Uncovering the drivers of honey bee colony declines and losses

EcoHealth Alliance, a nonprofit organisation that focuses on local conservation and global health issues, has announced the results of research conducted on honey bee colony declines and the factors attributed to honey bee losses.

In a paper published this week in the journal EcoHealth, scientists at EcoHealth Alliance investigated the causes of long-term declines of colony numbers and annual colony losses.

The work shows that socioeconomic and political pressures on honey production over the past few decades has caused a long-term reduction in the number of colonies in production in the USA, Europe and many other countries.

More recently honey bee managers have reported increased losses in their stocks each year (so-called ‘annual colony losses’). EcoHealth Alliance’s research shows that pests, pathogens and management issues likely play a major role in this, and are under researched and poorly understood drivers.

Honey bees provide ecosystem services through pollination of crops worth $US215 billion annually worldwide. Concern over honey bee declines in recent decades as well as annual losses has sparked debate over their causes and led to hypotheses that a specific novel syndrome, ‘Colony Collapse Disorder’, is plaguing bee populations.

Many scientists have proposed new drivers such as pollution from pesticides as the cause of these declines.

EcoHealth Alliance conducted an in-depth, critical review of the science behind these declines and losses and have shown that:

1. The long-term multi-decadal downward trend in the number of bee colonies in many countries reflects a reduction in the profitability of bee keeping due to economic and/or political change, with many bee keepers leaving the profession;

2. Data on annual losses is sparse and collected in a non-uniform way that makes comparing the extent and potential cause of losses to those in previous years difficult.

3. There are significant inconsistencies with the way researchers (and thus potentially bee keepers) define CCD, suggesting that it may be over-reported; and

4. The major causes of annual losses include pests (e.g. the Varroa mite), pathogens (e.g. viruses that these mites carry), and the need for research and advancements in management techniques available for large-scale apiaries which have evolved from smaller “back-yard” productions.

Dr. Peter Daszak, Disease Ecologist and President of EcoHealth Alliance, said there is a growing understanding of the role that introduced pests and pathogens play in species declines.

He said:

“We call this phenomenon ‘Pathogen Pollution’, and bees are no exception – the role of introduced mites and the pathogens they carry is under researched and desperately in need of more work.”

Long-term declines have been documented in Europe and the USA, yet the overall number of colonies globally has increased 45 percent since 1961.

This in conjunction with the 300% rise in pollinator-dependent crops requires the industry to manage honey bees like never before. Millions of honey bees are moved annually to pollinate crops.

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