Section B
Q- Write short note on Secondary metabolism .
A- Secondary metabolism refers to the set of metabolic processes that produce secondary metabolites, which are organic compounds not directly involved in the normal growth, development, or reproduction of an organism. Unlike primary metabolites, which are essential for basic cellular functions such as energy production, growth, and reproduction (e.g., amino acids, nucleotides, and carbohydrates), secondary metabolites are often species-specific and serve specialized functions.
Q- Write short note on Bacillus thuringiensis ?
A - **Bacillus thuringiensis (Bt)** is a gram-positive, spore-forming bacterium that is widely known for its ability to produce crystal proteins (Cry proteins) that are toxic to various insect pests. This makes Bt an important biological control agent in agriculture.
### Key Characteristics:
1. **Cry Proteins**: Bt produces crystalline inclusions during sporulation. These inclusions contain Cry proteins, which are insecticidal delta-endotoxins. When ingested by susceptible insects, these proteins dissolve in the alkaline gut, get activated by gut proteases, and then bind to receptors on the gut cells, causing cell lysis and death of the insect.
2. **Specificity**: The insecticidal activity of Bt is highly specific, targeting particular insect orders such as Lepidoptera (butterflies and moths), Diptera (flies and mosquitoes), and Coleoptera (beetles), while being harmless to humans, animals, and most beneficial insects.
3. **Strain Diversity**: Different Bt strains produce different Cry proteins, which vary in their spectrum of activity against insect pests. This diversity allows for targeted pest control strategies.
### Applications in Agriculture:
1. **Biopesticides**: Bt formulations are used as biopesticides in organic and conventional agriculture. They provide an environmentally friendly alternative to chemical insecticides. When sprayed on crops, Bt spores and crystals are ingested by pest larvae, leading to their death.
2. **Genetically Modified Crops**: Bt genes have been incorporated into various crops, such as Bt corn, Bt cotton, and Bt soybeans, to provide built-in resistance to insect pests. These transgenic crops reduce the need for chemical insecticide applications, leading to lower production costs and reduced environmental impact.
### Benefits and Safety:
- **Environmental Impact**: Bt-based products degrade quickly in the environment and do not accumulate, minimizing ecological disruption.
- **Safety**: Extensive studies have shown that Bt is safe for humans, animals, and non-target organisms, making it a preferred choice for integrated pest management (IPM).
### Challenges:
- **Resistance Management**: Continuous use of Bt crops and biopesticides can lead to the development of resistance in target insect populations. Integrated pest management strategies, including crop rotation and refuges (areas planted with non-Bt crops), are essential to delay resistance.
Q - Write short note on Agrocin ?
A- •Agrobacterium radiobacter is used to treat roots during transplanting, that checks
crown gall.
•Crown gall is a disease in peaches, grapevine, roses and various plants caused by soil
borne pathogen Agrobacteriumtumefaciensm.
•The effective strains of A. radiobacter possestwo important features:
✓They are able to colonize host rootsto a higher population density.
✓They produce an antibiotic, agrocin, that is toxic to A. tumefaciens.
Q- Explain Virulence and Pathogenicity ?
A - ****Virulence** and **pathogenicity** are related concepts in the study of infectious diseases, but they refer to different aspects of a pathogen's ability to cause disease.
1. **Pathogenicity**:
- **Definition**: The ability of a microorganism to cause disease in a host.
- **Description**: It refers to whether or not an organism can produce disease. If a microorganism is pathogenic, it means it has the potential to cause disease in a host organism.
2. **Virulence**:
- **Definition**: The degree or severity of pathogenicity.
- **Description**: It indicates how severe the disease caused by the pathogen can be. Virulence is often measured by the extent of damage caused to the host, the speed of disease onset, and the number of organisms needed to cause infection.
In summary, pathogenicity is about the capability to cause disease, while virulence is about the intensity or severity of the disease caused.
Q- Explain plant incorporated protectants in details.
A - **Plant-Incorporated Protectants (PIPs)** are pesticidal substances produced by plants that have been genetically engineered to express specific traits for pest resistance. These protectants are derived from genes inserted into the plant’s genome, enabling the plant to produce proteins or other compounds that provide protection against pests.
### Key Concepts and Mechanisms:
1. **Genetic Engineering**:
- PIPs are developed by introducing specific genes into the plant’s DNA through genetic engineering. These genes typically originate from other organisms, such as bacteria, and are selected for their ability to confer pest resistance.
2. **Mechanism of Action**:
- The inserted genes enable the plant to produce pesticidal proteins or other substances that target specific pests. These substances can act in various ways, such as:
- **Toxins**: Proteins that are toxic to particular insects or pests when ingested. For example, Bacillus thuringiensis (Bt) genes are commonly used to produce Bt toxins that kill specific insect larvae.
- **Antifungal or Antiviral Proteins**: Proteins that inhibit the growth of fungi or viruses.
- **Enzyme Inhibitors**: Compounds that interfere with the digestive processes of pests.
### Examples of PIPs:
1. **Bt Crops**:
- Bt corn, Bt cotton, and Bt soybeans are examples of crops engineered to produce Bt toxins. The Bt gene from the bacterium *Bacillus thuringiensis* is inserted into the plant genome, allowing the plant to produce the toxin, which is lethal to specific insect pests like the European corn borer and cotton bollworm.
2. **Virus-Resistant Papaya**:
- Papaya has been engineered with genes from the Papaya ringspot virus (PRSV), enabling the plant to produce proteins that protect against the virus, effectively controlling the disease.
### Benefits of PIPs:
1. **Targeted Pest Control**:
- PIPs provide highly specific pest control, targeting only the intended pest species without affecting non-target organisms. This reduces the impact on beneficial insects and other wildlife.
2. **Reduced Chemical Pesticide Use**:
- By providing inherent pest resistance, PIPs reduce the need for chemical pesticide applications. This leads to lower production costs and minimizes environmental contamination.
3. **Sustainable Agriculture**:
- PIPs contribute to sustainable agricultural practices by enhancing crop yields, reducing crop losses due to pests, and promoting environmentally friendly pest management strategies.
Q - Mass production technology of biopesticides.
A-
Section c ]
Q - Classify biopesticides.
A - Biopesticides can be classified into three major categories based on their source and mode of action: microbial biopesticides, plant-incorporated protectants (PIPs), and biochemical biopesticides.
Types of biopesticides -
### 1. Microbial Pesticides:
These biopesticides are derived from microorganisms such as bacteria, fungi, viruses, and protozoa. They target specific pests and often work by producing toxins, infecting the pest, or outcompeting harmful organisms.
#### Examples:
- **Bacteria**: *Bacillus thuringiensis* (Bt) produces Cry proteins toxic to certain insects.
- **Fungi**: *Beauveria bassiana* and *Metarhizium anisopliae* are used to control insect pests.
- **Viruses**: Nuclear polyhedrosis viruses (NPVs) and granulosis viruses (GVs) target caterpillar pests.
- **Protozoa**: *Nosema locustae* is used against grasshoppers and locusts.
### 2. Plant-Incorporated Protectants (PIPs):
These are pesticidal substances produced by plants that have been genetically modified. The genes coding for specific pesticidal proteins are introduced into the plant genome, enabling the plant to produce these proteins and protect against pests.
#### Examples:
- **Bt Crops**: Bt corn, Bt cotton, and Bt soybeans express Bt toxin genes, providing resistance to specific insect pests.
- **Virus-Resistant Plants**: Genetically modified papaya resistant to Papaya ringspot virus (PRSV).
### 3. Biochemical Pesticides:
These are naturally occurring substances that control pests through non-toxic mechanisms. They include plant extracts, pheromones, and other natural compounds.
#### Examples:
- **Pheromones**: Used in traps to disrupt mating behaviors of pests (e.g., codling moth pheromone traps).
- **Plant Growth Regulators**: Compounds like methoprene that mimic insect juvenile hormones, disrupting development and reproduction.
- **Repellents**: Garlic oil, capsaicin, and other natural substances that repel pests.
### 4. Botanical Pesticides:
These are derived from plants and include a wide range of extracts and essential oils that have pesticidal properties.
#### Examples:
- **Neem Oil**: Extracted from the neem tree (*Azadirachta indica*), containing azadirachtin, which acts as an insect repellent and growth inhibitor.
- **Pyrethrum**: Derived from chrysanthemum flowers, used to control a variety of insect pests.
- **Rotenone**: Extracted from the roots of certain legumes, used as an insecticide and piscicide.
- **Essential Oils**: Oils from plants like rosemary, peppermint, and clove can be used as insect repellents or fungicides.
### 5. Biotic Agents (Parasitoids and Predators):
These are living organisms that control pest populations by predation, parasitism, or other biological interactions.
#### Examples:
- **Parasitoids**: Insects like wasps (e.g., *Trichogramma* species) that lay their eggs inside or on the bodies of pest insects, with the developing larvae consuming the host.
- **Predators**: Organisms such as lady beetles (ladybugs), lacewings, and predatory mites that feed on pest insects.
Q - Explain mode of action of BT Toxin ?
A - The mode of action of Bacillus thuringiensis (Bt) toxin involves several precise steps, resulting in the death of target insect larvae. Bt produces crystal (Cry) proteins, which are toxic to certain insects. Here's a detailed explanation of the Bt toxin's mode of action:
### 1. Ingestion by the Insect:
- **Feeding**: The insect larvae ingest Bt spores and crystalline (Cry) proteins when they feed on treated plant surfaces or genetically modified Bt crops that express these proteins.
### 2. Solubilization and Activation in the Gut:
- **Alkaline Environment**: Inside the insect's midgut, the highly alkaline conditions (pH 9-10) cause the crystalline proteins to solubilize.
- **Proteolytic Activation**: Solubilized protoxins are then activated by specific proteases (digestive enzymes) in the insect gut, converting the protoxins into active toxin fragments.
### 3. Binding to Midgut Receptors:
- **Receptor Binding**: The activated toxin binds to specific receptors on the epithelial cells lining the insect's midgut. These receptors are typically cadherin-like proteins, aminopeptidases, or alkaline phosphatases.
- **Conformational Change**: Binding to the receptors induces a structural change in the toxin, enabling it to integrate into the cell membrane.
### 4. Pore Formation and Cell Lysis:
- **Pore Formation**: The toxin molecules insert themselves into the gut cell membrane, forming pores or channels.
- **Disruption of Cellular Functions**: These pores disrupt the cell membrane's integrity, leading to an imbalance in ions (such as sodium and potassium) and causing the cells to swell and burst.
### 5. Midgut Disruption and Septicemia:
- **Gut Paralysis**: The damage to the midgut cells causes paralysis of the digestive system, preventing the insect from feeding and leading to starvation.
- **Leakage and Infection**: The compromised gut barrier allows gut contents, including Bt spores, to leak into the insect's hemocoel (body cavity). The bacteria can then multiply, leading to septicemia (bacterial blood infection).
### 6. Death of the Insect:
- **Systemic Infection**: The combination of gut cell destruction, systemic infection by Bt bacteria, and starvation leads to the death of the insect larvae within a few days.
### Specificity and Safety:
- **Target Specificity**: The specificity of Bt toxins is due to the presence of particular receptors in the midguts of target insects. Non-target organisms, including humans, do not have these receptors or the required alkaline gut environment, making Bt toxins safe for non-target species.
- **Environmental Safety**: Bt toxins degrade rapidly in the environment, minimizing long-term ecological impacts.
### Application in Agriculture:
- **Bt Crops**: Genetically modified crops, such as Bt corn, Bt cotton, and Bt soybeans, express Bt toxins. These crops provide built-in protection against specific insect pests, reducing the need for chemical insecticides and supporting sustainable agriculture practices.
### Summary of Steps:
1. **Ingestion**: Insect larvae ingest Bt spores and Cry proteins.
2. **Solubilization**: Cry proteins solubilize in the alkaline midgut environment.
3. **Activation**: Protoxins are activated by gut proteases.
4. **Binding**: Activated toxins bind to specific receptors on midgut cells.
5. **Pore Formation**: Toxins insert into the cell membrane, forming pores.
6. **Cell Lysis**: Midgut cells swell, burst, and die.
7. **Septicemia**: Gut content leakage and bacterial proliferation lead to insect death.
Q - Explain botanical insecticides in detail .
A - Botanical insecticides are naturally occurring pesticides derived from plants. They have been used for centuries to protect crops from pests and are considered an important component of integrated pest management (IPM) strategies due to their lower environmental impact compared to synthetic chemicals. Here is a detailed overview of botanical insecticides:
### Sources and Active Ingredients
Botanical insecticides are derived from various plant parts, including leaves, flowers, seeds, and bark. The active ingredients in these insecticides are often secondary metabolites that plants produce for their own defense against herbivores and pathogens. Some common botanical insecticides and their sources include:
1. **Neem (Azadirachta indica)**:
- **Active Ingredient**: Azadirachtin, along with other limonoids.
- **Mode of Action**: Azadirachtin acts as an antifeedant, growth regulator, and repellent. It disrupts insect molting and reproduction.
- **Target Pests**: Wide range of insects including aphids, whiteflies, beetles, and caterpillars.
2. **Pyrethrum (Chrysanthemum cinerariifolium)**:
- **Active Ingredient**: Pyrethrins.
- **Mode of Action**: Pyrethrins affect the nervous system of insects, causing paralysis and death.
- **Target Pests**: Broad spectrum, including mosquitoes, flies, moths, beetles, and aphids.
3. **Rotenone (Derris and Lonchocarpus spp.)**:
- **Active Ingredient**: Rotenone.
- **Mode of Action**: Inhibits cellular respiration in insects, leading to death.
- **Target Pests**: Leaf-feeding insects, beetles, and caterpillars.
4. **Essential Oils (various plants)**:
- **Examples**: Oils from rosemary, peppermint, clove, eucalyptus, and citronella.
- **Mode of Action**: Often act as repellents, antifeedants, and have direct toxic effects on insects.
- **Target Pests**: Varies depending on the oil, commonly used against flies, mosquitoes, ants, and mites.
5. **Ryania (Ryania speciosa)**:
- **Active Ingredient**: Ryanodine.
- **Mode of Action**: Affects the calcium channels in insect muscles, leading to paralysis and death.
- **Target Pests**: Caterpillars, beetles, and other chewing insects.
### Modes of Action
Botanical insecticides operate through various mechanisms:
1. **Neurotoxins**: Compounds like pyrethrins and ryanodine affect the nervous system, causing paralysis and death.
2. **Antifeedants**: Substances like azadirachtin deter insects from feeding on treated plants.
3. **Growth Regulators**: Azadirachtin disrupts the hormonal balance necessary for insect growth and development, affecting molting and reproduction.
4. **Respiratory Inhibitors**: Rotenone inhibits cellular respiration, leading to energy depletion and death.
5. **Repellents**: Essential oils and other compounds can repel insects from treated areas.
### Advantages
1. **Environmental Safety**: Botanical insecticides generally break down quickly in the environment, reducing the risk of long-term contamination.
2. **Low Toxicity to Non-Target Organisms**: These insecticides tend to be less harmful to beneficial insects, wildlife, and humans when used appropriately.
3. **Resistance Management**: Because they often contain multiple active compounds, the development of resistance in pest populations is slower compared to synthetic insecticides.
4. **Organic Farming**: Many botanical insecticides are approved for use in organic agriculture.
### Challenges
1. **Variability**: The concentration of active ingredients can vary depending on the source and extraction method, leading to inconsistent efficacy.
2. **Short Residual Activity**: Botanical insecticides degrade rapidly, requiring more frequent applications.
3. **Cost**: They can be more expensive to produce and purchase compared to synthetic pesticides.
4. **Regulatory Hurdles**: Obtaining regulatory approval can be challenging due to the complexity of botanical mixtures and the need for thorough safety evaluations.
### Application Methods
- **Sprays**: Diluted botanical insecticides are commonly applied as foliar sprays to control pests on leaves and stems.
- **Dusts**: Some botanical insecticides are formulated as dusts for application to plant surfaces.
- **Soil Treatments**: Certain botanicals, like neem, can be used as soil drenches to control soil-dwelling pests.
- **Seed Treatments**: Seeds can be treated with botanical insecticides to protect young plants from early pest attacks.
Q - Discuss mode of application of Biopesticides.
A -- The mode of application of biopesticides is critical for their effectiveness in pest management. The choice of application method depends on the type of biopesticide, the target pest, the crop, and environmental conditions. Here are the primary modes of application for biopesticides, along with their specific considerations and examples:
### 1. Foliar Sprays
#### Description:
Foliar application involves spraying biopesticides directly onto the leaves, stems, and other above-ground parts of plants. This method is suitable for controlling insects, mites, fungi, and bacteria that attack the foliage.
#### Application Techniques:
- **Hand-held Sprayers**: Used for small-scale applications in gardens and greenhouses.
- **Backpack Sprayers**: Suitable for larger areas where maneuverability is required.
- **Tractor-Mounted Boom Sprayers**: Used for large-scale agricultural fields.
- **Aerial Spraying**: Utilized for extensive coverage in large fields or forested areas.
#### Examples:
- **Neem Oil**: Sprayed on foliage to control a wide range of insects and mites.
- **Bacillus thuringiensis (Bt)**: Sprayed to target caterpillars, beetles, and mosquitoes.
- **Pyrethrum**: Applied as a contact insecticide against various pests.
### 2. Soil Treatments
#### Description:
Soil application involves incorporating biopesticides into the soil to control soil-borne pests and diseases. This method targets pests that live in or on the soil and pathogens that affect the roots.
#### Application Techniques:
- **Soil Drenches**: Liquid biopesticides are applied directly to the soil around the base of plants.
- **Granules and Pellets**: Solid formulations are scattered on the soil surface or incorporated into the soil.
- **Injection**: Liquid biopesticides are injected into the soil at the root zone using specialized equipment.
#### Examples:
- **Trichoderma spp.**: Used as a soil drench or incorporated into the soil to control fungal pathogens.
- **Metarhizium anisopliae**: Applied to the soil to control soil-dwelling insects like termites and root grubs.
- **Bacillus subtilis**: Used to suppress soil-borne diseases caused by fungi and bacteria.
### 3. Seed Treatments
#### Description:
Seed treatment involves coating seeds with biopesticides before planting. This method protects seedlings from soil-borne pathogens and early-season pests.
#### Application Techniques:
- **Seed Coating**: Seeds are coated with a biopesticide formulation using specialized equipment.
- **Seed Pelleting**: Biopesticides are incorporated into a pellet that surrounds the seed.
#### Examples:
- **Trichoderma harzianum**: Used as a seed treatment to protect against fungal diseases.
- **Bacillus thuringiensis (Bt)**: Coated on seeds to provide early protection against soil and foliage pests.
- **Pseudomonas fluorescens**: Applied to seeds to suppress soil-borne pathogens and promote plant growth.
### 4. Root Dips
#### Description:
Root dipping involves immersing the roots of seedlings or transplants in a biopesticide solution before planting. This method provides direct protection to the roots and promotes establishment.
#### Application Techniques:
- **Dipping**: Seedling roots are dipped in a biopesticide suspension just before transplanting.
#### Examples:
- **Beauveria bassiana**: Used as a root dip to control soil-borne insect pests.
- **Azospirillum spp.**: Applied as a root dip to promote growth and suppress pathogens.
### 5. Trunk Injections and Banding
#### Description:
Trunk injection involves injecting biopesticides directly into the trunk of trees. Banding involves applying a biopesticide around the trunk.
#### Application Techniques:
- **Injection**: Biopesticides are injected into small holes drilled into the trunk.
- **Banding**: A band of biopesticide is applied around the trunk.
#### Examples:
- **Emamectin benzoate**: Injected to control wood-boring insects.
- **Beauveria bassiana**: Applied as a trunk band to protect against trunk-infesting insects.
### 6. Baiting
#### Description:
Baiting involves using biopesticides in bait formulations that attract and kill target pests. This method is effective for controlling insects that forage for food.
#### Application Techniques:
- **Bait Stations**: Biopesticide baits are placed in stations that attract pests.
- **Scattered Bait**: Baits are scattered in the target area.
#### Examples:
- **Spinosad**: Used in bait formulations to control ants and fruit flies.
- **Bacillus thuringiensis israelensis (Bti)**: Used in mosquito bait formulations.
### 7. Post-Harvest Treatments
#### Description:
Post-harvest application involves treating harvested crops with biopesticides to control storage pests and diseases.
#### Application Techniques:
- **Sprays**: Biopesticides are sprayed on harvested produce.
- **Dips**: Harvested produce is dipped in biopesticide solutions.
- **Dusting**: Biopesticides are dusted onto stored grains.
#### Examples:
- **Bacillus subtilis**: Used to control fungal pathogens on stored fruits and vegetables.
- **Diatomaceous earth**: Used to protect stored grains from insect infestation.
Q - Difference between botanical pesticides and synthetic pesticides.
A- Here are ten key differences between botanical pesticides and synthetic pesticides:
### 1. Source and Composition:
- **Botanical Pesticides**: Derived from natural plant sources such as leaves, flowers, seeds, and bark. Examples include neem oil, pyrethrum, and rotenone.
- **Synthetic Pesticides**: Chemically synthesized in laboratories. Examples include organophosphates, carbamates, and neonicotinoids.
### 2. Environmental Impact:
- **Botanical Pesticides**: Generally biodegradable and break down more quickly in the environment, reducing long-term pollution.
- **Synthetic Pesticides**: Often more persistent in the environment, potentially leading to soil, water, and air contamination.
### 3. Toxicity to Non-Target Organisms:
- **Botanical Pesticides**: Typically less toxic to non-target organisms, including beneficial insects, wildlife, and humans, when used correctly.
- **Synthetic Pesticides**: Can be highly toxic to non-target species, including beneficial insects, wildlife, and potentially humans, leading to broader ecological imbalances.
### 4. Resistance Development:
- **Botanical Pesticides**: Pests are less likely to develop resistance due to the complex mixture of active compounds with multiple modes of action.
- **Synthetic Pesticides**: Pests can develop resistance more quickly due to the single, specific mode of action of many synthetic chemicals.
### 5. Mode of Action:
- **Botanical Pesticides**: Often have multiple modes of action, affecting various physiological processes in pests.
- **Synthetic Pesticides**: Typically have a single, well-defined mode of action, such as inhibiting specific enzymes or disrupting nerve function.
### 6. Human Health Risks:
- **Botanical Pesticides**: Generally pose lower risks to human health if used according to guidelines, though some can still be hazardous if misused.
- **Synthetic Pesticides**: Often pose higher risks to human health, including acute poisoning and long-term effects such as cancer or endocrine disruption.
### 7. Regulatory Approval:
- **Botanical Pesticides**: Often face fewer regulatory hurdles and are more readily approved for use, especially in organic farming.
- **Synthetic Pesticides**: Subject to stringent regulatory approval processes due to their potential toxicity and environmental impact.
### 8. Application Frequency:
- **Botanical Pesticides**: May require more frequent application due to their rapid degradation and lower persistence.
- **Synthetic Pesticides**: Usually require less frequent application because of their longer residual activity.
### 9. Cost:
- **Botanical Pesticides**: Can be more expensive due to the extraction and processing of plant materials, but costs can vary.
- **Synthetic Pesticides**: Often less expensive to produce in bulk, though costs can also vary based on formulation and regulation.
### 10. Compatibility with Organic Farming:
- **Botanical Pesticides**: Widely accepted and used in organic farming due to their natural origins and lower environmental impact.
- **Synthetic Pesticides**: Generally not permitted in organic farming systems due to their artificial origin and potential ecological and health risks.
Q - Discuss entomopathogenic pathogens as biopesticides.
A - Entomopathogenic pathogens are microorganisms that cause diseases in insects and are utilized as biopesticides for the biological control of pest populations. These pathogens include bacteria, fungi, viruses, and nematodes, each with unique mechanisms of action against their insect hosts. Here is a detailed discussion on the use of entomopathogenic pathogens as biopesticides:
### 1. Types of Entomopathogenic Pathogens
#### a. **Bacteria**
- **Examples**: *Bacillus thuringiensis* (Bt), *Bacillus sphaericus*, *Paenibacillus popilliae*.
#### b. **Fungi**
- **Examples**: *Beauveria bassiana*, *Metarhizium anisopliae*, *Isaria fumosorosea*.
#### c. **Viruses**
- **Examples**: Nucleopolyhedroviruses (NPVs), Granuloviruses (GVs).
#### d. **Nematodes**
- **Examples**: *Steinernema spp.*, *Heterorhabditis spp.*
ew infective juveniles into the environment.
### 2. Advantages of Entomopathogenic Pathogens
- **Specificity**: Many entomopathogenic pathogens are highly specific to their target pest species, minimizing impacts on non-target organisms and beneficial insects.
- **Safety**: Generally safe for humans, animals, and the environment, making them ideal for integrated pest management (IPM) and organic farming.
- **Resistance Management**: Lower risk of pests developing resistance due to the complex modes of action and natural adaptation processes.
- **Biodegradability**: Pathogens degrade naturally, reducing environmental persistence and pollution.
### 5. Examples of Successful Biopesticides
- **Bt-based Products**: Widely used against Lepidopteran larvae (e.g., Bt corn, Bt cotton).
- **Beauveria bassiana**: Used to control a variety of insects, including whiteflies, aphids, and thrips.
- **Nematode-based Products**: Effective against soil-dwelling pests like root grubs and termites.
