The word 'pest' is thrown around a lot in everyday life. You would normally call a mischievous puppy or your little sibling one, but pest is an important term in the agricultural world too! Owing to the name, pests are species which disturb the productivity of agricultural environments. This can mean anything from a caterpillar eating crops for breakfast or wolves preying on unknowing sheep at night. This article will cover the importance of pest control in agriculture, some different methods of controlling pests, and the dangers of inappropriate pest control.
- This article will cover the importance of pest control in agriculture.
- First, we’ll learn the meaning of pest control in agriculture.
- Then we’ll describe different methods of controlling pests, which include chemical, biological, and natural pest control methods.
- We’ll finish by analysing the dangers of inappropriate pest control.
The Meaning of Pest Control in Agriculture
Pest control in agriculture is the deterrence or extermination of species threatening agricultural productivity. Farms are often businesses and depend on output so that the workers can earn money and fund their lives. Therefore, any factors affecting produce must be acted on swiftly and in a cost-effective way. Here are some examples of agricultural pests you should know.
- Weeds are invasive plants that take nutrients, water, and space from the desired crops.
- Locusts are probably the most dangerous of all agriculture pests. Small in stature, these insects can eat their bodyweight in crops in a day and often swarm in the millions. Locust swarms have devastated agricultural land for centuries.
- Aphids and whiteflies feed on the sap of plants meaning they lack nutrients to build other plant structures. They also feed on the flowers and carry dangerous diseases and viruses.
- Colorado potato beetles get their names from their love for potatoes, but these insects will feed on various vegetation. They are most dangerous because of their innate ability to evolve resistance to many different pesticides quickly.
- Corn rootworms, as the name suggests, feed on the roots of corn in their larval stage. This reduces the ability of the roots to absorb water, and yield decreases.
Fig. 1: Swarms of locusts are the most dangerous agricultural pest
Importance of Pest Control in Agriculture
Here's why keeping on top of pests is essential for agricultural workers wanting to maintain a productive farm:
- Improving yield: insects, birds, and small animals feeding on crops reduce the yearly output of these crops and, therefore, the amount of money a farm makes.
- Animal and crop health: disease-spreading insects, rodents and parasites can cause disease to spread between crops and livestock. Dangerous diseases can kill off animals and plants, while more minor ones will slow down growth and reduce yields.
- Contamination of produce: the ruining of produce that is ready to be transported to shops is probably the most aggravating way pests can impact agriculture (e.g., disease-carrying rodents like mice and rats). The long process of cultivating plants or rearing livestock is wasted if pests infest storage and transport facilities.
- Unbalanced ecosystems: pests with access to an abundant resource (such as a field of crops) may increase in numbers rapidly. This can disturb the equilibrium in ecosystems, where these pests may predate or compete with other species which do not have access to the same amount of resources.
Pest control methods in agriculture
There are diverse pest control methods in agriculture, from ancient and more manual ones to more modern and technological ones. The main pest control methods in agriculture can be divided into chemical, biological, and natural pest control.
Chemical Pest Control in Agriculture
Chemical use in pest control became popular in agriculture during the 18th and 19th centuries, even though workers were not knowledgeable of the effects of the chemicals they were using. Because of extensive research, more refined chemicals are used today, and farmers know the possible complications of applying them.
Fig. 2: A tractor spraying chemicals into a field.
Let's have a look at some agrochemicals.
Agrochemicals help farmers in protecting their crops from pests and diseases. They also play a role in optimising crop yields and improving soil fertility.
Insecticides
These are chemicals that specifically exterminate or deter insects. Insecticides can either be repellent or non-repellent. Repellents are applied to the plant and will give off unpalatable smells or pheromones specific to the pest species. In contrast, non-repellents are spread over a large area and directly exterminate the pest. Repellents require a regular application which can be time-consuming, while non-repellents are quick and straightforward but can contaminate soil and potentially poison crops.
Pheromones are chemicals released into the air by animals and insects which can affect the behaviour of members of the same species. Certain insecticides try to replicate these chemicals to deter insects from crops.
Insecticides came to prominence along with the Agricultural Revolution and are one of the main reasons crop yields have improved so much over the last century. However, in recent years, ecologists have realised insecticides' knock-on effects on ecosystems. Reducing (sometimes wiping out) insect populations can affect individuals involved in interspecies relationships in the ecosystem.
Interspecies relationships include competitors, predator-prey relationships, and symbioses.
- An example of competition is two species of plant competing for sunlight. This is because competition occurs when two species benefit from the same niche, but cannot do so at the same time.
- Predation occurs when one species are damaged in some way since the other is feeding on it. The consuming species is the predator while the species being consumed is the prey.
- An example of symbiosis is between the fungus and algae that make up lichen. The fungus keeps the algae moist while the algae synthesises carbohydrates that feed the fungus. This is because symbiosis benefits both species.
Fungicides
Fungi and fungal spores can be hazardous in agriculture. They can grow uncontrollably on crops and plant roots and release dangerous toxins and pathogens which damage crops irreversibly. Farmers will use fungicides to counteract them, which are made up mostly of sulphur. Processing various plants like rosemary, oregano, and tea tree can be a great way of producing natural fungicides, as chemical ones can potentially poison plants and contaminate the soil.
Mycorrhizae fungi are the exception to this rule; they actually exhibit a symbiosis with certain plants and supply them with nitrogen ions gaining carbohydrates in return.
Herbicides
Herbicides are chemicals which target weeds. These pesticides are notoriously very difficult to produce and apply because you are trying to kill a plant right next to the crops you want to grow! Herbicides are applied directly to plants or the soil and can inhibit photosynthesis or even the production of essential compounds by the plant.
Biological pest control in Agriculture
Biological pest control makes use of natural living enemies of pests. Now that governments and environmentalists are knowledgeable about the devastating effects agrochemical-contaminated soils can have when polluting aquatic ecosystems, alternative methods of controlling pests are being explored. There are three types of biological control you need to get to terms with: importation, augmentation and conservation.
Fig. 3: Ladybugs are natural pesticides in vegetable and flower gardens.
- Importation: this method involves introducing the pest's natural enemy into the agroecosystem. Many ecological variables must be considered when implementing this method, like whether the introduced organism will survive in the ecosystem or will it cause damage to other components of the ecosystem.
- Augmentation: introducing more individuals to an already established species is caused augmentation. This is usually a sounder method than importation because farmers know the species is adapted to the environment and ecosystem. However, it must be considered what effect increased numbers will have on other species in the area.
- Conservation: this is the safest method for other species. If there are already potential biologically controlling agents in the ecosystem, pests can be controlled by providing the conditions for their numbers to be maintained and potentially increase.
The release of parasitoids effective in killing moths is a form of biological control, for example, the invasive moth, Cactoblastis cactorum (which is interestingly used as a biological control agent for weeds itself). The moth is controlled by either the introduction of parasitoids from its native home in South America or by inundation with parasitoids known to attack the moth native to Florida.
Natural Pest Control in Agriculture
Natural pest control methods, sometimes called organic methods, do not involve any use of artificial substances and do not disturb the balance of ecosystems. The conservation method of biological control can be described as natural. This is because ecosystem equilibrium is not being affected as the naturally occurring population is just being maintained or slightly increased rather than drastically changed. Here are some natural pest control techniques:
- Companion planting- this involves planting crops that naturally defend each other. This could be one releasing smells that deter pests from the other or helps disguise the plant next to it.
- Organic deterrents- many non-synthetic products comprise the chemicals actually released by plants, so they will not harm the environment.
- Physically removing- especially in terms of weeds, simply picking and removing the pests can work too.
Importance of Appropriate Pest Control
We briefly covered some complications of inappropriate pest control in each section. Farmers must be considerate when applying chemicals or introducing new species to their agroecosystems because sometimes, the productivity gained from poor pest control practices is lost in other farm components. Here are some examples:
- Soil contamination: chemical pesticides deter pests but can poison crops and reduce soil fertility. This may result in smaller yields and stunted growth in the long term.
- Useful wild plants: during large-scale application of chemical pesticides, some harmless wildflowers and plants can be damaged. These species often sustain biodiversity in the ecosystem and help with heterogeneity in the field. Therefore, the gene pool will become smaller, and disease will spread more quickly.
- Disturbing the ecosystem: introducing new species to counteract pests or providing the conditions for natural enemy populations to increase can negatively impact the ecosystem. These species will often have relationships with many species in the ecosystem, so increasing their numbers will disrupt the balance of these relationships.
Pest Control in Agriculture - Key takeaways
Pests can be very costly in agriculture. They reduce crop yield and size, spread disease, and can contaminate produce.
Chemical pest control involves the application of synthetic substances which aim to exterminate or deter pests.
Biological control involves introducing, increasing, or maintaining populations of the natural enemy to the pest.
Farmers must be considerate when applying chemicals or introducing new species to their agroecosystems because sometimes, the productivity gained from poor pest control practices is lost in other farm components.
Natural control regards organic methods that do not have any ramifications for the health of crops of livestock or the functioning of the agroecosystem.
References
- Fig. 1: Oxya yezoensis November 2007 Osaka Japan (https://commons.wikimedia.org/wiki/File:Oxya_yezoensis_November_2007_Osaka_Japan.jpg) by Laitche, Public domain.
- Fig. 2: Tractor Fertilize Field Pesticide And Insecticide (https://flickr.com/photos/137169575@N04/24443679794) by Aqua Mechanical (https://flickr.com/photos/aquamech-utah/), under CC BY 2.0 License .
- Fig. 3: Ladybug eating aphids (https://flickr.com/photos/36517613@N07/49527476158) by David S. Ferry III, Public domain.
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