Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2004
Publication Date: June 1, 2004
Citation: Evans, J.D., Lopez, D.L. 2004. Orally induced immune responses in the honey bee, Apis mellifera. Journal of Economic Entomology. 97:752-756. Interpretive Summary: Honey bees face numerous pathogens which generate high costs to the beekeeping industry. Honey bee health depends greatly on the ability of bees to fight off infections. As one defense, honey bees increase levels of antibiotic agents that seem capable of limiting the progression of diseases. We propose non-toxic dietary supplements that induce bees to fight disease. We found that bees fed these supplements showed a 20-fold increase in levels of one antibiotic, similar to the response achieved from exposure to disease-causing bacteria. We discuss ways that such a supplement can be delivered to bees within the colony. In addition, we develop an assay using non-toxic bacteria that bee breeders and researchers can use to screen bees for their abilities to mount an immune response. This screening can be used by researchers as well as bee breeders to help identify promising genetic lines of bees that are responsive against disease.
Technical Abstract: Honey bee larvae of four ages were exposed through feeding to spores of both a natural pathogen, Paenibacillus larvae larvae and to spores of a diverse set of non-pathogenic bacteria. Larvae responded by upregulating transcription of the gene encoding the antimicrobial peptide abaecin, both when exposed to the actual pathogen and to the probiotic mix. 1st-instar larvae responded significantly to the presence of the probiotic mix within 12 hours after exposure, a time when they remain highly susceptible to bacterial invasion. This response was sustained for two successive larval instars, eventually becoming 21-fold higher in larvae exposed to probiotic spores versus control larvae. The probiotic mix is therefore presented as a potential surrogate for assaying the immune responses of different honey bee lineages. It is also proposed that a dietary exposure to probiotic bacteria might help honey bee larvae, and other life stages, survive attacks from pathogens.