Transgenic crops carrying genes from Bacillus thuringiensis (Bt) have been developed to provide insect resistance as part of integrated pest management strategies. Bt genes encode crystal proteins that are toxic to certain insect orders. The two main strategies to delay insect resistance to Bt crops are the refuge approach, where non-Bt crops are maintained near Bt crops to promote mating with susceptible insects, and gene pyramiding, where crops are engineered with multiple genes providing multiple mechanisms of resistance. While Bt crops can reduce insecticide use, there are also limitations such as the potential for target insects or weeds to develop resistance over time. Ongoing research continues to develop new transgenic traits and gene combinations to provide environmentally friendly

1. ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
S. V. AGRICULTURAL COLLEGE, TIRUPATI
ENT-510
INTEGRATED PEST MANAGEMENT
TOPIC : IMPACT OF TRANSGENIC CROPS IN IPM
SUBMITTED BY:
M. Lokeswaridevi
TAM -2020-030,
Dept of Entomology
1

2. 2
Integrated Pest Management

3. Biotechnology in Agriculture?
Any technique that uses living organisms or substances from these organisms, to
make or modify a product, to improve plants or animals or to develop substance
for specific uses.
- Offers direct access to a vast pool of useful genes.
- Major contribution to the production of such inherently resistant/ tolerant
varieties
Dhaliwal and Koul,2010

4. Methodology in biotechnology
• Somaclonal variability
• Genetic engineering
• RNA interference (RNAi)
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5. Somaclonal variability
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• The genetic variations are inherited by the clones of the treated plant.
• The term Somaclonal Variation was first coined by Larkin and
Scrowcroft in 1981.
• Somaclonal variation sometimes may lead to desirable characteristics
like increased pest resistance etc. .(Jha and Ghosh, 2010)

6. Steps in isolation of somaclones for insect resistance
Growing of cell suspension for several cycles from
a high yielding variety
Regeneration of plants from such long
term cell lines
Evaluation of large population of
regenerated plants for insect resistance
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7. Genetic engineering techniques applied to plants
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The process of manipulating and transferring instructions
carried by genes from one cell to another

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Why genetically engineered plants???
• To improve the agricultural, horticultural (or) ornamental value of a
crop plant
• Resistance to certain pests, diseases and environmental conditions
• Reduction of spoilage
• Resistance to chemical treatments (Eg- Resistance to herbicide)
• Improving the nutrient profile of the crop

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• Vector mediated gene transfer
Agrobacterium mediated gene transfer
• Vectorless DNAtransfer 1. Gene gun
2.Electroporation
3.Microinjection
4. Direct uptake of DNA

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Vector mediated gene transfer

11. Vector less gene transfer
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https://www.goldbio.com/articles/article/Deep-Dive-Into-Plant-
Transformation-Protocols

12. Microprojectile bombardment
• Also called as “Gene gun or Micro-projectile bombardment”
method
• DNA is bound to tiny particles of gold or tungsten which
are shot into plant tissue
• The particles penetrate both the cell wall and membranes
• DNA separates from the metal and is integrated
into the plant genome inside the nucleus
• Successfully for monocots- Wheat, maize
• Disadvantage- Serious damage to the cellular tissue
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Electroporation
Short pulse of high voltage
are applied to protoplasts
which make temporary pores
in the plasma membrane to
increase their permeability
and facilitate the uptake of
foreign gene

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Microinjection
1. DNA of interest is taken in microinjector and then delivered
inside the cell
2. Micromanipulator
3. Successful- Tobacco &Alfalfa
4. Maximum of 40-50 protoplasts can be microinjected in one hr

15. Protoplast fusion
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Method of joining of two
cells by first removing
their cell walls

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RNA interference
 Method of blocking gene function by inserting short sequences of
double stranded ribonucleic acid (dsRNA) that match part of the target mRNA
sequence, thus no proteins are produced.
 Knock down the expression of genes.

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Sl.
No.
Technique Application Examples
1
Agrobacterium-based
plant transformation
Ti- plasmid –to carry novel DNA into
plants
Bt insectresistant crop
plants
2 Particle acceleration
DNA coated gold particles fired into
growingtissue
Transgenic soybean
3 Electroporation
Electric current used toalter
protoplast membranes permitting
DNA uptake
Transgenic rice
4 Microinjection
DNA injected into thenucleus or
cytoplasm of a protoplast
Transgenic tomato
5 RNA interference
Blockage of gene function by inserting
short sequences of RNA
Potential for protecting
cotton, rice and maize
against insectpests
Biotechnological methods employed for crop improvement
Atwal and Dhaliwal,2013

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20. Transgenic plants
• A normal plant with one or more additional genes from different
sources.
• Latest concept in IPM.
• Produce insecticidal, antifeedant proteins continuously in the plants.
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Meeusen and Warren,1989

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Before taking up any attempt to produce transgenic plants, the
following requirements and priorities need to be identified.
The factors for resistance should be controlled by single genes.
Standardization of methods for gene transfer.
Expression of transferred gene should occur in the desired tissues.
The transgenic crops should be safe for consumption.
Inheritance of the gene in the successive generation should be
very stable.
There should be no penalty for yield.

22. History of transgenics
❖First field trials of transgenic herbicide resistant crops were
conducted in USA and France in 1986.
❖Development of insect resistant transgenic plants o tobacco were
reported in 1987, containing δ-endotoxin to kil first instar larvae of
Manduca sexta and Heliothis virescens.
❖China was the first country to commercialize transgenics with
introduction of virus resistant tobacco in 1990.
❖First commercial transgenic food product was Calgene’s Flavr-
Savr™ delayed ripening tomato released in USA in 1994.
❖In India, Bt cotton is first introduced in 2002 against Bollworm
complex
(James, 1996)
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23. Crop Company Altered trait Year of
approval
Product
name and
gene
Soybean Monsanto Resistance to
herbicide glyphosate
1995 Roundup
ready
Cotton Monsanto Resistance to
bollworms and bud
worms
1995 Bollgard
(Cry1Ac)
Corn Ciba-Geigy Resistance to corn
borer
1995 Maximizer
Potato Monsanto Resistance to
Colorado potato
beetle
1995 New Leaf
(Cry3A)
Corn Monsanto Resistance to corn
borer
1995 Yieldgard
(Cry1Ab)
Cotton Monsanto Resistance to
herbicide glyphosate
1996 Roundup
ready
(James 1997)
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Classification of transgenic genes
• Bt genes
• Protease inhibitors (PI) genes
• Alpha amylase inhibitor genes
• Lectin genes
• Enzyme genes
• Pyramiding genes
(Sharma et al 2000)

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Bacillus thuringiensis – Toxins and Biotechnology
B. thuringiensis is a soil bacterium that produces a parasporal crystal made up of Cry- proteins
that is toxic to specific groups of insects.
 Ishiwata (1901) - from diseased silkworm larvae.
Berliner (1915) -diseased larvae of Ephetia kuhniella -Bacillus thuringiensis

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CRYSTAL PROTEINS OF Bacillus thuringiensis
AND THEIR SPECIFICITY
CRYSTAL PROTEINS INSECT ORDERS
Cry I Lepidoptera
Cry II Lepidoptera and Diptera
Cry III Coleoptera
Cry IV Diptera
Cry V Lepidoptera and Coleoptera
Cry VI Nematodes

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http://juratfuenteslab.utk.edu/Btresearchtable.html

28. List of transgenic plants carrying Bt genes for insect resistance
S.N0. Crop Genes Target insect
1 Brinjal Cry IIIb Leptinotarsa
2 Cotton Cry 1A(b) H.zea, PBW
3 Maize Cry 1A(b) O. nubilalis
4 Potato Cry 1A(b) PTM
5 Rice Cry 1A(b) YSB, LF
6 Sugarcane Cry 1A(b) D. saccharalis
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Protease inhibitors
•Insects have protease in their gut which are the enzymes helping in
digestion of protein
• PI inhibit the proteases and affect digestion in insects
•The PI are isolated from one plant and cloned into another to produce
transgenic plants
• Serine PI is the most important and also thiol proteases minor.

30. • Serine protease inhibitors
First gene of plant origin to be used in transgenic crop protection
Eg- Cowpea trypsin inhibitor (CpTi) gene derived from cowpea and
cloned into tobacco against Helicoverpa
• Cysteine protease inhibitors
 suggested for use in transgenic plants for control of coleopteran pests
 Recently, Oryzacystatin from rice has been isolated that inhibits all
proteolytic activity in the rice weevil and flour beetle midgut.
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20
Alpha amylase inhibitors-
Alpha amylase is a digestive enzyme present in insects for digestion of
carbohydrates. AAI affects the digestion of carbohydrates in insects. Transgenic
tobacco & tomato expressingAAI which are resistant to Lepidopteran pests
Lectin genes-
Lectin are a group of plant proteins that bind to carbohydrates,
including chitin. The deleterious effect of chitin binding lectins on insect development
is mediated by binding to chitin in the peritrophic membrane that lines the midgut of
insect thus interfering with the uptake of nutrients
Eg- Gene encoding the pea lectin (P- Lec) has been expressed in transgenic
tobacco against Helicoverpa virescens

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Chitinases and other genes
Enzymes genes
Derived from Target insects References
Enzyme
genes
Chitinase Rigev et al 1996
Chitinase Kramer et al 1997
Serratia
marcesens
Manduca
sexta
Streptomyces Purcell et al 1999
Cholesterol
oxidase
Chitinase Jianhui et al 2010
Chitinase
Metarhizium
anisopliae
Holotrichia
oblita
Spodoptera
littoralis
Heliothis
virescens
Anthonomus
grandis
Plutella
xylostella.
Helicoverpa
armigera
Xiaomin Liu 2011

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MANAGEMENT OF RESISTANCE TO BT
CROPS
• There are two main strategies for management of insect resistance to Bt
crops:
• Refuge and
• Pyramiding

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Refuge
The main approach for delaying evolution of resistance to Bt crops is the refuge strategy.
 Farmers are mandated to maintain an abundance of host non-Bt crops as a refuge
surrounding their Bt crops.
 The theory behind this strategy is that any Bt resistant larvae that arise on the Bt crops
will mate with susceptible individuals from neighbouring non-Bt crops.
 As long as inheritance of resistance remains recessive the offspring will be susceptible to
Bt crops.

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Pyramiding
The other major strategy to combat the evolution of Bt resistance is gene pyramiding.
The effectiveness and durability of resistance in transgenic crops is likely to be greater if
they engineered with multi- gene, multi- mechanistic resistance.
The serine protease inhibitors enhanced the activity of Cry1A, Cry3 and Cry4 against
their respective target insects.

36. Current and Future GM Crop Traits
1. Insect Resistance (Plant Incorporated Protectants) – ex: BT corn & cotton
2. Herbicide Tolerance – ex: Glyphosate Resistant Corn & Soybeans (i.e.
Roundup Ready), cotton
3. Stress Tolerance – ex: drought, salt resistant varieties
4. “ValueAdded” Crops ex: Golden Rice containing vitaminA
5. “Biopharming – Production of drugs, chemicals on agricultural scales
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37. • Amajor reduction in insecticide sprays.
• Increased activity of natural enemies.
• Reduced exposure of non-target organisms to
insecticides .
• Reduction in insecticide residues in food and
food products.
Transgenics in Pest Management:Advantages
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38.  Secondary pest problems.
 Environmental influence on gene expression.
 Development of resistance and evolution of new biotypes.
 Effects on non-target organisms.
 Gene escape into the environment.
 Social and ethical issues.
Transgenic Resistance to Insects: The Limitations
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39. ❖ Insects might develop resistance to pesticide-producing
GM crops.
❖ Certain gene products may be allergens, thus causing harm
to human health.
❖ There may be unintended harm to wildlife and non target
insects.
may cross-pollinate weeds,
❖ Herbicide-tolerant crops
resulting in “Superweeds“.
Possible risks of GM crops

40. Case Study I
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Dhillon and Sharma, 2013

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Dhillon and Sharma, 2013

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Seed cotton yield (mean ± SE) in Bt-transgenic and non transgenic cotton Dhillon and Sharma, 2013

43. ❖ Ongoing developments in biotechnology should provide exciting
new possibilities for the control of pest populations in an
environmentally friendly manner
❖ Global area under transgenic plants has increased 94-folds from
1996-2011
❖ Majority of insect resistant transgenics include toxins from Bacillus
thuringiensis
❖ In India, Bt cotton is rapidly adopted by farmers as it gives higher
returns and reduces pesticide use
❖ Stacking of multiple genes --- increased protection against multiple
harmful organisms, and has the added advantage of reducing the
risk of the emergence of herbivore resistance
Conclusions

44. ❖ Insect resistance to transgenic crops can be delayed by using
strategies such as refuge crops, high toxin expression etc.
❖ Transgenic crops coming in future, uses gene pyramiding
technique for multiple traits.
❖ Special attention should be given to food safety and resistance
management. Local systems, their constraints and socio-
economic implications should be strictly considered before
adopting of any GM material.
❖ We need to pursue the management strategies that reflect the
pest biology, insect plant interactions and their effect on the
natural enemies, to prolong the usefulness of the transgenics.
Conclusions

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REFERENCE
http://www.isaaa.org.
Stevens J, Dunse K, Fox J, Evans S, Anderson M. (2012).
Biotechnological Approaches for the Control of Insect Pests in
Crop Plants. http://dx.doi.org/10.5772/46233
Dhaliwal GS and Arora R, (2018). Integrated Pest Management
Concepts and Approaches. Kalyani publication. Pp : 340 – 368.

46. THANKYOU………..
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