Compounds in Honey Key to Activation of Detoxification Genes in Honey Bees

Three scientists from the University of Illinois (Illinois, USA) have detected key compounds in honey using high performance liquid chromatography (HPLC) that can up-regulate detoxification genes. HPLC was performed on ethyl acetate honey samples identifying four compounds that induce detoxification genes, potentially required for the detoxification of pesticides.

The western honey bee (Apis mellifera) is worth around $14 billion (US dollars) to the American agricultural economy alone; however, over the last five years there has been an approximately 30% drop in population numbers, according to the paper published in the Proceedings of the National Academy of Sciences.1 Scientists have labelled this phenomenon as “colony collapse disorder”, and it is characterized by the collapse of colonies as a result of the death of worker bees.

Leading author May Berenbaum told LCGC that the interactions between multiple stress factors, including pesticides and pathogens, appear to have caused this dramatic decline in honey bee populations in the United States. She said: “One common element influencing bee responses to multiple stresses is the nutritional adequacy of the diet, yet, despite its importance to bee health and thereby to the U.S. agricultural economy, little is actually known about the nutritional needs of honey bees.”

Berenbaum first became interested in the chemical composition of honey around 15 years ago, when honey was dismissed as “little more than sugar water” by several human nutritional science publications. According to Berenbaum, honey is concentrated plant nectar packed with a diverse range of phytochemicals that are essential to larvae and adult bee function. She told LCGC: “Among our first findings was that honey, depending on nectar source, can be a rich source of antioxidants even for human consumers.”

Ethyl acetate-extracted honey samples were analysed with HPLC and detected the presence of four major peaks  –p-coumaric acid, pinobanksin-5-methyl ether, pinobanksin, and pinocembrin.

The compounds were used in a “bioassay” whereby honey bees were fed either a diet of plain sugar water or sugar water supplemented with each of the compounds. P-coumaric acid was found to strongly increase the expression of detoxification genes.

The findings suggest that the widespread use of honey substitutes may need to be reviewed. Such substitutes include high-fructose corn syrup that lack these key compounds, specifically p-coumaric acid. P-coumaric acid is contained within pollen that, according to the paper, has been previously shown to reduce honey bee susceptibility to pesticides and pathogens. The results suggest that the immune system of honey bees could be improved by simply supplementing dietary sources of controlled colonies with p-coumaric acid.

Future investigations will probe how the processing of nectar and pollen by bees influences the phytochemical composition of honey. Berenbaum believes that bees are potentially able to change the composition of honey by incorporating enzymes, manipulating temperatures during storage, and even controlling fermentation reactions with symbiotic microbes.

Reference

1. W. Mao, M.A. Schuler, and M.R. Berenbaum, PNAS 10(22), 8842–8846
(2013).