Plain Tiger

''Danaus chrysippus'', also known as the plain tiger, African queen, or African monarch, is a medium-sized butterfly widespread in Asia, Australia and Africa. It belongs to the Danainae subfamily of the brush-footed butterfly family Nymphalidae. Danainae primarily consume plants in the genus ''Asclepias'', more commonly called milkweed. Milkweed contains toxic compounds, cardenolides, which are often consumed and stored by many butterflies. Because of their emetic properties, the plain tiger is unpalatable to most predators. As a result, its coloration is widely mimicked by other species of butterflies. The plain tiger inhabits a wide variety of habitats, although it is less likely to thrive in jungle-like conditions and is most often found in drier, wide-open areas.

''D. chrysippus'' encompasses three main subspecies: ''D. c. alcippus, D. c. chrysippus,'' and ''D. c. orientis.'' These subspecies are found concentrated in specific regions within the larger range of the entire species.

The plain tiger is believed to be one of the first butterflies depicted in art. A 3,500-year-old ancient Egyptian fresco in Luxor features the oldest known illustration of this species.

Description

''D. chrysippus'' is a medium-sized butterfly with a wingspan of about . The body is black with many white spots. The wings are orange, the upperside brighter and richer than the underside. The apical half of the forewing is black with a white band. The hindwing has three black spots in the center. The wings are bordered in black and outlined with semicircular white spots. This species exhibits slight sexual dimorphism, as the Male has large scent glands on his hindwings, which the female lacks. They appear as a large black spot with a white centre if viewed from the underside

''D. chrysippus'' is a polymorphic species, so the exact coloring and patterning vary within and between populations.

It is similar in appearance to the Indian fritillary (''Argynnis hyperbius''), which may coexist with it.

File:Plain tiger butterfly wing scales.jpg, Close-up of the wing scales of a male ''Danaus chrysippus''
File:Danaus chrysippus male 2 by kadavoor.jpg, Male showing the pheromone pouch and brush-like organ in Kerala

Geographic range

The plain tiger is found across the entirety of Africa, where the predominant subspecies is ''D. c. alcippus''. Its range extends across the majority of Asia throughout Indian subcontinent, as well as many south Pacific islands. The plain tiger is even present in parts of Australia. ''D. c. chrysippus'' is most common throughout Asia and in some select regions in Africa, while ''D. c. orientis'' is present in more tropical African regions as well as some African islands, including Madagascar and the Seychelles.
It is also found in Southern Europe and Kuwait. These insects are considered bioinvaders in North America.

Habitat

The plain tiger prefers arid, open areas, and is found in a variety of habitats, including deserts, mountains, deciduous forests, and human-tended gardens in cities and parks. It is comfortable at altitudes ranging from sea level to around .

Food resources

Larval food plants

The plain tiger's larval host plants are from several families, most importantly Asclepiadoideae (Apocynaceae):
* ''Asclepias'' – milkweeds (recorded on ''A. cancellata'', ''A. coarctata'', '' A. curassavica'', ''A. fulva'', ''A. kaessneri'', ''A. lineolata'', '' A. physocarpa'', ''A. reflexa'', ''A. scabrifolia'', ''A. semilunata'', ''A. stenophylla'', ''A. swynnertonii'', '' A.syriaca'')
* ''Aspidoglossum interruptum''
* ''Calotropis'' – mudar (recorded on '' C. gigantea'', '' C. procera'')
* ''Caralluma burchardii'' (recorded from Canary Islands/Spain)
* ''Ceropegia dichotoma'' (recorded from Canary Islands/Spain)
* ''Cryptolepis buchananii''
* ''Cynanchum'' (recorded on ''C. abyssinicum'', '' C. acutum'', ''C. altiscandens'', ''C. amplexicaule'', ''C. carnosum'', ''C. floribundum'', ''C. sublanceolatum'')
* ''Gomphocarpus fruticosus''
* ''Kanahia laniflora''
* ''Leichardtia australis''
* ''Leptadenia hastata''
* ''Marsdenia leichhardtiana''
* ''Metaplexis japonica''
* ''Orbea variegata'' (recorded from Canary Islands/Spain)
* ''Oxystelma pulchellum''
* ''Pentatropis'' (recorded on ''P. atropurpurea'', ''P. quinquepartita'')
* ''Pergularia daemia''
* ''Periploca linearifolia''
* ''Pleurostelma cernuum''
* ''Secamone'' (recorded on ''S. afzelii'', ''S. parvifolia'', ''S. platystigma'')
* ''Stapelia gigantea''
* ''Stathmostelma'' (recorded on ''S. gigantiflorum'', ''S. pedunculatum'')
* ''Tylophora'' (recorded on ''T. stenoloba'', ''T. sylvatica'')
Host plants from other families include ''Dyerophytum indicum'' (Plumbaginaceae), ''Ficus'' (Moraceae; recorded on ''F. laevis'', '' F. racemosa''), ''Ipomoea'' (Convolvulaceae; recorded on '' I. alba'', '' I. bona-nox''), ''Lepisanthes rubiginosa'' (Sapindaceae) as well as some Euphorbiaceae, Malvaceae, Poaceae, Rosaceae and Scrophulariaceae.

Adult food plants

Adult plain tiger butterflies obtain nectar from various flowering plants. The particular plants available vary depending on the geographic range of the butterfly population and the season, as certain plants do not flower throughout the entire year.

India

* ''Catharanthus roseus''
* ''Lantana camara''
* ''Vernonia cinerea''
* ''Tridax procumbens''
* ''Asystasia gangetica''
* ''Antigonon leptopus'', January through April and August through December
* ''Tecoma stans'', May through December
* ''Heliotropium indicum''

Australia

* ''Goodenia maidenian''
* ''Eucalyptus conglobata''
* ''E. oleosa''
* ''Ptilotis obovata''
* ''Asclepias''
* ''Lantana''
* ''Leucopogon''
* ''Daviesia''
In addition to nectar, adult plain tigers obtain pyrrolizidine alkaloids from the dead stems of different plant types. In Australia, the following plants have been identified as sources of pyrrolizidine alkaloids for ''D. chrysippus:''
* ''Parsonsia eucalyptophylla''
* ''P. straminea''
* '' Echium plantogineum''
* ''Senecio pterophorus''
* ''Heliotropium amplexicaule''

Parental care

Oviposition

Females lay eggs singly on the underside of the leaves of a larval food plant. The eggs are most often laid close to the ground.

Life history

Egg

The egg of the plain tiger is about long and across. When first laid it is white, but gradually turns brown over time. The egg is ridged and dome-shaped. Depending on temperature, the egg is typically hatched in 3–5 days.

File:Plain tiger butterfly egg.jpg, Egg at Tamil Nadu, India
File:Plain tiger egg.JPG, At Mananpur, Mumbai, Maharashtra

Caterpillar

The larvae of ''D. chrysippus'' proceeds through five instar stages. The first instar is about long, and its body is white while the head is black. The second instar is about long, and its body is primarily gray with yellow and black horizontal stripes. This coloration remains for the final three instar stages. The third instar is about long, the fourth about long, and the fifth about long. Depending on temperature, the larval stage can last from 12 to 20 days.

File:Plain tiger larvae just hatched and eat its own eggshell..JPG, Larva eating its own eggshell
File:Plain tiger moat.JPG, Caterpillar making "moat" to feed during the first instar
File:Danaus chrysippus second instar.JPG, Second instar
File:Plain Tiger Danaus chrysippus Caterpillar on Calotropis procera 2. by Dr. Raju Kasambe.jpg, Mature caterpillar
File:Plain Tiger (Danaus chrysippus) caterpillar on a Calotropis (Milkweed) species in Hyderabad, AP W IMG 7970.jpg, Older caterpillar

Prepupal and pupal stages

Before pupation, the caterpillar will become motionless and cease feeding. Its color shifts slightly from gray to brown, and it may lose a small amount of body mass. The prepupal stage lasts 1–3 days depending on temperature. The pupal stage lasts 9–15 days depending on temperature, and the pupa changes color over this period from a pale green to dark brown. Pupae are about tall and wide.

File:Chrysalide Danaus chrysippus.jpg, Pupa
File:Plain tiger pupa.jpg, Fresh pupa at Bandra Kurla Complex, Mumbai
File:Danauschrysippus pupa sec.jpg, Pink pupa due to pupation among inanimate objects

Adult

Male and female ''D. chrysippus'' butterflies look very similar and are also similar in size. Adult butterflies typically have a wingspan of . The bodies of adult plain tigers are about long, and their antennae are about long. Depending on temperature, males live about 10–15 days and females live about 7–12 days.

File:Newly emerged Plain tiger female.JPG, A newly emerged plain tiger female in captivity
File:Plain tiger m up.JPG, Male ''D. c. chrysippus'', recently emerged from chrysalis
File:Plain tiger form Alcipoides from Karanji lake Mysore IMG 7834.jpg, Form ''alcippoides'' in Mysore, Karnataka, India
File:Plain Tiger (Danaus chrysippus)- mud-puddling in Hyderabad, AP W IMG 9741.jpg, Mud-puddling
File:Plain Tiger (Danaus chrysippus), Bangalore, India.jpg, Resting with its wings closed
File:Danaus chrysippus02.jpg, Basking

Enemies

Predators

Egg and larval predators

Most predators of the early developmental stages of ''D. chrysippus'' are arthropods. Such potential predators include various kinds of spiders, assassin bugs, cockroaches, ladybugs, ants, and mantises. The caterpillars will even cannibalize each other. Egg and larval mortality is often high; as many as 84% of eggs may be lost to predation and up to 97% of larvae can be lost by the fifth instar, although most larval deaths occur during the third instar.

Adult predators

The most common predator of adult plain tigers are birds. In eastern Africa, the most common predator is the fiscal shrike ''L. c. humeralis''.

Parasites

There are several organisms which parasitize the larvae of ''D. chrysippus''. The fly ''S. flavohalterata'' of the Family ''Tachinidae'' is responsible for small amounts of parasitization in ''D. chrysippus'' populations. It is unclear whether the fly oviposits on the eggs of ''D. chrysippus'' or whether the fly oviposits on leaves which are then consumed by ''D. chrysippus'' larvae. ''S. flavohalterata'' does not kill the larvae, and development is normal until the pupal stage, when larvae dies and the parasite emerges from the pupa instead. ''A. chrysippi'', a parasitic wasp of the family Braconidae, oviposits on larvae early in their development and then kills them in the later stages. As many as fifty wasps may emerge from one large caterpillar, and they then pupate on the deceased host. Parasitic wasps of the genus ''Charops'' also infest plain tiger populations, likely during the egg or first instar stage, and then kill the larvae in a later instar stage.

''Sturmia convergens'' is also a parasitoid of ''D. chrysippus.''

Diseases

The plain tiger is infected by a male-killing bacterium called ''Spiroplasma''. Male-killing bacteria are transmitted vertically, from mother to offspring. Female plain tigers infected with ''Spiroplasma'' will produce all-female broods, because the bacteria kills infected male offspring during either their embryonic or first larval instar stage. Although male-killing bacteria are uncommon in species which lay eggs singly, experimentally treating infected females with antibiotics restored an even sex ratio to their subsequent broods, thus indicating that it is indeed ''Spiroplasma'' which is responsible for all-female broods in ''D. chrysippus''. However, the prevalence of this bacteria in the plain tiger seems to be restricted to east African populations.

Protective coloration and behavior

The plain tiger is mimicked by several species due to its unpalatability to potential predators. Previously, it was thought that cardenolides obtained from food sources during the larval stage were responsible for the aversive nature of adult ''D. chrysippus'', but many larval food sources lack cardenolides, and some adult West African populations of ''D. chrysippus'' do not store cardenolides well, yet still repel predators. More recently, pyrrolizidine alkaloids have been proposed to be also responsible for the unpalatability of ''D. chrysippus''. Adult male danaines often feed on plants containing pyrrolizidine alkaloids, and although females rarely do, they may be protected simply through their resemblance to males of the same species. The ability of ''D. chrysippus'' to store cardenolides varies across populations, so likely both cardenolides and pyrrolizidine alkaloids contribute to the unpalatability of ''D. chrysippus'' to different extents depending on the population.

Because the plain tiger is unpalatable (also called inedible