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Biological control (bioprotection) beginners guide

Theme: Basics of biocontrol

Biological control agents, such as ladybugs, are often used to control insect pests like aphids. Quartl/via Wikipedia – CC BY-SA 3.0

Overview

What is biological control (biocontrol)?
Why is biological pest control needed?
What are the different types of biological pest control?
What are the different biological control agents?
The advantages of biological control
The challenges of biological pest control

What is biological control?

Biological control (or ‘bioprotection’) is the use of living organisms and naturally-sourced (or nature-identical) compounds to control pest and disease populations.

The IBMA (International Biocontrol Manufacturers Association) defines biocontrol products as: 


Tools originating from nature, with low impact on human health and the environment, manage pests, weeds, and diseases.

People have successfully used this approach for over 100 years to manage the spread of pests, protect crops, and restore balance to ecosystems and habitats.  

Biological pest control as a natural alternative to pesticides

Biological control takes natural technologies and uses them to control pests in an environmentally safe way.
When used correctly, it can enable growers to reduce the use of synthetic chemicals. This reduction can have a devastatingly negative impact on humans, wildlife, soil health, and crop production.


Invasive species or non-native pests are often pests that have been moved to new environments without natural enemies, enabling unchecked spread. At CABI, biological control has been proven as an effective way to control invasive species or non-native through a method called Integrated Pest management (IPM).

What’s the goal of biological pest control and who should use it?

The goal of biocontrol is to protect growers from unwanted pests and diseases on their plants whilst not endangering humans, harming wildlife or promoting pest resistance. It might be used as a quick attack method or as a prolonged build-up of immunity in the growing system. It also suits people interested in organic and sustainable farming.

Why is biological pest control needed?

Close-up of trichoderma fungus from under a microscope
Trichoderma viride (above) is a fungus and a biofungicide. It can be used as a biocontrol method to suppress diseases caused by fungal pathogens. Photo from CABI

Biological control methods are rising in popularity due to the safety (environmental, wildlife and human) and pest-resistance issues surrounding traditional chemical pesticides. 

In addition, the rise in popularity of low residue and/or organic foods from consumers has resulted in an increase in more natural methods of pest control being sought.  

Reduce synthetic chemical inputs

Synthetic chemical pesticides can have detrimental effects on a variety of factors in agriculture. They can disrupt soil life which then limits basic processes of plant growth and vigour, they can harm wildlife in and around the farm and pollute water courses.  

Toxic synthetic pesticides can directly impact human life through farm exposure, water contamination, and crop losses affecting livelihoods.

New pests and diseases

Increasing trade and travel between countries has resulted in non-native species landing in foreign locations, wreaking havoc on delicately balanced native ecosystems. Loss of natural predators, pathogens, and competitors that normally control pests and diseases disrupts the balance. This gives the invading pest a huge unfair advantage over its neighbors.

What are the different types of biological pest control?

Parasitic wasp (Diadromus pulchellus) attacking a leek moth pupa
Diadromus pulchellus attacking a leek moth pupa

There are several different strategies or types of biological control: augmentative, classical (importation), and conservation. 

Augmentative biological control


Augmentative biological control involves releasing natural enemies of the pest. These include microorganisms, natural substances, predatory insects, and mites capable of killing or suppressing pest and disease populations.

The release can be small but consistent over or across seasons (inoculative), or a larger release looking for more of an immediate impact (inundative). 

Classical biological control


Classical biological control, also known as importation biological control, introduces an exotic organism to control pests in an invaded area.

The aim is not to eradicate the invasive insect, but to bring its density below a suitable ecological or economic threshold. 

CABI – the organisation that manages the CABI BioProtection Portal – has a rich history of classical biological control. It investigates potential biological control agents for various invasive species globally. Its work has included releases of the biological control agent Diadromus pulchellus, a wasp species used to control the invasive leek moth, Acrolepiopsis assectella, in Canada.

Conservation biological control

Conservation biological control is the preservation – or conservation – of natural enemies that already exist in a given environment, controlling a pest population. This might be considered one of the most straightforward strategies or types of biological control as the natural enemies are already doing their job. The aim of conservation biological control is to maintain the biological control agent.

What are the different biological control agents?

A close-up of a nematode from under a microscope and one of its eggs
A nematode, a microscopic worm that can be used for biological pest control, and one of its eggs. Image from CABI

There are various types of biological control agent including microbials, natural substances, invertebrates (insects, mites, nematodes) and semiochemicals. These can disrupt, deter, or kill pests and diseases attacking plants.

Microbials

This group contains bacteria, fungi, viruses and other microorganisms that have the capacity to kill pests or outcompete and prevent diseases. Global registration and mass production make microbials widely available for protecting plants against various pests and diseases.

They relate to a pest or disease control method that contains microbes or microorganisms – very small living things.

Natural substances

Natural substances are made of components, including natural chemicals, that originate from nature and have antimicrobial, insecticidal or pest repellent activity. They might be obtained from plants, animals, and microorganisms, though not exclusively. They can also be synthetic copies of their original form.

Semiochemicals


Animals or plants produce semiochemicals, message-bearing compounds used to change and disrupt a pest’s normal behavior.

A pheromone or chemical signals from one organism to another modify the behavior of the recipient in biocontrol.

Macrobials

Macrobials, or sometimes called invertebrate biocontrol agents, include insects, nematodes and mites that when released will parasitize and/or feed on pests. 

Biological control agents can use beneficial parasitoids, such as parasitoid wasps. They lay their eggs inside the eggs of pests, preventing the pests from hatching. 

In 2021, CABI and Koppert Biologicals Systems Ltd in Kenya undertook a project to manage the tomato pest Tuta absoluta in Kenya using, among other things, the predatory mirid Macrolophus pygmaeus (known as MIRICAL).

The advantages of biological control

A close-up of a virus infected caterpillar which shows deformities on a tree trunk
A gypsy moth caterpillar infected with the nuclear polyhedrosis virus. Image from David Cappaert, Bugwood.org

Targeted


Choosing a biocontrol method involves selecting it for its specific ability to combat a particular plant pest or disease, ensuring a high success rate.

Learn more about how bioprotection methods can seek out pests.

Sustainable

The use of natural substances in biological control methods means it is highly unlikely there will be adverse effects to people, wildlife or the environment. It is a viable long-term solution applicable to all types of growing, including farms, private gardens, and greenhouses.

Learn more about how bioprotection is environmentally friendly.

Cost

Growers can sometimes source natural products at a lower price than synthetic chemical pesticides. But also, over the longer-term, by promoting better soil health and avoiding repeated applications of failing/resistant chemical pesticides, biologicals can become very cost effective.  

With classical biological control this can be a permanent, self-sustaining solution. Once implemented there is no need to re-apply. 

Additionally, using biocontrol can help farmer to access more markets, such as organic.

Safety


Biocontrol methods, made from materials sourced from nature, are unlikely to have any dangerous side effects. Unfortunately, side effects from some of the more toxic chemical pesticides are common including those that can affect people, plants and ecosystems both acutely (short-term) and chronically (long-term).

Learn more about how biocontrol can be a safer alternative to chemical pesticides.

Resistance

Biological controls bring new modes of action compared to their chemical counterparts, which slows down the rate of pest and disease resistance, bringing it to manageable levels. Also, scientists are continuously looking for new organisms and new modes of action to be ahead of the game.

Learn more about how bioprotection can slow pest resistance.

The challenges of biological pest control

Storage

Due to the ‘live’ nature of biocontrol methods, they often need appropriate storage facilities, such as refrigeration in order to keep the components alive and usable, which some growers may not have access to. However, in these cases, one could source an alternative biocontrol method that does not require specific storage means.

Education

As a relatively new method of pest control, some growers may not have the knowledge they need to properly implement biological control. Or, they may prefer to stay with methods they have previous tried.  

Saying this, biocontrol products will always come with labels and detailed instructions for how to use them. Plus, advisors (where available) will be able to give good tips on how to use the products to ensure efficacy. 

User education is an issue that CABI actively work to improve, including on projects such as the CABI BioProtection Portal and the Plantwise Plus programme.  

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