Insect Pest Management in Cotton

B. L. Jat, K. Rolaniya and S. S. Yadav

Cotton, the commercial crop is the backbone of the textile industry as it employs vast majority of population directly or indirectly and earns the foreign exchange too.The insect pests spectrum of cotton is quite complex and as many as 1326 species of insect pests have been listed on this crop throughout the world. However, main losses in cotton production are due to its susceptibility to about 162 species of insect pests. Among these, the bollworms viz., American bollworm, Helicoverpa armigera, (Hubner), spotted bollworm, Earias vittella (Fabricius), spiny bollworm, Earias insulana (Biosdual), pink bollworm, Pectinophora gossypiella (Saunders), pose greater threat to cotton production.Besides these, a complex of sucking pests viz., green leaf hopper, Amrasca biguttula biguttula (Ishida), thrips, Thrips tabaci (Linnman), aphids, Aphis gossypii (Glover), whitefly, Bemisia tabaci (Gennadius), red cotton bug, Dysdercus koenigii (Fabricius) and dusky cotton bug, Oxycaranu shayalinipennis (Costa) occupy major pest status and contribute to lower yields.

Fruit and Boll Feeders

American boll worm (Helicoverpa armigera

Identification & Monitoring:

This is a major pest and active from July-October and February-April. The adult moth is stout, yellowish brown with a dark speck area on the forewings, which have grayish wavy lines and a black kidney shaped mark whereas the hind wings are whitish with blackish patch along the outer margin. The larva is about 35 mm long, greenish brown with dark gray yellow stripes along the sides of the body.  For 65-100 days old crop, one egg or larvae per plant or 5-10 % infested fruiting bodies is the ETL.

Damage:

The larvae feed on the leaves initially and then bore in to the square/bolls and seeds with its head thrust into the boll, leaving the rest of the body outside. A single larva can damage 30-40 bolls. The entry holes are large and circular at the base of the boll.

Cultural Control:

  • Plough deeply, clean cultivation to expose the resting pupae, crop rotation and avoidance of ratooning reduces pest population.
  • Use tolerant varieties.
  • Trap cropping with crops like tomato, and destroying them when the population is high.
  • Use of maize and cowpea on borders and wild brinjal and setaria as intercrop significantly helps in reducing the pest population.

Mechanical Control:

  • Cotton is harvested in 3-4 pickings by hand as the boll mature.
  • The number of pickings varies with the maturity habit of the variety.
  • Cotton from damaged boll should not be kept with good quality cotton.
  • Never pick wet cotton.
  • On dew days, pick cotton in late mornings to avoid moisture in cotton. 

Biological Control:

  • Release of egg parasitoids like Trichogramma chilonisor T. brasielenis or T. Achaea @ 150,000 /ha from 45th day onwards at 10-15 days interval (6 releases) and larval parasitoids such as Chilonus blackburni or Bracon brevicornis or Telenomus heliothidae or Carceliaillotaor Coteria kazat or Campoletis chloridae @ 2000 adults/ha at 15 days interval.
  • Release pupa parasitoids Brachymeria sp
  • Release of the predators Chrysoperla zastrouviearabica or Scymnus sp. or Eulophids would suppress the population of larvae.
  • Spray HaNPV @ 250 LE/ha from 35th to 60th day of crop stage. 
  • Apply BtkI @ 1 kg/ha.
  • Application of fungal pathogens like Beauveria bassiana or under humid conditions is effective.
  • Use 5% neem seed kernel extract (NSKE).

Chemical Control:

  • The following insecticides are effective against the pest:
  • Endosulfan 35 EC 2.5 lit/ha; or
  • Quinalphos 25 EC 2.0 lit/ha; or
  • Chlorpyriphos 20 EC @ 2 lit/ha; or
  • Cypermethrin 10 EC 600-800 ml/ha
  • Trizophos 40 EC @ 1.5 lit/ha

Pink bollworm (Pectinophora gossypiella Saunders)

Identification & Monitoring:

This is a major pest, is active from October - November.  The adult moths are dark with blackish spots on forewings. The margins of hind wings are deeply fringed. Wing span is 8-9 mm. The caterpillars are creamy yellow when young and turn pink when grown, 8-10 mm long with distinct brown head.  Eggs are laid on the underside of tender parts of the plant (shoots, flower buds, leaves and green bolls).

Damage:

The damage is caused by the caterpillars by feeding on the flower buds, panicles and bolls. The holes of entry close down by excreta of larvae which are feeding inside the seed kernels. They cut window holes in the two adjoining seeds thereby forming "double seeds" and finally damage them. The attacked buds and immature bolls drop off. Lint is destroyed, ginning percentage and oil content are impaired.  For 65-100 days crop, 5-10% infested fruiting bodies is the ETL.

Cultural Control:

  • Clean cultivation and destruction of crop residues (fallen leaves, twigs etc.) before the onset of season.
  • Plough deeply to expose the hibernating larvae / pupae.
  • Avoid late sowing of the crop. Early sowing helps in early maturity facilitating escape.
  • Use of tolerant varieties (Khandwa-2, JKH-1, Abadita, LH 900, Sujay and Desi cotton).
  • Withholding irrigation water to avoid prolonged late boll production/ formation to reduce the buildup of over-wintering population.

Mechanical Control:

  • Use pheromone traps baited with insecticides to kill the pest/ monitor pest population.

Biological Control:

  • Release of egg parasitoids Trichogramma chilonis or Bracon elechidae or Elasmus johnstoni or pupal parasitoid Microbraconlefroyi would keep in check the population of PBW.
  • Encourage the activities of predators Chrysoperla zastrouviearabica Scymnus sp. or Triphles tantilus or Pyremotesventricosus (mite) or release them in the fields.
  • Apply bacterial formulations Btk. @1 kg/ha. 

Chemical Control:

  • Hot water treatment of the seeds up to 600 ° C kills the hibernating larvae. Treat the seeds with Aluminium phosphide.
  • Application of insecticides like Chlorpyriphos20 EC or Endosulfan35 EC or Triazophos40 EC @ 2.5 l/ha spray.

Tobacco caterpillar (Spodoptera litura Fab.)

Identification & Monitoring: 

The adult moth is stout with brownish forewings and whitish hind wings.  The caterpillars are pale green with dark markings initially which later turn dark brown with numerous transverse and longitudinal bands, 25-35 mm long.  It is found throughout the year. Set-up pheromone traps to monitor the ETL.

Damage:

The larvae feed gregariously on the under surface of the leaves and skeletonize them leaving only the mid-rib and veins in severe cases. They also attack flowers, buds and squares causing considerable loss.

Cultural Control:

  • Plough deeply to expose the pupae and hibernating larvae.

Mechanical Control:

  • Mechanical collection when larvae are feeding in groups, i.e., the younger larvae.
  • Collection and destruction of egg masses. 
  • Set-up pheromone traps.

Biological Control:

  • Release egg parasitoids Trichogramma sp. (1.5 lakh/ha) and larval parasitoids Chelonus blackburni or Telenomus remus or Bracon sp.
  • Release of predators Chrysoperla zastroviearabica @ 50,000 /ha.
  • Spray Spodoptera NPV @ 250 LE/ha.
  • Apply Btk @ 1 kg/ha.

Chemical Control:

  • Spraying of insecticides Endosulfan35 EC @ 600-750 ml/ ha effectively reduces the population.
  • Spraying synthetic Pyrethroids Fenvalerate20 EC @ 400-500 ml/ha or Cypermethrin10 EC or Decamethrin2.8 EC @ 600 - 700 ml/ha is also effective.

Spotted bollworm (EariasinsulanaBoisdEariasvitella Fab.)

Identification & Monitoring: 

These are major pests. E. vitellais abundant in high rainfall areas and E. insulana in areas of scanty rainfall.  The pest attacks the crop from 35-110 days of age.  The moths of both the species have wings of about 25 mm. The forewings are grassy green in E. insulana and pea green with a wedge shaped white band running from base to outer margin in E. vitella Larva is about 20 mm long, spiny, brownish with white streaks dorsally and pale yellow ventrally in E.vitella and greenish white with blackmarks and orange spots on prothorax in E. insulana.

Damage: 

The caterpillars cause damage by boring into the growing shoots, buds, flowers and bolls.  The attacked shoots wither, droop and ultimately die, and flowers and buds drop off.   Infested bolls do not shed, open prematurely and the quality of the lint is spoiled due to rot setting.  Sometimes pupation takes place in the bolls itself impairing the development of bolls.

Cultural Control:

  • Plough deeply to expose resting pupae.
  • Avoid use of nitrogen fertilizers at the reproductive stage.
  • Use of resistant varieties
  • Planting trap crop of Okra, uprooting and burning it when the larval population reaches its peak reduces infestation.
  • Don't extend the crop period.

Mechanical Control:

  • Collection and destruction of plant debris and trash before sowing.
  • Collection and destruction of infested bolls.
  • Set-up pheromone traps @ 10/ha for monitoring the ETL and timing of spray.
  • Set up bird perches.

Biological Control:

  • Release egg parasitoid Trichogramma chilonis, T. brasiliensis, and larval parasitoids Chelonus blackburni or Bracon brevicornis at 35 to 70 days.
  • Conserve and encourage the activity of the spiders Thomisus sp. and Neosiana sp. 

Chemical Control:

  • Spray insecticides like Endosulfan35 EC or Triazophos40 EC @2.5 l/ha or Cypermethrin10 EC @ 600-800 ml/ha.
  • Avoid use of conventional sprays repeatedly. Use Neem based insecticides like 5% Neem seed kernel extract (NSKE) and commercial Neem based formulations @ 500-600 ml/ha, starting from 45 days age of the crop or when ETL is reached.

Sap Feeders

Jassids (Amrasca biguttula biguttula)

Identification & Monitoring:

Pest attacks the crop during 1-50 days age and attack is severe during winter.   Adults are about 3 mm long and greenish yellow during summer whereas they develop reddish tinge during winter. The hind portion of the forewings has two black spots on the vertex.  Nymphs are greenish yellow and wedge shaped.  The eggs are laid into the parenchymatous tissue of the leaves.  Nymph and adult stages last for 7-21 days and 35-50 days respectively. There are a total of 7-8 generations in a year.

Damage:

Both adults and nymphs suck sap from the underside of the leaves and devitalize the plants.  Leaves turn pale, red rust, curls downwards and dry up when infestation is severe.

Cultural Control:

  • Sow the crop early.
  • Use resistant varieties such as Khandwa-2 or the varieties having leaves rich in tannin contents.
  • Do not use high doses of nitrogenous fertilizers.
  • Grow cowpea/onion/soybean as an intercrop in cotton to reduce early stage pest.
  • Use Okra as a trap crop.
  • Adopt proper crop rotation.
  • Summer deep ploughing to expose soil inhabitating insects.
  • Remove and destroy crop residues/alternate host plants.

Mechanical Control:

  • Use yellow sticky traps.
  • Hand picking and destruction of various insect stages.
  • Destruction of affected plant parts.
  • Destruction of stressed floral bodies.
  • Destruction of resettled flowers.
  • Installation of bird perches: "T" shape wooden/bamboo sticks @ 50/ha should be erected for encouraging predatory birds.

Biological Control:

  • Release predator Chrysoperla zastrouviearabica or Coccinella septempunctata or Syrphus / Scymnus sp.
  • Conserve spiders Distinaalbida and ants like Camponotus sp.

Chemical Control:

  • Apply chemical pesticides only if pest population crosses the ETL.
  • Spray methyl Demeton25 EC or Dimethoate30 EC.

Cotton aphid (Aphis gossypii)

Identification & Monitoring:

Pest is active from June-October and February-April.  Aphids are small, soft-bodied insects with a pair of tubular structures. Aphids live in colonies and reproduce parthenogeneticlly.  Nymphs are light yellowish green, or greenish black or brownish. Nymphal period lasts for 7-9 days.  Adults are mostly wingless, but few winged forms can also be seen with thin transparent wings. Adults live for 12-20 days.  Females are either lay eggs or directly produce young ones which mature in about 7 days, hence population increases very fast.  Leaves appear shiny and sticky due to honey dew excreted by the insects.  Later, sooty molds grow on honey dew and leaves have a black coating.  Cool weather and humid conditions favor the rapid growth, while heavy rains wash away the aphid colonies.   Optimal temperature is 25-30 ° C. Low light is favorable whereas strong light reduces longevity.  15-20% affected plants counted randomly or appearance of honey dew on 50% plants.

Damage:

Both adults and nymphs suck sap from the tender leaves, twigs and buds, and weaken the plants.  Leaf crumbling and downwards curling  Each aphid makes several punctures and excretes honeydew which encourages development of sooty mold on twigs and leaves and this leaves a blackened look of the plants.  Honeydew attracts ants and sooty mold aids in the development of pathogenic bacteria.

Cultural Control:

  • Avoid late sowing and excessive use of nitrogenous fertilizers.
  • Destroy infested shoots during early stages.

Mechanical Control:

  • Handpicking and destruction of various insect stages and the affected plant parts.

Biological Control:

  • Release predator Chrysoperla zastrouviearaabica or Coccinella septumpunctata or Syrphus / Scymnus sp.
  • Conserve spiders Distinaalbida and ants like Camponotus sp.

Chemical Control:

  • Seed treatment with Imidacloprid(5 g/kg seed) keeps the crop free of sucking pests over a month.
  • Apply chemical pesticides only if pest population crosses the ETL.
  • Spray chemicals Dimethoate30 EC or Methyl O Demeton25 EC @ 500-700 ml/ha when the population reached ETL.

Thrips (Thrips tabaci)

Identification & Monitoring:

The pest is active from May- September. The adults are slender, yellowish brown, 1 mm long. The tip of the abdomen is curved and abdominal segments are transversely banded with dark brown lines. Males are wingless and females have a long narrow strap like wings, fringed with hairs. Nymphs are smaller in size and blackish in color. The eggs are laid in slits in leaf tissues; eggs hatch in 5 day time, nymphal and pupal period lasts for 5 and 4-6 days, respectively. The adults survive for 2-4 weeks. High temperature with low rainfall favors multiplication.

Damage:

The nymphs and adults suck sap from the lower surface of leaves lacerating the leaf tissues. The upper side of the older leaves turn brown and the lower side becomes silvery white. Leaves become curled, wrinkled and finally get dried.

Cultural Control:

  • Avoid late sowing of the crop.
  • Grow cowpea/onion/soybean as an intercrop in cotton to reduce early stage pest.
  • Deep ploughing in summer and weed free field and surroundings.
  • Grow certified acid de-linted seeds of tolerant varieties.

Biological Control:

  • Encourage the activity of parasitoids Thripoctenusbriu, Triphlepstantilus and mite Campsid sp.
  • Release Trichogramma chilonis 1.5 lacs/ha and Chrysoperella grubs @ 1-2 plants.
  • Release Chrysoperla zaastrouviearabica @ 2 larvae/plant in early stage of the plant and 4 larvae/plant in later stage.
  • Release Cheilomenes sexmaculata @ 1.5 lakh adults/ha at random on crop canopy.

Chemical Control:

  • Apply NSKE 5% (Neem Seed Kernel Extract) to control sucking pests.
  • Apply methyl -o-demton 25 EC @ 1500 ml/ha; or
  • Trizophos 40 EC @ 1500 ml/ha; or
  • Dimethoate 30 EC @ 750 ml/ha; or
  • Cartap hydrochloride @ 50 SP @ 1000 g/ha; or
  • Ethofenprox 10 EC @ 1000 g/ha

White Fly (Bemisia tabaci)

Identification & Monitoring:

The pest occurs throughout the year. Generally infests the crop from November to February.  Nymphs and adults are sluggish creatures, clustered together on the under surface of the leaves.  Nymphs are pale yellow and adults are yellowish with white waxy coating on the body.  The hind wings are prominently long.  Eggs are laid singly on the under surface of the leaves.  Routinely check all parts of all fields for whiteflies using adult and nymph scouting methods.  When populations exceed the thresholds, treat them where needed.  Be especially alert for rapid whitefly buildup when nearby host crops are in decline.  Sticky traps may be useful for detecting whitefly movement into cotton fields.  Timely insecticide treatment prevents outbreaks and reduces the chance of sticky cotton and yield loss. Always use action thresholds for insecticide application.

Damage:

The nymphs and adults feed on the cell sap, reduce the vitality of the plant interfering with normal photosynthesis due to the excretion of honeydew and formation of sooty mold all the over surface of the leaf and lints of opened bolls resulting in process of blackening. Chlorotic spots develop on leaves and in severe cases the vein becomes translucent, thickened and in many cases it drops off prematurely. Sooty mold contaminates the lint. The insects help in transmitting and spreading of leaf curl virus (CLCV) disease.   

                                                                                                                                                                       

Cultural Control:

  • Avoid late sowing and adopt crop rotation with crop which is not the host of white fly wherever crop rotation is recommended.
  • Use resistant varieties K-2.
  • Cultivate alternate host crops such as tomato and castor on the boundaries to trap and destroy them.

Mechanical Control:

  • Set up yellow pan sticky traps at various places at the canopy height in field.
  •  Remove and destroy crop residues after last picking.

Biological Control:

  • Encourage activities of parasitiods like Encarsia shafeei or Eretmocerou smundus.
  • Release predators such as Chrysoperla zaastrouviearabica or Melochilus sexmaculatus or Coccinella septempunctata or Brumus sp. or Scymnus sp.
  • Release Chrysoperla zastrouviearabica @ 2 larvae/plant in early stage of the plant and 4 larvae/plant in later stage.
  • Release Cheilomenes sexmaculata @ 1.5 lakh adults/ha at random on crop canopy.
  • Spray neem products 1500 ppm.

Chemical Control:

  • Apply insecticide Imidacloprid, Monocrotophos36 WSC or Quinalphos 25 EC or methyl-o-Demeton25 C or Aephate or Trizophos or Profenophos at fortnightly intervals.
  • The application of Syntheic Pyrethroids (Cypermethrin or Decamethrin) be restricted or used in rotation with conventional insecticides.
  • Apply Neem oil + Teepol @ 3-3.5 litres + 500 ml/ha.
  • Apply fish oil resin soap @1.4-1.5 kg/ha.
  • Seed treatment with Imdacloprid @ 5g per kg seed.

Foliage and Shoot Feeders

Bihar hairy caterpillar (Diacrisia obliqua Walker)

Identification & Monitoring:

This pest is a minor pest  The pest is active during July-November.  The adult moths are dull yellow and are profusely covered with hairs, pale buff crimson abdomen with black spots.  The caterpillars are gregarious in nature, brownish orange to yellow, 40-45 mm long and with hairy head.  Eggs are laid in clusters on the under surface of leaves and pupation takes place in soil or in plant debris in cocoons.  The life cycle is completed in 6-12 weeks.

Damage:

Caterpillars feed on the leaves voraciously and defoliate the plants, leaving only the mid-ribs and veins in severe cases.

Cultural Control:

  • Planting of castor crop along the borders.

Mechanical Control:

  • Collection and destruction of egg masses.
  • Mechanical removal of young larvae, up to 10-14 days of age.

Biological Control:

  • Release larval parasite Apanteles diacrisiae.

Chemical Control:

  • Dust the crop with Methyl Parathion 2% or Malathion5% @ 30 kg/ha OR
  • Spray the crop with Chlorpyriphos 20 EC @ @ 1.5 lit/ha or Endosulfan35EC @1.25 lit/ha.

Author:

B. L. Jat, K. Rolaniya and S. S. Yadav

Department of Entomology, CCS Haryana Agricultural University, Hisar, Haryana, 125 004

Email:  This email address is being protected from spambots. You need JavaScript enabled to view it.