Biocontrol Agents

The agents that control the growth of pests or insects by using their natural living enemy organisms are called biocontrol agents. The process in which biocontrol agents work is called biological control.

Biological control is an effective method to remove invasive plants and get pest-free fields. In the biological control process, the biocontrol agents have been used to control pests, insects, and pathogens and eradicate unwanted weeds and plants. The main purpose of biocontrol agents is to increase crop yield by eradicating pests and insects. They only destroy harmful organisms such as parasites, pests, and insects and do not harm the useful organisms present in the soil.  

Microbes are single-cell organisms that can be both harmful as well as useful. They are widely used as biocontrol agents to kill weeds, pests, insects, and other organisms.

Features of biological control agents

• It is a natural method to control weeds, pests, insects, and other living organisms that affect growth. It is used to increase crop yield and production.
• The principle used in biological control is predation and parasitism. It kills the insect without causing any effects to human health—some of the microbes used as biocontrol agents are the Bacillus thuringiensis, Trichoderma, Baculoviruses, and Nucleopolyhedrovirus.
• Biological control also falls under organic farming.
• Sometimes chemical fertilisers can kill the necessary and wanted organisms present in the soil, so farmers use biocontrol agents to kill only unwanted organisms that cause disease to the plants.
• To approach the biological control process, one must know about pest management and its life cycle. For example, spraying BT solution made from seeds on the plant will kill the butterfly caterpillars. The dried seeds expel toxins from the intestines of worms and kill them.

Types of biocontrol agents

The biocontrol agents are broadly classified into two types. They are

1. Classical biocontrol (Importation)
2. Inductive Biocontrol (Augmentation)

Let’s see the types of biocontrol agents in detail- 

Classical biocontrol (importation)

• It entails the prey-predator relationship. Examples of classical biocontrol are aphid, parasitoid, baculovirus, and moths.
• A separate relationship is formed between plants and biological control animals.
• It is a natural organic method to control weeds, pests, insects, and other organisms.

Inductive biocontrol (augmentation)

• Here pathogens are used as biocontrol agents to kill the enemies that affect plant growth.
• Nematodes are examples of inductive biological control where nematodes prevent invasive plants from implementations.

Different biological control agents

Here are some biocontrol agents that control pests and weeds

1. Fungi
2. Predators
3. Bacteria
4. Virus
5. Parasitoids

We will further discuss the different biological control agents.

FUNGI

• Fungi is one of the components of rapid biocontrol methods and does not cause any harm to the environment.
• It has proven efficacy in controlling pesticides, more than chemical fertilisers and pest controllers.
• Entomophagy (fungi) is one of the forms of pest control against green peach aphids.

PREDATORS

• They consume a large number of organisms and remain as free-living organisms.
• Some predators that act as the biocontrol agents are spiders, dragonflies, lacewings, lady beetles, etc.

BACTERIA

• Coccobacillus bacteria are considered ideal bacteria for pest control and weed control.
• Bacillus Thuringiensis (soil-dwelling bacteria) is another example of bacteria.

VIRUS

• A virus also acts as an effective biocontrol agent, and it selects the specific targets for pests. Creating a virus that would selectively target pests and act as biological control is still being researched. Examples include baculovirus and nucleopolyhedrovirus.

PARASITOIDS

• It may cause death to the host by laying eggs as the larvae crave food from the host.
• Wasps and beetles are examples of parasitoids.
• The Aphidius colemani is one kind of wasp that lays an egg inside the aphid species. The larvae extract energy from the aphid that leads to death.

Advantages of biocontrol agents

• There are plenty of advantages to the biocontrol agents. They are eco-friendly, prevent soil pollution, and do not harm humans and other useful organisms in the soil.
• They are easy to use, available in all seasons, and cheaper than agrochemical pesticides and insecticides.
• They reduce the impact of chemicals and pesticides on the human body.
• They are cost-effective.

Disadvantages of biocontrol agents

• It is a very slow procedure. It takes a lot of patience and waiting for the biocontrol agents to work. 
• Biocontrol agents may not be able to remove the pest completely. 

Biocontrol agents: examples

Insects predators such as

• spiders
• files
• ladybugs
• wasps
• beetles
• dragonflies

Pathogenic microorganisms such as

• virus
• bacteria
• fungi

Parasitoids

• laying of eggs inside the host body

Microbial Biocontrol Agents and types

Ladybirds are common insects that eradicate aphids, and dragonflies are common insects that eradicate mosquitoes.

Microbes are used as biocontrol agents in three ways: causing disease in the host body, fighting with the host, or killing the host organisms.

Biotechnology has developed many biocontrol agents to eradicate pests and weeds by natural processes.

For example, Bacillus Thuringiensis is one of the best biocontrol agents as when humans spray them on the plants, the fluid fills the spores of the plants and kills the caterpillars.

These spores intake the Bt bacillus and release the toxin substance to kill the butterfly caterpillars. They release the toxin in the gut of the butterfly larvae to kill them.

Pest resistance and disease-resistant plants are developed using biotechnology. By injecting Bacillus thuringiensis into the plants, they become resistant to diseases and pests.

For example, BT cotton is one of the plants that are disease resistant and pest-resistant.

• Trichoderma (fungus) and Baculoviruses are some of the microbial biocontrol agents.
• Bacillus Thuringiensis controls the larvae of black flies, butterfly caterpillar larvae, and wax moth larvae.
• Beauveria Bassiana (fungus) acts as a biopesticide for bugs, mites, whiteflies, aphids, etc.

Arthropods and some other insects are affected by Baculoviruses, and it is also beneficial IPM (integrated Pest Management).

Trichoderma(fungus) is used for the treatment of plant disease.

Conclusion

In the Biocontrol Agents, we have seen the different types of Biological agents, biocontrol agents with some examples such as Bacillus thuringiensis, Beauveria Bassiana (fungus), Trichoderma (fungus), etc. In the biological control process, the biocontrol agents have been used to control pests, insects, and pathogens and eradicate unwanted weeds and plants.