Paenibacillus larvae

Definition

A Gram-positive, rod-shaped, spore-forming bacterium (Firmicutes: Bacilli: Paenibacillales: Paenibacillaceae) and the causative agent of American foulbrood, a highly contagious and fatal disease of honey bee (Apis mellifera) larvae. Endospores remain environmentally viable for decades, resisting heat, desiccation, and many disinfectants; infection occurs when nurse bees feed spore-contaminated food to young larvae, after which the bacterium proliferates in the larval gut and kills the host.

Etymology

New Latin: Paenibacillus (from Latin paene 'almost' + Bacillus, reflecting its near-relationship to the genus Bacillus) + larvae (genitive of larva, referring to its host specificity for insect larvae).

Example

Beekeepers detect Paenibacillus larvae infection by the characteristic appearance of infected brood: sunken, darkened cell caps with puncture holes, and a glue-like, ropey consistency of the dead larval remains that adheres tenaciously to the cell wall.

Synonyms

• Bacillus larvae (obsolete)
• P. larvae

Related Terms

• American foulbrood
• honey bee disease
• endospore
• Apis mellifera
• melissopalynology
• colony collapse disorder
• brood comb
• foulbrood scale

Usage Notes

The species comprises two recognized subspecies: P. larvae subsp. larvae and P. larvae subsp. pulvifaciens. Formerly classified in Bacillus, it was reclassified to Paenibacillus in 1994 based on 16S rRNA phylogeny. Spore viability exceeding 35 years makes eradication from contaminated equipment extremely difficult; many jurisdictions mandate hive destruction or irradiation upon detection. Not to be confused with European foulbrood (caused by Melissococcus plutonius), which presents similar symptoms but requires different management.