1. Identification of insect pests of Cotton
and their damage symptoms
Dr. M. Thippaiah
professor
Dept. of Entomology
College of Agriculture
GKVK, UAS
Bangalore- 65
2. It is a important fiber crop in India and also high valued
commercial crop for textile industries
India occupies the largest area in the world under cotton and
it ranks third in production
At present this crop is grown in an
Area- 12.18 million ha
Production- 13.73million bales (170kgs each)
All the 4 spices of cotton i.e.
Gossypium herbaium
G. herborium
G. hirsutum
G. barbadens
are grown in India commercially that's why India is much important
in cotton cultivation
Factors that affects poor yield in cotton
Cultivation in rainfed condition
Timely not taking plant protection measures
Use of high yielding varieties- attracts more pest
Indiscriminate use of pesticides particularly broad spectrum
pesticides leads emergence pests
3. Maximum pesticides consumption
In cotton – 52.58 %
Rice - 24 %
Pulses - 17.18 %
60 % of total pesticides produced are diverted to cotton because of this
Pest resurgence – only the crop where in synthetic pyrethroids are
recommended
Main problems of synthetic pyrethroids are
Resurgence of white flies in 1995 in AP
Resurgence of Helicoverpa in 1988-89 in AP
To avoid this they recommended only 2-3 sprays of pyrethroids
alternated with conventional insecticides
Change in species composition
Environmental pollution
Health hazards
Destruction of natural enemies
Most of the insects develops resistance
Crop loss – 50-60 % due to insect pests
4. In India expenditure on plant protection i.e. pest control on
varalaxmi hybrid ranges from 43-72 % i.e. 12-25 sprays are
taken up to control different insect pests
There are more than 1326 species of insects have been reported
attacking cotton in the world. However, in India only 162 species
have been recorded ,
Among which 14-15 species may be called as major pests due to
their occurrence in serious proportions almost every year
5. Insect pests of cotton are classified as
Sucking pests
Boll worms
Defoliators
Root / Stem feeders or Borer pests
Non insect pests
7. Leaf hopper : Amrasca biguttula biguttula
( Cicadellidae : Hemiptera)
It is a major pest in all cotton growing region of India
Introduction of American cotton the leaf hopper become severe
in 1970’s and J.K series are also more susceptible to leaf hoppers
Favourable conditions for multiplication
Dry weather or cloudy weather in South India ideal for multiplication of
leaf hoppers
Adults are small, measures 2-3mm in length, wedge shaped hoppers
and green in colour with black spots on the head and posterior end of
fore wings
8. Nature and symptoms of damage
Both nymphs and adults suck the sap from under surface of leaves as a
result tender leaves turn yellow, the leaf margin curl down wards, margins
become yellow in the beginning and later reddish in colour and starts drying
In severe cases, leaves get a bronze or brick red colour which typical
‘hopper burn’ and crop growth retarted
The infestation occur in seedling stage and seedlings gets killed, the number
of flowers and bolls are reduced
Life Cycle of the pest
Eggs : are laid singly with in leaf veins and epidermis on upper surface of the leaf
Matured leaves of one month old crop are more preferred for egg laying
Each female lays – more than 20 eggs
I.P – 4-11 days
Nymphs – there are 4 nymphal instars
Nymphs are light green in colour and translucent found between veins of
leaves on ventral surface
N.P – 7-21 days
Total life cycle- 15-45 days
There are 11 generations / year
9. Leaf curl down wards, margins become yellow in the beginning
and later reddish in colour and starts drying
Symptoms
The leaf gradually dries up and drops
The plants become stunted
The number of flowers and bolls production gets reduced
The quality of cotton lint is also reduced
The loss of plant vitality, there will be up to 35 % in yield
10. Aphids : Aphis gossypii
( Aphididae : Hemiptera)
Adults are soft bodied, yellowish green in colour, winged or
wingless insects
They produce parthenogenetically / Ovo-viviparously
They produce – 8-22 nymphs/ day/female
Nymphs: there are 5 nymphal instars, N.P – 2weeks
11. Nature and symptoms of damage
Nymphs and adults suck the sap from the tender shoots and leaves
as a result Plant cause stunted growth, gradual drying and leaf curl
down wards and finally death of the plants
Infestation occur both in the early stage and later stage
They also excrete lot of honey dew and sooty mould development
takes place on the leaves and plants are dark appearance
The damage is more severe in young seedlings
12. Solenopsis mealy bug : Phenacoccus solenopsis
( Pseudococcidae : Hemiptera )
P.Solenopsis has emerged as a major pest of cotton
in the Northern zone, causing heavy reduction in yield.
13. P.Solenopsis has two dark stripes on either side of the middle
ridge of the body is a distinctive character of females
Dark stripes
It takes 25-30 days to complete one generation
A female adult produces about 150-600 eggs in the ovisac and within
3-9 days the crawlers come out and actively move and spread
out and settled down for food on plant parts and gradually develops
waxy coating
14. Nature of damage
The insect sucks the sap from almost all parts of the plant including
leaves, stems, exposed roots and fruiting bodies, thus considerably
weakening these parts
The shoot tips develop a bushy appearance and the entire plant may
become stunted
In affected plants bolls are few in number, deformed and small in size
The pest secrete sweet honey dew, which encourages the
development of black sooty mould, adversely affecting photosynthesis
Ants attracts by the honey dew, have been observed carrying
mealy bugs from plant to plant
15. White fly : Bemisia tabaci
( Aleyrodidae : Hemiptera )
Adult white flies Adults fly
Both nymphs adults congregating
on the under surface the leaf
Adults are small soft bodied,
yellow coloured insects with
Wings and body are dusted
with white waxy coating
16. It is a polyphagous pest it attacks bhendi, potato, tomato etc.,
In early days it is a minor pest and in 1980’s on wards it become
a major pest
Life cycle of the pest
Eggs : stalked eggs laid singly on the lower surface of the leaves
Each female lays 120 eggs
I.P – 3-5 days
Nymphs : First instars are very active , highly mobile are called as
crawlers and greenish yellow in colour
Second and third instar nymphs are flat, scale like
and immobile
After fourth moult it stops feeding, and 4th nymphal stage is
pseudopupal stage and extends 2 days
N.P -5-33 days
Total life cycle – 45-50 days when temp. 40-500
C
Complete its development with in 15 days at 30o
c
17. Nature and symptoms of damage
Adults and nymphs insert their stylets on under surface of the leaves
and suck the sap
As a result the vitality of plant and plant growth is stopped and shedding of
buds and bad opening of bolls, retention quality of lint decreases
They excrete honey dew as a result development of sooty mould and they
decrease photosynthetic activity of the plant
It also transmits the leaf curl virus disease of cotton
18. Symptoms
White chlorotic spots appear on the leaves and later join
to form irregular yellowing of leaves.
Leaves fall prematurely
Number and quality of flowers, squares and bolls gets reduced
Nymphs and adults secrete honey dew which leads to
sooty mould formation
19. Favourable condition for multiplication of the white flies
Introduction of new variety which is susceptible
to the pest
Prolonged dry spell
Excess nitrogen application
Frequent irrigation and closer spacing
Indiscriminate use of insecticides, especially
synthetic pyrethroids
Abiotic factors i.e Change in
Temp.
RH and
Intermittent rainfall
20. Thrips : Thrips tabaci – Infests flowers
Scirtothrips dorsalis – Usually found on leaves
(Thripidae : Thysanoptera )
Nymphs and adults lacerate the tissues on the undersurfaces of the leaves
and suck the sap as a result shriveling of leaves and curl up and become
crumbled or crinkled.
When infestation is severe, we observe
Silvery patches seen on lower surface in
early stage of attack and brown colour
in the upper surface in theadvanced stage
Ragged edges / broken edges and
Finally plants are sickly appearance
Adults are small, slender, yellowish to brown with fringed wings
Nymphs are very minute, slender yellowish and microscopic
22. Red cotton bug : Dysdercus cingulatus
( Pyrrhocoridae : Hemiptera )
Adults are bright red coloured bugs with eyes, scutellum
and antennae are black in colour
Ventral side of the abdomen with white stripes
A prominent black spot is present on each side of the hemelytron
23. Nymphs and adults suck the sap from tender ripening bolls as well as from
developing Seeds
The seeds become shriken and loose its viability and quality of the lint is
reduced
The proboscis of this bug will always have a bacterium, Nematospora gossypii
The moment they insert the proboscis, the bacterium enter the boll and multiply
and lint get discolured that why this bug also called cotton stainer
Eggs : are laid in loose soil in masses and protect with soil or dry leaves
Each female lays 100-130 eggs around the base of the plant
I.P – 4-7 days
Nymphs : are reddish with white band on the abdomen
N.P – 28-29 days
Nature and symptoms of damage
24. Overall :
Development of bolls will be affected
Oil content of seed is reduced
Staining of the lint
Seeds become unfit for sowing
Alternate hosts:
Bhendi, Hibiscus, Maize, Sorghum etc.,
25. Dusky cotton bug : Oxycaraenus hyalinipennis
( Lygaeidae : Hemitera )
Adults are small flat bugs with dusky brownish in
colour or blackish in colour with dusky white
wings/ transparent wings
The activity starts once the bolls gets open
26. Nymphs and adults live together and suck the sap from developing seeds
such seeds fail to ripen, they shrivel, oil content decreases
The faecal matter accumulates and staining the lint black colour
These will enter the storage and continue to feed and affect the
quality of the lint
During ginning these bugs get crushed and then lint get stained
Some factors favours more incidence of the pest
Sow the crop late
On ratoon crop
Prolong the season
Eggs : are cigar shape, white in colour and laid in clusters of 2-10
on half opened bolls or flower buds I.P – 6-10 days
Nymphs : there are 5 nymphal instars
N.P – 30-40 days
Nature and symptoms of damage
28. 1 American bollworm Helicoverpa armigera Noctuidae Lepidoptera
2 Spotted bollworms Earias vittella &
E. insulana
Noctuidae Lepidoptera
3 Cotton pink
bollworm
Pectinophora gossypiella Gelechiidae Lepidoptera
Cotton bollworms are the most destructive group of insects found on cotton in all
cotton growing areas of the world.
There are three kinds of bollworms, viz., spotted bollworms, American bollworm
and pink bollworm. Among the three, the spotted bollworms occurs early,
when the plant is 15-20 cm height and continues to feed on shoot.
The other two occur from square formation stage, and pink bollworm continues
till picking of kapas and goes even to ginning mills
29. American boll worm : Heliocoverpa armigera
( Noctuidae : Lepidoptera)
It is a polyphagous pest and it has got large number of
alternate hosts i.e.
96 species of crops
61 species of weeds
It will keep multiplying and will be always above ETL
Damage- 40-65% of damage to cotton plant
Adult
Adults are medium sized, light brown
coloured moths
Fore wings- are light brown with a
prominent black spots on the wing
Hind wing- are grey coloured with broad
black patch along the apical margin
30. Lifecycle of the pest
Eggs- are laid singly on tender shoots,
squares, flower buds, bracts, bolls
I.P – 3-4 days
Larva
Pupa- Pupation takes place in soil
P.P- 9-12 daysAdult moth
Larva passes 5-6 instars, measures
3.5 to 4.0cm in length, variously coloured /
different colour morphs, palegreen,
dark green, pale brown, dark brown and can
be recognized by a yellowish line on either
side of the body
L.P- 30-40 days
31. Nature and symptoms of damage
In the early stage – the larva feeds on tender leaves
later bores in to squares or young flower buds and developing bolls
and feeds internally as a result the buds and young bolls flare up and
finally drop off
Larva habit of putting of head and thorax inside the boll and remaining
body out side with this habit it has potentiality of destroying more bolls
than what it feeds
Entry hole don’t be plugged with excreta(large entry holes) a single
larva can damage more of bolls
Matured bolls does not drop-off one or two locules will be affected
Microorganisms will colonize and colour the lint and larva usually feed
on the seeds
In the initial stage the incidence is low but once the crop producing boll
its incidence is high and it will continue till harvest
34. Larva habit of putting of head and thorax inside the boll and
remaining body out side with this habit it has potentiality of
destroying more bolls than what it feed.
36. Spotted boll worms or Spiny boll worms
1.Earias vitella
( Noctuidae : Lepidoptera )
2. Earias insulana
Adult moth of E. vitella Larva and adult
of E.vitella
E. vitella
More predominant in South India, especially in high rainfall area
Fore wings are yellowish white with wedge shaped green band in the
middle from base to outer margin
Larva : light brown with white patches and ventral aspect green in colour
and body covered with bristles / setae
These two species are the most important pests of cotton causing heavy loss to the
crop every year Damage loss : 40-50 % of young shoots, 50-57 % of bolls
These are small to medium sized moths, measuring 25mm in length
37. Fore wings are yellowish white with wedge shaped green band
in the middle from base to outer margin
39. Earias insulana
More predominant in North India i.e areas where receiving
scanty rains
Fore wings are completely green in colour
Larva : Dull greenish white in colour with No. of black
markings and orange coloured dots on prothoracic
region
40. Life cycle of the pest
Eggs – are laid singly or in groups of 2-3 on tender leaves, squares,
young shoots, bolls
Each females lays 63 - 700 eggs
I.P – 3-10 days
41. Caterpillars are light brown in colour with white patches or markings,
ventral aspect green in colour and measures 1.5- 2cm in length and
body covered with bristles or setae
42. Larva dull greenish white and number of black markings
and orange coloured dots on prothoracic region
L.P- 9-20 days in warm weather
50-60 days in winter
43. Pupa- Pupation takes places out side the bolls in tough boat shaped dirty white
silken cocoon or on the plants , fallen leaves or soil or base of the plant
P.P – 4-87 days depending on temp.
44. Nature and symptoms of damage
The newly hatched larva bores in to tender shoots during vegetative
stage feeds internally as a result infested shoots withers, droops and dries
During reproductive stage- They bore into the buds , flowers and
bolls and feeds internally as a result infested
buds, flowers and bolls drop down
Bored holes on bolls plugged with excreta and entire inner content
of square totally fed and quality can be destroyed
Symptoms
Drying and drooping of young shoots
Shedding of buds, flowers, bolls, flaring of bracts
Bored holes on bolls are plugged with excreta
45. The newly hatched larva bores in to tender shoots during vegetative
stage feeds internally as a result infested shoots wither.
47. Pink boll worm
Pectinophora gossypiella
( Gelechiidae : Lepidoptera )
Adult is a dark brown moth and measure 1 cm in length.
Fore wings- are narrow, trapezoidal in shape
Hind wings- are round to wards apical margin
Both fore wings and hind wings are fringed
48. Life cycle of the pest
Eggs : female moth lays small flat eggs singly on the tender leaves,
flowers, squares and developing bolls
Each female lays 400 eggs
I.P – 4-25 days
Larva : there are 3 larval instars
First instars and second instars larvae are green in colour and
later instars, smooth pinkish coloured body with brown coloured
head
L.P – 8-41 days
Pupa : the fully grown larvae pupates among fallen leaves, debris,
dropped bolls, under clods of soil
P.P- 10-15 days
Climate plays an important role in determining the abundance of the pest
Moderate temp.
Cloudy weather
Moderate rains
49. Nature and symptoms of damage
Larvae feeds on leaf tissues and later bores in to flower buds, flowers
bores in to the bolls
First brood develops by feeding on the anthers, style and occasionally
on ovaries in the flower buds
When they are found on flowers, the flowers do not open and give
‘ rosette appearance ’
Subsequent broods develop within young and matured bolls, and entry
hole not visible out side and they feed on inner contents thus affecting
bolls, flowers, young infested bolls drop down and finally lint become
black colour
Symptoms
Premature shedding of flower buds and bolls
Infested flowers are rosette appearance or clustering together
Premature opening of the bolls
Lint quality declines and seed germination reduced
Presence of interlocular burrow in the opened bolls
