Pests On Cotton – Pest Affects the cotton – Study material

PESTS ON COTTONCotton Aphid,  Aphis gossypii (Aphididae : Hemiptera)

  • World wide, potential pest – Highly polyphagous, wider host range 
  • Nymphs and adults desap on young crop in colonies.
  • Tender leaves curl up, reduced in size, gradually fade and dry up. 
  • Plant growth severely shunted. Leaves show oily appearance 
  • Sooty mould develops on honey dew on lower leaves
  • Ants are seen moving briskly on plants 
  • Adults and nymphs are yellowish / greenish brown in colour. Alate and apterous forms are seen. Reproduce parthenogenetically and are viviparous. 
  •  Life cycle – 7-9 days

Leaf hopper/ jassid,   Amrasca devastans Cicadellidae : Homoptera
  • Damage on young seedlings may be 80-100%. 
  • Hosts: Bhendi, hollyhock, brinjal, potato, mesta, sunflower, cucurbits. 
  • Dry conditions in early stages favour the pest. 
  • Adults- greenish / greenish yellow. wedge shaped 
  • Nymphs- Initially pale yellow turning green slowly.  Eleven generations in a year is observed.  
  • Symptom: Toxemia (by injection of saliva into plant tissues by nymphs and adults) resulting in hopper burn.
  • Initially leaf margins turn pale green, yellow and finally brick red or brown. 
  • Leaves become crinkled and curled resulting in complete drying and dropping of leaves. Plants stunted. Number of flowers, bolls, seed weight, and quality of lint reduced. 
Thrips, Thrips tabaci, Scirtothrips dorsalis (Thripidae : Thysanoptera)
  • Hosts :  Bhendi, Chillies, brinjal, onion, tomato, sunflower, mango, citrus, tea 
  • T. tabaci – on flower ; S. dorsalis – on leaves 
  • Nymphs and adults lacerate tissues, desap .
  • Leaves shrivel with ragged edges, brittle, fall off mal formed- Silvery metallic sheen on leaf under surface 
  • Adults, small, yellowish or brown with fringed wings ; Nymphs – minute, slender yellowish. Life cycle:  EP: 2-3 d; NP: 5-8 d; PP: 3-5 d.
WhiteflyBemesia tabaci Aleyrodidae: Hemiptera
  • Serious pest on cotton whenever synthetic pyrethroids are indiscriminately used. Highly polyphagous 
  • Hosts:  Tobacco, Cassava, bhendi, hollyhock, safflower, sunflower etc.,
  • Nymphs found in colonies on leaf under surface and desap. 
  • Leaves turn chlorotic, drop down, Sooty mould, Reduced vigour, boll-shedding, buds, flowers, improper boll-bursting. 
  • vector of Cotton leaf curl disease 
  • Adult- Small, moth like with white hyaline wings dusted with white powdery scales, body yellow. Nymphs : Green-on leaf undersurface. 
  • 10-12 generations / year 

Red Cotton bug / StainerDysdercus civigulatus (Pyrrhocoridae :  Hemiptera)
  • Nymphs and adults desap on tender unopen bolls
  • Tender bolls show microscopic punctures 
  • Boll opening erratic 
  • Bacterium, Nematospiora gossypii stains lint Yellow 
  • Seeds unfit for sowing and oil extraction 
  • Adult: Medium sized, black markings on hemielytra with a black spot – long antenna. Adults – hibernate in winter 
  • Life cycle : EP : 4-7 d ; NP : 50-90 d (5 instars)

Dusky cotton bug, Oxycarenus hyalinipennis  (Lygacidae : Hemiptera)
  • Damage at boll-bursting stage 
  • Nymphs and adults are dusky brown 
  • Desap seeds at boll burst in small groups 
  • Seeds shrivel, shrunken, Lint stained black 
  • Adult :  Small, flat with dark brownish black body and transparent wings 
  • white eggs – laid in clusters of 2-10 inside half-opened bolls, on the bolls, flowers or buds.   
  • Nymphs : Five instars. Life cycle 30-40 days

Spotted bollwormsEarias vitella, E. insulana (Noctuidae : Lepidoptera)
  • Incidence starts 40-50 DAS. Potential pest of cotton 
  • Bolls with irregular bore holes smeared with excreta, 
  • Dropping of bolls, irregularly bored Lint 
  •  Larva bores tender shoot-causing dead hearts drooping and drying of shoot tips 
  • At square formation, bores squares causing flaring and dropping of squares 
  • Pupa: Boat shaped leathery cocoon on buds, bolls or debris 
  • Life cycle: EP: 3-4 d; LP: 10-12 d; PP : 7-10 d.  
  • E. vitella: Small moth forewings yellow with green band. Hind wings yellow / hyaline 
  • Larva: brown with white median longi stripe and no finger-like processes 
  • E. insulans : forewings – totally green 
  • Larva: more creamy with small finger – shaped processes (on 2, 3 Thorax  and abdomen) and orange dots on prothorax 

Pink BollwormPectinophora gossypiella (Gelechiidae : Lepidoptera
  • Damage:  85-100% 
  • Premature shedding of buds, bolls 
  • At flowering – Rosette bloom- Petals are webbed together without opening.  
  • Inside the Rosetted flowers yellowish white larva devours style, anthers and ovary
  • Bore-holes will not be seen outside as the young larva enters the boll through the tip which heals up
  • Premature opening of bolls exposing lint to saprophytic fungus – reducing ginning qualities
  • Inside the bolls, seeds and locules are damaged 
  • larva bores adjacent seeds to form double seeds for hibernation
  • Lint stained
  • Larva: Young ones pale yellow , before pupation attain pink colour 
  • Pupate in soil among fallen leaves, flowers, clods.  
  • Moth:  Small, active, dark brown, dull yellow or live grey with dark spots on forewing.  
American Bollworm/ Gram pod borer Helicoverpa armigera (Noctuidae : Lepidoptera)

  • Tender buds, bolls attacked, flaring squares 
  • Young larvae feed on foliage causing irregular holes 
  • On bolls, round holes are seen
  • Larva  cannibalistic
  • Green larva thrusts – head alone inside tail outside 

Stem weevilPhempherulus affinis (Curculionidae : Coleoptera)
  • Severe pest on summer cotton. Damage in young seedlings 60-80% 
  • Plants suddenly wilt and dry up.At collar region galls seen 
  • Plant tend to break at the collar region, Gall – result of phytotoxaemia  
  • Yellowish white grub / pupa or small brown weevil seen inside tunnels
  • Adult, small snouted brown weevil. Grubs fleshy, yellowish white, feeding on tissues. Pupa :  inside the chamber on stem 

Semi loopers 
  • Larvae feed on foliage causing irregular feeding holes 
  • Crop becomes sickly with stunted growth with reduced squares, bolls, flowers 

Anomis flava Medium, forewings reddish brown with brown  spot and faint cross stripes. Males brighter. Larva: Green with 5 longitudinal stripes red prologs.
Acontia graellsi  Medium, forewings lemon yellow with transverse brown streak and Larva: Green with brown horse-shoe shaped markings and black warts 
Tarache nitidula Adult:  White wings with dark markings. Larva:  Dark brown 
Leaf Roller : Sylepta derogate (Pyraustidae : Lepidoptera)

  • Larva rolls the leaves and feed within leaves dry and drop, trumpet-shaped rolls 
  • Results in total defoliation 
  • Moth :  Medium, whitish, yellow with brown wary markings
  • Larva : Green, glistening, brist-moving scrapping and feeding leaves – sparse hairs. Pupa  : Within leaf fold / debris in ground 

Tobacco caterpillarSpodoptera litura (Noctuidae : Lepidoptera)  

Leave a Reply

Your email address will not be published. Required fields are marked *