What are the Pest Control Methods in Agriculture?

Pest control methods can be grouped into five major categories based on the control agent used. These categories are natural pest control, biological pest control, chemical pest control, mechanical pest control, and Genetic control.

Natural Pest Control Methods

Natural Pest Control involves the use of natural methods of controlling pest population. These methods do not involve use of artificial compounds and do not hamper the ecological balance. Common methods include:

• Companion planting: In this method, two species of plants are together planted in the field. These species mutually benefit each other. One species may release compound that keep away pests and the other can attract predators of the pests. For example, planting aromatic herbs like basil or marigolds near tomatoes can repel pests like aphids and whiteflies, while attracting predatory insects like ladybugs and hoverflies.
• Physical removal: In this method, pests are removed by picking or uprooting. This method is labor intensive. Weeding is one example of such methods where weeds are handpicked from the fields.
• Use of biochemicals: This methods involve using natural products like neem extracts, eucalyptus oil, etc. to prevent the growth of pests and repel them.

Chemical Pest Control Methods

Chemical pest control involves use of agrochemicals to control the pest populations. These chemicals are together called pesticides. Pesticides can be grouped into different categories based on the type of pests they target. The main categories include Herbicides, Insecticides, Rodenticides, and Fungicides.

Herbicides

Herbicides are chemical substances used to control or kill unwanted plants, commonly known as weeds, in agricultural fields, gardens, lawns, and other areas. They can be applied to the plant directly or can be injected through soil. These chemicals work by disrupting essential plant processes such as photosynthesis, growth, or reproduction.

Depending on the mode of action, herbicides can be grouped as selective, non-selective, pre-emergent or post emergent herbicides.

• Selective herbicides target specific plants.
• Non-selective herbicides have a broad spectrum mechanism and can harm any plant they come in contact with.
• Pre emergent herbicides can prevent the germination of weeds.
• Post-emergent herbicides can kill actively growing weeds.

Common examples of herbicides include Glyphosate, 2,4-D or 2,4-Dichlorophenoxyacetic acid, Dicamba, Altrazine, Metolachlor, etc.

Rodenticides

Rodenticides are chemical substances used to control or eradicate populations of rodents, such as rats and mice. These chemicals come in form of pellets and are formulated in such a way that rodents get attracted to them and ingest them in lethal doses.

Rodenticides can be classified into different categories based on their toxicity and mode of action. Primarily they are classified as anticoagulant and non-anticoagulant rodenticides.

• Anticoagulant Rodenticides interrupt with clotting process of blood and lead to profuse internal bleeding and death. Examples include Warfarin, bromadiolone, etc.
• Non-anticoagulant Rodenticides interrupt with other vital mechanisms and hamper the functioning of vital organ systems that ultimately result in death. Common examples include zinc phosphide, Vitamin D3, and bromethalin.

Insecticides

Insecticides are chemical substances used to control populations of insects. These chemicals are formulated to target specific insect species and can be applied in various forms, including sprays, dusts, or as systemic treatments.

Depending upon their chemical composition and mode of action, insecticides can be classified as organochlorides, organophosphates, growth regulators, pyrethroids, carbamates, etc.

Fungicides

Fungicides are chemicals that are used to kill fungal populations. They can be broad spectrum or narrow spectrum depending on the number of fungal species they can target.

A broad spectrum fungicides targets a large number of species whereas a narrow spectrum fungicides is specific to few species.

Fungicides can also be classified based on the mode of their action. If they target more than one metabolic function, they are called multi-action fungicides, and if they target a specific metabolic function, then they are called single action fungicides.

Common examples of fungicides used in agriculture are ethylene bisdithiocarbamates (EBDCs), Triazoles, Captan, Azoxytrobin, etc.

Also read: Agrochemicals and their effects on soil

Biological Pest Control

Biological pest control includes methods in which biological agents such as natural predators, viruses, protozoans, insects, etc are used to control pest populations. These agents are also called bio pesticides or biocontrol agents. Biopesticides are mainly of two categories: bioherbicides and bio insecticides.

Bioherbicides

Bio -herbicides are those organisms which can destroy weeds without harming the useful plants. These organism are host specific and thus do not impact the standing crops. Bio herbicides can be a fungus, bacteria, protozoa, insects, or even another plant species. For example:

• The bacterium Pseudomonas fluorescens produces compounds that inhibit weed germination.
• Plants like maize, sorghum, etc. produce compound that inhibit weed growth around them.
• Some common insects like beetles, mites, etc. are host specific pests of certain weeds and can be used to control weed growth.

Bio-insecticides

Bio-insecticides are those organisms which can kill insect pests. They can be natural predators, pathogens ,or plants that release compounds toxic to a insect population.

For example:

• The oil from the flowers of neem tree is a natural insecticide and is applied on tree barks to protect them from termites.
• Ladybug is a natural predator of aphids and hence are released into field prone to aphid attacks where they keep the aphid population under control by feeding on them.
• Baculovirus heliothis, a virus that can be used to kill pests that destroy plants like tomato, cotton, and maize.

Mechanical Pest Control

Mechanical pest control involves the use of physical methods and barriers to manage pest populations and prevent damage to crops.

Common methods include handpicking pests, using traps and barriers, implementing cultural practices like crop rotation and sanitation, and employing mechanical destruction techniques such as tilling and vacuuming. These methods are highly labor intensive but are preferred due to their eco-friendliness and sustainability.

Genetic Control

Genetic control of pests involves manipulating the genetic makeup of pests to reduce their reproductive capability or susceptibility to control measures. This can be achieved through techniques like genetic engineering or selective breeding to introduce traits that make pests less harmful or easier to manage.

For example, genetically modified BT crops produce the BT toxin that when ingested by pest can prove lethal for it. Thereby controlling the pest population.

Pest control methods in agriculture include several processes that control the growth of pests. Pests are organisms that harm agricultural produce and livestock. Methods of controlling pests include the use of predators, chemical pesticides, natural pesticides, mechanical pest barriers, etc. When used individually, these methods can present detrimental effects to a greater extent. Hence, integrated control methods are implemented most of the time and these processes are together called integrated pest control methods. Pest control in agriculture is of immense importance as it ensures larger produce with less economic losses.