05 June 2010

Life History of the Striped Albatross

Life History of the Striped Albatross (Appias libythea olferna)


Butterfly Biodata:
Genus: Appias
Hübner, 1819
Species: libythea Fabricius, 1775
Subspecies:
olferna Swinhoe, 1890
Wingspan of Adult Butterfly: 55mm
Caterpillar Local Host Plants:
Cleome rutidosperma (Capparaceae, common name: Purple Cleome, Fringed Spiderflower).


A female Striped Albatross visiting a flower of Bidens alba.


Another female Striped Albatross with its upperside revealed.

Physical Description of Adult Butterfly:
The forewing apex is acute in the male but rounded in the female. Vein 9 on the forewing of both sexes arises before the end of vein 10. The male has a pair of hair pencils between the 8th abdominal segment and the saccus (a male mating structure). Above, the wings are white with a dentate black border in the male, and heavily black dusted with several broad white streaks and a series of yellow submarginal spots on the forewing in the female. Beneath, the wings are white in the male and yellow dusted in the female. The veins are dark dusted. A yellow basal streak, broader and longer in the female than in the male, lies along the costa on each hindwing.


A male Striped Albatross in a open-wing posture on a leaf perch.


A male Striped Albatross puddling on a damp patch.


Field Observations of Butterfly Behaviour: Although common in countries such as India, Sri Lanka and Myanmar, the Striped Albatross only established itself in Singapore and Malaysia about 70 years ago. The species has become rather common due to the widespread occurrence of its local host plant, Cleome rutidosperma, which is a weed found in many areas. The fast flying adults are most active in sunny weather and frequently visit flowers for nectar. They can be found in open habitats such as fringe of the nature reserve, wastelands, grass fields and even in urban and residential areas. The males have the habit of puddling for mineral intakes.


A newly eclosed female Striped Albatross.


A male Striped Albatross visiting a flower of the Coat Button (Tridax procumbens).

Early Stages:
The host plant, Cleome rutidosperma, is a common herbaceous weed with violet-blue to pink flowers. The caterpillars of the Striped Albatross feed on the relatively young to middle-aged leaves as well as young shoots, stems and flower parts.


Host plant: Cleome rutodosperma.


A mating pair of the Striped Albatross.

A mother Striped Albatross laying an egg on its host plant.

The eggs of the Striped Albatross are laid singly on a leaf or flower part of the host plant. The egg is spindle-shaped and standing on one end with a height of about 1mm, about 2.5 times as tall as broad. It has vertical ridges and numerous transverse striations. The vertical ridges end in low projections encircling the micropylar. The color of the egg is initially white but changes to orange overnight.


Two eggs of the Striped Albatross.


Two maturing eggs of the Striped Albatross.

The egg takes about 2 days to hatch. The newly hatched has a length of about 1.8mm and has a yellowish orange head capsule. Its cylindrically-shaped body is also yellowish orange and featuring sub-dorsal, dorso-lateral and lateral rows of small tubercles running lengthwise. Each tubercle has a short setae emerging from the middle of it. The end of each setae bears a tiny droplet of fluid.

A newly hatched caterpillar eating its egg shell.


Two views of a 1st instar caterpillar, early in this stage, length: 2mm.

The newly hatched eats the empty egg shell for its first meal, and then moves on to eat the leaf lamina. The body takes on a strong green undertone with the intake of leaf diet. The 1st instar growth is fast paced and the body length reaches about 4mm. After about 1.5 days of the 1st instar, the caterpillar moults to the 2nd instar.

Two views of a late 1st Instar caterpillar hours before its moult, length: 3mm.

The 2nd instar caterpillar is yellowish green in body color with similar setae-bearing tubercles as in the 1st instar. In addition, there are nuermous small conical tubercles dotting the body surface.The head capsule has changed to pale yellow. Laterally, the body surface is covered in numerous light brown speckles which are only discernible with a close-up examination. The posterior end also two tiny and short pointed ends.
This instar lasts about 1.5 days with the body length reaching 5.5-6mm.



Two view of a 2nd instar caterpillar, length: 4.5mm


Two view of a 2nd instar caterpillar, late in this stage, length: 5mm

The 3rd instar caterpillar resembles the 2nd instar caterpillar closely except for the appearance of a faint yellowish dorsal band and a stronger green undertone in the body color. The head capsule is now yellowish green. It is also easier to discern the two anal points. This instar takes about 1-1.5 days to complete with body length reaching about 9mm.



Two views of a 3rd instar caterpillar, length; 6mm.



Two views of a 3rd instar caterpillar, length: 8.5mm.

Again, the 4th instar retains all the features as the 3rd instar. In addition, a white lateral line appears sub-spiracularly, initially faint in appearance but becoming more prominent as growth progresses. Numerous fine setae moderately long appear laterally just below the white lateral lines. This penultimate instar lasts 1-1.5 days with body length reaching about 17.5mm.


Two views of a 4th instar caterpillar, early in this stage, length: 9.5mm.


Two views of a 4th instar caterpillar, late in thie stage, length: 17.5mm.

The 5th and final instar caterpillar resembles the 4th instar caterpillar closely. The many tubercles dotting the body surface are blue to dark blue, giving the body a speckled appearance. The green head capsule also carries numerous conical tubercles with some fine setae emerging from most of them. The 5th instar lasts for 2-2.5 days, and the body length reaches up to 33mm.


Two views of a 4th instar caterpillar, newly moulted, length: 17.5mm.


Two views of a 5th instar caterpillar, length: 24mm.


Two views of a 5th instar caterpillar, late in this stage, length: 33mm.On the last day of the 5th instar, the body of the caterpillar shortens and changes to a dull shade of pale green. It ceases feeding and comes to rest on the underside of the stem/stalk of the host plant or larger leaves of other plants in the vicinity. Typically the caterpillar shows a strong preference for a vertical or steeply inclined surface. Here the caterpillar spins a silk pad and a silk girdle to secure itself and then becomes immobile in a head-up pre-pupatory pose.


Left: The head of a 5th instar caterpillar.
Right: The anal points of a 4th instar caterpillar.


Two views of a pre-pupatory larva of the Striped Albatross.


Pupation takes place about 0.5 day later. The yellowish green pupa secures itself with the same silk girdle as in the pre-pupal stage, but with cremaster replacing claspers in attaching the posterior end to the silk pad on the stem. The pupa has a long, pointed, slightly curved cephalic horn which is yellow in colour. There is a prominent thoracic ridge which is sharply raised dorsally at thoracic segment 2, and is colored in white to yellow along the ridge line. The abdominal segments 2-4 are produced laterally into a pointed tooth at each side of the abdominal segment 2. Two lateral ridge lines, white mostly and twice interrupted with yellow, run from the abdominal segment 2 to the posterior end. Length of pupae: 21-22mm.


Two views of the pupa of a Striped Albatross.


Two views of the maturing pupa of a female Striped Albatross.
Right panel shows the pupa in more advanced stage of development.


Two views of the maturing pupa of a male Striped Albatross.
Right panel shows the pupa in more advanced stage of development.

After about 5 days of development, the pupal skin turns translucent as the development within the pupal case comes to an end. The markings on the forewing upperside become discernible and indicative of the gender of the soon-to-emerge adult. The following day, the adult butterfly emerges from the pupal case.


Newly eclosed Striped Albatross drying wings on their respective pupal case.
Left: female; Right: male.

References:
  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006.
Text by Horace Tan, Photos by Benedict Tay, Henry Koh, Sunny Chir, Khew S K and Horace Tan

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