Bollworm complex in cotton

INTRODUCTION

Cotton is most important fibrous, oilseed and cash crop. It play a significant role in the industrial & agriculture economy of the country. In production of cotton India ranks second after China. But from recent 3-4 years crop loss in cotton becomes very high due to the attack of bollworm which led to poor sustainability of farm production and the main reason for this is that resistance power developed by pest against Bt-gene.

Definition:

Bollworm complex  are the most injurious group of insect found on cotton in the world they are American bollworm, Spotted bollworm and Pink bollworm.

 BOLLWORM COMPLEX

COMMON NAME	SCIENTIFIC NAME	ORDER	FAMILY
American bollworm	Helicoverpa armigera	Lepidoptera	Noctuidae
Spotted bollworm	Earias insulana & E. vittella	Lepidoptera	Noctuidae
Pink bollworm	Pectinophora gossypiella	Lepidoptera	Gelechidae

 

DISTRIBUTION OF PEST

INSECT	DISTRIBUTION	HOST RANGE
American bollworm	Canada , United states, Malaysia, South Africa, India	Okra, chickpea, Tobacco, pigeon pea, cabbage etc.
Spotted bollworm	Australia, Asia, India, Spain, syria etc.	Okra, Sun hemp and other Malvaceae plant.
Pink bollworm	America, Australia, Asia, India	Okra, Lucerne etc.

1. AMERICAN BOLLWORM (Helicoverpa armigera)

How to identify:

• The adult moth is yellowish brown with a dark speck area on the forewings, which have grayish wavy lines and a black kidney shape mark.
• The hind wings are whitish with blackish patch along the outer margin.
• The larvae is greenish brown with dark gray yellow stripes along the sides of the body.

Damaging symptoms:

• The larva initially feed on the leaves and bore flower-bolls and seed with its head thrust into the boll leaving the rest of body outside the boll. 
• The entry hole are large and circular at the base of the boll.
• The damage boll drop away from the plant and unopened.
• The open boll are not attacked by this.
• A single larva is capable to damage 35-40 bolls.

Economics threshold level:

• One larve per plant 10% of damage boll.

2. SPOTTED BOLLWORM (Earias insulana & E. vittella) 

How to identify:

• It has green forewing with white streak in each of them.
• E.insulana has complete green forewing and hindwing are whitish in colour.

Damaging symptoms:

• The caterpillar bores into top tender shoot, the above portion damage withers drops and dries.
• when squares and bolls begin to develop then the caterpillar move from the shoot and start damaging the boll by making hole in them, the injured boll drop away from the plant. 
• Such injured bolls may prematurely open badly.

Economics threshold level:

• One larve per plant 10% of damage boll.

3. PINK BOLLWORM (Pectinophora gossypiella) 

How to identify:

• Forewings of adult moth are dark in colour with blackish spot.
• The margins of hindwings are deeply fringed.
• Generally larva are of various colour according to its instar, young larva are white in colour and late instar almost brown, black or green to pale or pink with several light and dark alternating bands.

Damaging symptoms:

• The caterpillar initially feed on flower and bore into boll, they feed on developing anther and style and occasionally on ovary, when they found in flower it does not open and give rosette appearance.
• The hole of entry closed down by excreta of larva which feed inside the kernel seed. 
• The young boll attacked are shed after few day the large boll remain on the plant.
• Lint is destroy ginning percentage and oil content get reduce.

Economics threshold level:  

• One larve per plant 10% of damage boll.

INTEGRATED PEST MANAGEMRNT STRATEGY FOR FARMERS 

Cultural practice:

• Deep summer plough in month of Feb-April.
• Synchronous  sowing with early maturing cultivar. 
• Crop rotation practice to be followed to break the life cycle.
• Use authentic Bt-cotton cultivar.
• Growing caster as intercrop or border crop to attract tobacco cut worm.
• Complete the sowing during April. It will escape the attack of America bollworm.

Biological practice:

• Release of trichogramma bactrae @ 60000/acer thrice at weekly interval between 90-120 days, avoid spraying of insecticide at least 10 days form the date of release.
• Spray HaNPV @ 250 LE/ha from 35-65 days of crop.

Mechanical practice:

• Install pheromone traps initially 45 days after sowing for monitoring @ 5 traps/ha. 
• Economic threshold level of bollworm is 8 moths catch per pheromone traps from consecutive 3 days.
• Use lures of authentic quality and change at recommended intervals.
• Install light trap (160 W mercury vapour lamp) 1 light trap/ha.

Chemical practice:

• Spray chemical insecticide only after inspect  presence of damage of bollworm by plucking 20 green boll from different plant randomly, if at least 2 out of 20 boll having white or pink larva /exit hole, then spray.
• Spray neem seed kernel extract 5% + neem oil 50ml + detergent power 10gm in 10 liter of water in 50-60 days.
• Spray Chlorpyrifos50 EC@2ml/l or Quinalphos or Thiodicarb75WP@1g/l during mid September-November.
• Strictly avoid spraying pyrethroids such as Lambdacyhalothrin Cypermethrin etc. before November.

RECOMMENDED INSECTICES	DOSE
Profenophos 50 EC	2.0ml/l OR
Thiodicarb 75WP	1.0g/l OR
Methomyl 40 SP	0.6g/l OR
Indoxacarb 14.5 SC	0.5ml/l OR
Spionosad 45 SC	0.2ML/l OR
Emamection benzoate 5SG	0.25g/l OR
Chlorantraniliprole	0.2ml/l OR
Fludendiamide 20SG	0.2g/l OR
Lamdacyhalothrin	0.5 ml/l OR
Decamethrin 2.8 EC	0.5ml/l OR
Cypermethrin 10 EC	0.5ML/l OR
Novaluron	1g/l OR

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