Cotton Insect Pest
PINK BOLLWORM
Pink Bollworm in bt Cotton
Common Name :
Pink bollworm
Local Name :
Gulabi/Shendri bond Ali
Scientific Name :
Pectinophora gossypiella Saund.
Family :
Gelechiidae
Order: Lepidoptera
Pest Category: Borer
Description of Insect Stages:
Egg:
 |
| Pink Bollworm Stages of Life Cycle |
Adult:
Eggs are pearly iridescent white, flattened, oval
measuring approximately 0.5 mm long, 0.25 mm wide
and sculptured with longitudinal lines. Eggs are laid
singly or in groups of four
to five.
First two instars
are white, while from
third instar pink color
develops. The larvae
have the characteristic
dark brown head due to
the sclerotized
prothoracic shield
Pupae:
Pupae are light
brown when fresh,
gradually become dark
brown as the pupation
proceeds. Pupa measures
up to 7 mm in length.
 |
| Pink Bollworm ( Pectinophora gossypiella ) Early Stage |
Adult:
The adult moth is
greyish brown with
blackish bands on the
forewings and the hind
wings are silvery grey.
Moths emerge from
pupae in the morning or
in the evening, but are
nocturnal, hiding
amongst soil debris or
cracks during the day.
Nature of Damage:
Larva when attacks the
bud of fewer than 10 days
old, shedding of bud
occurs and larva dies. But
with older bud, the larva can
complete development.
There can be cent percent
pink bollworm
infestation on bolls but
there need not be any
shedding. Larva in flower
bud spins webbing that
prevents proper flower
opening leading to
“rosette-bloom”. Ten to
twenty days old bolls are attacked from under
bracteoles. Larvae feed
on the developing seeds.
While in younger bolls
entire content may be
destroyed, in older bolls
development could be
completed on three to
four seeds. Interlocal
movement is also seen.
Several larvae can infest
a single boll.
 |
| Pink Bollworm ( Pectinophora gossypiella ) Early Stage |
|
Symptoms:
' Rosetted flower '
(improper opening of
petals) is typical of
bollworm attack. Small
exit holes (smaller than
the feeding holes of other
two bollworms viz.,
Earias & Helicoverpa)
are seen in developing
green bolls. Stained lint
around feeding areas
resulting in bad quality Cotton is seen in open
bolls. Improper boll
opening with damaged
seeds are obvious. Small
round holes are seen on
the septa between locules
of open bolls. Lint of pink
bollworm attacked bolls
is of inferior quality
Life History:
 |
| Pink-Bollworm-(Pectinophora-gossypiella)-Adult-Stage |
Early in the season, eggs are laid in any of the sheltered
places of the plant axis of petioles or peduncles, the
underside of young leaves, on buds or flowers. Once the
bolls are 15 days old,
these become favored
sites for oviposition. The incubation period is 3-6
days. The first two instars are white, while the third instar pink color develops. The larval cycle lasts for 9-14 days in hotter regions. white, while from the third instar pink color develops. The larval cycle lasts for 9-14 days in hotter regions.
 |
Pink Early Stage is Attack for
Square to Flower - 1 |
 |
Pink Bollworm Early Stage is Attack for
Square to Flower - 2 |
The mature larvae are either 'short-cycle'
and will go on to pupate or 'long cycle' to enter a state of
diapause. While the former is the observed phenomenon
in South India, diapause is seen in the North and Central
parts of India. Short cycle larvae pupating may cut a
round exit hole through carpel wall and fall to the ground or
may tunnel the cuticle, leaving it as a transparent window
and pupate inside. Pupation is inside a loose-fitting
cocoon with a highly webbed exit at one end. The pupal period
ranges between 8 and 13 days. The life cycle is completed
in 3-6 weeks. The late-season has invariably overlapping
broods. The long cycle larvae entering diapause spins a
tough thick-walled, closely woven, spherical cell referred to as “ hibernaculum” with no exit hole. Always, the longterm larvae occur during the end of the crop season, where there
are mature bolls present and larvae often form their
hibernacula inside seeds.
Hibernacula may occupy single seeds or double seeds. P.gossypiella hibernate as full-fed larvae during cold weather. Diapause larvae often spin up in the lint of an open boll and if still active in ginnery, will spin up on bales of lint, bags of seed or in cracks and crevices. Moths emerging from the hibernating larvae are long-lived with females and males alive for 56 and 20 days, respectively.
 |
Pink Bollworm Early Stage is Attack for
Square to Flower - 3
|
Seasonal Dynamics:
The insect is highly adaptable to different climatic conditions and larvae hide over unfavorable season inside empty cottonseed in which they are well protected and remain alive for many months. Survival of the pest from one season to another is entirely through hibernating larvae in seeds, soils, and plant debris. Incidence of P. gossypiella during the season commences from the moth emerging from the overwintering larvae through the summer season. This is the only pest, which peaks at harvest. Depending upon the periods of crop maturity the seasonal incidence and infestation levels vary. The effective population buildup starts after 100 to 110 days of crop emergence, while the peak infestations occur after 140 days.
 |
Pink Bollworm Early Stage is Attack for
Square to Flower - 5 |
|
 |
Pink Bollworm Early Stage is Attack for
Square to Flower - 4 |
The crop with late maturity suffers heavy attack with 50-75 % of the bolls showing damaged locule (s) in open bolls. In the last five years, the levels of incidence were high during 2002 & 2003, whereas 2005 had the lowest incidence as well as damage. The higher damage levels despite lower incidence arise due to less number of bolls available at the end of the season. If the pink bollworm appears early in the crop season due to favorable weather conditions, the damage is much more intensive during the late season.
Predicition Criteria :
Maximum temperature greater than 33 C, morning
relative humidity less than 70 %, evening relative
humidity greater than 40 % during the standard weeks of
40, 41 and 43, and less than 12°C minimum temperature
between 48 and 49, respectively result in P. gossypiella
severity.
 |
Pink Bollworm is
Attack for Boll Formation Stage
- 1 |
 |
Pink Bollworm is
Attack for Boll Formation Stage
- 2 |
Pest Management Options:
Cultural control plays a key role in keeping down the
number of pink bollworm carry-over between cotton
crops. Maintenance of host-free period during the off-season
is a must to ensure a pink boll worm-free next season.
Therefore, effective measures of prevention of pink
bollworm damage include post-harvest, off-season and
replanting actions. Allowing cattle grazing of the left
over green bolls on the plant at the end of the crop season,
timely crop termination to maintain closed season, clean
up/ destruction of cotton stubbles immediate to harvest,
avoiding stacking of cotton stalks for fuel purpose over
long periods and summer deep plowing to expose the
pupae of the surviving larvae constitute post-harvest and
offseason cultural measures. These practices adopted on
a field-to-field basis over large areas of cotton growing
regions by the cultivators would largely bring down the
attack of pink bollworm in the ensuing season. While
planning for the next season selection of varieties with
early maturity, drying of seeds under the sun for 6-8 hours
and sowing of acid delinted seeds are effective and
economical to prevent the carryover of pink bollworm to
the next cotton season.
During the cropping, season care must be taken to monitor
pink bollworm infestation on the crop. This can be done
easily through the use of gossyplure pheromone baited
traps that attract males. Once few male moths are
found in the traps it is an indication of the incidence
starting in the bolls of the cotton plants. One approach of
pink bollworm suppression is to trap most of the male
moths in the crop ecosystem by using a large number of
pheromone traps (@ 20 nos./ha) so that mating is
disrupted and the population development is arrested. For
this method to be effective traps should be placed over
many fields over larger areas. Since the damage and
stages of pink bollworm are not visible the decision of insecticidal spray is arrived at using the male catches in
the traps. If the moth catches exceed eight per trap for
three consecutive days an insecticidal spray in the field is
desired. When much of the bolls on the plants are 20-25
days old during October end and November insecticidal
protection is a must. In the absence of pheromone traps,
assessment of pink bollworm damage should be based on
destructive sampling (boll cracking method) and
chemical spray should be taken up when two live larvae
are found in 20 medium-sized green bolls sampled per
acre. Pyrethroids can be used against pink bollworm
during this period. The open bolls on the plants should be
harvested before the spray, as there is a likelihood of aphid
resurgence. When there is a resurgence of aphids that
would affect the quality of cotton it is recommended to
spray anyone organophosphorus insecticides. This takes
care of pinkies as well as stainers resulting in the harvest
of quality cotton.
 |
American Bollworm Insect Pest are Control Chemical Name Suggesting to CICR, Nagpur
|
The amount of spray fluid varies more with the canopy
size than with the crop age. It is recommended that power
sprayers be used against bollworm management through
insecticides. Normally 200-300 liters/ha of water should
be used for a crop that had attained eight to sixteen nodes.
No comments