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Plantwise Technical Factsheet

castor semilooper (Achaea janata)

Host plants / species affected
Arachis hypogaea (groundnut)
Citrus
Corchorus (jutes)
Dalbergia sissoo
Dodonaea viscosa (switch sorrel)
Euphorbia hirta (garden spurge)
Glycine max (soyabean)
Lagenaria siceraria (bottle gourd)
Punica granatum (pomegranate)
Ricinus communis (castor bean)
Rosa chinensis (China rose)
Solanum lycopersicum (tomato)
Tamarindus indica (Indian tamarind)
Theobroma cacao (cocoa)
Vigna mungo (black gram)
Ziziphus mauritiana (jujube)
List of symptoms/signs
Fruit  -  external feeding
Fruit  -  frass visible
Fruit  -  ooze
Growing point  -  external feeding
Growing point  -  frass visible
Inflorescence  -  external feeding
Inflorescence  -  frass visible
Inflorescence  -  lesions; flecking; streaks (not Poaceae)
Inflorescence  -  twisting and distortion
Inflorescence  -  webbing
Leaves  -  external feeding
Leaves  -  frass visible
Leaves  -  webbing
Description
Detailed studies on the morphology of A. janata have been carried out by John and Muraleedharan (1989) and John (1991).

Eggs

The eggs are small, spherical (0.85-0.95 mm diameter), beautifully sculptured, with a greenish colour, convex on the dorsal side with ridges and furrows on the surface radiating from a circular depression at the apex and concave on the ventral side. They are deposited in a scattered manner, singly and in clusters, on the undersurface of small tender leaves.

Larva

First-instar larva

The first-instar larvae are thread-like, having a feeble brown colour with a transparent integument, through which the green contents of the alimentary canal are visible. Distinct black dots are seen on the transparent body in a longitudinal row on either side of the midline and laterally. Brown, bristle-like hairs are seen scattered on the body. The larva is 0.48-0.67 cm long, 0.49-0.67 mm wide, and weighs 0.94-1.28 mg. The first two pairs of prolegs are undeveloped, hence they have the gait of a looping caterpillar. The third and fourth pairs of prolegs are well developed. On the XIth segment, two black spots, which later became tubercles, are seen, and behind it lie two other black dots which gave rise to the black patches in the subsequent instars.

Second-instar larva

The body becomes spongy and the larvae slowly change in colour to grey with a whitish bloom. Black dots are seen on the mid-dorsal line as well as laterally on each segment from this instar onwards. The second pair of prolegs now develop but the first pair still remains as a stump. From this instar onwards, the head capsule appears in a black and white design. The second-instar larva is 1-1.2 cm long, 1.16-1.34 mm wide and weighs 2.94-9.31 mg. Two black small tubercles and two black patches are seen on the anal end.

Third-instar larva

The larvae grow, become conspicuously longer and greyish-white. The second pair of prolegs are small and the first still remains as a stump, hence they retain the semiloop gait. At the anal end, the two black tubercles and black patches become larger. The larvae are 1.7-2.1 cm long, 1.95-2.07 mm wide and weigh 19.7-41.8 mg.

Fourth-instar larva

These larvae are larger than the third-instar larvae (2.8-3.6 cm long, 3.05-3.66 mm wide and weigh 103.8-242.5 mg). They have a black streak running longitudinally along the mid-dorsal line of the body. Two conspicuous, white spots become evident on the tergum of the Vth segment of the body, lying on the longitudinal white streak on either side. The first pair of prolegs remain as a stump and the second pair are smaller. Prolegs are seen on the VIth segment, but are very small, so the mid-ventral sternum with its white coloration appears like an inverted 'V' form. The two larger, tubercle-like projections on the XIth segment are black, behind these are two black patches. On each segment, black spots are seen on the mid-black streak.

Fifth-instar larva

The fifth-instar larvae are fairly large: 5.5-6.1 cm long, 4.94-5.06 mm wide and weigh 464.8-905.6 mg. The body has a spectacular, beautiful, velvety, appearance with a mid-dorsal black streak running longitudinally on a black background with noticeable anal tubercles. On either side of the mid-black streak, two narrow, yellow and orange streaks run longitudinally. On the tergum of the Vth segment, two white spots on the midline with an orange base can be recognized flanked by two white patches on the longitudinal orange streak. Just above the patches on the VIth segment are two white dots. On the tergum of the VIth segment on the midline are two small orange patches. At the intersegmental area of the sternum, short, vertical, white bars can be distinguished running longitudinally to the end of the body. On the first and IV-XIth segments, laterally placed oval-shaped, light-orange stigmata can be seen. On the dorsal side of the XIth segment, there are two prominent, red, tubular projections, each with a hair on them. On the XIIth segment there are two small black projections with a hair on the dorsal side. Epicranial plates have a large, white spot on a black background. Bristle-like structures are distributed scarcely all over the body. There are two large, white patches around each proleg. The thoracic legs are chitinous and horny.

Prepupa

The feeding phase of the fifth-instar larva is followed by a non-feeding prepupal stage. The larva shrinks, turns black and the body wall becomes thicker (3.8-4.8 cm long, 5-6.5 mm wide). They attain a maximum weight of 1072.9 mg. The body gradually forms a comma-shape and enters the prepupal stage. They remain in the comma-shape for 1 day. The prepupa is 2.4-2.6 cm long, 5-5.6 cm wide and weighs 799.1 mg. Gravimetric analysis showed an increase in weight up to the spinning period and thereafter a decrease in the prepupal stage.

Pupa

The pupa is whitish-green. The body is very soft, gradually tanned to a dark brown, with a hard cuticle coated with white dust. Pupae are obtect, spindle-shaped, with a tapering posterior end armed with cremastral setae of four different sizes, in pairs numbering eight in both the sexes, which are twisted firmly into the strands of silk. The pupa is 2-2.5 cm long, 5-7 mm wide and weighs 706 mg. During the entire pupal lifespan (8-10 days), the weight decreases gradually, with a sudden decrease (521.1 mg) at adult emergence.

Adult

An almost wet imago emerges out of the pupa. The soft, crumpled wings become dry after a period of rest, and they start fluttering. Adult moths are light brown, with characteristic black and white patterns in the posterior region of the hind wings and dry brown scales all over the body. The length of the forewing is 1.65-2.75 cm and that of the hindwing is 1.23-2.25 cm. The moth is 1.8-2.3 cm long, 5-6.5 mm wide and the early moth weighs 257 mg. An increase in weight is seen on the second day (361.8 mg) and thereafter declines as mating and egg laying starts.

Sex identification of larva, pupa and adult

The method of sexing has been reported by John and Muraleedharan (1989) and John (1991). The sex of larvae can be distinguished by microscopic examination. They are distinct in the fourth- and fifth-instar larvae, though rudiments can be traced at early stages. In the female larva, two pits on small, white spots on the venter of the XIth and XIIth abdominal segments can be seen; these are absent in the males. The abdominal segments, VIII, IX and X are fused in the pupae; this is most distinct on the ventral side. There are two mid-ventral openings. The narrow, split-like, longitudinal opening anterior to the cremaster is the genital pore and this is seen on an elevation of the Xth abdominal segment and is surrounded by an area of wrinkled integument, the anal rise. The genital opening is a rounded pore lying on an elevated tubercle bisecting the IXth segment in males. In females it lies near the upper margin of the VIIIth abdominal segment and lacks an elevated pad. The genital opening in males is more prominent than in females. The last spiracle and the genital opening are in the same segment in females. Adults show sexual dimorphism. In males the anal end is narrow with a tuft of hair. The genital opening is on the VIIIth segment. Females have a broad abdomen with genital opening on the VIIth segment.
Prevention and control

Cultural and Physical Control

Sudden outbreaks of A. janata on castor (Ricinus comunis) or other hosts often make it difficult to apply natural control methods. However, hand picking of larvae is effective to a certain extent. The construction of open spaces around and across fields attracts birds, which attack the larvae when they attempt to cross the open spaces. These practices have been around since the beginning of this century (Fletcher, 1914).

Various traps designed for the adult moths of A. janata have not been successful (Gaikwad and Bilapate, 1992).

Chemical Control

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources:


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