Biocontrol, short for biological control, is the practice of using living organisms or their products to suppress populations of harmful organisms such as insect pests, plant pathogens, or invasive species. By exploiting natural ecological interactions rather than chemical pesticides, biocontrol aims to reduce pest damage while minimizing environmental impact.
Agents and mechanisms of biological control
Biocontrol strategies rely on a variety of natural enemies and antagonistic microorganisms. Predators like ladybird beetles, lacewings, and predatory mites consume large numbers of herbivorous insects. Parasitoids, such as Trichogramma wasps, lay their eggs inside pest eggs or larvae, leading to internal development and death of the host. Entomopathogenic fungi like Beauveria bassiana and Metarhizium anisopliae infect insects through their cuticles, while insect-specific viruses like nucleopolyhedroviruses (NPVs) cause lethal infections in caterpillars. Bacteria including Bacillus thuringiensis produce crystal proteins that disrupt insect gut epithelium; these toxins are formulated as biopesticides and expressed in some transgenic crops. Other microbes, such as Pseudomonas fluorescens and Trichoderma species, suppress plant pathogens by producing antibiotics, lytic enzymes, or by inducing systemic resistance in plants. Mechanisms of biological control also include competition for nutrients and space, parasitism of weeds by insects or rust fungi, and the sterile insect technique, which reduces populations by releasing sterilized males.
Examples and applications in pest management
Biocontrol has been integrated into pest management programs worldwide. Classic examples include the introduction of the vedalia beetle (Rodolia cardinalis) to Australia in the 1880s to control the cottony cushion scale, saving the citrus industry, and the release of the moth Cactoblastis cactorum to manage invasive prickly pear cacti. Today, growers regularly release predatory mites to suppress spider mites in greenhouse crops and use parasitic wasps like Encarsia formosa against whiteflies. Bacillus thuringiensis formulations are applied against caterpillars in organic agriculture, and strains of Pseudomonas and Bacillus are used as seed treatments to protect roots from fungal pathogens. Conservation biocontrol practices, such as planting hedgerows and reducing broad-spectrum insecticides, foster the survival of native natural enemies. Biocontrol is a key component of integrated pest management strategies, providing long-term pest suppression while reducing reliance on chemical pesticides.
By harnessing ecological relationships and carefully matching control agents to target species, biocontrol offers a sustainable approach to managing pests and diseases. When implemented alongside cultural practices and monitoring, it contributes to resilient agroecosystems and biodiversity conservation.
Related Terms: Biological control, Integrated pest management, Bacillus thuringiensis, Predator, Biopesticide