2. GENERAL DISCRIPTION
*P. gossypiella is an insect known for being a pest in cotton
farming. The adult is a small, thin, gray moth with fringed
wings. *The
larva is a dull white, eight-legged caterpillar with conspicuous
pink banding along its dorsum. The larva reaches one half
inch in length. *The
pink bollworm is native to Asia, but has become an invasive
species in most of the world's cotton-growing regions *The
Pink Bollworm life cycle includes four stages. These are the egg,
larva, pupa, and adult. *Completes four
to six generations per year.
3.
4. DISTRIBUTION
Pink Bollworm is of south-Asian origin, and has spread to all regions where cotton
is cultivated.P. gossypiella is distributed throughout tropical America, Africa, Asia,
Australia, including subtropical regions, Pakistan, Egypt, USA (Arizona) and
Mexico. The distribution includes records based on specimens of P. gossypiella
from the collection in the Natural History Museum (London, UK).
In india it is distributed throughout Andhra Pradesh , Assam , Bihar , Delhi
,Gujarat, Haryana , Himachal Pradesh , Indian Punjab , Jammu and Kashmir ,
Karnataka , Kerala , Madhya Pradesh , Maharashtra , Manipur , Odisha ,
Rajasthan and Tamil Nadu.
5. Life Cycle
*The Pink Bollworm life cycle includes
four stages. These are the egg, larva, pupa,
and adult.
*The time required from egg to egg varies
because of temperature and other conditions
but generally is about one month during
the summer month
Seasonal cycle---------------------
6. EGG
*Female pink bollworm moths lay eggs singly or, more commonly, in small groups.
*Eggs are white when first laid but then turn orange, and later the larval head capsule is visible
prior to hatching.
*The eggs are small and difficult to see without some magnification.
*Eggs hatch in about three to four days after they are laid.
*Eggs of the first field generation in the spring are often laid on
vegetative cotton plants near cotton squares & sometimes on.
Squares.
*Second and sub-sequent generation eggs are usually laid under the
calyx of bolls.
7. Larva
*Larvae immediately begin to bore into squares or bolls after hatching. In squares, larvae
complete most of their development before blossoming occurs and often cause rosetted blooms.
Final development is completed in the blossom.
*In bolls, larvae feed within one to five seeds to complete
development before exiting & dropping to the soil for pupation.
*While moving from seed to seed, the larva causes damage by
cutting through the lint with its mouthparts.
*Lint is also damaged as the larva tunnels out of the boll.
*Larvae are white with a brown head when they hatch.
*They have four stages of growth (instars) and begin to turn
pink in the fourth instar.
*They generally require 12–15 days to complete develop-ment
after which they go into puation.
8. Pupa
It is in pupation that the pink bollworm makes the drastic transformation
from a larva to an adult moth. Most pupa-
tion occurs in the top layer of soil beneath
cotton plants. The pupa is brown and
approximately one-half inch long. It does
not feed or move about during the pupal
period of seven to eight days.
9. ADULT
*Adult pink bollworms are mottled brown to gray moths
and are about 1 1/2 inch long.
*They emerge from pupae in an approximately 1:1 male to
female ratio.
*There is a time period of 2-3 days after emergence during
which the female mates and prepares to lay eggs.
*After this preoviposition period the female lays most of
her eggs in about ten days.
*Both male and female adults feed primarily on nectaries
located on the bottom of cotton leaves and may live for one
to two months.
The female produces a sex pheromone that aids the male in
locating her for mating purposes.
10. Main host
P. gossypiella is an oligophagous pest. Gossypium (cotton) is its main host.But
apart from cotton P. gossypiella also affects the following species : Abelmoschus
esculentus (okra),Abutilon (Indian mallow),Abutilon indicum (country
mallow),Althaea (hollyhocks),Hibiscus (rosemallows),Hibiscus cannabinus
(kenaf),Hibiscus sabdariffa (Jamaica sorrel),Malvaceae,Medicago sativa (lucerne).
MAIN HOST;Cotton and other members of the family Malvaceae, especially
Hibiscus spp.
In a survey of okra, deccan hemp (Hibiscus cannabinus [kenaf]) and
roselle (H. sabdariffa) in Egypt in autumn 1988, P. gossypiella was found to prefer
okra over cotton towards the end of the season when the cotton boll surface was
hard (Khidr et al., 1990).m
11. ADULT CHARACTERS
*The adult pink bollworm varies in size but is rarely over 3/8 inch in length. It is mottled
grey in color with oval shaped wings.
*The wings are strongly fringed at the edges. The forewing is pointed at the tip. When at
rest, the moth’s wings are folded close to the body.
*Under magnification, palpi can be seen emerging from the lower front part of the head.
*In contrast to most other moths, the palpi of pink
bollworm are relatively thick, curved upwards and have
light and dark colored bands.
*Also, the pink bollworm moths have a few stout hairs
which project forward from the base of the antenna.
*Pink bollworm moths will typically live 4 to 8 days.
*In the genitalia, the male uncus is broad at the base,
tapering to a point and the aedeagus has a hooked tip.
The female ovipositor is weakly sclerotized.
12. damage
*Soon after emergence, pink bollworm moths mate and if cotton fruiting forms are
available, the females begin laying eggs on them.
*Some overwintering adults will emerge before there is squaring cotton available.
*This emergence is termed “suicidal” since the eggs are laid on vegetative tissue and
the larvae do not survive.
*Pink bollworm larvae enter cotton fruit less than one hour after they hatch from the egg.
*Squares need to be 7 to 10 days old before they can support the growth and
development of a pink bollworm larvae.
*The larvae feed and mature in cotton fruit. The first generation in the early summer
feeds in squares, primarily on the anthers.
*Pink bollworm larvae burrow into cotton bolls to feed on the cotton seeds. In the
process they destroy the cotton lint. This feeding damage allows other insects and fungi
to enter the boll and cause additional damage.
*When the larva exits the cotton boll it leaves a perfectly round and clean cut exit hole
which is diagnostic of pink bollworm damage.
13. Prevention and ControL
*In cotton production, there are many factors that can reduce crop yield and one
important cause is the attack of insect pests. Insect pests’ attacks reduce yield and
quality of cotton, and oil content in the seeds.
*Cotton is vulnerable to an extensive array of insect pests and among these the cotton
bollworms are the most destructive fatality. Methods for prevention and control of P.
gossypiella are:
*Biological Control method, *Integrated Pest Management, *Chemical Control,
*Cultural Control, *Pheromonal Control, *Sterile Male Release
14. Pheromonal Control
*Female pink bollworm moths produce and release into the air a sex pheromone which
is highly attractive to male pink bollworm moths. Male moths respond to the
pheromone.
*Scientists have successfully produced synthetic pink bollworm sex pheromone in the
laboratory. When slow release systems containing pink bollworm sex pheromone are
spread throughout pink bollworm infested cotton fields, the ability of males to find
females and mate is greatly impaired.
*Unmated females do not contribute to pink bollworm population growth. Even delays
in mating slow the rate of pink bollworm population development.
*Trapping with the synthetic pheromone gossyplure has been widely used and is
reported to have resulted in a 60-80% reduction of the pest population in China (Gao
et al., 1992). Pheromone trapping has also been used in India for an attempted
eradication programme (Simwat et al., 1988).
15. Biological control
*P. gossypiella has been a target for biological control, particularly in the USA.
Parasitoids were introduced there from India, from the Indonesia-northern Australia
region and from several other countries, but only Bracon kirkpatricki became
established (Greathead, 1989).
*Biological control agents were first obtained from India, in the belief that it was the
origin of the pest. When these failed later introductions were from Indonesia-Australia
as opinion shifted in favour of an origin in this region.
*Only few natural enemies of the pink bollworm are known, and none seem to have
any controlling effect.
16. Integrated Pest Management
*Combinations of biological and chemical controls have also proved successful. Tuhan
et al. (1987) found that application of Trichogramma brasiliense in combination with
chemical insecticides gave good control of pink bollworm in India, and Bacillus
thuringiensis has been found to be effective in combination with chemical insecticides in
Egypt (Hussein et al., 1990).
*The Pectinophora gossypiella IPM project in California, USA, was reviewed by Walters
et al. (1998). The project used the release of sterile insects, cultural controls, intensive
monitoring with pheromone baited traps for adult males and boll sampling, pheromone
applications for mating disruption, very limited use of pesticides and the widespread use
of genetically engineered cotton.
*In Pakistan, Ahmad et al. (2001) found a combination of Biological control and mating
disruption techniques to be effective.
17. Chemical Control
*Organophosphates were used in the past to control the pest, whereas pyrethroids are
more common now.
*Insecticidal control is hindered by the larvae being internal feeders; moreover,
resistance to insecticides develops making it often more expensive than other methods.
*The efficacy of asymethrin has been tested in India by Dhawan et al. (1992), that of
chlorpyriphos in India by Dhawan et al. (1989), of synthetic pyrethroids by Dhawan et al.
(1990) and Butter et al. (1990), chlorpyrifos and fenpropathrin by Mahar et al. (1987), of
chloropyrifos and teflubenzuron by Green and Lyon (1989), of pyrethroids and organic
insecticides with high contact toxicity (carbaryl) in China by Gao et al. (1992), of
cyhalothrin and fluvalinate in India by Thangaraju et al. (1993) and of fenvalerate by
Tadas et al. (1994). Application methods were assessed in Brazil by Ramalho and Jesus
(1989). A strain in Arizona has been found to be resistant to permethrin (Osman et al.,
1992).
18. Cultural Control
*Late planting of crops has been used as a cultural control method where the end of
diapause is triggered by day length.Larvae that emerge before the crop is ready then
have no food supply (Frisbie et al., 1989).
*Threshing and thoroughly burying all plant remains after cotton picking is also
recommended for pink bollworm control.
*Research has shown that when a cotton producing area maintains seven or more
months each year free of fruiting cotton plants, pink bollworm damage generally
declines to the point that it is of minor economic significance.
*Adventitious cotton plants growing around commercial fields and any harvested cotton
remains lying by roadsides should also be destroyed.
*Other cultural methods include killing the larvae within seeds or lint bales by heating
to about 60ºC. *Winter
irrigation of the previous season’s cotton fields is also a very effective cultural practice
to reduce overwintering pink bollworms, and rotating to small grains, an alternative
19. Sterile Insect Technology(SIT)
*Sterile Insect Technology (SIT) is another form of highly effective, non-traditional
biological control that is being used to eradicate and control pink bollworm.
*IN this technique Pink bollworms are mass reared in a laboratorY.
*The larvae pick up a red dye which has been added to the diet mixture so that lab
reared moths can be distinguished from wild moths.
*Lab reared moths are sterilized with radiation and quickly shipped in internally cooled
shipper/release boxes to cotton producing locations where they are released by
special equipped aircraft over targeted fields.
*Sterile moths compete for mating with wild males and females. No viable larvae are
produced by matings of sterile males with wild female moths.
*
