Sunspot activity affects honey bees’ ability to find their way home.

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.”

The paper: “Magnets, magnetic field fluctuations and geomagnetic disturbances impair the homing ability of honey bees (Apis mellifera)” can be viewed at:-
http://www.ibrabee.org.uk/index.php/component/k2/item/3598

The International Bee Research Association (“IBRA”) is the world's longest established apicultural research publishers and promotes the value of bees by providing information on bee science and beekeeping worldwide.

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