Exercise

Exercise - 8

Exercise: Identification of Insect Pests of Legume Vegetables, Onion, Garlic and leafy Vegetables and their Damage Symptoms.

Insect Pests of Peas


1. Pea pod borer/ Lentil pod borer, Etiella zinckenella (Phycitidae: Lepidoptera)

  • Damage: Damage is caused by the caterpillars. They consume floral parts, newly formed pods and seeds inside the developing pods, there by resulting heavy reduction in the yield.
  • Larvae: Newly emerged caterpillars are greenish in colour whereas full grown larvae are rosy with purplish tinge.
  • Adults: The moths are grey with a wing expanse of about 25 mm. The forewings have dark marginal lines and are interprised with orcheous scales.

2. Tomato fruits borer, Helicoverpa armigera (Noctuidae: Lepidoptera):
  • Discussed under the insect pests of tomato.

3. Pea Leaf miner, Chromatomyia horticola (Agromyzidae: Diptera):
  • Damage: Maggots mine in to leaves, feed on mesophyll leaving the two epidermal layers intact. The mines start from the periphery and ends up towards the mid rib. The mines become wider as the larva grows in size and the faecal matter left by the larva can be seen in these galleries. The minute slender larva can be seen feeding within the mines if the attacked leaves are held against bright light. The photosynthesis is considerably reduced due to larval feeding. Under severe infestation leaves wither away and are shed as a result of which flowering and fruiting is reduced considerably.
  • Eggs: The eggs are oval, spherical, tapering, forwards bluntly rounded end, translucent white when freshly laid but turns dull white before hatching.
  • Larvae: The larva is translucent white and the inverted ‘Y’ shaped oral hook is clearly visible having dark brown colour. The second instar larva is cylindrical tapering anteriorly. Both anterior and posterior spiracles are visible. Third instar also looks like second instar.
  • Pupae: Pupa is fusiform with distinctly defined segments. Initially it is light brown but turns dark towards maturity.
  • Adults: Adults are two winged flies having grayish black mesonotum. Females are black with brown head.
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4. Pea stem fly or bean fly, Ophiomyia phaseoli (Agromyzidae: Diptera)
  • Damage: The maggots mine through the leaves and petioles into tender stems and tunnel down words. Sometimes adult females also puncture the leaves. As a result of severe infestation, the leaves turn yellow, giving the plants a dry appearance. The stems turn brown, become swollen and break down. The spring crop usually suffers less infestation than the late summer crop where up to 70 per cent infestation may occur. The attacked plants bear fewer pods which are mostly empty or having very small seeds.
  • Eggs: Eggs are slender, oval in shape, less than 0.5 mm long and white in colour.
  • Larvae: Maggots are initially white in colour, but later they become yellowish. They are small in size, less than 1 mm in length.
  • Pupae: Pupae are barrel shaped and brown in colour.
  • Adults: Adults are metallic black flies, 2.0 to 2.5 mm long with hyaline wings having a distinct notch in the coastal regions. Female are slightly bigger than males, wing expense is on an average 5 mm.

5. Pea aphid, Acyrthosiphum pisum (Aphididae: Hemptera)
  • Damage: Nymphs and adults such the cell sap from young shoots, ventral surface of tender leaves and also from stems. Affected leaves get cupped or become irregularly distorted, while the shoots become stunted and malformed. Aphids also excrete honey dew which encourage the growth of sooty mould and this superficial black coating on leaves and stems hinders the photosynthesis of the plant as a result of which the plants become weak and the pod formations is adversely affected.
  • Adult aphids are large pear shaped, green, yellow or pink in colour with long conspicuous cornicles. Both alate as well as apterous forms are present and these are generally females and males are rare.

6. Pea leaf roller, Hedylepta (Nacoleia) indicata (Pyraustidae: Lepidoptera):
  • Eggs: Eggs are flat and scale like.
  • Adults: Moths are fulvous yellow with abdomen showing white rings. Wings are suffused with fuscous except costa of fore wing and have discocellular spot. Fore wings have obliquely curved antemedial black line, hind wings have post medial line bent outwards between vein 5 and 2. Both wings have marginal black line as well as line at the base of cilia which are fuscous on fore wings and white on hind wings. Wing expanse is about 20 mm.
7. Pea blue butterfly, Lampides boeticus (Lycaenidae: Lepidoptera)
  • Damage : Damage is caused by caterpillars by boring in to the buds, flowers and green pods, there by reducing the yield considerably.
  • Eggs: Eggs are round and light green in colour.
  • Larvae: Newly emerged larva is green with yellowish tinge, black head, dark brown patch on prothorax, cylindrical body with scattered hairs. The brownish mid-dorsal and yellowish lateral lines are well marked. The full grown larva is yellowish green to yellowish red.
  • Pupae: Pupa is dark brown in colour. Pupation takes place on leaves or in the infested pod itself.
  • Adults: Adult are blue coloured butterflies

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8. Groundnut Thrips, Caliothrips indicus (Thripidae: Thysanoptera)
  • Damage: Damage is caused by both nymphs and adults by feeding on cell sap. They lacerate the leaf surface with their asymmetrical piercing mouth parts and suck the oozing sap due to which white patches develop on the infested leaves. A severe infestation results in the formation of white silvery sheens all over the leaf surface and the infested leaves may appear completely bleached.

Last modified: Tuesday, 19 June 2012, 5:33 AM