Honey constituents up-regulate detoxification and immunity genes in the western honey bee Apis mellifera

Abstract

As a managed pollinator, the honey bee Apis mellifera is critical to the American agricultural enterprise. Recent colony losses have thus raised concerns; possible explanations for bee decline include nutritional deficiencies and exposures to pesticides and pathogens. We determined that constituents found in honey, including p- coumaric acid, pinocembrin, and pinobanksin 5-methyl ether, specifically induce detoxification genes. These inducers are primarily found not in nectar but in pollen in the case of p- coumaric acid (a monomer of sporopollenin, the principal constituent of pollen cell walls) and propolis, a resinous material gathered and processed by bees to line wax cells. RNA-seq analysis (massively parallel RNA sequencing) revealed that p- coumaric acid specifically up-regulates all classes of detoxification genes as well as select antimicrobial peptide genes. This up-regulation has functional significance in that that adding p- coumaric acid to a diet of sucrose increases midgut metabolism of coumaphos, a widely used in-hive acaricide, by ∼60%. As a major component of pollen grains, p- coumaric acid is ubiquitous in the natural diet of honey bees and may function as a nutraceutical regulating immune and detoxification processes. The widespread apicultural use of honey substitutes, including high-fructose corn syrup, may thus compromise the ability of honey bees to cope with pesticides and pathogens and contribute to colony losses.

Timing and size of daily pollen meals eaten by adult females of a solitary bee (Nomia melanderi) (Apiformes: Halictidae)

“…Such regular pollen feeding highlights the importance of pollen, not just nectar, in the diet of adult solitary bees. These results support Richard's (1994) assertion that dietary pollen underpins a female solitary bee's ability to reproduce and, extrapolating from honeybee studies (Mao et al 2013;Brunner et al 2014;Wang et al 2014), may generally extend bees' longevity and maintain a healthy immune system. Given the magnitude and regularity of pollen feeding by adult female N. melanderi , combined with Taniguchi's (1956) broad taxonomic survey, we expect similar ingestion patterns from nesting females of other solitary bee species.…”

“…The sugars of ingested nectar are the primary source of energy for both adults and larvae of all bees, whereas pollen provides all essential amino acids, some lipids (i.e., sterols), vitamins (Schmidt and Buchmann 1985;Roulston and Cane 2000), and other chemicals central to bee health (Mao et al 2013;Brunner et al 2014). The manner in which pollen is incorporated into the diet of adults contrasts among bees, especially between eusocial and solitary species.…”

Pharmacophagy and pharmacophory: mechanisms of self-medication and disease prevention in the honeybee colony (Apis mellifera)

“…Nutrigenomic studies used methanol and ethylacetate extracts of honey to measure transcriptional changes in healthy bees (Johnson et al 2012;Mao et al 2011Mao et al , 2013. As a common result, genes related to detoxification processes and innate immunity (antimicrobial peptide genes) were upregulated in groups of bees fed with these extracts.…”

“…A single substance seemed to modulate the measured transcriptional changes. The phenolic acid p -coumaric acid, the monomer of sporopollenin (the major plant spore and pollen outer wall compound), was isolated from these extracts and shown to actively detoxify pesticides and to activate innate immune system gene expression (Mao et al 2011(Mao et al , 2013. p -Coumaric acid can be detected in honey, pollen, beebread and propolis, but not in nectar.…”

Healing power of honey

“…When I look back at that first day of class, I expected the answer to be "insects are cool" so that I could start discussing unique aspects of their physiology. In PNAS, Mao et al (3) substantiate my view, unravel unique aspects of the physiology of the honey bee, demonstrate how honey plays a crucial role in bringing bees back home, and suggest that current beekeeping practices may be responsible, at least in part, for CCD.…”