Microbiology of feces of the larval honey bee,Apis mellifera

Methods for collection and microbiological examination of feces of larval honey bees, Apis mellifera, are described. Feces collected on sterile agar were inoculated onto selective media, some of which were acidified to approximate more closely the pH of larval food and the larval gut. A total of 104 microbial isolates were obtained from fecal collections of 20 larvae, although the feces of 4 of these larvae contained no detectable microbes. Microorganisms isolated in order of frequency were Bacillus spp., Gram-variable pleomorphic bacteria (Achromobacter eurydice?), molds (primarily Penicillia), actinomycetes, Gram-negative bacterial rods, and yeasts. It appears that larvae can become inoculated with microorganisms which are found in adult bees and pollen from ingestion of contaminated food. However, evidence for a constant symbiotic microflora which could contribute significant amounts of biochemicals to larvae is lacking.