Msc entomology, Central agricultural University, India

1. Change in pest scenario in the light of Bt
cotton in India
Presented by:
PARTHA DEBNATH
CAU/CPGS/ENTO/M14/04
Credit seminar

2. Cotton crop:
• Cotton (Gossypium sp.) is designated as
“White Gold” and “King of fibres”
among all the fibre crops.
• It belongs to the family Malvaceae.
• India ranks 2nd in world cotton
production 6423 metric tons (Statista,
2015).
• It is cultivated in India in 126.55 lakh
hectare area with a production of 401.00
lakh bale of seed cotton per year (Cotton
Corporation of India, 2014).

3. • The pest spectrum of cotton is quite complex and as many as
200 species of insects have been reported to attack cotton at
different stages of crop growth in India (Anon., 1981).
• But among these, the bollworm complex consisting of three
notorious bollworms are considerd to be of great menace.
o American bollworm- Helicoverpa armigera Hub.
o Pink bollworm- Pectinophora gossypiela Sau.
o Spotted bollworm- Earias vitella and Earias insulana Fab.
( Patil et al., 2007)

4. • Cotton occupies 5 % of the total cultivable area
however consumed 55 percent of the totally used
pesticides in all crop cultivation in India (Barwale et
al.,2004).

5. Insect pests present in cotton in India
 Sucking pests:
 Jassids- Amrasca biguttula
 Red cotton bug- Dysdercus
cingulatus
 Aphid- Aphis gossypii
 Mealybug- Phenacoccus
soleneopsis
 White fly- Bemesia tabaci

6. Damage symptoms of the bollworm complex
• Pink bollworm:
 Pin head size holes on the
bolls.
 Rosette flowers.

7. • American bollworm:
 Bolls showing regular,
circular bore holes.
 Presence of granular faecal
pellets outside the bore hole.
 Yield loss upto 80% ( CICR,
technical bulletin no-22).

8. • Spotted bollworm:
 Drying and drooping of
terminal shoots.
 Flaring up of bracts
during square and
young boll formation
stage.
 Holes on bolls and rotting of
bolls.

9. Bt cotton
 Bt cotton is a
genetically modified
cotton crop.
 It expresses an
insecticidal protein
which is derived from a
soil bacterium, Bascillus
thuringiensis var
kurstaki.

10.  Bt was first discovered by a
Japanese scientist Isiwata in
1901.
 The Bt gene cry1Ac was
used to develop the first Bt
cotton variety.
 The acreage under Bt
cotton was increased to 6.33
million hectares in 2007-08
from 3.69 million hectares
during 2006-07(ISAAA,
2007).

11. Why do we need Bt cotton?
 About 162 species of insects occur in cotton at various stages
of growth of which 15 are key pests (Kannan et al., 2004).
 About 9400 M tonnes of insecticides worth Rs 747 crores were
used only for bollworm control in 2001 (Kranthi, 2012).
 Before the introduction of Bt cotton, insecticide quantity
applied on cotton was the highest, relative to other cultivated
crops.

12.  Cotton bolls are highly vulnerable to hidden insects such as the
American bollworm, Pink bollworm and Spotted bollworm.
 The pink and spotted bollworms are hidden feeders and
generally do not come into direct contact with insecticide
sprays.
 The American bollworm comes into contact with insecticides,
partially, has developed resistance to almost all the insecticides
recommended for its control in all regions of the world.

13.  About 50.0% of all insecticides in India were being
unsuccessfully used for cotton pest control, until the year
2001, before Bt cotton was introduced.
 Of these insecticides about 70.0% was for bollworm control
and the rest for sap-sucking insects. (Kranthi, 2012).

14. Mode of action of Bt:
• In the commercialized transgenic Bt-cotton plants, the protein
is expressed in all parts of the plant.
• When the larvae feed on Bt plants, they ingest Bt protein along
with the plant tissues.
• If it is a susceptible insect like bollworms, the Bt protein gets
activated in the mid-gut.
• The activated molecules bind themselves to certain receptors
present on the gut membrane.

16. Bt strain active against various types of
insects
Strain Target insects
Bt subsp. Kurstaki, sotto, aizwai Lepidopteran larvae
Bt subsp. israelensis Mosquito larvae
Bt subsp. tenebrionis Coleopteran larvae
Bacilus poppilae var. poppilae Japanese beetle larvae
Reddy, 2010

17. Classification of cry genes and their
pathogenecity
Cry gene Toxic to the insect order
Cry1A(a), Cry1A(b), Cry1A(c) Lepidoptera
Cry1B, Cry1C, Cry1D Lepidoptera
Cry II Lepidoptera, Diptera
CryIII Coleoptera
CryIV Diptera
CryV Lepidoptera, Coleoptera
Prasad, 2004

18. Chronology of development and approval of Bt
cotton in India
Year Development of bt cotton in India
1995 Mahyco applied to DBT for permission to import a small stock
of Bollgard® (Bt-cotton) seeds from Monsanto Company,
USA.
1996 •A nucleus stock of the American variety Coker 312
containing the Bollgard® was received by Mahyco from
Monsanto, USA.
•Mahyco initiated crossing Coker 312 with the Indian cotton
breeding lines to introgress cry1Ac gene.
1996-1998 •Risk-Assessment Studies were conducted in laboratories and
fields.
•These included pollen escape, aggressiveness and
persistence, biochemical analysis, toxicity and allergenicity.

19. Year Development of bt cotton in India
1998-1999 Multi-location field trials at 40 locations in 9 states to assess
agronomic benefits and safety. Data submitted to RCGM.
1999-2000 Field trials repeated at 10 locations in 6 states. Data submitted to
RCGM
2000 Based on the recommendations of RCGM, the GEAC gave permission
for large scale field trials in 85 ha and seed production in 150 ha.
2001 •Kharif 2001 – Large scale field trials covering 100 ha.
•Field trials were also conducted by All India Coordinated Cotton
Improvement Project of the Indian Council of Agricultural Research
(ICAR).

20. Year Development of Bt cotton in India
2002 •On 26 March 2002, GEAC approved Mahyco’s three Bt-cotton hybrids,
viz. MECH 12Bt, MECH 162Bt and MECH 184Bt, for commercial
cultivation in India.
Source: Manjunath, T.M., AICBA, 2007

21. How Bt cotton is developed
 For development of any transgenic crop, there are five
important steps:
 Identification of effective gene or genes.
 Gene transfer technology.
 Regeneration ability from protoplast.
 Gene expression of the product at desired level.
 Proper integration of gene.
 In case of cotton, Agrobacterium-mediated gene transfer
technique has been essentially used (Firozabady et al., 1987).

23. Advantages of Bt cotton in India
 Bollworm control: Preventing yield losses from an estimated
damage of 30.0 to 60.0% each year in India thus far from 2002
to 2011.
 Increased yield: Yields are estimated to have increased at
least by 30.0% due to effective protection from bollworm
damage.
 Reduction in pesticide use for bollworm control: 46% in 2011,
26% after 2006 and 21% during 2011-12 (Kranthi, 2012).

24. Disadvantages of Bt cotton
 Small and marginal farmers of India can not afford the high
cost of Bt cotton seeds, Rs.1600 for 450 g of seeds.
 Effectiveness up to 120 days, after that the toxin producing
efficiency of the Bt gene drastically reduces (Jeyakumar et al.,
2008).
 Adverse effect on insecticide manufacturing companies due to
reduced use of pesticides significantly by Bt cotton.

25. • Ineffective against sucking pests like jassids, aphids, whitefly
etc.
• Adverse effect on the employment of those persons engaged
in pesticide industries.
• Promotes malpractices such as mixing of low-cost non Bt
cotton seeds with high cost Bt cotton seeds for sale. This
severely affects on cotton production and economic condition
of the farmers using such fake seeds.

26. Bt cotton: Now and Then
• Insecticide usage for bollworm control:
 From 1995 to 2004 was average 6767 M tonnes.
 From 2005 to 2011 was average1089 M tonnes.
• Insecticide usage for sucking pests:
 From 1995 to 2004 was average 3335 M tonnes.
 From 2005 to 2011 was average 4600 M tonnes. (Kranthi,
2012).
 Over all , up to 69% reduction in usage of pesticides has been
achieved through Bt transgenic cottons (Kranthi and Khadi,
2011).

27. • Insecticide use on cotton was 46% of the total
insecticides used in India in 2001 and before.
• But soon declined to 25% within 4 years of Bt cotton
introduction.
• Insecticide usage on cotton further declined to only
21% of the total usage in India during 2009 and 2010
(CICR, 2011).

28. Pest resurgance in Bt cotton:
• Tobacco caterpillar S. litura has been noted as emerging pest
in BG-I genotypes in India (Jeyakumar et al., 2007) with
advent of Bt genotypes.
 Cotton mealybug:
• A new pest, mealybug which was not familiar earlier started
destroying cotton crops.
• Reducing yields up to 40-50% in affected fields since 2006
(Compendium of Cotton Mealybugs, 2011).

29.  Mealybug infestation were recorded in 2006 on G. hirsutum in all
the nine cotton-growing states of India- Punjab, Haryana,
Rajasthan, Gujarat, Madhya Pradesh, Maharashtra, Tamil Nadu,
Andhra Pradesh and Karnataka. (Dhara Jothi et al., 2008).
 Nearly 2000 acres of cotton crops were destroyed by mealybug
(Goswami, 2007).
 Outbreak is serious in both Bt and non Bt cottons.

31. Whitefly: a black story
• Whitefly became a major pest on cotton in India only after
1984.
• It feeds on more than 500 plant species and by sucking sap
from under surface of leaves causes yellowing and upward
curling of the leaves.
• Cotton losses were estimated to be in the range of 15-20% and
sometimes up to 30% (Cotton Statistics and News, 2015).

32. • In August, 2015, a whitefly outbreak devastated the bt cotton
crop in Bathinda, Faridkot districts of Punjab and Sirsa
district of Haryana.
• The insect infestation and whitefly incidence were higher than
the previous three years.
• Whitefly incidence ranged from 1.6 to 90 adults /3 leaves
during July-August in Sirsa. Thus far, high levels of whitefly
infestation were noticed in the second week of August in both
the two states.

33. • Fields sprayed with repeated
insecticide sprays, insecticide
mixtures, fipronil and pyrethroids had
the highest levels of whitefly
infestation.
• 15 farmers committed suicide due to
failure of crop. (TOI, 2015).

34. Causes of outbreaks
• Synthetic pyrethroids and acephate induce bollworms and
whiteflies where spinosad induces mealybugs infestations (Cotton
Association of India, 2015).
• The natural enemies of whitefly are generally more susceptible to
insecticides than the insect pests. For example, the whiteflies have
a waxy coating over the body which protects against insecticides,
but its natural enemies are not protected.

35. • The whiteflies feed from under surface of the leaf where
insecticides do not easily reach.
• The natural enemy predators and parasites are generally present
all over the plant and get exposed to insecticides.
• Insect pests become resistant quickly to insecticides whereas
natural enemies take a longer time for resistance development.

36. • There is a phenomenon reported with whiteflies and American
bollworms, called ‘Hormoligosis’ which causes insects to
rapidly reproduce and multiply when the surviving insects
perceive chemical stress.
• Some reports also describe insecticide-induced physiological
changes in the plant which become more favourable to insect
pests. Thus more the insecticide sprays -more the problem.

37. • This season insecticides such as fipronil and synthetic pyrethroids
were used frequently also as mixtures with organophosphate
insecticides (monocrotophos, acephate and triazophos) in north
India right through July-August (CAI, 2015).
• These insecticides severely induce pest populations leading to
resurgence and outbreaks.
• This year, in many parts of the north, there was delay in sowing by
15-20 days, which helped the whitefly with rainfall less than 100
mm and cloudy weather with high humidity.

38. Insecticide resistance of
Whitefly
• Studies conducted by CICR showed that whiteflies in north
India have developed resistance to all the commonly used
insecticides.
• ‘Neonicotinoid’ group insecticides are most commonly used
in north India. Whitefly resistance to the neonicotinoid
insecticides is high in north.
• This led to the severe whitefly outbreaks and further
development of resistance.

39. • CICR showed that high level of insecticide resistance to
acetamiprid, thiomethoxam, imidacloprid, monocrotophos,
cloropyriphos, triazophos and acephate is there in north
India.
• So, for effective management of this pest, crop natural
ecosystem should be least destroyed.

40. Is it true that Bt cotton is responsible for
emergence of new pests: Controversy
• Pests like mirid bugs, mealybugs, dusky and red cotton bug used
to occur even before the advent of Bt-cotton, but used to be
controlled due to repeated spraying mainly against bollworms.
• In case of Bt-cotton, the insecticide usage has been drastically
reduced and since Bt does not control such minor pests and if no
suitable control measures are taken against them in time, they
multiply and cause damage ( Manjunath and Mohan, 2015).

41. Conclusion
To get the full benefit of Bt cotton, the ideal approach is
integrated pest management (IPM) where Bt-cotton is relied
upon to control bollworms while it is necessary to be watchful
and take appropriate control measures against those pests not
controlled by Bt-cotton.