Microbes as Biocontrol Agents Questions in English

(A) : $Trichoderma$ species are free-living fungi that are very common in root ecosystems.
They act as effective biological control agents against several plant pathogens.
$Nucleopolyhedrovirus$ (Baculoviruses) are used for insects and arthropods,not for white rust.
$Bt$-cotton is a genetically modified crop,not a direct microbial biocontrol application.
Ladybird beetle is a predator,not a microbe.

(D) : The natural method of pest and pathogen control involving the use of viruses, bacteria, and other organisms (which are their natural predators) is called biocontrol or biological control.
For example, the free-living fungus $Trichoderma$ exerts biocontrol over several plant pathogens to control plant diseases.
$Baculoviruses$ (mostly of the genus $Nucleopolyhedrovirus$) are also used as biocontrol agents, but they are primarily used for the control of insects and arthropods.
$Bacillus \text{ } thuringiensis$ is a soil bacterium used as a biopesticide.
$Glomus$ species are the most common fungal partners of mycorrhiza residing in the roots of higher plants.

(C) : The natural method of pest and pathogen control involving the use of viruses, bacteria, and other insects (which are their natural predators) is called biocontrol or biological control.
$Trichoderma$ $harzianum$ is a free-living fungus that acts as a biocontrol agent against several plant pathogens.
$Nucleopolyhedrovirus$ $(NPV)$ belongs to the genus $Baculovirus$ and is used as a narrow-spectrum insecticidal agent.
$Bacillus$ $thuringiensis$ is a soil bacterium widely used as a biopesticide to control insect larvae.
$Xanthomonas$ $campestris$ is a bacterium known for causing plant diseases (e.g., black rot in crucifers) and is not used as a biopesticide.

(B) : The natural method of pest and pathogen control involving the use of viruses, bacteria, and other organisms (which are their natural predators) is called biocontrol or biological control.
$Trichoderma harzianum$ is a free-living fungus that is very common in root ecosystems and acts as an effective biocontrol agent against several soil-borne plant pathogens.
$Baculoviruses$ (mostly of the genus $Nucleopolyhedrovirus$) are used as narrow-spectrum insecticidal applications.
$Bacillus thuringiensis$ is a soil bacterium used as a biopesticide.
$Glomus$ species are fungal partners in mycorrhiza that help in nutrient absorption.

(B) $Paecilomyces$ $lilacinus$ is a fungus that acts as a biological control agent against various plant-parasitic nematodes. It infects and destroys the eggs of nematodes,thereby reducing the population of these pathogens in the soil and protecting plant roots from infection.

(D) The characteristics provided describe $Baculoviruses$.
$Baculoviruses$ are pathogens that attack insects and other arthropods.
They are excellent candidates for species-specific,narrow-spectrum insecticidal applications.
They have been shown to have no negative impacts on plants,mammals,birds,fish,or even non-target insects,making them ideal for integrated pest management $(IPM)$ programs.

(D) $Trichoderma$ species are free-living fungi that are very common in root ecosystems. They are effective biocontrol agents used against several plant pathogens. They are not symbiotic,nor are they photosynthetic.

(D) The correct answer is $D$. Baculoviruses are pathogens that attack insects and other arthropods. The majority of baculoviruses used as biological control agents are in the genus $Nucleopolyhedrovirus$. These viruses are excellent candidates for species-specific,narrow-spectrum insecticidal applications. They have been shown to have no negative impacts on plants,mammals,birds,fish,or even non-target insects,making them ideal for integrated pest management $(IPM)$ programs.

(B) $Baculoviruses$ are pathogens that attack insects and other arthropods. The majority of $Baculoviruses$ used as biological control agents are in the genus $Nucleopolyhedrovirus$. These viruses are excellent candidates for species-specific,narrow-spectrum insecticidal applications and have been shown to have no negative impacts on plants,mammals,birds,fish,or even on non-target insects.

(A) The characteristics described refer to the genus $Trichoderma$.
$1$. $Trichoderma$ species are free-living fungi that are very common in the root ecosystem (rhizosphere).
$2$. They are highly effective biocontrol agents against several plant pathogens.
$3$. They are widely used in agriculture as biological control agents to treat various soil-borne plant diseases.
Therefore,the correct option is $A$.

(C) Biopesticides are biological agents used to control pests.
$1$. $Trichoderma$ is a fungus used as a biocontrol agent against several plant pathogens.
$2$. $Bacillus$ $thuringiensis$ $(Bt)$ is a bacterium used to control butterfly caterpillars.
$3$. $Nucleo$ $Polyhedro$ $Virus$ $(NPV)$ are species-specific,narrow-spectrum insecticidal applications.
$4$. $Clostridium$ $butyricum$ is a bacterium primarily known for producing butyric acid and is not used as a biopesticide.
Therefore,the correct option is $C$.

(D) $Trichoderma$ $harzianum$ is a free-living fungus that is very common in the root ecosystem.
It is widely used as a bio-control agent against several soil-borne plant pathogens.
It acts by producing antibiotics,competing for nutrients,and parasitizing the pathogens,thereby protecting the crops from diseases.

(D) The fish $Gambusia$ is widely known as the larvicidal fish.
It is used as a biological control agent to manage mosquito populations.
$Gambusia$ feeds on the larvae of mosquitoes,thereby preventing them from reaching the adult stage and reducing the spread of diseases like malaria and dengue.

(C) Biological control refers to the use of biological methods for controlling plant diseases and pests. The main difficulty in this method is that the introduced predator or parasite may not always survive or adapt well when introduced into a new environment,which limits its effectiveness in controlling the target pest population.

(C) Biological control refers to the use of biological methods for controlling plant diseases and pests. In this process,one organism is used to control or destroy another organism (the pest) by utilizing its natural physiological processes,predatory behavior,or parasitic nature. This method is environmentally friendly and reduces the reliance on toxic chemical pesticides.

(D) Third-generation pesticides are defined as substances that are highly specific to target pests and have minimal impact on non-target organisms and the environment.
Insect hormone analogues (such as juvenile hormone mimics) are classified as third-generation pesticides because they disrupt the growth and development of specific insects without causing widespread environmental toxicity.
Unlike first-generation (inorganic chemicals) and second-generation (synthetic organic chemicals like $DDT$) pesticides,these are more selective and safer.

(D) The fungus $Paecilomyces \text{ } lilacinus$ is a well-known biological control agent used to manage plant-parasitic nematodes.
It acts as a parasite on the eggs of nematodes, thereby reducing their population and preventing crop damage.
$Pisolithus \text{ } tinctorius$ is an ectomycorrhizal fungus, $Gliocladium \text{ } virens$ is used against soil-borne pathogens, and $Pseudomyces \text{ } lilacinus$ is an incorrect nomenclature for the species in question.

(D) The correct answer is $Trichoderma$.
$Trichoderma$ species are free-living fungi that are very common in the root ecosystems.
They are effective biocontrol agents of several plant pathogens.
$Baculoviruses$ are pathogens that attack insects and other arthropods.
$Bacillus$ $thuringiensis$ is used to control butterfly caterpillars.
$Glomus$ is a genus of arbuscular mycorrhizal fungi that helps in nutrient absorption.

(A) $1$. $Trichoderma$ species are free-living fungi that are very common in the root ecosystems and are effective biocontrol agents of several plant pathogens.
$2$. Nucleopolyhedroviruses are excellent candidates for species-specific,narrow-spectrum insecticidal applications,not for plant diseases like white rust.
$3$. $Bt$-cotton is a genetically modified crop designed for pest resistance,not a microbial biocontrol agent for plant diseases.
$4$. Ladybird beetles are predators used to control aphids,but they are insects,not microbes.
Therefore,the correct option is $A$.

(A) Biocontrol refers to the use of biological methods for controlling plant diseases and pests.
$Trichoderma$ species are free-living fungi that are very common in the root ecosystem.
They are effective biocontrol agents of several plant pathogens.
$Chlorella$ is an alga,$Anabaena$ is a cyanobacterium (often used as a biofertilizer),and $Lactobacillus$ is a bacterium used in the production of curd from milk.
Therefore,the correct option is $A$.

(B) Biocontrol agents are organisms that are used to control plant diseases and pests.
$1$. $Bacillus$ $thuringiensis$ $(Bt)$ is a bacterium used as a bio-insecticide to control butterfly caterpillars.
$2$. $Trichoderma$ species are free-living fungi that are very common in the root ecosystems and are effective biocontrol agents of several plant pathogens.
$3$. $Baculoviruses$ are pathogens that attack insects and other arthropods. The majority of $baculoviruses$ used as biological control agents are in the genus $Nucleopolyhedrovirus$.
Therefore,the correct group of biocontrol agents is $Trichoderma$,$Baculovirus$,and $Bacillus$ $thuringiensis$.

(B) $Trichoderma$ is a free-living saprophytic fungus that commonly lives on dead organic matter in the soil and rhizosphere (root ecosystem).
It acts as an effective biocontrol agent by inhibiting soil-borne plant pathogens.
It produces secondary metabolites like gliotoxin,viridin,gliovirin,and trichodermin,which suppress the growth of harmful fungi and bacteria,thereby protecting plants from diseases.

(D) Integrated Pest Management $(IPM)$ relies on the use of biocontrol agents that are highly selective.
An ideal biocontrol agent must be species-specific,meaning it targets only the specific pest species causing damage.
Furthermore,it must be inactive on non-target organisms,such as beneficial insects,pollinators,or other wildlife,to maintain ecological balance and biodiversity.
Therefore,option $D$ is the correct characteristic for an effective biocontrol agent.

(B) Biocontrol refers to the use of biological methods for controlling plant diseases and pests.
In modern society,these problems have been tackled increasingly by the use of chemicals,such as insecticides and pesticides.
These chemicals are toxic and extremely harmful to human beings and animals alike,and they have been polluting our environment,fruits,vegetables,and crop plants.
Our soil is also polluted through our use of weedicides to remove weeds.
Biocontrol agents are living organisms or their products used to manage pests and diseases in an eco-friendly manner.

(N/A) Biological control refers to the use of biological methods for controlling plant diseases and pests. In agriculture,this method relies on natural predation and parasitism rather than introduced synthetic chemicals.
- The organic farmer works to create a system where insects,often called pests,are not eradicated but kept at manageable levels through a complex system of checks and balances within a living,vibrant ecosystem.
- Unlike conventional farming practices that use chemical methods to kill both useful and harmful life forms indiscriminately,this is a holistic approach that seeks to understand the webs of interaction between the myriad organisms that constitute the field fauna and flora.
- The organic farmer holds the view that the complete eradication of creatures described as pests is not only impossible but also undesirable,as beneficial predatory and parasitic insects that depend on them for food or as hosts would not survive without them.
- The use of biocontrol measures significantly reduces our dependence on toxic chemicals and pesticides.
- An important part of the biological farming approach is to become familiar with the various life forms that inhabit the field,including predators and pests,as well as their life cycles,feeding patterns,and preferred habitats. This knowledge helps in developing appropriate means of biocontrol.

(N/A) Microbes play a crucial role in the biological control of pests and diseases,reducing the reliance on toxic chemicals.
$1$. $Bacillus$ $thuringiensis$ $(Bt)$: These bacteria are used to control butterfly caterpillars. Dried spores are mixed with water and sprayed on vulnerable plants like brassicas and fruit trees. When larvae ingest these,the toxin is released in their gut,killing them while leaving other insects unharmed.
$2$. Genetic Engineering: Scientists have introduced $Bt$ toxin genes into plants,creating insect-resistant crops like $Bt$-cotton.
$3$. $Trichoderma$: These are free-living fungi found in root ecosystems. They are effective biocontrol agents against several plant pathogens.
$4$. Baculoviruses: These are pathogens that attack insects and arthropods,specifically those in the genus $Nucleopolyhedrovirus$. They are excellent for species-specific,narrow-spectrum insecticidal applications and have no negative impact on non-target organisms,making them ideal for Integrated Pest Management $(IPM)$ programs.

(B) Nucleopolyhedroviruses are used as biological control agents specific to certain insects.
Most Baculoviruses belong to the genus Nucleopolyhedrovirus.
These viruses are excellent candidates for species-specific,narrow-spectrum insecticidal applications.
They do not have negative impacts on plants,animals,birds,or non-target insects; therefore,they are highly suitable for use in $IPM$ (Integrated Pest Management) programs.

(B) The basis of various biological control methods is the concept of $Predation$.
$Predation$ is a biological interaction between the predator and the prey,whereby the predator feeds on the prey.
Hence,the predators regulate the population of prey in a habitat,thereby helping in the management of pest insects.

(B) The term 'Nematophagous' is derived from two words: 'Nematode' (roundworms) and 'phagous' (eating).
Therefore,Nematophagous organisms are those that feed on or consume nematodes.
These are often specialized fungi or bacteria that trap and digest roundworms to obtain nutrients,particularly nitrogen,in nutrient-poor environments.

(C) Microbes reduce environmental degradation through a process called bioremediation.
Certain microorganisms,such as $Pseudomonas$ species,possess the ability to degrade complex chemical pollutants,including hydrocarbons found in oil spills.
For example,the genetically engineered 'Chakravarthy Bug' (a strain of $Pseudomonas$ with multiple plasmids) is highly effective in cleaning up oil spills.
Other microbes like $Coliform$,$Clostridium$,and $Micrococcus$ also play significant roles in breaking down various toxic industrial chemicals and organic wastes into simpler,non-toxic substances,thereby restoring environmental health.

(N/A) Biological control refers to the use of biological methods for controlling plant diseases and pests. It is a natural and eco-friendly approach that relies on natural predation and parasitism rather than synthetic chemicals. The main ideas include:
$1$. Use of natural predators or parasites to reduce the population of harmful pests.
$2$. Utilization of antagonistic microorganisms to inhibit the growth of plant pathogens.
$3$. For example,$Trichoderma$ species are free-living fungi that are very common in root ecosystems and are effective biocontrol agents of several plant pathogens.
$4$. Another example is $Bacillus$ $thuringiensis$ $(Bt)$,which is used to control butterfly caterpillars.
$5$. These methods maintain ecological balance and reduce environmental pollution.

(C) Gambusia is a type of larvivorous fish that feeds on mosquito larvae. It is often introduced into ponds and water bodies to control the population of mosquitoes,thereby helping in the prevention of diseases like malaria and dengue.

(D) Biocontrol refers to the use of biological methods for controlling plant diseases and pests.
$A$ $Ladybird$ (beetle with red and black markings) is a well-known biocontrol agent used to get rid of aphids.
$B$ $Aphids$,$Jassids$,and $Mosquitoes$ are considered pests or vectors,not biocontrol agents.
Therefore,the correct option is $D$.

(D) In biological control,specific predators are used to manage pest populations.
Dragonflies are effective in controlling mosquitoes.
Ladybirds (ladybird beetles) are effective in controlling aphids.
Therefore,the correct sequence is mosquitoes and aphids.

(A) $Trichoderma$ species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens. Since they do not depend on a host for survival,they are classified as free-living fungi.

(D) $Trichoderma$ species are free-living fungi that are very common in the root ecosystems. They are effective biocontrol agents of several plant pathogens. They act as biological control agents by suppressing the growth of various soil-borne plant pathogens,thereby protecting the crops from diseases. Therefore,they are used in the treatment of plant diseases.

(A) The bacterium $Bacillus$ $thuringiensis$ $(Bt)$ is used to control butterfly caterpillars.
Its spores are available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees.
When these are eaten by the insect larvae,the toxin is released in the gut of the larva and kills it.

(C) The bacterium $Bacillus$ $thuringiensis$ $(Bt)$ is used as a biological control agent to manage insect pests. In the market,$Bt$ is available in the form of dried spores (sachets) which are mixed with water and sprayed onto vulnerable plants such as $Brassica$ and fruit trees. When these spores are ingested by the insect larvae,the toxin is released in the gut,killing the larvae.

(C) Baculoviruses are pathogens that attack insects and other arthropods.
They are excellent candidates for species-specific,narrow-spectrum insecticidal applications.
They have been shown to have no negative impacts on plants,mammals,birds,fish,or even on non-target insects.
This is especially desirable when beneficial insects are being conserved to aid in an overall integrated pest management $(IPM)$ program.

(B) $Baculoviruses$ are pathogens that attack insects and other arthropods. The majority of $Baculoviruses$ used as biological control agents are in the genus $Nucleopolyhedrovirus$. These viruses are excellent candidates for species-specific,narrow-spectrum insecticidal applications.

(B) The use of chemical pesticides and insecticides has been significantly reduced due to the adoption of biocontrol agents.
Biocontrol refers to the use of biological methods for controlling plant diseases and pests.
These agents, such as $Bacillus \text{ } thuringiensis$ (Bt), Trichoderma, and Baculoviruses, target specific pests without harming beneficial insects or the environment, thereby promoting sustainable agriculture.

$(A)$ The correct matches are:
$(a)$ Ladybird beetle is a predator that feeds on aphids.
$(b)$ $Bacillus \text{ } thuringiensis$ $(Bt)$ is a bacterium used to control butterfly caterpillars.
$(c)$ Dragonflies are predators that feed on mosquitoes.
$(d)$ $Baculovirus$ (specifically $Nucleopolyhedrovirus$) is used as a biological control agent for insects and other arthropods.
Therefore, the correct sequence is $a-1, b-3, c-2, d-4$.

(A) The correct matches are as follows:
$(a)$ Dragonflies are used to get rid of aphids and mosquitoes $(ii)$.
$(b)$ Bacillus thuringiensis is used as a biocontrol agent for lepidopteran plant pests $(iv)$.
$(c)$ Glomus is a fungal genus that forms mycorrhizae and absorbs phosphorus from the soil $(v)$.
$(d)$ Baculoviruses are used for narrow-spectrum insecticidal applications $(iii)$.
Therefore, the correct sequence is $(a)-(ii), (b)-(iv), (c)-(v), (d)-(iii)$.

(A) $Gambusia$ is a genus of small freshwater fish,commonly known as the mosquito fish.
It is widely used in biological control programs because it is a voracious predator that feeds on mosquito larvae.
By consuming these larvae,$Gambusia$ helps in controlling the population of mosquitoes and,consequently,the spread of diseases like malaria and dengue.

(D) The bacteria $Bacillus$ $thuringiensis$ $(Bt)$ is used as a biological control agent to manage various insect pests.
It produces specific insecticidal proteins that are toxic to certain insect larvae,such as butterfly caterpillars,moths,and other agricultural pests.
These $Bt$ toxins are activated in the gut of the target insects,leading to their death.
Therefore,it is widely used in agriculture to control insect populations.

(C) Rotenone is a natural compound extracted from the roots of plants such as $Derris$ $elliptica$ and $Lonchocarpus$. It acts as a broad-spectrum bioinsecticide and piscicide by inhibiting the mitochondrial electron transport chain,specifically targeting Complex $I$.

(C) $Bacillus \text{ } thuringiensis$ is a natural bioinsecticide. It produces a crystalline protein toxin known as $Cry$ toxin (or $Bt$ toxin), which is effective against various insect pests such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes).

(A) $Trichoderma$ species are free-living fungi that are very common in root ecosystems (rhizosphere).
They are effective biocontrol agents and are used as biopesticides.
They are highly effective against several soil-borne plant pathogens.