Fungi can be used as biocontrol agents to control plant diseases. Some key fungal biocontrol agents include Trichoderma species, Gliocladium virens, Coniothyrium minitans, and Ampelomyces quisqualis. Trichoderma reduces plant pathogens through direct antagonism mechanisms like mycoparasitism, antibiosis, and competition. Commercial products containing Trichoderma are used as biopesticides. Fungal biocontrol agents can also be used to control nematodes, insects, and other pests through parasitism and production of toxins. Beauveria bassiana is an entomopathogenic fungus used as a biological insecticide against various insect

1. Role of Fungi As Biocontrol Agents for
the Control of Plant Diseases
BS-Biotechnology
Group-ll
Fungal Biotechnology
Instructor:
Dr. Shumaila Sikandar

2. • Biological control is the process which decreases the inoculum density of the
pathogenic microbes, present in dormant state by the other microbes.
Generally, it involves either the naïve or genetically modified microbes which
reduce the effect of pests, pathogen, and diseases. The plant disease is
controlled by the pesticides, which are now extensively used. Due to excessive
use of pesticides, socioeconomic and environmental pollution issues have
been resulted, which demand the alternative method to reduce content of
chemical pesticides. Biological control is an eco-friendly method employed to
control the plant diseases, with the aim of developing a sustainable system in
agriculture. Biological control mecha- nism involves the interaction among the
antagonists and pathogens, which aid in selection and manipulation to
develop an effective control system. Currently, this approach is employed
when no other alternative is available. Emergent of fungal antagonistic has
made it a promising biological control strategy to control the plant diseases.
Introduction

3. Cont…
• Biological control is the process which reduces the number of microbes or patho- gens by other
microorganisms, without the external intervention of humans (Cook and Baker 1983). In 1967,
Beirner stated that biological control is the controlling of one microbe by the other. This can be
stated either as a large community of pest (DeBach 1964) or as an inhibitor of severe pest
damage irrespective of the pest inhabitants (Cook and Baker 1983). It largely depends on the
understanding of biological interactions with ecosystem and microbes up to cellular and
molecular level, which are more complex and difficult to control in comparison to physical as well
as chemical methods. Additionally, this method is a highly stable and long- lasting process (Baker
and Cook 1974). This method is claimed to be a valuable alternative approach to regulate the
plant diseases, in which one microbe inhibits the proliferation and infection caused by the other
microbes (Cook 1993; Baker 1987). Being an eco-friendly approach, thus in few cases, this
approach is predominantly used to save the plant from pathogenic microbes (Cook 1993). The
approach employs natural predators which have the ability to eradicate and control the growth of
pest as well as pathogens. This method explores the antagonism potential of microbes, which
makes it an eco-friendly approach to control the plant disease. Thus, by calculating the cost of
hazardous pesticides and other chemical agents, biological control is an efficient and eco-friendly
method for controlling plant dis- eases, which can be used worldwide.

4. Significanceof Biological Control
• Biological control provides protection to the plant throughout its
cultivation period. The biological agents proliferate rapidly in soil and
leave no residue. Being non- toxic, it is safer for humans and plants.
This approach is not limited for controlling the disease; additionally, it
also enhances the growth (especially root) and yield of the crop. Due
to easy handling and manufacturing, it can be used in combination
with bio-fertilizers. Moreover, it is a cheap, safe, and eco-friendly
method.

5. Importance of Biological Control
• Chemical pesticides were used to enhance crop yield, but extensive use
affects the nontargeted organism and surrounding environment. Thus, the
current scenario demands the eco-friendly approach for controlling the
pest, as chemical pesticides being not suitable for cultivation of crop.
Bacteria, fungi, nematodes, protozoans, and virus have been extensively
studied because of advantageous characteristics. Overexploitation of
fungicides has resulted in gathering of the toxic molecules which are
harmful to the environment and humans, but pathogenic microbes have
adapted themselves by getting resistant to it. In order to overcome this
global prob- lem related to chemical control, alternative approaches are
being exploited. Additionally, this biological control approach is highly
effective for sustainable agriculture and is a vital component of integrated
pest management (IPM) program.

6. Microbial Biocontrol Agents
• Aspergillus spp., Ampelomyces sp., Candida sp., Coniothyrium sp.,
Gliocladium sp., and Trichoderma spp. are fungal. Among them, the
most versatile fungal agent belongs to Trichoderma sp. for controlling
the growth of pathogenic fungi.
• Presently, commercial Trichoderma products are used as biopesti- cides
which amend the soil and increase the plant growth.
• In 1934, Weindling showed the bio- control potential of Trichoderma
lignorum (viride) against Rhizoctonia solani, a fungal pathogen.
• Further, Trichoderma lignorum (viride) also showed mycoparasitic
activity against Phytophthora, Pythium, Rhizopus, and Sclerotium rolfsii
(Wells 1988).

7. Efficacy of Microbial Biocontrol Agents
• In addition to properties discussed above, there are few amendments which
enhance the efficiency of this method.
• First, inappropriate usage of this technique should be prevented, which is
mostly because of improper knowledge.
• Second, one should be able differentiate failure which is cause by low-
quality inoculum
• Moreover, inefficacy occurs because the compost/fertilizers containing
biocontrol agents are not of superior quality as available in registered plant
products.
• To improve the efficiency of the biocontrol agents, the strain should be
assessed and verified against the tar- geted disease plus optimum condition
should also be noted.
• Specific substrates and carriers also aid in enhancing the efficacy of the
agents. Exploration of effective strains will also improve the quality of
biocontrol agents and lessen the required amount.

8. Mass Production of Biocontrol Agents
• Mass production of the biocontrol agents is required to meet the
commercial demand.
• There is no effective method for the mass production of these biocontrol
agents at industrial level, as the production of these biocontrol agents
requires continuous resource which should be readily available.
• Trichoderma spp. have been reported to grow on various solid substrates
such as coffee husk, saw dust, sorghum grain, waste of tea leaf, wheat grain
and bran, etc.

9. Commercial Products of Biocontrol Agents
• Commercially available biocontrol products which control the plant disease
are a new prospect.
• But it started in 1979, when Agrobacterium radiobacter strain K 84 was
enlisted in EPA (United States Environmental Protection Agency) list for
controlling crown gall disease in plant.
• Later on, Trichoderma harzianum ATCC 20476,the first fungal strain, was
enlisted in EPA list for controlling the plant diseases.
• Presently, 12 fungi strains have been recorded by EPA which aid in
controlling the plant disease (Fravel 2005). The majority of these biocontrol
agents are commercially marketed .

10. Fungi as biocontrol agent
• Fungi possess a number of characteristics that make them
potentially ideal bio control agents.
• Firstly, many saprophytic species antagonize, representatives of
all the pest organisms, including plant pathogenic fungi, weeds
and insects.
• Secondly, fungi can be readily grown in culture so that large
quantities can be economically produced for release, mainly as
spores or mycelial fragments, into the environment.
• These inoculants then germinate or grow to produce active
mycelium which can parasitize or otherwise inhibit the pest
without damaging the non-target organisms. Fungi also survive
for relatively long periods as resting bodies, and can then
germinate to grow and control the target population thereby
making continual re-inoculation with the bio-control agent
unnecessary.

11. Example of Bio Control Agents Used Commercially:
1. Trichoderma harzianum—White rot onion
2. Phlebia gigantean—Heterbasidion root rot pine
4. Sporidesmium sclerotivorum—Lettuce drop lettuce
5. Talaromyces flavus—Damping off sugarbeet.

13.  Reduce the negative effects of plant pathogens and promote
positive responses in plant.
 Inoculated plants are sensitized to respond more rapidly to
pathogen attack
 Alleviation of abiotic stresses
 Improve photosynthetic efficiency, especially in plants subjected to
various stresses
 Increase nutrients absorption and nitrogen use efficiency in plants
 Enhance the growth and yield parameters
Role of BCF’s
1
3

14. Fungal compounds involved in induction of plant responses
 Compounds that are released by Trichoderma spp. into the zone of interaction
induce resistance in plants
 Primarily proteins with enzymatic activity
 xylanase, cellulase, swollenin and endochitinase
 Enhance defense, through induction of plant defense–related proteins and
peptides that are active in inducing terpenoid, phytoalexin biosynthesis and
peroxidase activity.

15. Mechanisms of Fungal BiocontrolAgents
1
5

16. Type Mechanism Examples
Direct antagonism Hyperparasitism/predation
Lytic/some nonlytic mycoviruses
Ampelomyces quisqualis
Lysobacter enzymogenes
Pasteuria penetrans
Trichoderma virens
Mixed-path antagonism Antibiotics
2,4-diacetylphloroglucinol
Phenazines
Cyclic lipopeptides
Lytic enzymes
Chitinases
Glucanases
Proteases
Unregulated waste products
Ammonia
Carbon dioxide
Hydrogen cyanide
Physical/chemical interference
Blockage of soil pores
Germination signals consumption
Molecular cross-talk confused
Indirect antagonism Competition
Exudates/leachates consumption
Siderophore scavenging
Physical niche occupation
Induction of host resistance
Contact with fungal cell walls
Detection of pathogen-associated,
molecular patterns
Phytohormone-mediated induction

17. Mycoparasitism
• The term mycoparasitism or
"hyperparasitism" has been used to
indicate the interrelationships of a
parasite and a fungus host. The
term mycoparasite refers to
organisms that have the ability to
parasite fungi, and mycohost means
the fungi act as host to be
parasitized

18. “ Interactions that involve a low-
molecular weight compound or an
antibiotic produced by microorganism
that has a direct effect on another
microorganism”
Antibiosis

19. Competition
• Competition for nutrient and space.
• Biocontrol agent decreases the availability of a particular
substance thus limiting the growth of the plant pathogenic agents
• Trichoderma spp produce siderophores that chelate iron and stop
the growth of other fungi

20. Applications In Plant Disease
Control
2
0

21. Coniothyrium minitans
• Sclerotinia blight, caused by the soilborne fungus Sclerotinia minor
Jagger, is an important disease of peanut
• During favorable conditions for Sclerotinia blight, peanut farmers can
lose up to 50% yield as a result of the disease. Fungicides for control
of Sclerotinia blight alone can cost producers as much as $104 per
hectare for a single application, with up to three applications made in
a season. Consequently, there is a pressing need to reduce the cost of
managing Sclerotinia blight.
• A number of microorganisms have been reported to parasitize
sclerotia of Sclerotinia spp., including Coniothyrium minitans.

22. Gliochdium virens
• The efficacy of Gliochdium virens (G 1 and G 2) and Trichoderma
longibrachiatum (T 1 and T 2) as biocontrol agents of economically
important soil-borne plant pathogens Rhizoctonia solani, Sclerotium
rolfsii and Pythium aphanidermatum has been investigated. The G.
virens isolate G 1 yielded remarkable protection against groundnut
root rot (74.4 %), cotton (66.4 %) and tomato (58.4 %) damping-off
but only moderately reduced (36 %) the groundnut stem rot
incidence, whereas G 2 was much less effective. Of the two T.
longibrachiatum isolates, T 1 was more potent against groundnut root
rot (65.6 %) while against tomato damping-off, T 2 conferred greater
protection (49.2 %).

23. Trichoderma species
• Trichoderma species reduces the growth of all the four soil borne
pathogens: Sclerotium rolfsii, Fusarium solani, Rhizoctonia solani
and Sclerotionia sclerotiorum significantly in different level and,
therefore, can be incorporated for integrated disease management of
soil borne plant pathogens. Hence, Trichoderma species can be used
as a potential biocontrol agent against these pathogens. However, its
efficacy against Sclerotium rolfsii(a fungal Plant pathogen in tobacco
plant) was found to be more in comparison to others.
• Trichoderma sp. was found to be effective against Sclerotium rolfsii
causing the damping-off, root rot, and seed rot disease in mung bean
and sunflower, and moreover, it also increased the plant growth.

24. Trichoderma species
Commercial Application
• Several strains of Trichoderma are commercially available to control
plant disease in environmentally friendly agriculture.
• Fungal Formations
• TUSAL made from T. harzianum and T. viride cultures to prevent the
growth of pathogen soilborne fungi responsible for leaf-falling
disease in several crops

25. Paecilomyces lilacinus and Glomus
fasciculatum
• Root-knot nematode (Meloidogyne incognita) is a limiting factor
causing yield reduction in FCV tobacco crop. As an alternative to
nematicides of chemical origin, beneficial fungi such as Paecilomyces
lilacinus and Glomus fasciculatum significantly reduced the number of
egg masses/g root and final soil nematode population.

26. Ampelomyces quisqualis
(Deuteromycetes)
• The fungus Ampelomyces quisqualis is a naturally occurring
hyperparasite of powdery mildews. It infects and forms pycnidia
(fruiting bodies) within powdery mildew hyphae, conidiophores
(specialized spore-producing hyphae), and cleistothecia (the closed
fruiting bodies of powdery mildews). This parasitism reduces growth
and may eventually kill the mildew colony.

27. Entomopathogenic Fungus
An entomopathogenic fungus is a fungus that can act as a parasite of insects and
kills or seriously disables them.
Since they are considered natural mortality agents and environmentally safe, there
is worldwide interest in the use and manipulation of entomopathogenic fungi for
biological control of insects and other arthropod pests.
In particular, the asexual phases of Ascomycota (Beauveria spp., Lecanicillium
lecanii, Metarhizium spp., Paecilomyces spp. and others) are under intense scrutiny
due to the traits favouring their use as biological insecticides.

28. Use of Fungi to Control Nematodes:
Fungi that parasitise nematodes (nematophagus fungi) can be divided into nematode-
trapping fungi, endoparasitic species and fungi that parasitise nematode eggs. Nematode
trapping fungi capture nematodes with specialized structures such as constrictive and non-
constrictive rings, adhesive knobs or, lastly, by producing an adhesive material along the
entire mycelial surface. Endoparasitic nematophagous fungi live in soils where they
produce adhesive spores.
These become attached to body of the nematode, on germination, a germ tube enters the
body where it grows and consumes the host. Egg parasites, as their name suggests, are
nematophagous fungi that parasitise the eggs of nematodes.

29. Use of Fungi to Control Insect Pest:
Over 400 species of fungi attack insects and mites, so there is great potential
for the use of these organisms as biological insecticides. As insect bio control
agents, fungi are markedly superior to other microorganisms because they
are generally non-specific in their action and are useful against a wide range
of insect pests.
Most of the so-called entomopathogenic fungi are phycomycetes and
Deuteromycetes. Spores of these fungi attack either the external or gut
cuticle of their insect hosts. They then germinate and hyphae penetrate the
haemocoel. Death may result from the production of a toxin by the fungus.

30. Beauveria bassiana,Introduction
Is a fungus
Grows naturally in soils throughout the world and acts as a parasite onvarious
arthropod species,
Causes white muscardine disease in silkworms mostly
Belongs to the entomopathogenic fungi.
It is being used as a biological insecticide to control a number of pests
such as termites, thrips, whiteflies, aphids and different beetles.

31. Panther - BB, a microbial insecticide, is of fungal
origin causing a lethal disease (white muscadine
disease) in insects.
Wide variety of insects like white flies, aphids, mealy
bugs, thrips, leaf hoppers etc. succumb to the
application of Panther - BB. Panther BB does not
leave any residual toxicity on the crops
Beauvaria, Commercially…

32. Wide range oftargets
Aphids
Whiteflies
Mealybugs
Lygus bugs
Chinch bug
BeetlesPsyllids
Grasshoppers Black vine weevil
Thrips Strawberry root weevil
Termites Coffee borer beetle
Fire ants Colorado potato beetle
Flies Mexican bean beetle
Stem Borers Japanese beetle
Mites Boll weevil
Fungal gnats Cereal leaf beetle
Shoreflies Bark beetles
Caterpillars
European corn borer
Codling moth
Douglas fir tussock moth
Silkworm

33. Entomogenous Species ofHirsutella
A. SPECIES ON ORTHOPTERA
[Grasshoppers and locusts; crickets]
Hirsutella fusiformis
B. SPECIES ON HOMOPTERA
[Plant lice (aphids); whiteflies; cicadas; leafhoppers; plant hoppers;
scale insects and mealybugs; spittle insects]
Hirsutella citriformis
Hirsutella abeitina
C. SPECIES Of COLEOPTERA
[Beetles]
Hirsutella entomophila

34. …Continued
D. SPECIES ON LEPIDOPTERA
[Moths and butterflies]
Hirsutella barberi
Hirsutella subulata
Hirsutella gigantea
E. SPECIES ON DIPTERA
[true flies and mosquitoes and gnats and crane flies]
Hirsutella radiata
Hirsutella dipterigena
F. SPECIES ON HYMENOPTERA
[bees; wasps; ants; ichneumons; sawflies; gall wasps; etc.]
Hirsutella saussurei
Hirsutella formicarum

35. Crop disease Pathogen Biocontrol agents
Blight of Sesamum Phytophthora sp. T. harzianum
T. viride
Root rot of Sesamum M. phaseolina Trichoderma sp.
Gliocladium sp.
Root rot chilli S. rolfsii T. harzianum
Dieback of chilli Colletotrichum capsici T. viride
T. harzianum
Wilt of eggplant F. solani T. viride
T. koningii
Damping-off of eggplant P. aphanidermatum T. viride
Table 16.1 List of crop diseases controlled by various biocontrol agents

36. Wilt of tomato F. oxysporum T. harzianum
f.sp. lycopersici
Root knot of tomato Meloidogyne incognita T. harzianum
M. javanica
Wilt of okra Pythium spp. A. niger
Leaf blight of sunflower Alternaria helianthi T. virens
Wilt of pigeon pea Fusarium udum T. viride
T. hamatum
T. harzianum
T. koningii
Wilt of chickpea F. oxysporum T. viride
f.sp. ciceri T. harzianum
T. virens
Dry root rot of soybean M. phaseolina T. viride
T. harzianum
Stem rot of groundnut Sclerotium rolfsii T. harzianum
Damping-off of mustard Pythium aphanidermatum T. harzianum
T. viride
Root rot of mung bean M. phaseolina T. harzianum
T. viride
Table 16.1 List of crop diseases controlled by various biocontrol agents

37. Advantages of BioControl
• Biological control provides an alternative to the use of synthetic pesticides
with the advantages of greater public acceptance and reduced
environmental impact
• Antagonism between species of naturally competing fungi has been
observed
• Trichoderma species are free-living fungi which are highly interactive in
root, soil and foliar environments. Considered to be eager colonizers and
particularly invasive fungi, they work against fungal phytopathogens either
indirectly by competing for nutrients and space, modifying environmental
conditions or promoting plant growth and plant defensive mechanisms and
antibiosis; or directly through mechanisms such as mycoparasitism.served
in virtually every fungal ecosystem

38. Advantages of Biological Control
• Biological control is an eco-friendly approach, as it is nontoxic to
plants and a non- targeted microbe, decreases the pesticide
accumulation in food, regulates the activ- ity of natural predators, and
increases the microbial diversity in managed system. This process is
less prominent but more stable and long-lasting, in comparison to
physical and chemical controls (Baker and Cook 1974). Some of the
advantages of biological controls are listed below:

39. 1. Biocontrol Agents Are Host Specific
2. Nontoxic to Plants
3. Application by Conventional Methods
4. Ability to Multiply in Their Target Host
5. Production Technology Available
Advantages of Biological Control

40. High Cost of Production
7. Additional Control Measures
8. Time of Application
9. Mortality
10. Viability
11. Difficulty in Mass Production
12. Legal Protection
Disadvantages of Biocontrol Agents

41. Conclusion
• The extensive use of fertilizer and pesticides has resulted in
environmental pollution (especially, soil pollution). Over-usage of
these agrochemicals and rumors created by the pesticide rivals have
significantly reformed the attitude of consumers to use pesticides in
their agricultural land. Controlling the large proportion of pest and
disease has elevated the usage of these hazardous chemicals for
proper management. Generation of resistant against fungicide and
pesticide is emerging as new problem. Thus, there is a need to
employ eco-friendly pesticides as they are less toxic and have low
residual problem and low level of resistance. Thus, biological control
approach should be used in collaboration, as efficiency of one
approach varies with time, location, and environmental conditions.

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