Exercise

Exercise - 2

Aim: Identification of Insect-Pests of Crucifiers and their Damage Symptoms

1. Diamondback moth, Plutella xylostella (Yponomeutidae: Lepidoptera)
  • Egg: Yellowish white with greenish tinge.
  • Larva: Full grown larvae are 8-12 mm long, green in colour.
  • Pupa: pupate in silken cocoon which is about 20mm
  • Adult: 8-10mm in length, grayish brown in colour having pale white narrow wings with inner margins yellow. There are three pale white triangular markings on hind margins of each fore wing and when at rest, a dorsal median patch of three diamond shaped spots is clearly visible. Wing expanse is 15mm.
  • Damage symptoms: Young caterpillars scrap epidermal leaf tissue, producing typical white transparent patches. Older larvae bite holes on the leaves.
     
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2. Cabbage butterfly, Pieris brassicae (Pieridae: Lepidoptera):
Identification:
  • Eggs: Yellow cylindrical eggs are laid in clusters of 50-90 on ventral surface of leaves
  • Larvae: Pale yellow when young and become greenish yellow later on. The head is black and the dorsum is marked with black spots and short hairs.
  • Adults: Butterflies are pale white having smoky shade on the dorsal side of the body. The wings are pale white with a black patch on the apical angle of each hind wing. The females measure about 6.5cm across the wings and have two conspicuous black spots on the dorsal side of each fore wing. The males are smaller than females and have black spots on the underside of each fore wing.
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3. Cabbage aphid, Brevicoryne brassicae (Aphididae: Hemiptera):
Identification:
  • Eggs: Pale-yellow with greenish tinge.
  • Nymphs: 1-1.5 mm long and yellow green in colour.
  • Adults: About 2 mm in length and ash grey in colour
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4. Cabbage semilooper, Thysanoplusia orichalcea (Noctuidae: Lepidoptera)
  • Larvae: plump and pale green having three pairs of prolegs and are generally found mixed with the caterpillars of P. brassicae.
  • Adults: light brown with a golden patch on each fore wing and measures about 42mm across the wings.
     
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5. Crucifer leaf weber, Crocidolomia binotalis (Pyralidae: Lepidoptera)
  • Larvae are about 20mm in length, green in colour with red head and longitudinal red stripes on the body
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6. Cabbage head borer, Hellula undalis (Pyralidae: Lepidoptera)
  • Eggs: pinkish and oval shaped eggs laid singly or in clusters on the under surface of the leaf.
  • Caterpillars: Creamy yellow with a pinkish tinge and has seven purplish brown longitudinal stripes. Full grown larva spins a cocoon among the leaves touching the ground or larval tunnels for pupation.
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(Source: www.infonet-biovision.org)
  • Adults: Moths are slender, pale yellowish-brown, having grey wavy lines on the fore wings. Hind wings are pale dusky.
     
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7. Mustard sawfly, Athalia lugens proxima (Tenthredinidae: Hymenoptera)
  • Larvae: Newly hatched grubs are 2-3 mm long, smooth, cylindrical and greenish grey in colour. Full grown grubs are 16-20 mm long and greenish black in colour. They look and behave like caterpillars but have 8 pairs of prolegs.
     
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Source: www.thomasburg-walks.blogspot.com and www.infonet-biovision.org
  • Adults: They are 8-12 mm long having dark head and thorax, orange coloured abdomen and translucent smoky wings with black veins. Females have strong saw like ovipositor
     
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Source: www.uark.edu
8. Painted bugs, Bagrada cruciferarum and Eurydema pulchrum (Pentatomidae: Hemiptera)
  • Bagrada crucifererum: The adults are black with yellow and pink spots on dorsal side of body. The males (5.29x3.04 mm) are smaller than females (7.12x3.94 mm).
  • Eurydema pulchrum: The adults are black with red spots on dorsal side of the body. Males are 7.37x4.07 mm and females are 8.72x4.60 mm in size.
     
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9. Cutworms, Agrotis segetum and A. ipsilon (Noctuidae: Lepidoptera)
     
  • Eggs: globular in shape, 0.5 mm in diameter, ribbed and whitish in colour.
  • Caterpillars: smooth, stout, cylindrical, 40-50 mm long, blackish- brown dorsally and grayish green laterally with dark stripes. They coil up at the slight touch.
     
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  • Pupae: 18-22 mm long and reddish brown in colour.
  • Adult: Moths are medium sized, stout, dark greenish brown with reddish tinge and have grayish brown wavy lines and spots on the fore wings. Hind wings are hyaline having dark terminal fringe which is darker in female than in male. Wings expanse is 45-50 mm. expanse is 45-50 mm.
     
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10. Tobacco caterpillar, Spodoptera litura (Noctuidae: Lepidoptera)
Identification:
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  • Larvae: About 35-40 mm in length when full fed. They are velvety black with yellowish green dorsal strips and lateral white bands.
  • Adults: The moths are about 22 mm in length and about 40 mm across the wings. The forewings have beautiful golden and grayish brown pattern
     
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Cabbage flea beetle:
Identification:
  • The larvae are dirty white with pale white head, 5 mm in length. The adults vary in colour from shiny black to black. All species have very stout femora with which they jump like fleas.
     

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Last modified: Saturday, 16 June 2012, 7:15 AM