Marsh fritillary

Euphydryas aurinia
male E. a. aurinia, Dorset
female E. a. aurinia, Dorset
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Lepidoptera
Family:	Nymphalidae
Genus:	Euphydryas
Species:	E. aurinia
Binomial name
Euphydryas aurinia (Rottemburg, 1775)
Synonyms
List Papilio artemis Denis & Schiffermüller, 1775 Papilio maturna Esper, 1777 Papilio lye Bergsträsser, 1780 Papilio koloswarensis Piller & Mitterpacher, 1783 Papilio matutina Thunberg, 1791 Papilio merope De Prunner, 1798 Melitaea brunnea Tutt, 1896 Melitaea ochrea Tutt, 1896 Melitaea virgata Tutt, 1896 Melitaea nana Rehfons, 1910 Melitaea turbida Gélin & Lucas, 1912 Melitaea unipuncta Kiefer, 1916 Melitaea hoffmanni Kiefer, 1916 Melitaea semifuscata Cabeau, 1919 Melitaea epimolpadia Reverdin, 1919 Melitaea didyma Heinrich, 1923 Melitaea rectiangula Cabeau, 1924 Melitaea catherini Le Charles, 1924 Melitaea perianthes Cabeau, 1926 Melitaea interligata Derenne, 1926 Melitaea gracilens Cabeau, 1927 Melitaea geminifasciata Cabeau, 1927 Melitaea transversa Cabeau, 1928 Melitaea deficiens Cabeau, 1928 Melitaea leucophana Cabeau, 1928 Melitaea frigescens Verity, 1928 Melitaea moritura Verity, 1928 Melitaea debilisprovincialis Verity, 1928 Melitaea valentini Nitsche, 1928 Melitaea semigriseis Cabeau, 1931 Melitaea tetramelana Cabeau, 1931 Melitaea semigracilens Cabeau, 1931 Melitaea melanoleuca Cabeau, 1932 Melitaea flavofasciata Hackray, 1934 Melitaea insterburgia Braun, 1937 Euphydryas albofasciata Frohawk, 1938 Euphydryas suffusa Frohawk, 1938 Melitaea infra-rectiangula Caruel, 1939 Melitaea ocellata Caruel, 1944 Melitaea arcuata Caruel, 1944 Melitaea commacula Caruel, 1944 Melitaea ligata Caruel, 1944 Melitaea splendida Mauny, 1949

The marsh fritillary (Euphydryas aurinia) is a butterfly of the Nymphalidae family. Commonly distributed in the Palearctic region, marsh fritillary got its common name from living in marshy, damp wetlands and grasslands. The prolonged larval stage that lasts for approximately seven to eight months includes a period of hibernation over the winter. The larvae are dependent on the host food plant Succisa pratensis, not only for feeding but also for hibernation because silken webs are formed on the host plant as the gregarious larvae enter hibernation. Because female butterflies lay eggs in batches on the host plant, females are selective about the location of oviposition. The cost of laying the batches of eggs at an unfavorable location is high and extensive.

Over the past few decades, the E. aurinia population has faced rapid decline in population frequency and become endangered as a consequence of landscape and climate changes. Loss of habitat due to decline of host plant population has been the biggest factor. Although efforts of conservation and management have revived the population slightly, the metapopulations of E. aurinia are still vulnerable to extinction. 

Taxonomy

E. aurinia is represented by many subspecies. The most widely accepted are:

• Euphydryas aurinia aurinia central Europe, southern Europe, western Siberia
• Euphydryas aurinia bulgarica (Fruhstorfer, 1916) Carpathian Mountains
• Euphydryas aurinia laeta (Christoph, 1893) central Siberia, Altai, Sayan, Transbaikal
• Euphydryas aurinia beckeri (Lederer, 1853) Morocco (Middle Atlas, Rif Mountains)
• Euphydryas aurinia barraguei (Betz, 1956) Algeria
• Euphydryas aurinia provincialis (Boisduval, 1828) (France and northern Italy)

but the total number of described subspecies is much higher especially in the eastern Palaearctic. The insect may be best considered a superspecies.

• 
  E. a. aurinia male
• 
  E. a. beckeri
• 
  E. a. provincialis
• 
  E. a. estonica, Estonia

Distribution

This species is widespread in the east Palaearctic ecozone from Ireland in the west to Yakutia in the east, and to north-west China and Mongolia in the south. The marsh fritillary is in decline in Europe and it is one of eleven butterflies covered by the United Kingdom Biodiversity Action Plan. Within the British Isles, it is more frequent in the south and west.

Habitat

This species lives in calcareous grassland, in woodland clearings and in damp marshy areas (hence the common name) and in heathy grassland, dominated by tussock forming grasses, including purple moor and rush pastures. In Finland, E. aurinia has been shown to favor semi-permanent grasslands and impermanent clearcuts in the forest. Young clearcuts were preferred over old clearcuts due to the dense growth of vegetation in old clearcut forests. In the United Kingdom, two types of grasslands can be inhabited by E. aurinia: damp grasslands that are either neutral or acidophilus and dry grasslands that have an abundance of plants that grow in lime-rich soil (calcicolous grasslands). These butterflies can reach an elevation of 10–2,200 metres (33–7,218 ft) above sea level.

In the British Isles the marsh fritillary is usually to be found in damp heathy grasslands which are called rhos pastures from the Welsh word rhos meaning heath. Small populations can be an important element of the ecology because they can produce lots of mobile individuals which can found other populations. The marsh fritillary is protected under British law. It is listed under Schedule 5 of the Wildlife and Countryside Act, also the EU Habitats and Species Directive (Annex II). The Devon Wildlife Trust owns a number of sites for which it monitors this species. Examples include Stowford Moor (near Holsworthy, Devon), Dunsdon nature reserve (near Bude), Mambury Moor (near Great Torrington), Vealand Farm nature reserve (near Holsworthy), Volehouse Nature Reserve (near Holsworthy). In 2009, counts of number of species had significantly increased from years 2007 and 2008.

Factors for Optimal Habitat

Several factors are important in providing an optimal habitat for E. aurinia. The availability of larval food plant S. pratensis and the height of grass.

Host Plant Availability

Because caterpillars live in communal webs formed around their host plant and hibernate through the winter inside the web, the density of host plant is a crucial factor in forming the habitat of E. aurinia. Studies have shown that the density of host plant is directly correlated to the number of larval webs found, which in turn is directly related to the number of adult butterflies. Therefore, a habitat suitable for the larvae can indirectly influence the proliferation of adult butterflies.

Sward Height

Not only is the density of host plant crucial for a favorable habitat, but also the height of the sward. Sward height that is too short can lead to increased exposure of the larvae to predators and limited food availability leading to starvation. However, if the sward height is too tall and densely packed, then it becomes difficult for adult butterflies to locate the host plant to oviposit on. Thus, the level of sward height is most optimal when it is medium height.

Description

Euphydryas aurinia has a wingspan of 30–42 millimetres (1.2–1.7 in) in males. The females are usually larger than the males, with a wingspan of 40–50 millimetres (1.6–2.0 in). These small butterflies are very variable in markings and colouration, with many forms and subspecies. The adult butterflies usually show a chequered pattern of brown, orange and yellow markings. Yellow markings are present on the hindwing edge. The underside of the wings is patterned with yellow orange and brown without any silver colouration at all. The eggs are yellow identified by being in a large batch, and the larvae are black.

• 
• 
  Underside

Food Resources

Host Plant for Caterpillars

The caterpillars are recorded as feeding primarily on Succisa pratensis and species of Digitalis, Plantago lanceolata, Knautia arvensis, Scabiosa succisa, Scabiosa columbaria, Veronica (Veronica dubravnaya, etc.), Geranium, Sambucus, Gentiana, Valeriana, Lonicera implexa, Filipendula, Spiraea and Viburnum.

Methanol Emission from Feeding

One study measuring the level of volatiles released by plants that are consumed by herbivores has shown that huge amounts of methanol and other volatile substances (monoterpenes, sesquiterpenes and lipoxygenase-derived volatile compounds) are emitted by E. aurinia caterpillars feeding on the host plant S. pratensis. Methanol is a biochemically active compound that is commonly released by metabolic activities of anaerobic bacteria.

Adult Feeding

Adult butterflies feed on nectar opportunistically so the density of host plant S. pratensis does not affect adult butterfly feeding. In fact, by the time adult butterflies emerge, S. pratensis does not even flower. Feeding polyphagously, adult butterflies generally feed on Ranunculus ssp., Cirsium ssp., Leucantherum vulgare, Myosotis ssp., Rubus ssp most often.

Parental Care

Oviposition Discrimination

E. aurinia females are batch-layers, meaning they lay a large number of eggs at one site. Because 200-300 eggs are at stake every time an egg-laying site is chosen, batch-laying females tend to undergo a discrimination phase in searching for a location to lay eggs on. Each plant can serve as an egg-laying site for four to five clusters of eggs, meaning than more than a thousand larvae may hatch on a single plant. If so, the newly-hatched larvae will face serious food shortage and fierce competition for food, which is a huge repercussions on offspring survivorship. Therefore, Euphydryas and other batch-laying females such as Melitaeini females take longer to choose a place to lay eggs and are more selective when looking for a host plant

Size of Host Plant and Vegetation Density

Female oviposition depends largely on the size of host plant as well as density of vegetation cover. Studies have shown that females prefer to lay eggs on large-sized host plants as opposed to smaller plants. This is to prevent food shortage and starvation of the larvae. Also, sparse, open vegetation structure is favored over dense, thick grasslands when the host plant S. pratensis is used for oviposition. The presence of tall non-host plant (e.g. Deschampsia caespitosa) was negatively correlated with egg nests. Therefore, the optimal conditions for oviposition are shown to be meadows with plants that grown in lime-rich soil that have been abandoned recently or the edges of such meadows because the vegetation structure and plant height fit the female butterfly preference for oviposition. For such reasons, croplands are favored over meadows for oviposition because croplands tend to have concentrated number of large-sized host plants.

Color of Host Plant

Females prefer to lay eggs on leaves with the highest chlorophyll contents. Therefore, the reflectance and chlorophyll concentration of leaves also affects oviposition sites of E. aurinia. Chlorophyll content (the “greenness” of plants) can be an indicator for increased fitness of the host plant, which in turn will provide an optimal growth opportunities for the newly hatched larvae. Females therefore use visual cues to seek out the greenest leaves to lay their eggs on. However, there are other indications that imply that plants that receive more egg clusters are favored by females because of attraction to presence of conspecific egg clusters, not the high chlorophyll concentration.

Other Favored Factors for Oviposition

In Czech Republic, the presence short grasses that can serve a cushion-like function (especially Nardus stricta) in the vicinity of the host plant was positively correlated with nest numbers. In general, conditions that promote host plant growth and proliferation are also favorable for nests. Dry, acidic conditions with limited nitrogen resources are preferred for nests because these conditions lead to short swards. Short swards facilitate larval basking, thus is a factor considered by females during oviposition.

Life cycle

Euphydryas aurinia is a univoltine species.

Egg

The eggs are laid in groups on the underside of the leaves in May and June. Up to 350 are laid in a single batch. They turn from pale yellow when first laid, to bright yellow, then crimson, and finally to dark grey just prior to hatching.

Caterpillar

The caterpillars hatch in about three weeks from the end of June onwards. There are six instars for E. aurinia larvae. The first four are gregarious: the first three are prehibernation instars and the fourth is post-hibernation. First three instars form a communal web around the food plant S. pratensis and feed on the host plant for about three weeks. The young caterpillars become conspicuous by the end of August. In the autumn they make stronger webs, closer to the ground usually within a dense grass tussock, where they will start to hibernate.

In the spring, the fourth instar emerges from hibernation. All three of the post-hibernation instars bask in the sun. Basking is a behavior in which the instar increases its body temperature using heat from solar radiation. This allows them to be relatively independent of ambient temperature, which allows them to develop faster. They change color from brown to black.

Pupa

At the end of the sixth instar, pupae start forming. This occurs in the Spring, around the end of March or beginning of April.

Adult

Adults emerge and undergo the flight period between May and June. Adults have short life spans, usually lasting about two weeks. 

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  Courting
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  Mating
• 
  Eggs
• 
  Young caterpillars
• 
  Pupa

Migration

Metapopulations

Research work on the population dynamics of the marsh fritillary has shown that they live in metapopulations. A metapopulation is defined as a collection of local populations that are connected together as a result of occasional dispersal. Amongst these some will disappear and others will be founded. An important feature of metapopulations is that there will always be empty habitat within the system. It is possible for the majority of the habitat patches to be empty. The security of suitable places where the butterfly does not presently occur is essential to its survival in the long term.

Local Dispersal

E. aurinia butterflies tend to exhibit sedentary behavior, which leads to an increase in local dispersal than regional or long-distance dispersal. Males are more likely to emigrate more than females, and even so, E. aurinia rarely move to neighboring patches. The average local population size increases as a result of such limited mobility of adult butterflies. Thus, the fluctuation of one habitat patch population size is unlikely to affect the population size of another habitat patch . The relative turnover rate of extinction and recolonization of previously empty habitat patches is higher for E. aurinia, which indicates that extinction of one local population can be balanced by re-colonization of another. Such classic metapopulation characteristics explain why there is greater within-population genetic structuring in E. aurinia.

Enemies

The caterpillars are liable to be attacked by the parasitoid wasp Apanteles bignellii, especially in warm spring weather. Pupae form from mid-April, low down deep within grass tussocks or dead leaves. Adults mainly emerge from mid-April to mid-July, however in southern regions they can be on wing starting from late May.

Management

The aim is to produce an uneven patchwork of short and long vegetation by the end of the grazing period, between 8 and 25 cm. This is to allow the food plant to grow. This can be achieved through low intensity grazing using cattle and burning. Monitoring and indicators of success are mainly represented by the frequency of larval webs, the frequency of flowers and larval food plant.

Bibliography

• Aldwell, B. and Smyth, F. 2013. The Marsh Fritillary (Euphydryas aurinia (Rottemburg, 1775)) (Lepidoptera: Nymphalidae) in Co. Donegal. Irish Naturalists' Journal 32: 53 - 63 Crory, Andrew.(?) 2016. Fritillary Butterflies. The Irish Hare, Issue: 113. p. 4

External links

• Schmetterling-raupe.de
• Kimmo Silvonen Larvae of North-European Lepidoptera
• McKee, L. 2008. "Bid to halt decline of butterfly". Belfast Telegraph. 18 July 2008. p. 10 (www.belfasttelegraph.co.uk)
• Paolo Mazzei, Daniel Morel, Raniero Panfili Moths and Butterflies of Europe and North Africa
• Devon Wildlife Trust manages a number of strongholds for the species including Volehouse Moor, Dunsdon, Meshaw Moor and Vealand farm