Antibiotic

Definition

A substance, natural or synthetic, that selectively inhibits growth or kills bacteria by disrupting cell-wall synthesis, protein production, DNA replication, or other essential metabolic processes. In entomology and arachnology, antibiotics are used therapeutically to treat secondary bacterial infections from arthropod bites and stings, prophylactically in laboratory insect colonies to control bacterial pathogens, and experimentally to eliminate or study bacterial symbionts (e.g., Wolbachia, Buchnera) that influence host reproduction, nutrition, or immunity.

Etymology

From Greek anti- ('against') + bios ('life').

Example

Researchers treat aphid lines with rifampicin to eliminate their obligate bacterial symbiont Buchnera aphidicola, revealing the symbiont's role in synthesizing essential amino acids that the aphid cannot obtain from plant sap alone.

Synonyms

• antibacterial agent

Related Terms

• antimicrobial
• Symbiont
• Wolbachia
• bacteriocyte
• gut microbiota
• prophylaxis
• secondary infection

Usage Notes

Antibiotics are ineffective against viruses, fungi, and most eukaryotic parasites—distinct from antivirals, antifungals, and antiparasitics. In insect biology, antibiotic treatment is a common experimental tool to distinguish effects of the host genome from those of microbial associates, though results can be confounded by incomplete clearance or off-target effects on non-bacterial microbiome members. Overuse in laboratory settings can select for resistant bacterial strains.