Maculinea rebeli
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''Phengaris rebeli'' (formerly ''Maculinea rebeli''), common name mountain Alcon blue, is a species of
butterfly Butterflies are insects in the macrolepidopteran clade Rhopalocera from the Order (biology), order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The ...
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 butterfl ...
. It was first found and described in
Styria Styria (german: Steiermark ; Serbo-Croatian and sl, ; hu, Stájerország) is a state (''Bundesland'') in the southeast of Austria. With an area of , Styria is the second largest state of Austria, after Lower Austria. Styria is bordered to ...
, Austria, on Mount
Hochschwab The Hochschwab in the Upper Styria Upper Styria (german: Obersteiermark), in the Austrian usage of the term, refers exclusively to the northwestern, generally mountainous and well-wooded half of the federal state of Styria. The southwestern half ...
around 1700. Although it was initially classified as a subspecies of '' P. alcon'', a European researcher, Lucien A. Berger, designated it as a separate species in 1946. Genetic similarities between ''P. rebeli'' and ''P. alcon'' have led many researchers to argue that the two are the same species and differences are due to
intraspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...
variation. Although ''P. rebeli'' is found across the
Palearctic 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-Sibe ...
(see subspecies), it is difficult to determine the species' precise range due to confusion with ''P. alcon''. Behavioral ecologists have found its role as 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 its own ...
to be of particular interest as, unlike many brood parasites, it does not directly oviposit in the hosts' nests. ''P. rebeli'' parasitizes the colony ant
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
''
Myrmica schencki ''Myrmica schencki'' is a species of ant in the genus '' Myrmica''. Distribution and habitat ''Myrmica schencki'' is distributed across Europe (from Great Britain, Sweden, Finland in the North to Spain, Italy and the Balkans in the South), the C ...
'' as a
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
by using chemical mimicry to trick the ants into believing that they are ant larvae; thus, the ants bring ''P. rebeli''
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 Sym ...
s back to their nests and feed them. ''P. rebeli'' is dependent on the plant ''
Gentiana cruciata ''Gentiana cruciata'', the star gentian or cross gentian, is a herbaceous perennial flowering plant in the Gentianaceae family. Description ''Gentiana cruciata'' is a hemicryptophyte scapose plant of small size, reaching on average in height ...
'' early in its life cycle and is vulnerable to parasitism by ''
Ichneumon eumerus ''Ichneumon eumerus'' is a species of parasitic wasp belonging to the family Ichneumonidae, subfamily Ichneumoninae. It is a specialist parasite of the larva of the mountain Alcon blue butterfly (''Phengaris rebeli''). Life cycle The life cycle ...
'' while inside the nest of ''M. schencki''. It was placed on the
IUCN Red List 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 biol ...
in 2000 and is classified as a species vulnerable to
extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
.


Taxonomy

The
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''
Phengaris ''Phengaris'' is a genus of gossamer-winged butterflies in the subfamily Polyommatinae. Commonly, these butterflies are called large blues, which if referring to a particular species is '' P. arion'', a species resident in Europe and some parts o ...
'' was previously considered a subgroup within the genus ''
Maculinea ''Phengaris'' is a genus of gossamer-winged butterflies in the subfamily Polyommatinae. Commonly, these butterflies are called large blues, which if referring to a particular species is '' P. arion'', a species resident in Europe and some parts ...
'' (explaining why ''P. rebeli'' was formerly known as ''M. rebeli'') and the ''Maculinea-Phengaris'' clade is thought to be a section within ''
Glaucopsyche ''Glaucopsyche'', commonly called blues, is a Holarctic genus of butterfly in the family Lycaenidae, found mainly in Palearctic Asia. For other species called "blues" see subfamily Polyommatinae and genus ''Plebejus''. SpeciesLepIndex: synonymi ...
''. There are three groups within this ''Maculinea-Phengaris'' clade: the ''alcon'' group, the ''teleius'' group, and the ''Arion-Phengaris'' group. The groups are divided based on their alternative parasitization strategies of the host ants. The
predatory Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
strategy (in which the caterpillar consumes the host ants) and cuckoo strategy (in which the caterpillars feed off of the ants' regurgitation) are derived characteristics from the ''alcon'' group, with the predatory strategy having evolved from the ''teleius'' group and the cuckoo strategy having evolved from the ''arion-Phengaris'' group. Another way these groups are categorized is by whether or not they release a
chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...
(
dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...
nectary
organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic keyboard instrument ** Hammond ...
secretions) to attract the attention of the host ant. This trait is not as prominent in ancestors of the ''alcon'' group and in '' M. nausithous'', which is part of the ''teleius'' group. ''P. rebeli'' is most closely related to both
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
of ''
Phengaris alcon ''Phengaris alcon'', the Alcon blue or Alcon large blue, is a butterfly of the family Lycaenidae and is found in Europe and across the Palearctic to Siberia and Mongolia. Description from Seitz ''L. alcon'' Schiff. (= areas Esp., ''euphemu ...
'' (''P. alcon alcon'' and ''P. alcon kondakovi'') with ''P. alcon alcon'' being more closely related to ''P. rebeli'' than to ''P. alcon kondakovi''.


Subspecies

*''Phengaris rebeli rebeli'' (Hirschke, 1904) Central and Southern Europe *''Phengaris rebeli cordidula'' (Jachontov,
909 __NOTOC__ Year 909 ( CMIX) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. Events By place Britain * King Edward the Elder and his sister, Princess Æthelflæd of Mercia, raid Danish ...
Caucasus Major The Greater Caucasus ( az, Böyük Qafqaz, Бөјүк Гафгаз, بيوک قافقاز; ka, დიდი კავკასიონი, ''Didi K’avk’asioni''; russian: Большой Кавказ, ''Bolshoy Kavkaz'', sometimes translat ...
*''Phengaris rebeli imitator'' Tuzov, 2000 northern
Tian-Shan The Tian Shan,, , otk, 𐰴𐰣 𐱅𐰭𐰼𐰃, , tr, Tanrı Dağı, mn, Тэнгэр уул, , ug, تەڭرىتاغ, , , kk, Тәңіртауы / Алатау, , , ky, Теңир-Тоо / Ала-Тоо, , , uz, Tyan-Shan / Tangritog‘ ...
,
Dzungarian Alatau The Dzungarian Alatau ( mn, Зүүнгарын Алатау, ''Züüngaryn Alatau''; ; kk, Жетісу Алатауы, ''Jetısu Alatauy''; russian: Джунгарский Алатау, ''Dzhungarskiy Alatau'') is a mountain range that lies on t ...
*''Phengaris rebeli kondakovi'' Kurentzov, 1970
Transbaikalia Transbaikal, Trans-Baikal, Transbaikalia ( rus, Забайка́лье, r=Zabaykalye, p=zəbɐjˈkalʲjɪ), or Dauria (, ''Dauriya'') is a mountainous region to the east of or "beyond" (trans-) Lake Baikal in Far Eastern Russia. The steppe and ...
,
Amur Oblast Amur Oblast ( rus, Аму́рская о́бласть, r=Amurskaya oblast, p=ɐˈmurskəjə ˈobləsʲtʲ) is a federal subject of Russia (an oblast), located on the banks of the Amur and Zeya Rivers in the Russian Far East. The administrative ...
,
Ussuri The Ussuri or Wusuli (russian: Уссури; ) is a river that runs through Khabarovsk and Primorsky Krais, Russia and the southeast region of Northeast China. It rises in the Sikhote-Alin mountain range, flowing north and forming part of the Si ...
northeast China *''Phengaris rebeli monticola'' (Staudinger, 1901)
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 ''Ox ...
*''Phengaris rebeli'' ssp.
Altai mountains The Altai Mountains (), also spelled Altay Mountains, are a mountain range in Central Asia, Central and East Asia, where Russia, China, Mongolia and Kazakhstan converge, and where the rivers Irtysh and Ob River, Ob have their headwaters. The m ...


Conflicts over classification

Several researchers argue that ''P. rebeli'' has not
evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...
into a separate species from ''
Phengaris alcon ''Phengaris alcon'', the Alcon blue or Alcon large blue, is a butterfly of the family Lycaenidae and is found in Europe and across the Palearctic to Siberia and Mongolia. Description from Seitz ''L. alcon'' Schiff. (= areas Esp., ''euphemu ...
'' and that any variation between the two groups is due to
intraspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...
variation. Both species share a similar adult morphology, DNA and allozymes. Furthermore, they both have similar methods of parasitizing the host ant: they act as parasitic "cuckoos" within the ant nest and feed upon the ants' regurgitation. This is compared to the alternative method of predation used by ''Maculinea arion''. To test this hypothesis, researchers examined how each species utilized the host ants. ''M. schencki'' and ''M. sabuleti'' are parasitized by ''P. rebeli'' while ''M. salina'' and ''M. vandeli'' are parasitized by ''P. alcon''. ''M. scabrinodis'' is parasitized by both ''P. rebeli'' and ''P. alcon''; however, ''P. alcon'' is far more likely than ''P. rebeli'' to parasitize ''M. scabrinodis''. Researchers found that in general, ''P. alcon'' was far more likely to parasitize the host ant than ''P. rebeli''; however, ant nests that supported ''P. alcon'' were much smaller and supported lower populations than ant nests that supported ''P. rebeli''.


Appearance

''P. rebeli'' are noted for their large blue wings, with the males displaying a violet blue shade and the females displaying blue basal areas interspersed with brown spots, similar to other butterflies in the genus. The undersides of the wings are a dark brown with small black spots that are circled in white. This species can be distinguished from its close relative, ''P. alcon'', by the broader black margins of the upper-side the wings of males and the extensive blue basal areas of wings of the females. It has a wingspan of approximately 32–36 mm.


Habitat

It resides in fairly dry areas at lower elevations and damp meadows among trees at alpine elevation and is found in altitudes of 1000–2000 meters. Populations of ''P. rebeli'' are concentrated in the northern part of Portugal and Greece, the western Pyrenees, France, and eastern part of Germany.


Lifecycle

This butterfly begins life as eggs laid on leaves of ''
Gentiana cruciata ''Gentiana cruciata'', the star gentian or cross gentian, is a herbaceous perennial flowering plant in the Gentianaceae family. Description ''Gentiana cruciata'' is a hemicryptophyte scapose plant of small size, reaching on average in height ...
'' plants. The caterpillars hatch and feed upon the flowers and developing fruits of the plant. After feeding and growing for four instars, the caterpillars drop to the ground. There, the caterpillar releases chemicals which mimic the larvae of ''
Myrmica ''Myrmica'' is a genus of ants within the subfamily Myrmicinae. It is widespread throughout the temperate regions of the Holarctic and high mountains in Southeast Asia. The genus consists of around 200 known species and additional subspecies, ...
'' ants. If an ant finds the caterpillar, it will carry the caterpillar back to its nest. Once inside the nest, the caterpillar tricks the ants into feeding and caring for it. ''P. rebeli'' pupates within the ant nest and crawls out as an adult.


Host plant

''P. rebeli'' choose where to lay their eggs based on the size of ''G. cruciata''
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
and not upon the location of the closest ''Myrmica'' ant colony. This fact is supported by the timing of its oviposition. ''P. rebeli'' lays their eggs during the warm summer season, when ''Myrmica'' ants are most likely to be underground. Researchers also observed females did not base their
oviposition The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...
on where they found ''Myrmica'' nests. Larger populations of ''G. cruciata'' are associated with higher production of flowers and
seeds A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm pl ...
, but also with an increased frequency of ''P. rebeli'' feeding upon the plant. Researchers are particularly interested in the ''G. cruciata'' plant because both ''P. rebeli'' and ''G. cruciata'' are endangered. Lepidopterists have suggested that conservation of ''P. rebeli'' requires focus on conservation of ''G. cruciata''.


Parasitism of ants


Discovery

''Phengaris rebeli'' 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 its own ...
, an organism that manipulates another organism (the host) to raise its offspring; in this case, the ''P. rebeli'' parasitizes a particular species of ant, the ''
Myrmica schencki ''Myrmica schencki'' is a species of ant in the genus '' Myrmica''. Distribution and habitat ''Myrmica schencki'' is distributed across Europe (from Great Britain, Sweden, Finland in the North to Spain, Italy and the Balkans in the South), the C ...
''. The ''P. rebeli'' was first discovered to be a brood parasite when a researcher observed ''M. schencki'' ants bringing the ''P. rebeli''
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
back to their own nest. One of the proposed hypotheses for this parasitism was that ''P. rebeli'' larvae released chemicals to confuse the ants into believing they were ant larvae. It was determined that ''P. rebeli''
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
use chemical
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 persuade the ''M. schencki'' ants that they are part of the ant brood. Furthermore, ''M. schencki'' ants cannot distinguish the physical differences between the ''P. rebeli'' larvae and other non-kin brood because the ''P. rebeli'' larvae are far more similar to the ''M. schencki'' larvae than to any other ant species larvae. ''P. rebeli'' live in different habitats; therefore, they do not parasitize the same ''Myrmica'' ant species. Through observation and experimentation, researchers found that if ''P. rebeli'' try to parasitize a different ''Myrmica'' ant species than the one they normally do, the ''Myrmica'' ants will identify the ''P. rebeli'' larvae as intruders and will kill 100% of the ''P. rebeli'' larvae. The differences between the ''P. rebeli'' are that they synthesize different hydrocarbons, which allow them to mimic different species of ''Myrmica'' ants. This explains why they have no success in being mistaken for another species of ''Myrmica'' ant and the ensuing 100% mortality rate when the other ''Myrmica'' ant species is not fooled.


Acoustics and social rank in host hierarchy

Once ''P. rebeli'' larvae infiltrate the host's brood, they ascend to the highest social ranks of the host's hierarchy by using acoustics to achieve social acceptance from worker ''M. schencki'' ants. ''P. rebeli''
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
and pupa accomplish this by mimicking the sound that the queen of the ant colony makes, both while as a larva and as a pupa in the colony. While ''Myrmica'' ant colony members can identify each other through chemical signaling, social ranks are partially determined by sound acoustics. Therefore, once the ''P. rebeli'' begin to mimic the sound of the queen ant, the worker ants begin to treat the ''P. rebeli'' as if it were the queen ant. On the other hand, the queen ant treats the ''P. rebeli'' larvae and pupae as if they were rivals, as she is the only one in the colony that recognizes that the ''P. rebeli'' larvae is not ant larvae. The most common functions of the queen ant sounds are to recruit workers, smell nestmates, and facilitate oral exchanges of food and pheromones. Most importantly, however, is the fact that distress noises made by the queen causes workers to raise their guard and bolster her protection. Researchers speculate that acoustical
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 ...
is related to the level of interaction between the host and parasite. In the genus ''Phengaris'', there are two different strategies: the cuckoo strategy used by ''P. rebeli'' and the predatory strategy used by ''
Phengaris arion The large blue (''Phengaris arion'') is a species of butterfly in the family Lycaenidae. The species was first defined in 1758 and first recorded in Britain in 1795. In 1979 the species became mostly extinct in Britain but has been successfully ...
''. In ''P. rebeli'', the ''Phengaris'' larvae become integrated into the colony and are attended by worker ants. However, larvae in predatory species prey on the ants’ brood and consequently spend much of their life hiding in pockets of the brood nest.


Integration into host's life

There are two phases in the integration of ''P. rebeli'' into a ''Myrmica schencki'' ant colony: initial integration and full integration. In both stages, a ''P. rebeli'' caterpillar is brought into the brood nest; however, in full integration, ''P. rebeli'' also achieves its high social status within the host society. That status is crucial for surviving periods of host colony stress such as food shortage. Studies have shown that ''P. rebeli'' caterpillars benefit more when they parasitize a ''Myrmica schencki'' ant colony than a colony of any other ant species. When ''Myrmica'' ant colonies encounter a period of food shortage, more ''P. rebeli'' caterpillars survive than if this food shortage were to occur in colonies of other species. This is because the ''P. rebeli'' caterpillars have a lower social rank in other ant species compared to their social rank in the ''M. schencki'' ant colony. This phenomenon is seen during times of stress, when some of the hungry ''P. rebeli'' caterpillars secrete compounds to attract attention from the ant colony it has parasitized. While the ''M. schencki'' ants are still fooled into believing that the ''P. rebeli'' are of their own brood, these compounds do not mimic those of non-host species' societies in other ant species, and thus, results in the ''P. rebeli'' being identified as intruders and killed. On the other hand, ''M. schencki'' prefers to feed ''P. rebeli'' during times of food shortage. Thus, in periods of starvation, ''P. rebeli'' caterpillars overall exhibit a higher survival rate than those of the ''M. schencki'' larvae.


Polymorphism of growth in larvae

Many butterflies are polymorphic. ''P. rebeli'' caterpillars are polymorphic, having two strategies for living and growing underground: to exist as fast-developing
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
(FDL) or slow-developing larvae (SDL). After the ant brood adopts the FDL, which comprise approximately 25% of the total ''P. rebeli'' larvae, the FDL complete growth the following spring and eclose (emerge as an adult from the pupa) in early summer to complete their life cycle. The SDL, which comprise 75% of ''P. rebeli'' larvae, do not grow much during the first year, but grow rapidly during the early part of the second summer and remain a second winter within the ant colonies. While both larva types ultimately form similar-sized pupae, their polymorphic growth rates could indicate alternative fitness strategies and different ways to exploit the ''M. schencki'' food resources. Other researchers hypothesize that another alternative growth strategy will evolve in the ''P. rebeli'', in which the ''P. rebeli'' will parasitize the ''M. schencki'' ants for an even longer period of time than the slow developing larvae. Most researchers, however, find this hypothesis highly unlikely because it is not an evolutionarily stable strategy. At the rate the ''P. rebeli'' parasitizes the ''M. schencki'' ants, the host colony is unlikely to last as a viable food source for more than two years (the average lifespan of the longer polymorph of ''P. rebeli''). Once the host colony reaches its lifespan of two years and dies, the ''P. rebeli'' loses its food source and dies as well. ''P. rebeli'' developmental rate shows great phenotypic plasticity (changing its developmental rate in response to changes in the environment), as it develops very quickly in the lab and in the Pyrenees and Southern Alps. Scientists hypothesize that this
plasticity Plasticity may refer to: Science * Plasticity (physics), in engineering and physics, the propensity of a solid material to undergo permanent deformation under load * Neuroplasticity, in neuroscience, how entire brain structures, and the brain it ...
is due to warm conditions and more light exposure, which affects larval development. Abundant food resources are also thought to play a part in quickened development. Studies have shown that smaller-sized ''P. rebeli'' from Hungary normally eclose at the end of June or mid-July; however, when these populations are studied in laboratories, they do not eclose until late August. This has led researchers to speculate that ''P. rebeli''
larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
that do not receive adequate food can still fully develop in one year and act as a functioning adult. However, they are unlikely to be bivoltine (producing two broods in one season). This hypothesis is supported by the fact that certain researchers claim that ''P. rebeli'' larvae can have continuous development.


Vestigial mutualism

The parasitic relationship between ''P. rebeli'' caterpillars and their ant hosts is thought to have evolved from a mutualistic relationship. ''P. rebeli'' larvae prey upon ant brood while producing sugar-rich secretions which worker ants imbibe. In an experiment, ''P. rebeli'' individuals which consumed ant larvae developed more quickly than those who did not. In addition, despite their nourishing offering to the ant colony, they invariably imposed a net loss in the survival rates of workers and brood, demonstrating that the species is parasitic (rather than mutualistic) at all stages in its host colony.


Relationship with the parasitic wasp, ''Ichneumon eumerus''

Though ''P. rebeli'' is a parasite, it acts itself as a host to the
parasitoid In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...
ichneumon wasp, ''
Ichneumon eumerus ''Ichneumon eumerus'' is a species of parasitic wasp belonging to the family Ichneumonidae, subfamily Ichneumoninae. It is a specialist parasite of the larva of the mountain Alcon blue butterfly (''Phengaris rebeli''). Life cycle The life cycle ...
''. ''I. eumerus'' attempts to parasitize ''P. rebeli'' caterpillars within a ''Myrmica'' nest. The adult wasp searches for ''Myrmica'' ant nests by sense of smell, and responds strongly only to nests containing ''P. rebeli'' which it most commonly and successfully parasitizes. After locating an ''M. schnecki'' nest, the wasp enters only if it contains ''P. rebeli'' caterpillars. It is able to enter the nest without being swarmed by releasing a chemical which causes the worker ants to attack one another instead of concentrating their efforts on the wasp. Once the wasp reaches the caterpillars, it oviposits an egg in them. Once the wasp's eggs hatch, the larvae feed on the caterpillar, eventually killing it.


Conservation status

''P. rebeli'' has been rigorously studied in Europe because it has priority conservation status and was classified as "vulnerable" in 2000 by 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 ...
. It was first brought to the IUCN's attention and listed on the IUCN Red List of Threatened Species in 1986. The species was categorized as "vulnerable" because its population decreased by 20-50% in the last 25 years and has been extirpated from at least one country. The causes of this drastic population reduction are thought to be agricultural land use changes, abandonment of
extensive management Extensive farming or extensive agriculture (as opposed to intensive farming) is an Agriculture production system that uses small inputs of labour, fertilizers, and capital, relative to the land area being farmed. Systems Extensive farming is ...
, and deforestation. As the habitat of the food plant ''
Gentiana cruciata ''Gentiana cruciata'', the star gentian or cross gentian, is a herbaceous perennial flowering plant in the Gentianaceae family. Description ''Gentiana cruciata'' is a hemicryptophyte scapose plant of small size, reaching on average in height ...
'' decreases, ''P. rebeli'' population also decreases.


Gallery

File:Maculinea rebeli eggs.jpg, Eggs on host plant File:Maculinea_rebeli_pupa_in_ant_nest.jpg, Pupa in ant nest


References


External links

{{Taxonbar, from=Q2047011 Phengaris Brood parasites Butterflies described in 1904 Butterflies of Europe Parasitic insects Taxa named by Hans Hirschke Taxonomy articles created by Polbot Taxobox binomials not recognized by IUCN