From: Issue 47
Viruses, parasites, invasive species and pesticides are proving too much for the world's bee population, the decline of which is having a profound impact on how crops get pollinated, and how the world gets fed
Every year, the numbers heading to work in California’s central valley increase. In a pattern reminiscent of the mass migration illustrated in John Steinbeck’s The Grapes of Wrath, millions ride trains and buses to provide much-needed labour in the fertile valley. Only this time, it’s honey bees that are the labourers, sent to pollinate the massive almond crop that provides 85 per cent of global production.
About 1.5 million bee colonies – an estimated 60 per cent of the beekeeper-maintained domestic population – can now fetch up to $200 a hive for rental. The need to import over 30 billion honey bees from as far away as Florida has exposed the extent of modern agriculture’s dependence on the honey bee, and the food security dangers that lie in store as the worldwide pollination crisis unfolds.
More than 20,000 known species of bees serve as the lynchpin of a global pollination ecosystem that also includes hummingbirds, beetles, flies, moths and many others. “Every time we look deeper, we find the pollination system to be even larger and more complicated than our current models,” says bumblebee ecologist and conservation expert Dave Goulson. “The research is pretty nascent in this area, but it only points in one direction.”
The Food and Agriculture Organization of the United Nations has found 80 per cent of all flowering plant species and 35 per cent of worldwide crops to be reliant on these pollinators for reproduction. A team of researchers from four German universities recently estimated the value of ecological pollination services at approximately €265 billion (US$360 billion) a year.
Although researchers and ecologists have long warned about the mounting threats challenging pollinators across the globe, the emergence of colony collapse disorder (CCD) has focused research efforts and media attention on the problem. In 2006, honey bee populations in Europe and North America began dying off at a much greater rate than before. Unlike previous spells in apicultural (beekeeping) history, it has shown no signs of subsiding.
“We’ve been facing a general decline in bee populations, around 30 per cent or higher for the past seven years,” says Canadian Association of Professional Apiculturists president Rheal Lafreniere. “There’s little doubt that it has to do with their health.”
Researchers agree that a confluence of factors is driving honey bee deaths, while also serving to weaken the remaining population. For University of Maryland entomologist Dennis vanEngelsdorp, establishing causality remains a work in progress. “We know that it involves the parasitic varroa mite, poor bee nutrition, and there is increasing evidence in the U.S. that more and more land in the Midwest is being ploughed under by corn and soybean, with more exposure to pesticides,” he says.
The spread of viruses and parasitic mites has steadily accelerated as bees are brought together from different areas of the globe. Strict regulations ban bee exports and imports along the Canadian border, but bees from Michigan mingling with bees from Florida results in a mass exchange of parasites. The Asian varroa mite has proven to be particularly deadly, spreading from Indonesia to every continent but Australia. The International Centre of Insect Physiology and Ecology, based in Nairobi, has uncovered a number of European diseases in Kenyan bees.