What is biological control？
Biological control is one of the core pillars of modern sustainable agriculture. It refers to the use of organisms or their metabolites to control harmful organisms (such as pests, weeds, and pathogens). The core idea is not to completely eliminate pests, but to control their populations below the economic threshold (i.e., the level that causes economic losses), thereby restoring and maintaining ecological balance.
Biological control techniques are divided into four categories:
Microbial is microbial based and includes but is not limited to bacteria, fungi, protozoa, viruses, viroids, peptides, mycoplasmas, and can include whole microorganisms, living and dead cells, any associated microbial metabolites, fermentation materials, and cell debris.
Semiochemicals are substances released by plants, animals, and other organisms for intra- and/or interspecies communication, with a target-specific and non-toxic mode of action.
Natural substances consist of one or more components derived from nature, including but not limited to: plants, algae/microalgae, animals, minerals, bacteria, fungi, protozoa, peptides, proteins (e.g., enzymes, antibodies), viruses, viroids, and mycoplasmas. They may be derived from nature or synthesized to be identical to nature. This definition excludes semiochemicals and microorganisms, which have their own definitions.
Among natural substances, IBMA considers peptides and proteins containing modifications to peptide/protein sequences from nature to be considered nature-identical if all of the following conditions are met: (1) they contain only naturally occurring amino acids; (2) the modifications do not alter the three-dimensional structure; (3) the modifications do not alter biological function; and (4) biodegradation occurs in a predictable manner according to natural pathways.
Invertebrate biocontrol agents (also known as macrobial control agents) are natural enemies such as insects, mites, and nematodes that control pest populations through predation or parasitism.
Advantages and disadvantages of biological control：
Advantages：
Environmental – Biological control is natural and does not rely on artificial chemicals that could adversely affect ecosystems. It can also reduce the amount of herbicide required for weed control.
Cost – After deducting initial research costs, once the agent is established and has an impact on weeds, the only further expenditure required would be for monitoring activities.
Sustainability – It is permanent and therefore completely sustainable. The weed is constantly attacked by an army of natural enemies.
Spread – The control agent, whether an insect or pathogen, locates and affects most, if not all, weed populations until they are stopped by physical, environmental, or chemical barriers, just as they would in their native range.
Safety – Biological control agents pose no threat to human health, crop production, or beneficial organisms.
Landscape – When these agents are effective, previously eliminated native species can gradually recover and recolonize areas without the need for large-scale replanting.
Disadvantages：
Control, not eradication – A successful agent should not eradicate the weeds it relies on, but rather reduce them to acceptable levels. Alternative control methods may have associated costs.
Timescale – This takes time. It may take 5 to 10 years from release to successful control.
Impact — The full impact on the target weed cannot always be predicted.
In addition to biological control, chemical pesticides are also common in modern agriculture. The relationship between biological control and chemical pesticides is not simply one of opposition or substitution, but rather one of synergy, complementarity, and integration. The core of modern integrated pest management (IPM) lies in how to scientifically combine the two, leveraging their respective strengths while mitigating their respective weaknesses.
What is Chemical pesticides？
Chemical pesticides are synthetic chemicals used to prevent, eliminate, or control agricultural pests, weeds, and other harmful organisms. They typically act quickly and effectively, but they can also cause environmental residues, pesticide resistance, and damage to non-target organisms.
Advantages and disadvantages of Chemical pesticides：
Advantages:
Fast and Efficient: Can quickly eliminate large-scale pest and disease outbreaks and save crop losses..
Convenient: Easy to store, transport, and apply.
Cost-Controllable: In the short term, the cost per unit area for pest control is relatively low.
Disadvantages:
3Rs: Pesticide residues, resistance, and resurgence.
Environmental Pollution: Pollution of soil, water, and air is a serious problem.
Ecological Damage: Indiscriminately killing pests’ natural enemies disrupts the natural balance, potentially leading to more severe pest outbreaks without natural enemies to control them.
Health Threats: Pesticide residues accumulate through the food chain, posing a potential risk to human health.
Comparison of biological control and chemical pesticides:
| Feature Dimension | Chemical pesticides | Biological control |
| Nature | Chemically synthesized substances | Living organisms or their metabolites |
| Mode of action | Direct poisoning, contact killing, stomach poisoning, fumigation, etc. | Predation, parasitism, competition, induced resistance, production of antibiotics, etc. |
| Speed of onset | Very fast (hours to days) | Relatively slow (a few days to a few weeks, or even longer) |
| Special effect period | Shorter (easy to degrade or lose) | Longer (once a population is established, it can be effective for a long time) |
| Targeted | Broad spectrum (good and bad) | Highly specific (usually targeting only specific pests or diseases) |
| Risk of drug resistance | Very high, which can easily lead to pest resistance | Very low, not prone to drug resistance |
| Environmental residues | Environmental residues may pollute soil, water and air | No or very low, environmentally friendly |
| Impact on the ecology | Larger, will kill natural enemies, pollinating insects and other beneficial organisms, destroying the ecological balance | Small, protect biodiversity, and be beneficial to ecological balance |
| Safety of humans and animals | Possibly toxic, with the risk of excessive pesticide residues | Highly safe, safe for humans, animals and non-target organisms |
| Cost | The initial cost is low, but the long-term cost may increase due to resistance | R&D and initial introduction costs may be high, but long-term costs are low |
| Technical threshold | Low, easy to use | High, requires professional knowledge and skills, high management requirements |
Conclusion:The development of biological control and chemical pesticides in modern agriculture reflects humanity’s deepening understanding of the relationship between humans and nature: a shift from an initial “confrontation and conquest” to today’s “regulation and harmony.”
Future developments in this field will demonstrate the following trends:
Biological control technologies will become more precise and intelligent, with new biopesticides and intelligent release devices based on gene editing and RNA interference technologies emerging in large numbers.
Chemical pesticides will further evolve toward “green” and “precision,” with nanocarriers and targeted delivery technologies reducing pesticide usage to extremely low levels.
The synergy between the two will become more seamless and efficient. Powered by big data, artificial intelligence, and the Internet of Things, decision-making systems will be able to analyze field data in real time and automatically determine the optimal combination of biological or chemical interventions, achieving true “smart crop protection.”
Ultimately, the modern agricultural plant protection system will be a multi-layered, three-dimensional ecosystem. In this system, biological control serves as the foundation and constant maintenance of system health, while chemical pesticides serve as the prudent, precise “scalpel.” The coordinated development of the two will safeguard our food security, environmental safety, and the future of sustainable agricultural development.