The large blue (''Phengaris arion'') is a species of butterfly in the family
Lycaenidae
Lycaenidae is the second-largest family of butterflies (behind Nymphalidae, brush-footed butterflies), with over 6,000 species worldwide, whose members are also called gossamer-winged butterflies. They constitute about 30% of the known butterf ...
. The species was first defined in 1758 and first recorded in
Britain
Britain most often refers to:
* The United Kingdom, a sovereign state in Europe comprising the island of Great Britain, the north-eastern part of the island of Ireland and many smaller islands
* Great Britain, the largest island in the United King ...
in 1795.
In 1979 the species became mostly extinct in Britain but has been successfully reintroduced with new conservation methods. The species is classified as "near threatened" on the
IUCN Red List of Threatened Species
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...
.
[ Today ''P. arion'' can be found in Europe, the ]Caucasus
The Caucasus () or Caucasia (), is a region between the Black Sea and the Caspian Sea, mainly comprising Armenia, Azerbaijan, Georgia, and parts of Southern Russia. The Caucasus Mountains, including the Greater Caucasus range, have historica ...
, Armenia
Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ''O ...
, western Siberia
Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part ...
, Altai, north-western Kazakhstan
Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...
and Sichuan
Sichuan (; zh, c=, labels=no, ; zh, p=Sìchuān; alternatively romanized as Szechuan or Szechwan; formerly also referred to as "West China" or "Western China" by Protestant missions) is a province in Southwest China occupying most of t ...
.[
The large blue can be distinguished by its unique speckled black dots on its wings with a blue background.
The large blue butterfly is well known in ]behavioural ecology
Behavioral ecology, also spelled behavioural ecology, is the study of the evolutionary basis for animal behavior due to ecological pressures. Behavioral ecology emerged from ethology after Niko Tinbergen outlined four questions to address wh ...
as it is a brood parasite
Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were it ...
of a single species of red ant, ''Myrmica sabuleti
''Myrmica sabuleti'' is a species of ant in the genus ''Myrmica''. The species is indigenous to Europe, and most colonies are polygynous. Caterpillars of the large blue butterfly (''Phengaris arion'') parasitically prey on this ant. The caterp ...
''.
Subspecies
*''P. a. arion'' Mainland Europe, western Siberia, Altai, north-western Kazakhstan
*''P. a. delphinatus'' (Fruhstorfer, 1910)
*''P. a. zara'' Jachontov, 1935 Caucasus, Armenia
*''P. a. buholzeri'' Rezbanyai, 1978
* ''P. a. eutyphron'' Fruhstorfer, 1915 formerly southern Britain
Description
Large blue caterpillar
Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths).
As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sy ...
s grow to about half an inch (13 millimetres) in length, and spend up to 9 months before they undergo metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
to a chrysalis
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...
to become a butterfly
Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group compris ...
. Large blue butterflies are one of the largest in the family Lycaenidae
Lycaenidae is the second-largest family of butterflies (behind Nymphalidae, brush-footed butterflies), with over 6,000 species worldwide, whose members are also called gossamer-winged butterflies. They constitute about 30% of the known butterf ...
, known as the gossamer-winged butterfly, with a wingspan of up to , and live only for a few weeks. The wings of the large blue butterfly are speckled with black dots.
Description from Seitz
L. arion L. (83 c). Larger, above of a lighter and more shining blue han ''arcas'', with a row of black spots across both wings, the spots being sometimes obsolete only on the hindwing of the male. At once recognized by the large number of ocelli on the underside, especially on the hindwing, and by the bright blue dusting of the base beneath. Europe and Anterior Asia, from North Europe, the Baltic provinces, and England to the Mediterranean (Corsica), and from Spain to Armenia and South Siberia. In ab. ''unicolor'' Hormuz. the upperside is entirely blue, all the black spots with the exception of the discocellular one being absent. ab. ''arthurus'' Melvill is without ocelli beneath. In ab. ''jasilkowskii'' Hornuz the ocelli are absent beneath in the cell as in ''euphemus'', from which this aberration is at once distinguished by its blue-green basal scaling on the underside. In ab. ''coalescens'' Gillm. the black spots of the upperside are confluent. — Quite a number of local forms have been separated Northern specimens, which are feebly spotted, are named ''alconides'' by Aurivillius. — ''obscura'' Christ. (83 c) is an alpine form in which the whole outer half of the wings above is black or dark brown; it occurs typically in the High Alps, being locally very plentiful, e. g. at Bergun, Zermatt, Stilvio and at many places in the Alpes Maritimes. This darkened form occurs also in the Ural (= ''ruehli'' Krulik.) — In the South two aberrant forms have been found, namely ''ligurica'' Wagn., at the Eiviera between San Remo and Bordighera, with a conspicuous row of white marginal ocelli on the upperside of the hindwing, and ''aldrovandus'' S. L., from the Vesuvius, the underside darkened with brown. — ''cyanecula'' Stgr. (83 d) is an Asiatic form, from the Caucasus to Mongolia, with the metallic blue green dusting of the hindwing beneath being abundant, bright, and extending almost to the distal edge. — Egg very flat semiglobular, pale bluish white, deposited on ''Thymus'' which just begins to flower. Larva adult pale ochreous, with a pale lilac tinge at the sides; head ochreous, marked with black anteriorly; prothoracic plate black; feeds until the autumn on Thyme, then disappears and is found full grown the next June in the nests of ants. It is therefore suggested that the ants feed it up (Frohawk) and perhaps also protect the pupae. The chrysalis the colour of amber except for the wing-cases, smooth, somewhat elongate, without web. The butterflies occur usually singly, being locally frequent on open ground, on broad roads through shrubby woods, flying about 1 m above the ground. They rest with closed wings, particularly on Thymes and Scabious. On the wing from the end of June into August.
Distribution
The large blue butterfly is found from coast to coast of the Palearctic realm
The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa.
The realm consists of several bioregions: the Euro-Si ...
, but is most concentrated in the areas from France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
to China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
.
Habitat
The habitat of the large blue butterfly is largely influenced by location of its food sources. The species requires a combination of abundant amounts of its larval food plant, '' Thymus drucei'' and the presence of ''Myrmica sabuleti
''Myrmica sabuleti'' is a species of ant in the genus ''Myrmica''. The species is indigenous to Europe, and most colonies are polygynous. Caterpillars of the large blue butterfly (''Phengaris arion'') parasitically prey on this ant. The caterp ...
'' ants in order to survive.
It has also been found that an underlying key factor for the survival of the large blue is site heterogeneity
Homogeneity and heterogeneity are concepts often used in the sciences and statistics relating to the uniformity of a substance or organism. A material or image that is homogeneous is uniform in composition or character (i.e. color, shape, siz ...
. The butterfly is most abundant in pastures and abandoned areas of diverse vegetation and shrubbery. This preference can be explained by examining the result of a uniform landscape. A constant landscape synchronizes many biological activities including flowering of host plants, adult emergence dates, or larval pressures on the ant colonies. If important biological functions take place at the same times, the population becomes much more susceptible to random unfortunate events such as environmental disasters. Thus traditional farming acts to desynchronize the biological system, and allows for re-colonization of patches that are temporarily untouched. The presence of differing sites and varied ecological structures provides differing microclimates that can make a huge impact on the survival of the large blue butterfly.
Extinction/conservation
In the late 1900s, '' Phengaris'' populations began decreasing drastically throughout Europe with the large blue butterfly being particularly affected. By the 1950s, only an estimated 100,000 adults remained in Britain, and by 1978, 48% of the UK's 91 known large blue populations had been lost. Initially experts were completely baffled by the disappearance of large blues as the sites did not appear to have changed. Leading hypotheses targeted collectors, insecticides
Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed t ...
, and air pollution as factors that led to the butterfly extinction. A large number of projects were conducted to combat these factors, but all were completely unsuccessful. The species became extinct in the Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
in 1964, in the UK in 1979. In Belgium
Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to ...
, it had been considered extinct until 1996, when a recolonized population was discovered in the south of the country. Severe decreases in population have also occurred in Denmark
)
, song = ( en, "King Christian stood by the lofty mast")
, song_type = National and royal anthem
, image_map = EU-Denmark.svg
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of Denmark
, establish ...
, Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
, France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, and Estonia
Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...
. Because of this decline they are being protected. The succession of extinctions and decreases in population has been characterized as a result of unsuccessful conservation efforts that stemmed from a lack of understanding of the behaviour of the butterfly.
Currently the large blue butterfly is classified as critically endangered in Britain as well as being endangered in many areas of Europe. It is a priority species of under the UK Biodiversity Action Plan
The United Kingdom Biodiversity Action Plan or (UK BAP) was the UK government's response to the Convention on Biological Diversity, opened for signature at the Rio Earth Summit in 1992. The UK was the first country to produce a national Biodiversi ...
. However, a long-term conservation project in the UK, led by the Royal Entomological Society, led to a significant increase in numbers in 2022, with the species described as "thriving".
Recent findings have also shown that there is a positive correlation between large blue butterfly conservation success and that of other endangered species. One specific example is the relationship between ''Myrmica'' ants, the large blue butterfly, violet seeds, and the violet-feeding butterfly (''Boloria euphrosyne
The pearl-bordered fritillary (''Boloria euphrosyne'') is a butterfly of the family Nymphalidae found in Europe and through Russia across the Palearctic to the north of Kazakhstan.
Description
The adult butterfly is orange with black spots o ...
''). The ants will bring the violet seeds into the nest. The seeds will often germinate in the nest, and their potential for germination increases as the nest becomes deserted. Since large blue butterfly predation of ant larvae can lead to desertion of the nest and ''B. euphrosyne'' tend to prefer violets growing on deserted ant nests, the fitness of ''B. euphrosyne'' appears to be indirectly affected by the presence of the large blue.
Behaviour
Brood-parasitic behaviour
Like many members of the genus '' Phengaris'', large blue butterfly caterpillars are brood parasite
Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were it ...
s, relying on another insect to raise their young. In this case, the hosts are species of '' Myrmica'' ant. By being physically and chemically similar to ''Myrmica'' ants in their larval stage, and possibly by using other forms of mimicry, ''Phengaris'' caterpillars trick the ants into taking them back to the ant nest. Once there, the caterpillar will either become a predator of the ant larvae, or beg for food by acting like an ant larva in what is known as a "cuckoo
Cuckoos are birds in the Cuculidae family, the sole taxon in the order Cuculiformes . The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals and anis. The coucals and anis are sometimes separ ...
" strategy. The "cuckoo" method is viewed as a more successful strategy, as studies have consistently found more larvae per nest for cuckoo butterfly species than predator butterflies. Through much research, it has been well documented that large blue butterflies act as predators in the host nests.
Early ideas of the ''Phengaris-Myrmica'' relationship resulted in the construction of a linear relationship between one predator and one host. It was proposed that each species of ''Phengaris'' had evolutionarily adapted to prey on one specific species of ''Myrmica'' with the large blue focusing on ''M. sabuleti''. More recent reports indicate that while each ''Phengaris'' species can prey on more than one ''Myrmica'' species, that ability varies between species and each butterfly species still prefers a specific ant species. While results are not conclusive, it has been shown that the large blue strongly favours ''M. sabuleti'' but has been documented to also prey on '' M. scabrinodis''. Studies have also shown that species of butterfly may exhibit different host preferences depending on the location. For example, in Finland, large blue butterflies exclusively fed off '' M. lonae'' nests. Due to differing reports and the difficulties involved in these types of studies, the nature of the host-parasite relationship is still inconclusive.
Female egg-laying behaviour
Since the parasitic-host relationship between the large blue and the ''Myrmica'' is essential for the caterpillar survival, female butterflies must lay eggs in areas where the larvae can be found by ant workers of the correct species. In the past it was unclear if ''Phengaris'' butterflies were capable of identifying areas of specific ''Myrmica'' species. It was believed that the certain species of ''Phengaris'' could detect specific odours to identify ''Myrmica'' species. It was also thought that certain species of ''Phengaris'' were capable of avoiding overcrowding on food plants by detecting high egg loads. New studies indicate that female egg laying is merely attuned to the ''Myrmica'' species, and that females do not take other factors into consideration.
Larva/caterpillar stage
Female ''Phengaris'' lay eggs on specific plants such as thyme
Thyme () is the herb (dried aerial parts) of some members of the genus ''Thymus'' of aromatic perennial evergreen herbs in the mint family Lamiaceae. Thymes are relatives of the oregano genus ''Origanum'', with both plants being mostly indigenou ...
. Wild thyme is the preferred food plant in the UK and in cooler or more mountainous areas in Europe, marjoram is preferred by populations in warmer areas. After about three weeks, larvae hatch to feed on the seeds and flowers of the plant. The caterpillar will stay in the vicinity of its food plant until its 4th instar
An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...
, when it will drop to the ground. From there the caterpillar will adopt various strategies to be found by ''Myrmica'' ants. Several caterpillar species of ''Phengaris'', such as '' P. rebeli'' and '' P. alcon'', will secrete pheromones that are specific to their respective hosts. The purpose of such behaviour is to mimic the pheromones of ant larvae that will become workers in the future. By successfully mimicking ant larvae, the caterpillars are taken back to the host nest and fed by the ants. Originally it was thought that the large blue butterfly behaved differently in that some believed it either secreted a poor pheromone mimic, or did not secrete one at all. Today it has been determined that it still secretes semiochemical
A semiochemical, from the Greek σημεῖον (''semeion''), meaning "signal", is a chemical substance or mixture released by an organism that affects the behaviors of other individuals. Semiochemical communication can be divided into two broa ...
s as a form of chemical mimicry
Chemical mimicry (also referred to as molecular mimicry) is a type of biological mimicry, involving the use of chemicals to dupe an operator. A chemical mimic dupes an operator (e.g. a predator) by showing an adaptive chemical resemblance to an obj ...
to gain acceptance into the host ant nest. Large blue caterpillars will sometimes follow ant trails or move away from the food plant during peak-foraging time to expose themselves specifically to ''Myrmica'' and not other ants. This results in workers generally ignoring the caterpillar once in the nest because it does not attract attention. The methods in which large blue caterpillars interact with the host ants are not yet known.
Behaviour in the host nest
"Cuckoo" strategy
While most ''Phengaris'' caterpillars behave similarly before entering the host ant nest, once adopted into a nest the larvae adopt one of two strategies. The first is the "cuckoo" strategy. This has been studied extensively in '' P. rebeli'', and consists of continued interaction between the caterpillar and the host ants. Once in the nest, the caterpillar uses acoustic mimicry
In evolutionary biology, mimicry is an evolved resemblance between an organism and another object, often an organism of another species. Mimicry may evolve between different species, or between individuals of the same species. Often, mimicry f ...
to hide its identity. The large blue larvae using the cuckoo strategy stay in close quarters with the ants while producing a noise very similar to that of a larval queen ant
A queen ant (formally known as a gyne) is an adult, reproducing female ant in an ant colony; generally she will be the mother of all the other ants in that colony. Some female ants, such as the '' Cataglyphis'', do not need to mate to produce offs ...
. By mimicking a queen, ''Phengaris'' species which employ the cuckoo strategy are fed by the worker ants and are given preferential treatment over the real ant larvae. Cuckoo strategy users become such high-status members of the nest that the ants will kill their own larvae to feed the caterpillar and will rescue the caterpillar first in the face of danger.
Predator strategy
Unlike other members of the genus ''Phengaris'', the large blue becomes a predator once in the ant nest. It feeds on the ant pupae while continuing to pose as a ''Myrmica'' ant. Even with mimicry, mortality for the large blue within the nest is high. One explanation is that each species of ''Phengaris'' is most suited for a single species of ''Myrmica''. Caterpillars that are adopted by an unfamiliar species of ant are often killed and eaten. Even if matched with the correct host, many large blue butterflies are unable to survive. If the mimicry is not perfect and the ants become suspicious, death is highly likely. Further, ants in nests without a consistent supply of food are much more likely to identify the large blue as an intruder. Large blue caterpillars are most likely to be attacked during the first 10 days after being adopted by the host ants. This is because in this time the caterpillars become larger than typical ''Myrmica'' ant larvae.
=Mimicry
=
Even once ''Phengaris'' butterflies have infiltrated the host nest, they continue to hide their identity as caterpillars and will go further in their act of deception. There have been many studies documenting the use of acoustic communication in ants, and it has been found that members of the genus ''Phengaris'' exploit this behaviour. For example, ''P. rebeli'' mimics the unique sound of the queen to elevate its status in the nest. This mimicry is effective enough to cause worker ants to prefer to rescue the ''P. rebeli'' over their own pupae in times of danger.
Previously it had been thought that only "cuckoo" strategy species used acoustic mimicry. The sound was so similar, that the sounds of the two caterpillars differed more than each did compared to the sound of the queen. Different ''Myrmica'' species utilize distinct semiochemicals to distinguish themselves, but they use very similar acoustic commands once in the nest.
=Lab studies and applications
=
Laboratory studies have shown that large blue butterfly larvae first consume the largest ant larvae. This evolved tactic maximizes efficiency not only because the largest larvae provide the most substance by volume, but also because it prevents the larvae pupating and becoming inaccessible prey. Further, it allows more newly hatched larvae time to grow bigger. While in the nest, large blue caterpillars acquire 99% of their final biomass, growing from an average of 1.3 mg to 173 mg. Results from laboratories estimate that 230 large larvae and a minimum of 354 ''Myrmica'' workers are needed to ensure the survival of one butterfly; however, such a large nest is very rarely found in the wild. This supports findings that large blue butterflies are extremely capable of withstanding starvation. This becomes extremely beneficial in situations when the ants desert the colony and leave the caterpillar behind. Large blue butterflies have been known to be capable of migrating to new nests once the original is deserted. In many cases, a nearby colony with a fresh brood will populate the nest allowing the surviving large blues to sequentially parasitize multiple ''Myrmica'' colonies.
Cuckoo vs. predatory strategies
Scientists remain unsure why there are multiple strategies within the host nest, but studies have been conducted to determine the effectiveness of each. The cuckoo strategy results in six times more butterflies per nest than the predatory strategy. While this seems to indicate a dominance of the cuckoo strategy, there are other factors to consider. Since the cuckoo caterpillars remain in close vicinity of the ants, they must secrete chemicals that are almost identical to the host species in order to survive. This explains why cuckoo strategy users are more likely to be predated by the host colony when adopted by a non-primary host than predatory strategy users. Current data seem to support the idea that cuckoo strategy users depend on a specific species of ''Myrmica'' ant while predatory ''Phengaris'' are more versatile overall but still perform better with a specific species.
The queen effect
It has been found that large blue butterflies are three times less likely to survive in nests that have queen ants present. This discovery has been explained with a theory called the "queen effect". In most '' Myrmica'' nests, the queen ant will lay two main batches of eggs, and the females that hatch from these eggs will either become workers or virgin queens. Whether these females become workers or virgin queens is dependent on the status of the queen in the nest. If the queen dies, worker ants have the largest of the female larvae transition into virgin queens. If the queen is present and healthy, she influences the nurse workers to neglect, starve and bite the female larvae which results in restricted growth and aids in the transition to workers. This indicates that ''Phengaris'' butterflies must maintain a strict balance between mimicking the queen in the presence of workers and appearing to be a worker to avoid the queen.
See also
*List of butterflies of Great Britain
This is a list of butterflies of Great Britain, including extinct, naturalised species and those of dubious origin. The list comprises butterfly species listed in ''The Moths and Butterflies of Great Britain and Ireland'' by Emmet ''et al.'' and '' ...
References
External links
Life cycle
Cornwall Wildlife Trust - large blue reintroduction
{{Taxonbar, from=Q161528
Phengaris
Butterflies of Africa
Butterflies of Asia
Butterflies of Europe
Butterflies of Japan
Butterflies described in 1758
Taxa named by Carl Linnaeus
Near threatened animals
Near threatened biota of Asia
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