Humans aren't the only ones to get confused when they fall ill. Bumble-bees, the fuzzy insects that most people love, actually fail to remember where nectar-rich flowers are located. Researchers at Britain's University of Leicester conducted a study to investigate the effects that illness has on bumble-bees. Their findings were recently published in the Royal Society journal Biology Letters.

In their study, the researchers split the sample of bees into two groups: the first was a control group, and the second was injected with lipopolysaccharide, a soluble acute-phase protein that binds to bacterial lipopolysaccharide to elicit immune responses. The bees in the second group did not have to be infected with a disease.

The researchers gave either blue or yellow artificial flowers to the bees. Only one of the coloured flowers contained sugar water. Each bee flew 90 times to these flowers; every flight was recorded by the research team. The findings showed that the bees used most of their time flying to the rewarding flowers. The immune-stimulated bees, however, took longer to reach this point, the researchers said.

'Disease can influence different behaviours including foraging, mate choice, and predator avoidance,' said Dr Eamonn Mallon, a lecturer in Animal Biology at the University of Leicester, and leader of the research team. 'Several recent papers have shown reduced learning abilities in infected insects. However, it is difficult to separate the effects of the immune response from the direct effects of the parasite,' he added. 'That was the purpose of our study.'

Dr Mallon pointed out that the research has two signification applications. 'Firstly, there is a lot of interest in the connections between the immune system and the nervous system in human biology. The Mallon lab was the first to show that these interactions also exist in the much more experimentally tractable insects.'

He went on to say that there is also a concern about what is currently happening in the bumble-bee world. The wild bumble-bee species is in decline and the effect of disease is having a major impact on the honeybee industry. 'It has been shown that learning is vitally important to how well a colony prospers,' Dr Mallon said. 'This effect of immunity on learning highlights a previously unconsidered effect of disease on colony success.'

The research was carried out between the University's Department of Biology and Department of Genetics. Future research will tackle the neuro-immune interaction issue, specifically to determine whether the immune system uses up some of the resources needed to form memories or if the damaging effect of the immune response on the nervous system is the culprit.