyne (Linnaeus, 1758) represents a cryptic species complex. This complex contains at least three distant species-level phylogenetic lineages. Here, we compile a set of morphology- and DNA-based evidences supporting the distinctiveness of two species in this group, i.e. P. mnemosyne s. str. and P. nebrodensis Turati, 1907 stat. rev. These species can be distinguished from each other based on a combination of diagnostic characters in the male genitalia structure, wing scale patterns, and the forewing venation. The species status of P. nebrodensis is supported based on unique nucleotide substitutions in the mitochondrial (COI, ND1, and ND5) and nuclear (Wg and EF-1a) genes. P. nebrodensis is endemic to the Western Mediterranean Region. This species shares a disjunctive range through the Pyrenees, Western and Central Alps, Apennines, and the Nebrodi and Madonie mountains on Sicily. Altogether 38 nominal taxa initially described as P. mnemosyne subspecies are considered here to be junior synonyms of P. nebrodensis. At first glance, P. nebrodensis can be assessed as an endangered species due to its restricted distribution, narrow range of habitats, and ongoing population decline. Isolated populations of this species scattered through mountain ranges need special management and conservation efforts.

Are all butterflies equal? Population-wise proboscis length variation predicts flower choice in a butterfly

Intraspecific morphological variation fundamentally influences individual resource exploitation. In plant–pollinator systems, variation in floral morphologies and pollinator mouthparts may affect pollinators' resource use. This relationship has frequently been studied across species, but hardly ever at the intraspecific level in natural circumstances. We studied flower visits of clouded Apollo butterflies, Parnassius mnemosyne . (1) We investigated whether proboscis (mouthpart) length variability influenced individual nectar plant choice within a single population. We hypothesized that flower depths would constrain butterflies’ flower visits via their proboscis lengths. (2) We studied whether individual proboscis length constrained feeding on the sticky catchfly, Silene viscaria , a species with ample nectar and the deepest corolla among the plants visited. We hypothesized that individuals observed visiting S. viscaria had longer proboscides than those not observed on this nectar source. We captured clouded Apollos, then measured proboscis length. We surveyed the population daily, identified marked individuals and recorded feeding on nectar plant species. We compared proboscis length to the flower depth of the six most-visited nectar plants and investigated whether individual visits on flowering plants were related to proboscis length. We found large intrapopulation variation in proboscis length, and high intra- and interspecific variation in flower depth of the six nectar plants. Flower depth of S. viscaria largely overlapped with proboscis length, while the other five plants had shorter flowers. Individuals with longer proboscides visited S. viscaria flowers more often than those with short proboscides. These results indicate the importance of morphological variation in the interaction between plants and pollinators. We provide the first evidence that individual variation in mouthpart length affects lepidopteran foraging in natural circumstances. We suggest that interactions between species in plant–pollinator systems are partially based on individually different continuous traits, rather than on well-defined discrete traits of different taxa as implied by the pollination syndrome hypothesis. • Clouded Apollo butterflies' mouthpart lengths show high population-wise variability. • Similar variability is found in the visited nectar sources' corolla depth. • Butterflies with long proboscides visit nectar plant with deepest flowers more often. • Intraspecific variation is important to understand plant-pollinator interactions. • Intraspecific variation's impact does not support pollination syndrome hypothesis.

Spatiotemporal Differentiation of Alpine Butterfly Parnassius glacialis (Papilionidae: Parnassiinae) in China: Evidence from Mitochondrial DNA and Nuclear Single Nucleotide Polymorphisms.

The Apollo butterfly, Parnassius glacialis, is one of the most charming members of its genus and includes two subspecies locally distributed in montane areas of south-central China and Japan. In this study, we investigated the genetic structure and demographic history of P. glacialis by analyzing partial sequences of four mitochondrial genes and nuclear single nucleotide polymorphisms (SNPs) via genotyping-by-sequencing (GBS) of samples from nearly the entire known distributional range in China. The mitochondrial DNA (mtDNA) data demonstrated that a total of 39 haplotypes were present, and the species was estimated to have diverged about 0.95 million years ago during the middle Pleistocene transition into two main clades that likely formed during the Kunlun-Huanghe tectonic movement. The two clades then dispersed independently in distinct geographic areas alongside the mountainous routes in central and southern China, most likely driven by the Pleistocene glacial-interglacial cycles. Nuclear SNP analysis was generally congruent with mtDNA results at the individual level. A minor incongruence of genetic structures that was detected between mtDNA and nuclear SNP data from the Laojunshan and Tiantangzhai populations was likely due to secondary contact and male-biased dispersal. Our work demonstrates that complicated dispersal-vicariance evolutionary processes likely led to the current geographic distribution of P. glacialis in China, particularly the uplift of the Qinghai-Tibet Plateau and related climatic oscillations during the Quaternary period.

Lifelong foraging and individual specialisation are influenced by temporal changes of resource availability

Resource availability largely determines the distribution and behaviour of organisms. In plant–pollinator communities, availability of floral resources may change so rapidly that pollinator individuals can benefit from switching between multiple resources, i.e. different flowering plant species. Insect pollinator individuals of a given generation often occur in different time windows during the reproductive season. This temporal variation in individual occurrences, together with the rapidly changing resource availability, may lead individuals of the same population to encounter and use different resources, resulting in an apparent individual specialisation. We hypothesized, that 1) individual pollinators change their resource use (flower visitation) during their lifetime according to the changing availability of floral resources, and that 2) temporal variation in individual occurrences of pollinators and in resource availability will partly explain individual specialisation. To test these hypotheses, we observed flower visitations of individually marked clouded Apollo butterflies Parnassius mnemosyne during one reproductive season. We found temporal changes in lifetime individual resource use that followed the changes in resource availability, indicating that butterflies can adjust foraging to varying resource availability. Individuals differed considerably in their resource use. This variation was partly explained by temporal variation in both floral resource availability and temporal occurrence of individual butterflies. We suggest the butterfly as a sequential specialist, i.e. short‐term specialist and long‐term generalist. This foraging plasticity can be essential for short‐living insect pollinators in rapidly changing environments. Although flowering dynamics do not fully explain the variability in foraging, our results highlight the importance of temporal dimension in resource use studies. Ultimately, the relative pace of environmental change compared to individual lifespan may be a key factor in resource use plasticity.

Testing the Role of the Red Queen and Court Jester as Drivers of the Macroevolution of Apollo Butterflies.

In macroevolution, the Red Queen (RQ) model posits that biodiversity dynamics depend mainly on species-intrinsic biotic factors such as interactions among species or life-history traits, while the Court Jester (CJ) model states that extrinsic environmental abiotic factors have a stronger role. Until recently, a lack of relevant methodological approaches has prevented the unraveling of contributions from these 2 types of factors to the evolutionary history of a lineage. Herein, we take advantage of the rapid development of new macroevolution models that tie diversification rates to changes in paleoenvironmental (extrinsic) and/or biotic (intrinsic) factors. We inferred a robust and fully-sampled species-level phylogeny, as well as divergence times and ancestral geographic ranges, and related these to the radiation of Apollo butterflies (Parnassiinae) using both extant (molecular) and extinct (fossil/morphological) evidence. We tested whether their diversification dynamics are better explained by an RQ or CJ hypothesis, by assessing whether speciation and extinction were mediated by diversity-dependence (niche filling) and clade-dependent host-plant association (RQ) or by large-scale continuous changes in extrinsic factors such as climate or geology (CJ). For the RQ hypothesis, we found significant differences in speciation rates associated with different host-plants but detected no sign of diversity-dependence. For CJ, the role of Himalayan-Tibetan building was substantial for biogeography but not a driver of high speciation, while positive dependence between warm climate and speciation/extinction was supported by continuously varying maximum-likelihood models. We find that rather than a single factor, the joint effect of multiple factors (biogeography, species traits, environmental drivers, and mass extinction) is responsible for current diversity patterns and that the same factor might act differently across clades, emphasizing the notion of opportunity. This study confirms the importance of the confluence of several factors rather than single explanations in modeling diversification within lineages.

Multiple factors correlating with wing malformations in the population of Parnassius apollo (Lepidoptera: Papilionidae) restituted from a low number of individuals: A mini review.

The Apollo butterfly, Parnassius apollo (Linnaeus), was common in Europe over 100 years ago, but currently it is considered as near threatened. Different conservation programs have promoted the persistence of this species; however, it is still endangered. An example of such programs was the action devoted to reestablish the Apollo butterfly population in Pieniny National Park (Poland) from only 20-30 individuals which had survived till the last decade of the 20th century. This reintroduction has been successful; however, unexpected developmental problems appeared. Butterflies with deformed or reduced wings became frequent in the population living in the natural habitat, and particularly among those reared under seminatural conditions (in the same environment, but fenced by a net). Until recently, reasons for these malformations remained unknown. However, reports published during last months indicated that there are genetic, biochemical, and microbiological factors contributing to this phenomenon. In the malformed individuals, lesions in the wingless gene and dysfunctions of laccase 1 and 2 were found to be significantly more frequent than in normal insects. A large fraction of butterflies with deformed or reduced wings was devoid of the prokaryotic symbiont Wolbachia, which was present in most normal individuals. Moreover, Yersinia pseudotuberculosis (Pfeiffer) Smith and Thal, and Serratia sp., bacteria pathogenic to insects, were detected in the biological material from both normal and malformed butterflies from this population. These findings are summarized and discussed in this review, in the light of conservation of insects and restitution of their populations from a low number of individuals.

Temporal changes in floral resource availability and flower visitation in a butterfly

Foraging affects survival and reproductive success in animals, including flower-visiting insects. Plant-derived floral food resources (i.e. nectar and pollen) may be rapidly changing in space and time and pollinators may need to quickly switch to new resources. Butterflies are suitable model organisms to investigate foraging behaviour of insect pollinators, because they can be easily monitored under natural conditions. We studied flower visitation patterns in the Clouded Apollo butterfly Parnassius mnemosyne in relation to the abundance of available floral resources. We recorded flower visitation daily in individually marked butterflies, listed flowering species and estimated flower abundance categories every 3 days in a single meadow, during five consecutive flight periods. Butterflies visited 35 nectar plants from the 71 species available. Few nectar plants were frequently visited (visit ratios for the annually most visited species: 37–60%), many were scarcely visited and no visits were observed on several abundant species. Flower abundance and visit ratio varied among years and within flight periods. The number of visits increased with flower abundance in the seven most frequently visited plant species, but not in the occasionally visited ones. Beside their choosiness, Parnassius mnemosyne butterflies were able to adjust foraging behaviour to rapidly changing resource distributions. Diet selectivity in adults might increase the vulnerability of this species. However, visitation plasticity may mitigate the effect of the lack of some nectar plants, as complementary resources can be used as alternatives.

Population dynamics and future persistence of the clouded Apollo butterfly in southern Scandinavia: The importance of low intensity grazing and creation of habitat patches

We investigated the population dynamics and future persistence of the last remaining Clouded Apollo butterfly metapopulation in southern Scandinavia. Based on three decades of surveys (1984–2015), we modelled colonization-extinction dynamics and local population sizes using habitat patch characteristics and connectivity, while accounting for imperfect detection and uncertainty in the local population sizes. The colonization probability increased with increasing connectivity and the local extinction probability decreased with increasing local population size in accordance with metapopulation theory. The local population size increased with increasing patch area, and was also affected by grazing intensity. Light grazing resulted in larger local populations compared to heavy grazing or no grazing at all. The butterfly population has decreased considerably during the study period and according to projections of future dynamics the estimated extinction risk within the coming 10years is 17%. However, it is possible to change the negative trends and decrease the extinction risk considerably by conservation actions. By optimizing the grazing pressure in existing patches the extinction risk was reduced to 11% (a reduction with 35% compared to the scenario with no conservation action). If a few new patches are created close to the occupied ones the extinction risk can be reduced further. In conclusion, there is a large risk that the Clouded Apollo butterfly will go extinct from southern Scandinavia within the coming decade. However, conservation measures that are focused to the core area of the current distribution and applied soon can considerably improve the situation for the butterfly.