Swallowtail butterfly

thumb|Swallowtail butterfly

thumb|A [[Polistes dominula|European paper wasp interacts with an anise swallowtail caterpillar which uses its osmeterium in defense. Most scenes are repeated in closeup at one-fourth speed.]]

thumb|A [[Pipilo maculatus|spotted towhee finds an anise swallowtail caterpillar to return to its nest and feed to its young.]]

Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, and include over 550 species. Though the majority are tropical, members of the family inhabit every continent except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of the genus Ornithoptera.

Swallowtails have a number of distinctive features; for example, the papilionid caterpillar bears a repugnatorial organ called the osmeterium on its prothorax. The osmeterium normally remains hidden, but when threatened, the larva turns it outward through a transverse dorsal groove by inflating it with fluid.

The forked appearance in some of the swallowtails' hindwings, which can be seen when the butterfly is resting with its wings spread, gave rise to the common name swallowtail. As for its formal name, Linnaeus chose Papilio for the type genus, as papilio is Latin for "butterfly". For the specific epithets of the genus, Linnaeus applied the names of Greek figures to the swallowtails. The type species: Papilio machaon honored Machaon, one of the sons of Asclepius, mentioned in the Iliad. Further, the species Papilio homerus is named after the Greek poet, Homer.

The Mon of the Taira clan of Japan is an Agehachō (swallowtail butterfly).

Taxonomy

Subfamilies

The genera of extant swallowtails are usually classified into three subfamilies, Baroniinae, Parnassiinae, and Papilioninae, the latter two being further divided into tribes. In swallowtails, besides morphological characteristics, the choice of food plants and ecological lifestyle reflect phylogeny and classification.

Baroniinae

The Baroniinae are a monotypic subfamily, restricted to a very small region in Mexico and are considered to be the most basal of the subfamilies. Baronia brevicornis is considered to be a relict species, and shares features with a fossil taxon Praepapilio. Baronia is unique among papilionidae' as having an Acacia species (family Leguminosae) as its food plant. The tribes recognized in the Parnassiinae are Parnassiini, Zerynthiini, and Luehdorfiini.

Tribe Parnassiini contains two genera, Hypermnestra, largely confined to central Asia and the genus Parnassius (the Apollos), a distinctive group of many species, all of which are alpine and capable of living at high altitudes. Most Parnassius have two small reddish spots on their hindwings. The tribe Luehdorfiini contains the genera Archon of Asia minor and the genus Luehdorfia of China and Japan. These two tribes have evolved to change their food plants, while the third tribe, Zerynthiini, has retained the archetypical papilionid food plant, the lowland vine Aristolochia. Zerynthiini comprises four genera – Sericinus, Bhutanitis, Zerynthia and Allancastria.

Subfamily: Parnassiinae.

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Papilioninae

The tribes recognized in the Papilioninae are Leptocircini, Teinopalpini, Troidini, and Papilionini.

Subfamily: Papilioninae.

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Praepapilioninae

An additional subfamily, Praepapilioninae, consisting of a single genus Praepapilio, includes two species of extinct butterflies, each member being described from single fossils found in a middle Eocene deposit in Colorado, United States (Durden and Rose, 1978).

Phylogeny

A phylogeny of the Papilionidae based on Nazari (2007) is given:

The Parnassinae, like the Papilioninae, were also believed to be monophyletic based on morphological studies but recent studies based on both morphological and molecular characteristics suggest that this is not the case.

and are now considered to be part of the tribe Parnassiini. Various species inhabit altitudes ranging from sea level to high mountains; species of Parnassius in particular often live at higher elevations. The majority of swallowtail species and the greatest diversity are found in the tropics and subtropical regions between 20°N and 20°S, particularly Southeast Asia, and between 20°N and 40°N in East Asia. Only 12 species are found in Europe and only one species, Papilio machaon, is found in the British Isles. North America has 40 species, including several tropical species and Parnassius.

The northernmost swallowtail is the Siberian Apollo (Parnassius arcticus), north of the Arctic Circle in northeastern Yakutia, at altitudes of 1500 meters above sea level. In the Himalayas, various Apollo species such as Parnassius epaphus have been found at 6,000 meters above sea level.

Food

thumb|[[Scarce swallowtail, lavender, near Adriatic|alt=Scarce swallowtail (Iphiclides podalirius) on lavender flowers, near the Adriatic]]

The caterpillars of various swallowtail butterfly species feed on a wide range of different plants, most depending on only one of five families: Aristolochiaceae, Annonaceae, Lauraceae, Umbelliferae (Apiaceae) and Rutaceae. By eating some of these toxic plants, the caterpillars sequester aristolochic acid which renders both the caterpillars and the butterflies of some of these as toxic, thus protecting them from predators. Similarly, the Parnassius smintheus sequesters sarmentosin from its host plant Sedum lanceolatum for protection from predators. Swallowtail tribes Zerynthiini (Parnassiinae), Luehdorfiini (Parnassiinae) and Troidini (Papilioninae), almost exclusively use the family Aristolochiaceae as their host plants.

For example, the eastern black swallowtail's (Papilio polyxenes) main host plant in the wild is Queen Anne's lace, but they also eat garden plants in the carrot family, including carrots, parsley, dill, and fennel.

Stages of development of a papilionid, the giant swallowtail (Papilio cresphontes)

Giant Swallowtail Egg.jpg|Egg

Giant Swallowtail Larva.jpg|Larva

Papilio cresphontes chrysalis.JPG|Pupa

Butterfly 8731-2.jpg|Butterfly

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Distinguishing characteristics

The key characteristics that differentiate the Papilionidae from the other butterfly families are:

Predators include the red-winged blackbird, Pennsylvania firefly, five-lined skink, green darner, goldenrod spider, Chinese mantis, fiery searcher, and striped skunk.

Biological basis for polymorphisms in mimicry

Not all individuals in some species are identical in appearance. For example, Papilio glaucus (eastern tiger swallowtail), Y-linkage determines whether the females are either wild-type (yellow and black) or melanic (dark melanin replaces the yellow background). This genetic difference stems from the fact that melanism is controlled by a single gene, which controls the level of dopamine in the organism. The enzyme BAS, which assists dopamine in producing the yellow pigmentation, normally found on the wings' background, is suppressed. Without the pigmentation, the butterfly appears mostly black (the melanic form) and is a Batesian mimic of Battus philenor, the pipevine swallowtail. There are also Papilio glaucus that are not wholly black; several possess an intermediate "sooty" color and are sensitive to temperature. Given that the males of the species, which do not have Batesian mimicry, are preyed upon much more frequently by predators than the females, an ongoing question is why females would exhibit the non-mimetic wing pattern, which would seemingly lower their fitness compared to the mimicry form. The pipevine swallowtail exhibits Batesian mimicry as well.

Several hypotheses for this phenomenon were made, the two noteworthy being the pseudosexual selection hypothesis and the male avoidance hypothesis. In the pseudosexual hypothesis, male butterflies aggressively approached the male-looking females and then mellowed their behavior into sexual behavior when they were close enough to identify them as females. In the male avoidance hypothesis, female butterflies disguise themselves in an attempt to evade male harassment, as courtship can be harmful, time-consuming, and attract predators.

One study recorded male responses to females of each morphs and found that the males consistently favored the Batesian mimics, then the black and yellow, and then the morph with orange patches. They lay individual eggs on the underside of the leaves of their food plants. There is no parental investment once the eggs have been laid.

The pupae are typically attached to the substrate by the cremaster but with head up held by a silk girdle. The Apollos, however, pupate in debris on the ground and also build a loose cocoon. In the temperate regions, the winters are passed in a pupal diapause stage.

In culture

Since swallowtail butterflies are large, colorful, and attractive, they have been targeted by butterfly collectors. The largest of these, the birdwing butterflies are particularly sought after and are cultured in butterfly farms to supply collectors.

Many members of the family, as larvae, feed on plants of the citrus family Rutaceae, and some of them are pests in citrus orchards.

The Oregon swallowtail is the state insect of Oregon. The eastern tiger swallowtail is the state insect of Virginia and the state butterfly of Georgia, Delaware, and South Carolina. The black swallowtail is the state butterfly of New Jersey and Oklahoma.

The tabletop role-playing game Lancer includes a support- and sensor-focused mech named the Swallowtail.

References

External links

"Papilionidae" on Tree of Life web project.
Revised GloBIS/GART Papilionidae species checklist.
GloBIS Database Includes type images
Natural History Museum, London web site on "Afrotropical Kite Swallowtails".
Photoset and description of lesser known species of swallowtails
Swallowtails Papilionidae of the World: a pictorial summary. Comprehensive.