The demise of the humble honey bee has long been bemoaned by naturalists. Now it is alarming traders as it threatens to send prices of nutty snacks and sweets sharply higher, as California's almond orchards are hit by a decline in bee colonies.
A mysterious deterioration in the health of bees is affecting farmers around the world, but there is particular concern among US almond growers, who use more than a million bee hives to pollinate their orchards. The global almond wholesale market, a mainstay for confectioners and cereal-makers, is worth about $5 billion.
The price of renting bees for pollination has already trebled over the past decade to $150 a hive in California, which accounts for 80 per cent of the world's crop, with some farmers having to pay $200 last pollination season.
The rise in bee pollination costs comes as almond prices are hitting eight-year highs, according to researchers Mintec, with global demand for the nut supported by healthier living habits including a growing appetite for almond milk, whose dominant brands include Blue Diamond and Silk.
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"We are holding our breath," said Dennis van Engelsdorp, research scientist at the University of Maryland, ahead of the next pollination next February.
More than 1.5m bee hives are needed to pollinate California's almond orchards every winter, and researchers have become increasingly concerned about the rise in mortality for kept bees. Over the past seven years, the average winter "die-out" rate has been above 30 per cent, up about 10 percentage points from the historical trend.
"We're managing fewer bees and they're dying off at a higher rate," says Jeff Pettis, head of honey bee research at the US Department of Agriculture. Environmentalists have blamed pests, chemicals used on plants, pollution and changes in weather patterns for the decline, while some researchers have blamed "travel stress" as bees are shipped from crop to crop.
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The increased expense for almond growers comes as demand for the nut rises among consumers in China, the biggest export market for Californian almonds, and the US. China's demand has soared over the past few years, while in the US, the appetite for almonds is also rising.
Since Californian almond prices act as a benchmark, the rise in prices is having an impact in Europe. Alpro, a leading producer of almond milk in Europe, said drought, pollination problems and high demand had raised prices. Although the company sourced its almonds from Europe, it said it was worried about the impact on prices.
In the US, Californian almond growers who rely exclusively on bees to pollinate about 800,000 acres of orchard, are the leading users of the country's hives. "As the size of the acreage grows, you are going to need more and more bees," says Giles Hacking, managing director of London based nut traders CG Hacking and the chairman of the International Nut and Dried Fruit Council.
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Industry experts predict rental prices will continue rising as acreage expands, although some specialists warn that the high mortality levels could further hit the bee industry, which is already seeing increasing costs.
Eric Mussen, a bee specialist at the entomology department of University of California, Davis, said that the die-off rate "may be too high for beekeepers to continue paying for replacement colonies".