Lab report

How many bees do we actually need? Nobody seems to know. Plus, stem cell research is finally put to the test
March 1, 2009
Will there be honey still for tea?

When should we start panicking about the bees? Einstein's often-quoted claim that without bees humankind would have only four years left is almost certainly invented, but his authority isn't needed to make the crisis real. Bee populations are being devastated worldwide. Three of Britain's 25 bumblebee species are now extinct, with seven more threatened. In the US, much crop pollination is now carried out by commercial, mobile bee colonies, which are themselves in a parlous state. In China, too many pesticides mean fruit trees are now often hand pollinated.

Everyone agrees that bees are vital for agriculture, with one estimate putting their value to the British economy at £1bn annually. But no one is quite sure about the reasons for their decline. Certainly, bees have been hit hard by viruses and parasites such as varroa mites. Irresponsible pesticide use has played a part. And climate change is implicated too: fur-coated bumblebees are driven northward by rising temperatures. Local weather events can play a part, as when some attributed the demise of nearly one in three British honeybee hives in 2008 (the usual mortality is just 5 to 10 per cent) to the preceding wet summer.

As in medicine, the first step in dealing with a poorly understood effect has been to slap a name on it: the global decline is now called colony-collapse disorder (CCD). But there's no consensus about what this is, or even whether it is a single phenomenon. That hasn't stopped attempts to attach blame: beekeepers cite bad insecticide practices, but crop farmers deny it. One suggestive survey found a paralysing virus in 83 per cent of hives that had fallen to CCD, but in only 5 per cent of hives that had not. More likely that the truth lies in a multiple-whammy.

Sadly, scientists seem unable to answer the most pressing question: how many bees do we need? Natural bees are running out in some areas—for instance during California's bee-hungry almond harvest—necessitating the greater use of "bee pollination services." If native bees continue to decline, the need for such things will only increase. But if the supply of mobile bees begins to falter too—as some fear it might—it won't just be honey suppliers that are in trouble.

Stem cells on trial in America

The US Food and Drugs Administration has approved the first clinical trial of stem-cell therapy. Although it has nothing to do with President Obama's promise to remove restrictions in this field imposed by the Bush administration, it is being seen as symbolic of the new freedom that American scientists anticipate. Bush banned the use of federal funds to make or study stem-cell lines created after August 2001. Thomas Okarma, CEO of the Geron Corporation, which will conduct the trial, says that "the delay caused by the White House has meant that there are people out there who might have benefited, but who now cannot."

That, however, will depend on whether the treatment works. The trial will give stem-cell transplants to people with recent spinal-cord injuries, in the hope that these will develop into the tissues that sheathe and protect remaining undamaged nerves. It won't yet enable damaged nerve fibres to recover, nor can it help patients with long-term injuries or paralysis.

The approach is effective in rodents, but some researchers worry about how humans will respond. Particularly troubling is the tendency of stem cells to proliferate into tumours. The beleaguered field could be harmed if the first clinical trial doesn't work, and opinion is divided on whether the data justifies the Geron trial. Okarma maintains that Geron has much more encouraging data than it is at liberty to make publicly available.

Stem-cell treatments have made slow progress regardless of Bush's policies. But their potential, ranging from remediation of neurodegenerative diseases to the growth of new organs, is so vast that the reality is almost bound to disappoint.

Plankton cannot save us

The lesson that "it's not as easy as that" is one confronting climate scientists too. It is more than 20 years since the oceanographer John Martin proposed that the growth of marine plant plankton (phytoplankton) could be fertilised by dumping iron, an essential nutrient, into the sea. Because plant growth fixes carbon dioxide into tissues, the idea was that enhancing phytoplankton "blooms" could offset greenhouse warming.

But we're little closer to knowing whether it would work. For one thing, there have been conflicting indications of whether plankton blooms will really respond to a dose of iron. And even if they do, might some other factor then kick in to limit growth? A new study from researchers at Britain's National Oceanography Centre seems to confirm the sceptics. The expedition to the Crozet Islands, about 2,000km southeast of South Africa, measured the effects of the increase in ocean iron provided by windborne iron-rich dust from the island group. The scientists found there was a much smaller boost to phytoplankton growth than was predicted from earlier measurements taken off the Kerguelen archipelago to the east. The reasons for the difference aren't clear, but the results imply that attempts to engineer climate by iron fertilisation would have little global impact.