Biocontrol Agents: Overview, Types, Merits and Demerits
Biocontrol agents are living organisms such as fungi, bacteria, viruses, and insects that control pests and plant diseases naturally. They play an important role in sustainable agriculture by reducing chemical pesticide use and maintaining ecological balance. Examples include Trichoderma, Bacillus thuringiensis, and ladybird beetles, making this a key NEET Biology topic.
This Story also Contains
- What are Biocontrol Agents?
- Types Of Biocontrol Agents
- Various Biocontrol Agents
- Characteristics of Biocontrol Agents
- Importance of Biocontrol Agents in Agriculture
- Exam Relevance
- Biocontrol Agents NEET MCQs
- FAQs on Biocontrol Agents
Biocontrol agents are living organisms used to control harmful pests, weeds, and diseases in agriculture. This method helps manage crop pests without using harmful chemicals, making it safe for the environment and human health. Biocontrol agents play a key role in maintaining the balance of the ecosystem by reducing dependence on chemical pesticides. It promotes sustainable agriculture and environmental conservation. Some of the common biocontrol organisms include Trichoderma (fungi), Bacillus thuringiensis (bacteria), and ladybird beetles (insects).
What are Biocontrol Agents?
Biocontrol agents prevent pests or insects from reproducing by using their natural enemies. Biological control is the process by which biocontrol agents operate. The use of naturally occurring strains of any microorganisms or genetically modified organisms to reduce the severity of diseases caused by plant pathogens is known as a "biocontrol agent" (BCA). Some basic facts about biocontrol agents are discussed below:
Biocontrol is the use of a living organism or biological agent to stop the growth of an insect or other pest.
The biocontrol agents defend plants from pests, bacteria, predators, and other natural enemies.
They aid in reducing plant pest infestations caused by weeds, nematodes, insects, and mites.
The biological control agents target harmful organisms only, and they leave the beneficial organisms in the soil alone.
Commonly Asked Questions
Host specificity refers to the degree to which a biocontrol agent targets only the intended pest species. Highly host-specific agents are preferred as they minimize risks to non-target organisms. Researchers extensively study an agent's host range before its introduction to ensure it won't harm beneficial or native species in the new environment.
Tritrophic interaction refers to the relationship between three trophic levels: the plant (first trophic level), the herbivorous pest (second trophic level), and the natural enemy or biocontrol agent (third trophic level). Understanding these interactions is crucial for effective biocontrol, as plants can influence both pests and their natural enemies through various mechanisms like chemical signaling or providing food and shelter.
Establishment refers to the ability of a biocontrol agent to survive, reproduce, and maintain its population in the new environment where it's introduced. Successful establishment is crucial for long-term pest control, especially in classical biological control. Factors affecting establishment include climate compatibility, availability of suitable hosts, and absence of hyperparasitoids or predators of the biocontrol agent.
Types Of Biocontrol Agents
Two categories of biological control exist:
Classical biocontrol (Importation)
Inductive Biocontrol (Augmentation)
These types are based on the method of introducing or enhancing natural enemies of pests. In classical biocontrol, new beneficial organisms are imported, while in inductive biocontrol, the population of existing agents is increased to control pests.
Type of Biocontrol Agents | Explanation | Examples |
Classical biocontrol agents |
| Moths, Parasitic insects, Baculovirus and Aphids. |
Inductive biocontrol agents. |
| Nematodes |
Commonly Asked Questions
Classical biological control involves the introduction of a natural enemy from a pest's native range into a new area where the pest has become problematic. This method aims to establish a long-term balance between the pest and its natural enemy, providing ongoing control without repeated interventions.
Augmentative biological control involves the periodic release of mass-reared natural enemies to boost their populations in the field. Unlike classical biocontrol, which aims for long-term establishment, augmentative control often requires repeated releases. It can be inundative (large releases for immediate control) or inoculative (smaller releases aiming for population build-up over time).
Conservation biological control focuses on protecting and enhancing existing populations of natural enemies in an ecosystem. This approach involves modifying the environment or management practices to favor beneficial organisms, such as providing habitat, alternative food sources, or reducing practices that harm natural enemies.
Various Biocontrol Agents
Common biocontrol agents include bacteria, fungi, viruses, and insects. Each plays a specific role in suppressing pests and plant diseases. Examples of biological pest control agents are provided below:
Biocontrol Agents | Explanation | Examples |
Fungi | This is a biological method of pest control which is effective against pest like green peach aphids. | Entomophagous, Fungi |
Predators | These are free-living organisms which consume their prey throughout their lives. It is most effective against those pests who feed upon the crops. | Spiders, Dragonflies and Lacewings |
Bacteria | Certain bacteria from the Cocobacillus family infect the digestive tract of the pest insect. This is natural yet one of the most effective biocontrol methods. | Coccobacillus species |
Virus | Viruses are being developed to control them selectively without affecting the non-target organisms. | Under development |
Parasitoids | Parasitoids lay eggs inside the host and their larva is used as a food source for the host. This eventually kills the host and the entire process acts as a biocontrol process. | Parasitic wasps |
Commonly Asked Questions
Parasitoids, typically wasps or flies, lay their eggs in or on host pests. When the eggs hatch, the larvae feed on the host, eventually killing it. This process helps control pest populations by reducing their numbers and reproductive capacity. An example is the use of Trichogramma wasps to control caterpillar pests in various crops.
Predatory biocontrol agents work by directly hunting and consuming pest species. They help reduce pest populations by feeding on them at various life stages. For example, ladybugs are used to control aphids in crops by eating both adult aphids and their eggs.
Pathogenic biocontrol agents are microorganisms (bacteria, viruses, fungi) that cause diseases in pest species. They infect the pest, multiply within it, and ultimately kill or weaken it. For instance, Bacillus thuringiensis (Bt) is a bacterium used to control various insect pests by producing toxic proteins that disrupt their digestive systems.
Competitive biocontrol agents work by outcompeting pest species for resources such as food, space, or nutrients. This competition reduces the pest's ability to thrive and reproduce. For example, some beneficial fungi are used to colonize plant roots, preventing harmful fungi from establishing themselves.
Characteristics of Biocontrol Agents
Biocontrol agents are natural and eco-friendly. They do not harm humans, animals, or crops. These agents help maintain balance in ecology and reduce the need for chemical pesticides. Some basic characteristics of biocontrol agents are:
It is a natural way to manage insects, weeds, pests, and other living things that hinder growth. It is applied to raise crop production and yield.
Predation and parasitism are the basic biological control principles. Trichoderma, Baculoviruses, and Nucleopolyhedrovirus are a few of the microbes used as biocontrol agents.
Farmers use biocontrol agents to kill only undesirable organisms that afflict plants with disease because chemical fertilizers can occasionally kill the desired and necessary soil organisms.
Pest management and the life cycle of the pest are necessary to understand how to approach the biological control process.
Spraying a plant with BT solution made from seeds will kill the caterpillars of butterflies.
Toxins from the worms' intestines are released by the dried seeds, killing them.
Commonly Asked Questions
Biocontrol agents are living organisms or natural substances that target specific pests, while chemical pesticides are synthetic compounds that often affect a broader range of organisms. Biocontrol agents typically have fewer environmental impacts, lower risk of pest resistance, and can be self-sustaining in the ecosystem.
Microbial biocontrol agents (e.g., bacteria, fungi, viruses) typically work by infecting pests or producing toxic compounds, while macro-organisms (e.g., predatory insects, mites) physically consume or parasitize pests. Microbials can often be mass-produced and applied like pesticides, while macro-organisms usually require more careful handling and release strategies.
Importance of Biocontrol Agents in Agriculture
Many farmers use chemical fertilizers to control the pest problems. These harmful chemicals affect human health and create environmental issues like soil pollution. Instead, biocontrol agents provide a much safer option.
Eco-friendly: Biocontrol agents are naturally occurring and they do not harm the ecosystem.
Safe for Humans: Biocontrol agents are non-toxic and have no side effects unlike the harmful chemicals.
Reduced Chemical Use: Using biocontrol agents significantly reduces the need for chemical fertilizers which harm the environment.
Improved Biodiversity: They support the maintenance of agricultural biodiversity by creating a chemical free and favorable habitat for the organisms.
Exam Relevance
During exam preparation, different types of questions about the Biocontrol Agents are asked. The table below contains the different patterns of questions asked in different exams.
Exam Type | Types of Questions Asked |
| |
| |
Paramedical |
|
Biocontrol Agents NEET MCQs
Q1. When a natural predator (living organism) is applied to the other pathogen organisms to control them, this process is called?
Biological control
Genetic engineering
Artificial control
Confusion technique
Correct answer: 1) Biological control
Explanation:
Biological control of pests and diseases - There is a method of controlling pests that relies on natural predation rather than introduced chemicals. A natural technique called biological control employs other living things to manage pests including weeds, insects, mites, and other agents that cause plant diseases. It depends on organic processes like herbivory, parasitism, and predation.
Hence, the correct answer is Option 1) Biological control.
Q2. Insect harms most crops in the ground. It can be prevented by
By using insect repellent
By eliminating breeding area
Plant breeding
More than one correct answer
Correct answer: 4) More than one correct answer
Explanation:
Applying insect repellent: By keeping pests at bay or eliminating them, insecticides and repellents help shield crops from insect damage.
Getting rid of breeding grounds: You can lower the number of insects and avoid damage by getting rid of weeds, standing water, and other places where they breed.
Plant breeding: Plant breeding can reduce the susceptibility of crops to insect infestations by creating crop varieties that are resistant to pests.
There are multiple right answers because all of these techniques help to lessen insect damage.
Hence, the correct answer is option 4) More than one correct answer.
Q3. Select the correct group of biocontrol agents:
Bacillus thuringiensis , Tobacco mosaic virus , Aphids
Trichoderma, Baculovirus, Bacillus thuringiensis
Oscillatoria , Rhizobium , Trichoderma
Nostoc , Azospririllum, Nucleopolyhedrovirus
Correct answer: 2) Trichoderma, Baculovirus, Bacillus thuringiensis
Explanation:
Trichoderma is a highly effective biocontrol agent extensively used to manage soil-borne diseases by suppressing the growth of pathogenic fungi. Baculovirus is a biological control agent with narrow insecticidal properties, specifically targeting and killing insects and arthropods without harming other organisms. Bacillus thuringiensis is a naturally occurring, spore-forming soil bacterium that produces protein crystals toxic to specific insects, making it an important tool for pest management in agriculture.
Hence, the correct answer is option 2)Trichoderma, Baculovirus, Bacillus thuringiensis
Also Read:
FAQs on Biocontrol Agents
What are biocontrol agents in biology?
Biocontrol agents are living organisms or natural substances used to control pests, diseases, or unwanted species in agriculture and ecosystems. They work by exploiting natural relationships between organisms, such as predation, parasitism, or competition, to reduce the population of harmful organisms without relying on synthetic chemicals.
What are the types of biocontrol agents?
Predators: Organisms that directly kill pests. e.g., ladybird beetle feeding on aphids
Parasitoids: Insects that lay eggs inside pests, larvae kill the host. e.g., Trichogramma wasps
Bacteria: Infect the digestive tract of the pest insect. E.g., Coccobacillus
Virus: designed to selectively kill pests without affecting the non-target organisms.
What are the advantages of biocontrol over chemical methods?
Eco-friendly: Does not pollute soil, water, or air.
Target-specific: Affects only pests, without harming beneficial organisms.
Safe for humans and animals: No harmful pesticide residues in food.
Cost-effective: Reduces repeated pesticide use and preserves soil fertility.
What are the drawbacks of using biocontrol agents?
The drawback of using biocontrol agents is that they do not completely eradicate the pest. Farmers are not knowledgeable about the techniques. They only work for long-term cultivation and may affect the quality of the crops.
Frequently Asked Questions (FAQs)
Environmental factors such as temperature, humidity, light, and soil conditions can significantly impact biocontrol agents' survival, reproduction, and effectiveness. For example, many predatory mites require specific humidity levels, while some microbial agents are sensitive to UV light. Understanding these requirements is crucial for successful implementation of biocontrol strategies.
Ecological fitting refers to the process by which a species can persist in a new environment by relying on pre-existing adaptations, rather than evolving new traits. In biocontrol, this concept is important when selecting agents, as it suggests that effective control might be achieved by introducing natural enemies that are pre-adapted to the target pest and the new environment, even if they don't share an evolutionary history with the specific pest population.