Microbial control of insects

Definition

The use of pathogenic microorganisms or their derivatives to suppress insect pest populations. This approach exploits natural enemies including bacteria (e.g., *Bacillus thuringiensis*), fungi (e.g., *Beauveria bassiana*, *Metarhizium* spp.), viruses (e.g., nucleopolyhedroviruses), nematodes (e.g., entomopathogenic *Steinernema* and *Heterorhabditis*), and protists (e.g., microsporidia) to infect, kill, or reduce fitness of target insects. Microbial control agents may be applied inundatively as biopesticides or conserved within agroecosystems to enhance endemic epizootics. The method is distinguished from biological control broadly by its specific reliance on microbial pathogens rather than predators, parasitoids, or competitors.

Etymology

From Greek *mikros* (small) + *bios* (life) + Latin *control* (regulation) + Latin *insectum* (cut into sections)

Example

Colorado potato beetle populations in organic potato fields may be suppressed by foliar applications of *Bacillus thuringiensis* var. *tenebrionis* (Bt), which produces Cry3A toxins lethal to beetle larvae upon ingestion.

Synonyms

• Microbial insect control
• Microbial biocontrol

Related Terms

• Biological control
• Entomopathogenic nematode
• Entomopathogenic fungus
• Bacillus thuringiensis
• biopesticide
• Integrated Pest Management
• epizootic
• Host-pathogen interaction

Usage Notes

Often used interchangeably with 'microbial biocontrol' but more precise than 'biological control,' which encompasses predators and parasitoids. Specialists distinguish 'microbial control' (pathogen-based) from 'microbial pesticides' (commercial formulations). Virulence and host specificity vary enormously: Bt is narrow-spectrum and gut-active, while *Beauveria* and *Metarhizium* are contact-active broad-spectrum pathogens. Environmental persistence and formulation stability are major practical constraints. Not all entomopathogens are suitable for augmentation; some are conserved primarily through habitat management.