Excessive use of harmful insecticides is now resulting in pesticide residues in the food chain, increasing pollution for natural enemies.
Entomology is the study of insects. This is an essential scientific discipline that helps us understand the complicated interactions that exist between insects and their environments. One of the problems that agriculture and forestry face is the damage caused by insect pests. To keep insect populations under control, integrated pest management provides cost-effective and eco-friendly tactics such as cultural, mechanical, biological, and chemical control.
Chemical control is last but not least. Unfortunately, chemical pesticides are frequently used in traditional pest management techniques. But they can have adverse effects on the environment, non-target species, natural killers (predators), and even human health.
Excessive use of harmful insecticides is now resulting in pesticide residues in the food chain, increasing pollution for natural enemies. It is also leading to an alarming increase in pest resistance. So, it becomes necessary to search for alternative means of pest control that can minimize the use of such synthetic chemicals. As a sustainable alternative, biological control uses nature’s resources to manage insect pests.
What is biological control?
Biological control is the process of controlling pest populations by introducing, enhancing, or manipulating natural enemies. These enemies can be pathogens, parasites, or predators that control pest populations and keep ecological balance normal.
Agents used in biological control are target-specific, thus minimizing their negative effects on beneficial organisms and the environment. These include entomopathogens, predatory insects, pheromone traps, parasitoids, and many predatory nematodes. Here we will discuss such agents and their benefits in biological control.
Entomopathogens:
Microorganisms are well known for their role in controlling the pest population through diseases. They inhibit growth and kill them without causing any harm to their predators. Other non-target populations, like pollinators or our crop, are also safe.
Entomopathogens are microbes that are specifically active pathogens in insects. These microbial pathogens include many bacteria, viruses, fungi, and nematodes. “Bacillus thuringiensis,” a well-known pathogen, serves in biological control against various notorious pests of many cash crops such as cotton, maize, and sugarcane.
Researchers also utilize many fungi, including Beauveria bassiana, Metarhizium anisopilae, Isaria fumosorosea, and Verticillium lacanii, to manage numerous insects like the fruit fly, Bactrocera zonata. While incorporating microbes into the host body of target pests usually takes time, manufacturers are now creating many liquid formulations for their easy and timely applications.
Parasitoids:
These are the organisms that lay their eggs either on the body or inside the body of their hosts. They are more dominant and effective natural enemies of insect pests. Their offspring feed on the host tissues and kill them. Parasitoids offer many benefits, such asthe fact that their life cycle is very short as compared to other predators, twhichincreases their reproductive rate.
They can locate their host insect on their own using chemical or visual clues called kairomones. Certain wasps and flies are commonly used as parasitoids in biological control. Trichogramma is one of the most widely used parasitoids, controlling over 28 different insect caterpillars of cotton, rice, sugarcane, vegetables, and other fruit trees.
Predatory insects:
Predators are the insects that feed on other insects, such as ladybirds, lacewings, coccinellid beetles, true bugs, mantids, dragonflies, etc.
These insects play an important part in pest population management by preying on important pests like aphids, mites, and other crop-damaging pests.
Predators have different modes of action for their prey. Some predators chew and devour their hosts, like ground beetles or ladybirds, also called coccinellids. Some have piercing, sucking mouthparts that try to suck fluids from their host bodies, while others are active hunters that run down their hosts. Predators are the best friends of gardeners.
Pheromone Traps:
Among all other practices, the use of pheromones or lures is becoming a famous biological control. Insects communicate using chemical synthesis. Many insect pests use plant volatiles to locate their hosts. Disturbing the mechanism for this process can be a very effective practice to control that pest.
The idea of using species-specific behaviour-modifying chemicals for the management of noxious insects in agriculture, horticulture, forestry, stored products, and for insect vectors of diseases has been a driving ambition through five decades of pheromones research.
Scientists use a large number of pheromones and other semiochemicals to monitor the presence and absence of insects to protect plants and animals. In most agricultural countries, air permeation and “attract-and-kill” techniques control insect populations on at least 1 million hectares.
Observations have shown that some plants emit volatiles that inform insects about the absence of a host or the presence of harmful substances. These repellent volatile substances can offer a new method for plant protection.”
So, we can say that plant volatiles have evolved to minimize the effects of herbivores, either directly by repelling them or indirectly by attracting their natural enemies. Three main elements account for the fascination of insect sex pheromones and their feasibility for insect management:
- They are species-specific.
- They are active in very small amounts.
- The vast majority of pheromones are non-toxic to other animals.
Pheromone-based control for long-term application decreases population levels of target species. Replacing insecticides with pheromone treatments in vineyards and orchards has rendered treatments against phytophagous mites superfluous, which compensates for the cost of the pheromone treatment.
This emphasises that the pheromone-based methods produce better results in the long run due to the recovery of the beneficial fauna. Pheromones are advantageous in controlling insects in hidden places, protected lifestyles, and those including underground or woodboring larval habits because they aim at the mobile adult life stage and are helpful to prevent oviposition.
Predatory nematodes:
Nematodes are microscopic worms that are effective predators of soil-dwelling insect larvae when put into the soil, offering an underground defence against damaging insects. These organisms do not affect plants or earthworms and feed on soft-bodied and slow-moving insect larvae.
These can be used to control pests that target underground parts of plants, like roots, etc. A parasitic nematode, Steinernema feltiae, is used to control pests on garden plants like shrubs and trees in their initial stages.
Benefits of Biological Control
Biological control not only controls the pest population but also offers some other benefits. Here we’ll discuss some benefits of biological control.
1. Eco-Friendly Pest Control:
Biological control methods are inherently sustainable, causing no harm to the environment. There is no residual effect issue that can contaminate the food chain, water, or soil. No hazardous effect means it promotes biodiversity.
2. Target-Specific:
Biological control agents are highly target-specific for their pests, so they pose negligible or no risk to beneficial organisms. So, ecological balance remains stable, favouring the growth of biodiversity.
3. Long-term stability:
Biological pest control, as opposed to conventional pesticides, which may lose effectiveness over time owing to pest resistance, can provide long-term pest management options.
4. Reduced Chemical Dependency:
Adopting biological pest management measures can result in a large decrease in the usage of chemical pesticides, reducing the dangers associated with their abuse.
Challenges and Considerations in Biological Control:
While biological control has many advantages, its success is dependent on a number of factors, including environmental conditions, proper implementation, and a thorough understanding of the ecosystem. Challenges may include the need for careful monitoring, ensuring control agent compatibility with existing agricultural practices, and overcoming resistance in target pests.
Conclusion:
Biological control in entomology offers a sustainable method for managing insect pests, ensuring effective control while preserving ecosystem integrity. With advancing research, integrating these methods into conventional agriculture promises a future that is environmentally sustainable and resilient. We can conclude that the biological method has become a mandatory step towards the management of insect pests.
We can save our economy by saving billions that are spent on insecticides annually and also by creating a safe and sound environment free from the hazardous effects of insecticides. Food security parameters can also be fulfilled by reducing the use of insecticides on edible crops like vegetables and fruits. The use of biological control agents with other pest management practices in the future will help ensure a clean and green environment as well.