By David Suzuki with Faisal Moola

What happens to them is unknown. The adults are simply gone — thousands of them. No corpses left behind, nothing out of place. They are just gone.

It may seem like the set-up for an episode of CSI, but this mystery isn't about missing people — it's about missing bees. Strange as it may seem, a mysterious phenomenon called Colony Collapse Disorder is threatening bees across the United States and may be making its way into Canada.

The problem has researchers baffled. All of the adult bees in a colony will suddenly disappear without a trace, leaving behind only a small number of juveniles. The hive appears unaffected, just deserted. Remaining juveniles refuse to eat the stores of honey or pollen left behind. Other bee colonies meanwhile avoid the deserted hive — even though healthy colonies normally raid abandoned hives for leftovers.

What's going on? Scientists don't really know, but concern is high enough to have prompted a working group of researchers in the U.S. to study the problem. From what they've been able to determine so far, stress may play a key role.

Colony Collapse Disorder is hardly the first problem honeybees have encountered in North America. Bee populations are in serious trouble — suffering losses from mites, pesticides, and monoculture crops, especially in the United States. There, five species of bumblebees have disappeared in less than a decade. In fact, the dirth of natural pollinators in the United States has led to a growing industry of migrant domesticated bees. Each spring, tens of thousands of bee colonies are packed onto flatbed trucks and driven across the United States to stop at various farms and pollinate crops.

But all that travel isn't good for bees. Bees are naturally used to having a variety of food in their diets, but on these trips, they are stuck with a single food source — the crop they are expected to pollinate. They are also packed into their hives for long periods of extended driving, exposed to temperature fluctuations and high levels of carbon dioxide. In addition, this kind of large-scale movement of stressed-out insects creates ideal conditions for the spread of pathogens.

All of this adds up to bad news for bees. But researchers still don't know which of these factors, or all of them, or something else entirely, is triggering the collapse of colonies in the United States. Fortunately, we haven't seen the problem in Canada — yet. Although bees here are also declining and under tremendous pressure, we don't have such a large-scale migrant bee industry right now, which could be preventing Colony Collapse Disorder from getting a foothold on this side of the border.

Why should you care about the fate of some insects? Well, honeybees are of course important for the honey they make. But they are also one of the most effective pollinators we have. In the United States, they pollinate over $3 billion worth of fruits and vegetables every year. According to the U.S. Department of Agriculture, 30 per cent of all American fruits and vegetables come from plants that have been pollinated by insects — especially bees.

So bees are very important indeed. Pollinators in general provide an essential service that would be extraordinarily expensive, if not impossible, to replicate in other ways. Yet, natural and domesticated pollinators are by and large considered irrelevant or "externalities" to our economic system. If we want to ensure that this essential service is available in the future, we need to look at all the factors resulting in their declining numbers — from pesticide use, to monoculture crops and genetically modified crops, to the loss of forested areas that provide homes for wild bees, and work to reduce these pressures and keep this critical ecosystem service functioning. Colony Collapse Disorder may be the most recent and dramatic of bee mysteries, but their consistently declining numbers is just as disturbing.

April 27, 2007