Optimal search patterns in honeybee orientation flights are robust against emerging infectious diseases.
Lévy flights are scale-free (fractal) search patterns found in a wide range of animals. They can be an advantageous strategy promoting high encounter rates with rare cues that may indicate prey items, mating partners or navigational landmarks. The robustness of this behavioural strategy to ubiquitous threats to animal performance, such as pathogens, remains poorly understood. Using honeybees radar-tracked during their orientation flights in a novel landscape, we assess for the first time how two emerging infectious diseases (Nosema sp. and the Varroa-associated Deformed wing virus (DWV)) affect bees' behavioural performance and search strategy. Nosema infection, unlike DWV, affected the spatial scale of orientation flights, causing significantly shorter and more compact flights. However, in stark contrast to disease-dependent temporal fractals, we find the same prevalence of optimal Lévy flight characteristics (μ ≈ 2) in both healthy and infected bees. We discuss the ecological and evolutionary implications of these surprising insights, arguing that Lévy search patterns are an emergent property of fundamental characteristics of neuronal and sensory components of the decision-making process, making them robust against diverse physiological effects of pathogen infection and possibly other stressors.
Rothamsted Research, Harpenden, UK.|School of Biological &Chemical Sciences, Queen Mary University of London, UK.
Stephan
S
Wolf
Rothamsted Research, Harpenden, UK.|School of Life Sciences, University of Sussex, Brighton, UK.
Elizabeth
E
Nicholls
Rothamsted Research, Harpenden, UK.
Andrew M
AM
Reynolds
Rothamsted Research, Harpenden, UK.
Patricia
P
Wells
Rothamsted Research, Harpenden, UK.
Ka S
KS
Lim
School of Biological Sciences, Queen's University Belfast, Belfast, UK.|Institute of Biology, Martin-Luther-Universität Halle-Wittenberg, Germany.
Robert J
RJ
Paxton
Rothamsted Research, Harpenden, UK.|Environment and Sustainability Institute, Penryn, University of Exeter, UK.
Juliet L
JL
Osborne
D000818:Animals; D001516:Bees / Q000502:physiology* / Q000821:virology; D005426:Flight, Animal / Q000502:physiology*; D007239:Infections / Q000662:veterinary / Q000821:virology*; D016818:Nosema / Q000472:pathogenicity / Q000821:virology; D009949:Orientation / Q000502:physiology*; D000072458:Orientation, Spatial; D057077:Varroidae / Q000472:pathogenicity / Q000821:virology