Chrysiridia rhipheus

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Madagascan sunset moth
Engraving captioned Urania riphaeus from Charles D. d'Orbigny’s Dictionnaire universel d'histoire naturelle (1849)
Engraving captioned Urania riphaeus from Charles D. d'Orbigny’s Dictionnaire universel d'histoire naturelle (1849)
Conservation status
Not evaluated (IUCN 3.1)
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Superfamily: Geometroidea
Family: Uraniidae
Subfamily: Uraniinae
Genus: Chrysiridia
Hübner, 1823
Species: C. rhipheus
Binomial name
Chrysiridia rhipheus
(Hübner, 1823), (Cramer, 1782)

(Drury, 1773, originally Papilio rhipheus[1])
Contained in Madagascar
Contained in Madagascar
Synonyms

Urania rhipheus
Urania ripheus[2]
Urania rhiphaeus[3]
Chrysiridia riphearia
Chrysiridia rhiphaeus[4]
Chrysiridia ripheus
Chrysiridia madagascariensis[3] (Less., 1831)
Chrysiridia crameri[5] (Maassen, 1897)

The Madagascan sunset moth, or simply sunset moth (Chrysiridia rhipheus, also known as Urania rhipheus, U. rhiphaeus,[3] C. rhiphaeus,[4] and C. madagascariensis[3]) is a diurnal moth of the Uraniidae family. It is very colourful, but the iridescent parts of the wings do not have pigment; the colors originate from refraction instead.[6] It is considered to be one of the most impressive and beautiful Lepidoptera,[7] for this reason it has gained an international reputation, is much sought by collectors,[8] and is featured in most "coffee table" books on the Lepidoptera.[9] It is the sole herbivore of the four species of the toxic shrubs and trees of the genus Omphalea in its native Madagascar; this toxicity is passed on by the feeding caterpillar to the pupa and the adult moth.[10]

Contents

[edit] Taxonomy

The Madagascan sunset moth was first described by British entomologist Dru Drury in 1773. Because of its resemblance to swallowtail butterflies, Drury had first described the species as Papilio rhipheus,[1] he mistakenly thought its antennae were clubbed,[11] a character frequently used to differentiate moths form butterflies. Once Drury’s inaccuracy was found, it was placed in the genus Urania, until 1823 when Hübner placed it in a new genus; Chrysiridia. It also has also been given other names, including U. crameri by Maassen in 1879 and U. var. madagascariensis by Lesson in 1831.[5]

Native Malagasy people call it Adriandolo or Lolonandriana,[3][12] from lolo for spirit or butterfly and andriana for noble or king,[13] therefore meaning noble butterfly,[3] noble spirit,[14] king butterfly[12] or king spirit.

The genus Chrysiridia is entirely African as the only other species is the closely related East African C. croesus. It is it, with Urania, sister-taxa to the most basal diurnal uraniine genus Alcides. All three genera feed on Omphalea, but Alcides also feeds on Endospermum.[10]

[edit] Description

Chrysiridia rhipheus (Drury, 1773) has a wingspan of 7.5 to 9 centimetres (3 to 3½ in).[15] As many of the uraniine moths, the sunset moth has an uncanny resemblance to Swallowtail butterflies because of its tails and colourful wings, both characteristics common to the latter. For those reasons it is easy to mistaken it for a butterfly.[16]

It is black with iridescent red, blue and green markings. Pattern variations are common, and the moth is often partly asymmetrical,[17] One of the factors for this is temperature shocks during the pupal stage.[18]

Chrysiridia rhipheus underside
Chrysiridia rhipheus underside
Chrysiridia rhipheus topside
Chrysiridia rhipheus topside

[edit] Wing microstructure

The iridescent parts of the wings do not have pigment; the color originates from refraction of light by the microstructures of the ribbon-like scales covering the moth’s wings. These structural characteristics make this species and its neotropical relative Urania common subjects of optical sciences.[6]

The iridescence on the Madagascan sunset moth's wings is produced by the alliance of two optic phenomena:

  • The first mechanism is an air-cuticle-multilayer that creates optical interference. Each scale is composed of one to six cuticle layers, depending on the portion of the scale, separated by air and held by connecting blocks.
  • The second mechanism is more unusual among Lepidoptera: The scales are highly curved, which creates a mechanism of inter-scale reflection. The proximal part of each scale is almost flat, gradually curves up and then steeply bends down at the distal end, covering the proximal part of the next row of scales. Because of this shape, adjacent rows of scales have valley-like grooves between them. Light is reflected from one row to the next, which makes the color more polarization dependent.

Although the biological function of this polarization-dependent change in color has not been studied, it may work as a visual signal among the species. That is if the insects possess polarization and color vision.[2]

[edit] Distribution and habitat

Chrysiridia rhipheus is endemic to Madagascar. The adult moths seasonally migrate in huge numbers between geographically isolated populations of their host plant Omphalea spp. They migrate from the three species from the dry deciduous forest in the west (O. ankaranensis, O. occidentalis, and O. palmata) to the eastern rainforest species (O. oppositifilia). The western species are largely protected. The eastern species on the other hand is mostly unprotected and is dispersed in widely scattered populations threatened by deforestation. Being the only evergreen species, O. oppositifilia is probably crucial for the moth’s survival. The Jamaican moth Urania sloanus, from the same subfamily (Uraniinae), became extinct after the loss of one species of its host plants.[10]

The moths migrate in response to changes in the host plants. Chrysiridia larvae defoliate the whole plant, and even eat flowers and fruit, thus having a considerable negative impact on the reproduction and survival of seedlings.[10] The plants probably react by changing the nutrient and secondary compound levels. They become toxic to the larvae and cause high mortality levels. Inversely Omphalea who do not sustain damage by predation for long periods have lowered moth-induced defences.[9] This allows for mass local emergences, followed by apparent population crashes. The population crashes are probably caused by the emigration of adults, or to a lesser probability, the high mortality levels in larvae. Through allelochemistry, the plant may recruit hymenopteran parasitoids as a protection, hence playing a role in the population dynamics of the moth.[10]

[edit] Host plants

Distribution of the four Madagascan species of Omphalea
Distribution of the four Madagascan species of Omphalea

Like C. croesus and species of the genus Urania, C. rhipheus is a specialist species whose larvae feed strictly on species of the pantropical genus Omphalea (Euphorbiaceae).[10] Four species of the genus Omphalea are endemic to Madagascar:

  • O. ankaranensis, a shrub from the limestone karst of northern Madagascar
  • O. palmata, a dry forest shrub, closely related to O. ankaranensis, but from western Madagascar
  • O. occidentalis, also a dry forest species of western Madagascar
  • O. oppositifilia, a tree from the east coast rainforest of Madagascar[19]

All Omphalea, in common with many other Euphorbiaceae, possess leaf nectaries attracting polistine wasps, which are known to be effective predators of early instar larvae. The leaf nectaries also attract ants. The ants usually protect their host plant, eating both the nectar and plant-eating insects on it. But they generally ignore completely Chrysiridia larvae, making it likely that the larvae possess a chemical deterrent as a primary defence.[10] This chemical deterrent comes from the host plants. The species from the genus contain polyhydroxy alkaloids potentially sequestered or excreted by the caterpillar, the pupa and the moth.[20]

[edit] Behaviour

The sunset moth is day flying while most moths are active at night. It is also toxic, as revealed by its aposematic colors, a common defense found in several diurnal moths. Another habit the moth has in common with many butterflies is the night resting posture; the wings are held vertically over the back. During their migrations they roost in a group for the night.[10]

[edit] Life cycle

The females lay their eggs late in the afternoon or at nightfall, and locate potential oviposition sites visually.[10] Like the eggs of other Uraniidae, the sunset moth’s are domed with projecting ribs.[21]

After they hatch, the small caterpillars only eat the tissue (mesophyll) between the veins of the leaves. They do this to avoid the sticky and toxic latex produced by the plant's laticifers and transported in the veins. Later instars still eat leaves but also flowers, fruit, tendrils and young stems, defoliating the entire plant. They can deal with the chemical defences in the latex and it does not cause problems of mouthpart coagulation.[10] The caterpillar is whitish-yellow with black spots and red feet and is covered in club-ended black setae.[22] It has five pairs of prolegs on the segments 3 to 6 and 10, with its six legs it has a total of sixteen.[23]

After completing all but its last moult, the caterpillar goes to the ground, and spins an open network cocoon out of silk. The caterpillar's last moult brings it to the stage of chrysalis.[22][24]

[edit] Nectar sources

Adult moths prefer white or whitish-yellow flowers as a nectar source, which indicates that visual cues play a large role in their selection. Most flowers visited are inflorescences of small flowers or have dense filaments, giving them the appearance of a bottle brush. Often because of the conspicuous projecting stamens as in many Leguminosae (Mimosoideae, Myrtaceae, and Combretaceae). But not all white flowers elicit a response: the white and showy flowers of Omphalea oppositifolia aren’t visited by the adult moths. Nectar sources include the flowers of:

All these flowers are white, with the exception of Camellia sinensis which has a yellow centre. And all either have dense filaments or are formed of tight clusters of small flowers.[10]

Eucalyptus melliodora inflorescence

Loquat (Eriobotrya japonica) inflorescence

Mango (Mangifera sp.) inflorescence

Tea (Camellia sinensis) flower

[edit] Relationship with humans

A cigarette card featuring a Chrysiridia madagascariensis fairy in 1928
A cigarette card featuring a Chrysiridia madagascariensis fairy in 1928

The spectacular moth is featured in most "coffee table" books on the Lepidoptera,[9] and has an international reputation.[8] It is considered to be one of the most impressive and beautiful Lepidoptera,[7] rivalling almost any of the butterflies in brilliance of coloring and form.[16] For these reasons it is much sought by collectors.[8] It is collected in the wild, and raised commercially for the international butterfly trade. Only one of the four species of host plants, Omphalea oppositifolia, is used to raise the moth commercially. Using mainly wild collected plants, but also cultivated at a small scale.[19]

It was known by Victorians who used its wings to make jewellery.[22]

[edit] Notes and references

  1. ^ a b Belouino, Paul (1852). Dictionnaire général et complet des persécutions souffertes par l'Église (in French). Paris: J.P. Migne Éditeur, 1784-1786. Retrieved on 2008-02-16. 
  2. ^ a b Yoshioka, Shinya; and Shuichi Kinoshita (March 5, 2007). Polarization-sensitive color mixing in the wing of the Madagascan sunset moth (PDF). Optics Express 15 (5): 2691–2701. Washington: Optical Society of America. doi:10.1364/OE.15.002691. Lay summary – Optics InfoBase. 
  3. ^ a b c d e f Decary, Raymond (1950). La Faune Malgache (in French). Paris: Payot. 
  4. ^ a b Biosecurity New Zealand (2005-08-24). Import Health Standard for the Importation of Tropical Butterfly and Moth Pupae into New Zealand. Commercial Imports. New Zealand Government. Retrieved on 2006-11-08.
  5. ^ a b Kirby, William Forsell (1897). A Hand-book to the Order Lepidoptera (PDF), Baldwin & Cradock, 50–53. Retrieved on 2008-03-21. 
  6. ^ a b Prum, Richard O.; Tim Quinn and Rodolfo H. Torres (January 31, 2006). Anatomically diverse butterfly scales all produce structural colours by coherent scattering (PDF). The Journal of Experimental Biology 209: 748–765. Cambridge: The Company Of Biologists. doi:10.1242/jeb.02051. 
  7. ^ a b Tait, Malcolm (2006-08-28). "1", Animal Tragic: Popular Misconceptions of Wildlife Through the Centuries. Think Books, 38. ISBN 184525015X. Retrieved on 2008-02-19. 
  8. ^ a b c Griveaud, Paul (1963). "4", The Invertebrates of Madagascar (PDF), 81–82. Retrieved on 2008-02-19. 
  9. ^ a b c Smith, Neal G. (March 1983). Host Plant Toxicity and Migration in the Dayflying Moth Urania. The Florida Entomologist 66 (1): 76–85. Florida Entomological Society. doi:10.2307/3494552. Lay summary – JSTOR. 
  10. ^ a b c d e f g h i j k Lees, David; and Neal Smith (1991). Foodplants of the Uraniinae (Uraniidae) and their Systematic, Evolutionary and Ecological Significance (PDF). The Journal of the Lepidopterists' Society 45 (4): 296–347. The Lepidopterists' Society. Lay summary. 
  11. ^ Swainson, William S. (1833). Zoological Illustrations, Vol III. Second series, London: Baldwin & Cradock, 130–131. Retrieved on 2008-02-19. 
  12. ^ a b Oberthür, Charles [1922]. Et́udes de lépidoptérologie comparée (in French). Retrieved on 2008-03-20. 
  13. ^ Webber, Joseph [1855]. Dictionnaire français-malgache (PDF) (in French). Retrieved on 2008-03-20. 
  14. ^ Shoumatoff, Alex. "Our Far Flung Correspondents (Madagascar)", The New Yorker, 1988-03-07, p. 62. Retrieved on 2008-02-16. 
  15. ^ The Sunset Moth (Urania riphaeus). ButterflyUtopia.com. Retrieved on 2006-12-23.
  16. ^ a b Klots, Alexander Barrett; Elsie Broughton Klots [1959] (2007-05-25). Living Insects of the World. Doubleday. Retrieved on 2008-02-19. 
  17. ^ Kaabak, L.. Лицом к лицу с природой (Russian). Retrieved on 2008-03-18.
  18. ^ Catala, R. (1940). "Variations expérimentales de Chrysiridia madagascariensis Less. (Lep. Uraniidae)". Archives du Muséum National D'Histoire Naturelle 17: Ph.D. Thesis. 
  19. ^ a b Gillespie, Lynn J. (1997). Omphalea (Euphorbiaceae) in Madagascar: A New Species and a New Combination. Novon 7 (2): 127–136. St. Louis: Missouri Botanical Garden. doi:10.2307/3392184. Lay summary – JSTOR. 
  20. ^ Kite, G.C.; Fellows, L.E., Lees, D.C., Kitchen, D. and Monteith, G.B. (1991). Alkaloidal glycosidase inhibitors in nocturnal and diurnal uraniine moths and their respective foodplant genera, Endospermum and Omphalea. Biochemical Systematics and Ecology 19 (6): 441–445. Oxford: Pergamon Press. doi:10.1016/0305-1978(91)90063-6. Lay summary – IBIDS. 
  21. ^ Minet, J. (1986). Ébauche d'une classification moderne de l'ordre des Lépidoptères. Alexanor 14 (7): 291–313. 
  22. ^ a b c Carter, David (2000). Butterflies and Moths (Eyewitness Handbook). Dorling Kindersley Publishing. ISBN 1-56458-062-8. 
  23. ^ Common, I. F. B. [1990]. Moths of Australia. Brill Publishers, 382. ISBN 9-004-09227-7. Retrieved on 2008-03-18. 
  24. ^ Chrysiridia rhipheus (French). Collection naturalisée. Insectarium de Montréal (2005-05-10). Retrieved on 2006-10-29.

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