Bee Smart, Bee Healthy

From Bee Craft: July 2009

Nigel Raine, PhD

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Learning ability is linked to strength of immune response

Bumblebees that learn rapidly are able to fight off injection bt more slowly

BUMBLEBEE COLONIES which are fast learners are also better able to fight off infection. Dr Nigel Raine from the School of Biological and Chemical Sciences, Queen Mary, University of London, and Akram Alghamdi, Ezio Rosato and Eamonn Mallon from the University of Leicester tested the learning performance and immune responses of bumblebees from 12 colonies.

The team tested the ability of 180 bees to learn that yellow flowers provided the biggest nectar rewards and to ignore blue flowers. To test the evolutionary relationship between learning and immunity, they also took workers from the same colonies and tested their immune response against bacterial infection.

LEARNING PERFORMANCE AND IMMUNE RESPONSE

Like humans, bees’ ability to learn appears reduced when they are ill. Links between the nervous and immune systems of bees led to the prediction that good learners would be worse at fighting infections, following the assumption that bees would trade off allocation of resources between these systems. However, surprisingly, this was not the case.

The team reports a positive relationship between a bumblebee colony’s learning performance and their immune response, as Dr Raine explains: ‘Bees from fast learning colonies are not only the best nectar collectors (Bee Craft, April 2008,page 9), but also better able to fight infections. These colonies are probably much better equipped to thrive under difficult conditions’.

The team expected that immunity is likely to be a really important trait in social species (like bumblebees, honey bees and ants) that have high contact rates with closely related individuals leading to a greater chance of infection. There were big differences between colonies in how well they could fight off a bacterial infection, but these differences did not affect learning performance as previous studies had predicted.

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Bees from colonies which were quickest to learn that the yellow ‘flower’ gave greater nectar rewards also had a greater ability to fight infections (Photo: Tom Ings)

The team found a positive correlation between the ability of a colony’s workers to learn and the strength of their immune response, so there was no evidence for an evolutionary trade-off between these traits. Dr Raine adds: ‘Once again the humble bee is proving more complex than most people thought. These essential pollinators learn many things in their short lives and fight off a range of infections to survive’.

REFERENCE

A Alghamdi, NE Raine, E Rosato and EB Mallon (2009). ‘No evidence for an evolutionary trade-off between learning and immunity in a social insect.’ Biology Letters 5: 55-57. D0l:io.iO98/rsbl.2OO8.O5i4

[This research was sponsored by the Natural Environment Research Council (NERC).]

 

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