Australasian Science: Australia's authority on science since 1938

Death in the Hive

By Andrew Barron

Almost 5 years since colony collapse was identified, the science tells us there is neither a single cause nor a single solution.

In the northern autumn of 2006, beekeepers in the USA began reporting mass deaths of honey bee colonies. Apiaries were full of empty hives. Colonies appeared abandoned. Food stores and sometimes dead brood were left inside hives, but few or no adult bees, or even corpses of adult bees, could be found.

Colonies had failed rapidly and catastrophically. The problem was named colony collapse disorder (CCD), and soon reports of similar devastating colony losses appeared across the globe.

The problems have persisted, and US beekeepers have realised that despite their best efforts they will lose over one-third of their hives each year. This is far more than the industry can sustain, and honey bee populations globally are in severe decline.

So what’s killing the bees? New forms of pesticides, genetically modified crops expressing insecticidal toxins, parasitic mites, fungal diseases, old bee viruses, new bee viruses, intensive agriculture, intensive bee management practices and climate change have all been fingered as causes of CCD. To greater and lesser degrees all of these factors are contributing to the decline of the honey bee.

These stresses on colonies interact in complex ways that are currently not well-understood. For example, pesticide exposure or insufficient diets from floral monocultures may weaken bees’ immune systems. As the global trade in bee stocks has spread every major bee pest and disease almost everywhere in the world, it is extremely hard for immune-compromised bees to survive.

The current scientific consensus is that we will never find the cause of CCD. Rather, CCD is now recognised as a highly complex multicausal syndrome. In short, the problems facing our bees are legion.

This paints a bleak picture. What can be done? Thankfully, a global and integrated research effort involving close collaboration of scientists and the bee industry is now in full swing to address the problems that can be addressed.

Sublethal effects of pesticides on bees are now under very close scrutiny, which has already led to the tighter regulation or even removal of some compounds from the market in Europe. New sustainable treatments for bee pests and diseases are being explored and developed.

Some bee hives are naturally “hygienic” in that they very quickly detect and remove diseased brood from the colony. Measures are underway to spread this hygienic trait in commercial bee stocks.

Better bee management techniques are also being explored. If bees must now battle it out in a disease-ridden, pesticide-soaked and food-poor environment, how can we manage colonies better to help them survive?

The death of a bee hive is more than just the death of a lot of bees. It represents the collapse of a complex integrated society. My own research examines what happens to that society when the members within it are under stress. Understanding how bees react to stress at the colony level is helping us understand the process of colony collapse, and why colonies transition from healthy to empty so quickly. This is revealing the most effective ways to intervene to stop the collapse.

The news that bees are under threat has generated a worldwide wave of passionate concern, the likes of which has never before been directed at an insect. The impacts of this public attention run far deeper than just the current explosion in the number of beekeeper hobbyists. The bees’ problems have brought about a far-reaching and intelligent discussion of the long-term impacts of intensive agriculture on our environment, and the consequences of the resultant environmental degradation.

Truly addressing the causes of colony collapse will involve some fundamental changes in how we use the landscape to restore a more bee-friendly environment. This is something all of us, not just bees, could benefit from.

Andrew Barron is a senior lecturer with the Department of Biology at Macquarie University.