Blackgram & Greengram: Insect, Mite and Nematode Pests Management

By Vikaspedia on 27 Oct 2017 | read
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Gram pod borerBiology

It is a polyphagous pest, infesting gram, lablab, safflower, chillies, groundnut, tobacco, cotton etc.

  • Egg: Spherical, yellowish eggs are laid singly on tender parts and buds of plants. The egg period lasts for 2-4 days.
  • Larva: Caterpillars are of varying colour, initially brown and later turn greenish with darker broken lines along the side of the body. Body covered with radiating hairs. When full grown, they measure 3.7 to 5 cm in length. The larval period lasts for 18-25 days. The full grown caterpillar pupates in the soil.
  • Pupa: Pupation takes place inside the soil in an earthen cell. Pupal stage lasts 7-15 days.
  • Adult: Moth is stout, medium sized with brownish/greyish forewings with a dark cross band near outer margin and dark spots near costal margins, with a wing expanse of 3.7cm.
Damage symptoms
  • Young larva feeds on the leaves for some time and then attacks fruits. Internal tissues are eaten severely and completely hollowed out. While feeding the caterpillar thrust its head inside leaving the rest of the body outside.
  • Bored fruits with round holes.
  • Fed leaves, shoots and buds.
  • The activity of Helicoverpa starts on Greengram, summer vegetables and maize and continues their generation by Aug-Sept months synchronizing with main crop.
Favourable conditions
  • Warm weather conditions followed by light rains and dry spells are favourable for multiplication.
Natural enemies of gram pod borer
  • Parasitoids: Trichogramma spp., Tetrastichus spp., Chelonus spp., Telenomus spp., Bracon spp., Ichneumon spp., Carcelia spp., Campoletis spp.
  • Predators: Lacewing, ladybird beetle, spider, red ant, dragon fly, robber fly, reduviid bug, praying mantis, black drongo (King crow), wasp, common mynah, big-eyed bug (Geocoris sp), earwig, ground beetle, pentatomid bug etc.
Spotted pod borerBiology

It is a polyphagous, infesting gram, lablab, safflower, chillies, groundnut, tobacco, cotton etc.

  • Egg: Eggs are laid on the under surface of leaves, terminal shoots and flower buds. The freshly laid eggs were milky white in colour and oval in outline, dorsoventrally flattened and glued to the surface.
  • Larva: Greenish white with brown head. Larval duration is15 –20 days.
  • Pupa: Pupates in dry leaves and debris
  • Adult: Brown forewings and white hind wings
Damage symptoms
  • Bore holes on the buds, flower or pods
  • Infested pods and flowers are webbed together
Natural enemies of spotted pod borer
  • Parasitoids: Trichogramma spp., Tetrastichus spp., Chelonus spp., Telenomus spp., Bracon spp.
  • Predators: Lacewing, ladybird beetle, spider, red ant, dragon fl y, robber fl y, reduviid bug, praying mantis etc.
Spiny pod borerBiology
  • Larva: Greenish initially, turns pink before pupation. It has 5 black spots on the prothorax
  • Adult: Brownish grey moth.  Prothorax – orange in colour. Fore wing has a white stripe along the anterior margin.
Damage symptom
  • Dropping of flowers and young pods
  • Older pods marked with a brown spot where a larva has entered
Red spider miteBiology
  • Egg: Hyaline, globular laid in mass
  • Nymph: Yellowish in colour
  • Adult: Red coloured small size
Damage symptoms
  • Affected leaves become reddish brown and bronzy
  • In severe infestation silken webbing on the leaves
  • Leaves wither and dry
  • Flower and fruit formation affected
Natural enemies of red spider mite:
  • Predators: Predatory mite, predatory thrips, oligota spp., orius spp., hover fly, mirid bug etc.
Bihar hairy caterpillarBiology

This pest occurs during October to December and of late it is also occurring from July. In recent years, it has become an important pest on groundnut also.

  • Egg: Female lays eggs in masses on leaves.
  • Larva: The larvae are pale yellow coloured with yellow hair over the body. They are polyphagous, feed on leaves and cause loss by way of defoliation. In severe cases only stems are left behind. In defoliated crops it also feeds on capsules.
  • Pupa: Pupates in leaf litter close to the plants.
  • Adult: Adult moth is reddish brown with black spots. Both the wings are pinkish and possess black spots. There are several generations per year.
Damage symptoms
  • Young larvae feed gregariously mostly on the under surface of the leaves.
  • Caterpillars feed on leaves and in severe infestation the whole crop is defoliated.
  • Drying up of infected leaves is the main symptom.
Natural enemies of Bihar hairy caterpillar
  • Parasitoids: Trichogramma spp., Bracon spp.
  • Predators: Lacewing, ladybird beetle, spider, red ant, dragon fly, praying mantis, ground beetle, shield bugs etc.
AphidBiology
  • Egg: Eggs are very tiny, shiny-black, and are found in the crevices of bud, stems, and barks of the plant. Aphids usually do not lay eggs in warm parts of the world.
  • Nymph: Nymphs are young aphids  they look like the wingless adults but are smaller. They become adults within 7 to 10 days.
  • Adult: Adults are small, back to dark brownish colour, 1 to 4 mm long, soft-bodied insects with two long antennae that resemble horns. Most aphids have two short cornicles (horns) towards the rear of the body.
Damage symptoms
  • In addition, plants may become contaminated by honeydew produced by aphids and sooty mould growing on honeydew.
  • Blackgram contaminated with honeydew and / or sooty moulds are not marketable.
  • Aphids are also vectors of diseases, including the bean common mosaic virus.
  • The black bean aphid is a widely distributed pest of beans. The black legume aphid usually attacks beans grown at low altitudes
Natural enemies of aphid
  • Parasitoid: Aphidius colemani, Aphelinus sp
  • Predators: Syrphid larva, lacewing, ladybird beetle, spider etc.,
Stem flyBiology
  • Egg: The stem fly inserts eggs on the underside of young leaves. Ovi positing sites present as pale pin prick spots when infested leaves are held up to the light.
  • Larva: The larvae are whitish, torpedo-shaped maggots that reach little more than 2mm. Larva pupate after 8-11 days. Before pupation, which takes place inside the stem, the larva makes an exit hole for the emergence of the adult.
  • Pupa: Pupae are smooth, light brown to pale brown, cylindrical in shape with rounded ends. Pupal stage lasts 6–12 days.
  • Adult: Adult flies are shiny black and about 2mm long with a pair of clear wings of wingspan 4-5 mm.
Damage symptoms
  • Infected stems are often red inside (sometimes pale) and a dis tinct zig-zag tunnel may be observed — with mag gots or pupae inside. Apart from the exit holes, the plants will initially appear healthy on the outside.
  • Large infestations (3 or more mag gots per plant) may cause wilting and may even cause plant death, especially in younger plants particularly if dam age occurs in the plant’s hypocotyl (basal stem) region.
Natural enemies of stem fly
  • Parasitoids: Tiny wasps
WhiteflyBiology
  • Egg: Pear shaped, light yellowish.
  • Nymph: On hatching - Oval, scale-like, greenish white.
  • Adult: White, tiny, scale-like adult.
Natural enemies of whitefly
  • Parasitoids: Encarsia formosa, Eretmocerus sp
  • Predators: Ladybird beetle, spider, lacewing, mirid bug, reduviid bug etc.
ThripsBiology
  • Egg: Eggs are white or yellow in colour and are microscopic and almost impossible to see. Eggs are inserted one by one by the females in the plant tissue. Only one end of the egg will be near the surface of the tissue to allow the immature to emerge. Adults prefer to lay their eggs in leaf, cotyledon, or flower tissues.
  • Nymph: Very small. Thrips pupae appear as an intermediate form between the immature and the adult. They have short antennae and the wing buds are visible but short and not functional. Pale yellow to brown in the base of the plant neck or in the soil At this stage thrips do not feed.
  • Adult: Adults measure up to 2 mm.  Adults have fully developed wings. The wings are very different from other insects. They have a single longitudinal vein in which there is several hairs connected perpendicular to the vein. The wing appears as fringe with hairs. When at rest, the wings are folded along the back of the insect. Pale yellow to dark brown the same as immatures Adults are more mobile than immatures and pupae because they can fly. They are attracted to yellow and white colors. They often will fly to one’s clothes or land on exposed skin.
Damage symptoms
  • The appearance of the damage is silvery patches or streaks on the leaves that shine in the sun. When damage is severe, these small patches can occupy most of the surface of the leaf and the plant cannot adequately photosynthesize. The plant loses more water than normal through the damaged tissues and plant pathogens penetrate the injured plant easily.
Natural enemies of thrips
  • Parsitoid: Ceranisus menes
  • Predators: Predatory mite, predatory thrips, Oligota spp., Orius spp., hover fly, mirid bug etc.
Blister beetle

The beetles are found to occur throughout the year in red gram, cowpea, green gram and black gram. Peak incidence is generally observed during September, causing a maximum flower damage of 95 per cent. Adults feed on the flowers, tender pods and young leaves resulting in fewer pods. In locations where pigeon pea is grown over large areas, blister beetles cause little damage. However, in small plots that are in the flowering stage during the period of peak adult activity (August-October in southern India), most of the flowers may be eaten by the beetles and crop losses may be substantial. The adults are medium to large (2.5 cm in length), usually black with large yellow spots and a red band across the abdomen, which sometimes changes into yellow spots. The antennae are orange or yellow. The immature stages (larvae) do not feed on plants. They live in the soil and eat grasshopper eggs, and are therefore beneficial.

Root-knot nematodeBiology
  • Most species of plant parasitic nematodes have a relatively simple life cycle consisting of the egg, four larval stages and the adult male and female.
  • Development of the first stage larvae occurs within the egg where the first molt occurs. Second stage larvae hatch from eggs to find and infect plant roots or in some cases foliar tissues.
  • Under suitable environmental conditions, the eggs hatch and new larvae emerge to complete the life cycle within 4 to 8 weeks depending on temperature.
  • Nematode development is generally most rapid within an optimal soil temperature range of 70 to 80°F.
Damage symptoms
  • Infected plants in patches in the field
  • Formation of galls on host root system is the primary symptom
  • Roots branch profusely starting from the gall tissue causing a ‘beard root’ symptom
  • Infected roots become knobby and knotty
  • In severely infected plants the root system is reduced and the rootlets are almost completely absent. The roots are seriously hampered in their function of uptake and transport of water and nutrients
  • Plants wilt during the hot part of day, especially under dry conditions and are often stunted
  • Nematode infection predisposes plants to fungal and bacterial root pathogens
Survival and spread
  • Primary: Egg masses in infected plant debris and soil or collateral and other hosts like Solonaceous, Malvaceous and Leguminaceous plants act as sources of inoculum.
  • Secondary: Autonomous second stage juveniles that may also be water dispersed.
Favourable conditions
  • Loamy light soils.

Source:NIPHM, NCIPM and Directorate of Plant Protection, Quarantine & Storage

 

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