Scientists have established that sick and infected bees leave their hives voluntarily, as an act of altruism, rather than being driven out by the healthy bee population.
Scientists were unsure whether honeybees infected with fungi - a growing infectious problem - left the hive through altruism or were driven out by other bees, with the healthy bees sensing that the infected bees were sick. This creates so-termed 'zombie bees'.
To show this, the scientists first established the the bees infected with either the parasitic mite, Varroa destructor, or the fungus Nosema ceranae, underwent a change. For this they noted changes to the chemical profile of the skin and in the brains of infected bees.
It was noted that hydrocarbons on the cuticle of bees provide a 'family' scent allowing bees from the same hive to recognize each other. The levels of these chemicals was altered by infection. However, the healthy bees did not drive the infected bees from the hive. Instead, the parasitized bees soon left of their own accord (ultimately to go away and to die) in order to protect other members of the hive from becoming infected.
Altruism is a term to describe the principle or practice of concern for the welfare of others. It tends to whip up considerable debate in relation to people (philosophically, economically, socially and so on). With a few types of insects, however, altruistic behavior is more clear cut and it appears, from the new research, that there is a new dimension in relation to bees.
The research was carried out by the INRA (French National Institute for Agricultural Research) and the findings have been published in the journal BMC Ecology. The paper is titled " Ecto- and endoparasite induce similar chemical and brain neurogenomic responses in the honey bee (Apis mellifera)."