Types, Merits and Demerits of Biocontrol Agents

May 20, 2023, 16:45 IST

Have you ever wondered what biocontrol agents do? Microbes are small single-celled organisms that can't be seen by our naked eyes. Some microorganisms are beneficial while some are harmful to humans. In this article, we will discuss everything about biocontrol agents, their types, biocontrol methods and types of biocontrol. A better understanding of the range of biocontrol agents will be provided in this article. It will also explain how they interact with the target pest which helps in the selection of a suitable agent for our production system. This article will also provide insight into how they can be more effectively used at a low cost.

Introduction

Biocontrol agents can be defined as biological measures to control pests and plant diseases; they are primarily utilised to reduce pest populations and generate the best pest-free crops. The infestation of plant pests such as weeds, insects, and mites is controlled by these agents. Biocontrol agents do not cause any harm to the organism present in the soil and are only effective on harmful organisms. Biocontrol strategies will play a vital role in reducing our reliance on hazardous chemicals and pesticides.

Biopesticides

These pesticides are produced from biological or natural agents such as plants, animals, bacteria, fungi, viruses, and other microorganisms. These are used to kill or control weeds, insects, and infections. Microbial pesticides and biochemical pesticides are the two main categories of biopesticides. On the other hand Insecticides and pesticides are based on chemicals which are exceedingly dangerous to humans and destroy the environment.

Biocontrol Methods

This method refers to using one type of living organism (insects, diseases, or grazing animals) to control a different type of living organism. It typically eliminates insect and weed infestations. For preventing the spread of invasive plant species this method is long-term and self-sustaining. The role of biocontrol agents which help in maintaining the balance is done by natural animals in the form of parasitism, predation along with other similar mechanisms. Scientists have categorised biological methods into three parts which are mentioned below.

• Introduction method

The introduction approach is the safe insertion of a small population of an upper trophic level species to regain ecological balance in a system that has been disturbed and safely taken over by a pest population.

• Augmentation method

Augmentation means the amplification of a beneficial organism's population at the appropriate time and place. The beneficial organism requires augmenting (increasing) its number from time to time because some intrinsic or extrinsic factor makes it incapable of regulating the target pest population to our satisfaction.

• Conservation method

The first subcategory of conservation methods is minimising the use of broad-spectrum pesticides, and the second is improving the landscape to provide suitable resources to promote natural enemy activity.

Types of Biocontrol

Biological control is broadly divided into two categories:

• Classical Biocontrol

The organic method of pest control is known as classical biocontrol. Classical biocontrol uses natural predators of the invasive plant. And if all the introduced species are not picked carefully, they can become significant pests.

• Inductive Biocontrol

Under this type, a large number of natural enemies are released into the soil to kill the target weed. The most suitable and effective inundation agent is nematodes.

Other types include

• Microbes (bacteria, fungi, viruses and other microorganisms or their metabolites or cell fragments) that can kill pests or outcompete and prevent diseases.
• Semiochemicals (message-bearing compounds) produced by animals or plants are used to change and disrupt a pest’s normal behaviour.

Different Biological Control Agents

Here are a few instances of biocontrol agents:

• Fungi

Fungi are believed to be a fast-evolving method that has proven to be a very efficient biocontrol alternative to chemical pesticides and does not cause any harm to the environment. As a biocontrol approach, fungi have gained popularity in recent years.

Ex:- Entomophaga (effective against the green peach aphid)

• Predators

The free-living species that eat prey throughout their existence are known as predators. Predators such as spiders, dragonflies, and lacewings are suitable for biological pest control as they mainly consume crops.

• Bacteria

In short, bacteria, which is the finest biological pest management method, infects the digestive systems of insects or other dangerous pests and restricts their range of options. Cocobacillus bacteria are more pathogenic to insects compared to other bacteria.

• Virus

Some studies found that viruses would be very unique to their hosts, making them efficient biocontrol agents. Scientific research is still on to develop a virus that would show a miracle in case of selectively targeting pests and acting as biological control.

• Parasitoids

The parasitoids are an effective biocontrol agent as they lay eggs in their hosts' bodies, which eventually kill them. This strategy of biological control is very common to use the dead host as a feeding source for the larvae.

Characteristics of Effective Biocontrol Agents

Biocontrol agents must meet several requirements and some of them are mentioned below.

• It should be able to colonise and multiply itself.
• It has the capacity to outlast competitors and endure longer in soil and host tissue
• It must not be pathogenic to the surroundings and not even to the hosts.
• A long shelf life after production must be present in biomass.
• A full expression of the agent must be allowed during delivery and application.
• It should possess a strong ability to search.
• And must include high rates of predation or parasitism
• shortest possible handling time capacity to endure at low prey densities
• Adaptability to a variety of environmental situations
• It must not be pathogenic to both plants and animals and be a strong competitor.
• Able to prevent or remove multiple pathogens
• have a high likelihood of survival in soil or host tissues

Advantages of Bio Control Agents

Biological control is a highly specialised and effective method.

Most of the time, predators will only control the population of the pest it is supposed to manage, making it a green alternative to chemical or mechanical pest control which is generally very hazardous.

• Very little effort is needed to maintain it running smoothly.
• Biological control may ultimately be more affordable.
• The pest population will often be reduced as the predator introduced is naturally predisposed to target the pests.
• Protection of biodiversity in managed ecosystems.
• Safety for humans and other non-target organisms;
• Are persistent, and able to kill throughout the season or life of the crop

Disadvantages of Biological Control

It is not always good in every manner. Here are some of the biological control’s drawbacks:

• All the pests will become uncontrollable in the end.
• It is designed to control a single problem and there is always the chance that the predator will switch to a different prey.
• This is a very time taking process but other treatments, such as insecticides, produce immediate results. Biological control has a long-term effect. It needs patience.
• Predators can only exist if they have food, so removing their food supply would threaten their survival so biological control is not the way to go if we want to entirely eradicate a problem. They can only lower the number of hazardous pests as the final result.
• A successful system of biological control takes a lot of time and money to design.
• Can sometimes fail in its specificity

Biocontrol Agent: FAQs

Q1. Is biological control effective?

Ans. Biological control, unfortunately, is not always effective. It is less effective against native insect pests and works best against exotic pests. It is advised to release

Q2. Why is biological control better than using weedicides and insecticides?

Ans. Yes, biological control is way much better because of the following reasons:

• Biological management does not harm crops and is preferred over weedicides and pesticides.
• Weedicides and pesticides erode soil quality on the other hand biological methods are environmentally friendly and do not harm the environment.
• Biological control is a self-sustaining and inexpensive method when compared to chemical products.

Q3. Why is Trichoderma used so much as a biological control agent?

Ans. The following is the reason we use Trichoderma as biological control agent

• Many enzymes that can disassemble the constituents of cell walls are produced by trichomonas.
• They emit several fungus toxic chemicals which stop fungal diseases from growing further.
• Many theories have been proposed to explain its effectiveness as a biocontrol agent to benefit plants.

Q4. What are the distinctions between biological control and natural control?

Ans. Beneficial insects and other environmental factors act as natural controls. A biological control refers to the deliberate modification of beneficial insect populations to control pest insects.

Q5. Why does biological control protect the environment better?

Ans. Insect populations are reduced through biocontrol, which has beneficial effects on the ecosystem. Natural enemies provide a more environmentally friendly alternative to the common practice of managing invasive species in the place of pesticides.