Black bean bug, Beetles and Pod Borers

Black bean bug, Beetles and Pod Borers

1. Black bean bug, Chauliops nigrescens (Lygaeidae: Hemiptera)
  • Distribution: Sri Lanka, Japan, south-eastern Australia, India etc. In India it is serious in northern states on many beans.
  • Host range: Soybean, cowpea, mothbean, French bean, horse gram and green gram.
Damage:
  • Both nymphs and adults suck the cell sap
  • Reduction of chlorophyll content
  • Less photosynthesis
  • Quality and the yield both are greatly reduced.
  • Severely damaged leaves show several minute yellow specks and small black pustules of excreta.
  • Leaves gradually wither and fall of.
Identification
  • The eggs are cylindrical, dark brown
  • Newly emerged nymphs are light orange in colour and 0.07 x 0.02 mm
  • Fourth instar nymphs are dull red and 1.9 x 0.9 mm.
  • Fifth stage nymphs are dark brown, 2.4 x 1.2 mm
  • The average size of female and male is 2.75 x 1.00 and 2.85 x 1.25 mm, respectively.
16.1 16.2
Life cycle
  • Incubation period is about 8 days
  • Nymphs mature through 5 instars
  • The total nymphal period is completed in 18-23 days.
  • Pre-oviposition period is about 9 days,
  • oviposition period is 15 days.
  • Adult longevity is about 25 days in females and in 21 days in males.
Salient features
  • The adult bugs appear during the on set of monsoon
  • The eggs are laid singly or sometimes in pairs glued to the leaf surface
  • Fecundity is 45 eggs.
  • There are 3 overlapping generations in a year.
Management:
  • Spray of phosphamidon, dichlorvos, dimethoate or oxy-demeton methyl at 0.05 per cent and malathion at 0.1 per cent
2. Blister beetles
  • Discussed earlier
3. Bean pod borer, Adisura atkinsoni (Noctuidae: Lepidoptera)
  • Distribution: All over the Indian subcontinent
Damage:
  • Caterpillars bore into developing pods
  • Feed on ripening seeds
  • Reduces the yield considerably.
Identification
  • Eggs are small and spherical.
  • Caterpillars are cylindrical, brownish green in colour, 25-33 mm long when full fed
  • Moths are medium sized and pale yellowish brown in colour
  • Fore wings are brown with grey tinge and outer margins pinkish
  • Hind wings are straw yellow in colour
  • Wing expanse is 30-35 mm
Life cycle
  • Incubation, larval and pupal periods last for 3, 14-15 and 11 days, respectively.
Salient features
  • The eggs are laid singly on leaves, buds, flowers and young pods
  • On hatching, caterpillars bore inside the developing pods and feed inside
  • Usually pupate in the soil, sometimes on flower spikes also.
4. Plume moth, Exelastis atomosa (Pterophoridae: Lepidoptera)
  • Distribution: All tropical regions of the world
  • Host range: Indian bean, red gram, horse gram, pigeon pea etc.
Damage:
  • Tiny caterpillar bore into the pods and feed on developing seeds
  • Do not bore completely, but the posterior abdominal portion remains out side
  • Sometimes the caterpillars emerging from eggs laid on flower buds enter into these buds and feed inside.
Identification
  • Eggs are minute in size, about 0.5 mm long oval in shape and pale green in colour.
  • Full grown caterpillars are 10-14 mm long, moderately stout, greenish and covered with spine like hairs
Last modified: Wednesday, 7 March 2012, 7:14 AM