Helicoverpa armigera (Grampod Borer)
- Class– Insecta
- Order– Lepidoptera
- Family– Noctuidae
- Genus– Helicoverpa
- Species– armigera
This pest is cosmopolitan in distribution. In India it causes heavy damage to a number of pulses.
It is polyphagous in nature but serious pest of gram (Cicer arietinum Linn) and red gram (Cajanus cajan (L)). This is also found damaging sorghum, maize, cotton, okra, bhindi, tomato etc.
The adult moth is of light brown or yellowish brown colour and is about 3.75 cm in length with wing expanse. Forewings are provided with wavy black linings and black spots on the upper surface while lower surface has kidney-shaped mark. The hind wings are white and provided with black bank on the outer margins. The adult is nocturnal in nature but found sitting on host plants in day time also.
The adult female becomes active in dusk period and starts egg laying singly on tender leaves and flowers of plants. One female can lay a total of about 741 eggs in 4 days.
The eggs are rounded, light yellowish in colour and look shining. After 2 to 4 days of laying, the eggs are hatched into young larvae in the months of April to October and start feeding voraciously on the tender pods of the host plant. The younger larvae are dark brown in colour but later they become yellow-green whitish and are provided with gray linings on both the sides of the body. The caterpillar becomes full grown after 13 to 19 days of hatching and attains a length of about 35 mm. It severely, damages the pods, foliage and grains. The full grown caterpillar leaves the pod and pupates in the soil. The pupa is of dark brown colour. The adult moth emerges out after 10 to 15 days of pupation in active season but in months of January and February they remain in the soil and emerge out in March and further start egg laying. The whole life cycle takes 3 to 7 weeks in summer and autumn months. Eight generations have been recorded in one year. In absence of proper nutritive host plants the caterpillars are found feeding on other caterpillars.
The caterpillars are polyhagous in nature but cause heavy damage to gram and red gram. This pest feeds on young pods, foliage and seed resulting in reduced yield of gram and red gram. In America it causes maximum destruction to cotton, hence there it is called ‘American Cotton Boll Worm‘.
Prevention and control
- After harvesting, the farms should be ploughed.
- The caterpillars hanging from pods can easily be picked up and destroyed.
- The crop rotation is best device to control this pest.
- The spraying of 0.1% carbaryl or 0.25% endrin is quite effective.
- 5% BHC dusting is also a good control measure.
- The dusting of the mixture of sodium fluosilicate and ash (1:8 w/w) is also effective.
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