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Honey contituents activate anti-bacterial and detox-controlling genes in bees, allowing them to break down pesticides and fend off infection. And this may explain bee population drops seen in recent years, because the food substitutes given to farmed bees to replace their honey lack these substances.
Bees are vital to pollinate our food crops, as well as to keep our wild areas diverse and beautiful. But their numbers have been in decline recently. Over the last 5 years, in the US, 30% of managed colonies have been lost each year.
Some people think this could be due to infection by pathogens, or to pesticides affecting the bees’ natural behaviour. A new paper, published this week in PNAS, however, suggests it may be due to the food they are eating.
Normally, bees collect pollen and nectar from flowers and use it to produce honey. But when food is scarce, or to save money, bee-keepers often substitute sugar syrup for the honey. Although nutritionally similar, Mao and colleagues from the University of Illinois have shown that it is lacking components that may be vital for the bees’ survival.
They extracted four components from honey, 3 of which cause increased activation of a family of genes, called cytochrome p450 oxygenases, that are responsible for detoxifying pesticides and metabolising other plant chemicals in the bee diet including honey flavonoids. The most potent gene-activating chemical was p-coumaric acid, which also up-regulated a gene encoding a protein that has anti-bacterial properties.
But modern bee-keeping methods mean that bees aren’t ingesting these compounds in as large a volume. This means they are less able to digest any poisonous compounds they encounter, or defend themselves against bacterial attack, which may be contributing to their decline.