Parasitic and immune-modulation of flight activity in honey bees tracked with optical counters

Abstract

Abstract Host-parasite interactions are often characterized by changes in the host behaviour, which are either beneficial to the parasite or the host, or a non-adaptive byproduct of parasitism. Those interactions are further complicated in animal society since the individual fitness is associated with the group performance. However, a better understanding of host-parasite interaction in animal society first requires to identify individual host behavioural modification. Therefore, we challenged honey bee (Apis mellifera) workers with the parasite Nosema ceranae or an immune stimulation and tracked their flight activity over their lifetime with an optic counter. We found that bees responded differently to each stress: both Nosema-infected and immune-challenged bees performed a lower number of daily flights compared to control bees, but the duration of their flights increased and decreased over time, respectively. Overall, parasitized bees spent more time in the field each day than control bees and inversely for immune-challenged bees. Despite the stress due to immune challenge, bees had a survival similar to control bees likely due to their restricted activity. We discuss how those different behavioural modifications could be adaptive phenotypes. This study provides new insights into how biological stress can affect the behaviour of individuals living in society and how host responses evolved.