Sunspot Activity Affects Honey Bees’ Ability to Find Their Way Home

IBRA     Press Release    September 14, 2014
 
Fluctuations in magnetic fields, including those caused by solar storms, may interfere with the 
magnetoreceptors in honey bees so that fewer bees return to their hives from foraging trips. A 
new study published today in the Journal of Apicultural Research finds that this disruption may 
be so severe that the flying bees disappear from their hive and that these losses may 
contribute to colony failure.
 
Bees can sense and use the earth’s magnetic fields to help them to identify their position and find their 
route home. This ability called magnetoreception is similar to that found in birds, fish and dolphins. 
Whilst bee magnetoreception has long been known, this new paper by Dr Thomas Ferrari from Pollen 
Bank, California, USA, for the first time identifies solar activity as one of the many causes of honey bee 
disappearance.

Widespread honey bee colony loss is not a new problem, and we now understand that many of these 
losses are due to various interacting factors including pests, diseases, pesticides and availability of 
suitable forage. Yet sometimes bees disappear without showing signs of illness, leaving adequate food, 
healthy brood but only a small cluster of bees. With good husbandry these remaining bees can 
sometimes be restored into a vibrant colony, and the disorder is not transmitted to other colonies. This 
situation can be distinguished from swarming behaviour and is one form of colony collapse - the flying 
bees simply vanish and their colonies fail. 

Like humans, bees use several different senses for navigation, but magnetoreception seems to become 
increasingly important the further the bee is from its hive. Through a series of experiments that subject 
foraging bees to magnetic fields to disrupt their ability to navigate, Dr Ferrari shows that they are less 
able to find their way home. Their homing ability also seems to be affected by uncontrolled, natural 
fluctuations in the Earth’s magnetosphere. The study links documented periods of increased levels of 
solar storms and disruption to the magnetosphere to increased levels of honey bee colony loss. 

IBRA Science Director Norman Carreck says: “For humans, the impact of sunspots on magnetic fields 
and their effects on bees is a difficult concept to grasp. Perhaps we could liken it to humans, who rely 
on sight, becoming lost in fog when we have no visual clues to help us identify our location. In 
unfamiliar territory any landmarks would be harder to recognise, so we find it harder is to work out 
where we are. This interesting study throws light on a curious aspect of bee biology. It is only part of 
the story of colony losses, but an aspect which merits further study.”