Do the level of energy reserves, hydration status and Borrelia infection influence walking by Ixodes ricinus (Acari: Ixodidae) ticks?

• Published in: Parasitology Vol. 139; no. 3; pp. 330 - 337
• Main Authors: HERRMANN, C., GERN, L.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.03.2012
• Subjects: Acari; Acclimation; Acclimatization; Animals; Arachnid Vectors; Arachnida; Arthropoda; arthropods; Bacterial Load; Bacterial Typing Techniques; Biological and medical sciences; Borrelia burgdorferi; Borrelia burgdorferi - genetics; Borrelia burgdorferi - isolation & purification; Energy Metabolism; Energy reserves; Energy resources; Energy sources; Fat Body - metabolism; Fundamental and applied biological sciences. Psychology; General aspects; General aspects and techniques. Study of several systematic groups. Models; Humidity; Hydration; Infection; Invertebrates; Ixodes - microbiology; Ixodes - physiology; Ixodes ricinus; Ixodidae; Motion; Nymph - microbiology; Nymph - physiology; Polymerase chain reaction; Real-Time Polymerase Chain Reaction; Relative humidity; Spirochetes; Vectors; Walking; energy resource; humidity; Ixodes ricinus; vector behaviour; Borrelia burgdorferi s.l; tick movement; Spirochaetaceae; Environmental factor; Energy resources; Acari; Spirochaetosis; Humidity; Bacteria; Vector; Ixodidae; Metabolic storage; Parasitiformes; Status; Borrelia burgdorferi; Spirochaetales; Hydration; Borrelia infection; Parasite; Infection; Arachnida; Ixodida; Arthropoda; Bacteriosis; Ectoparasite; Invertebrata
• ISSN: 0031-1820; 1469-8161; 1469-8161
• DOI: 10.1017/S0031182011002095

Ixodes ricinus horizontal movement within a humidity gradient and the influence of infection by Borrelia burgdorferi sensu lato (s.l.) on tick walking were investigated. Nymphs were placed within an arena containing a humidity gradient ranging from 45 to 95% relative humidity (RH). After 1 h of acclimation at 70% RH ticks were released so that they could either stay, or walk towards either the wet or the dry end. Their position was recorded 2 h post-release. Fat content was quantified and Borrelia infection was detected using real-time PCR and PCR followed by Reverse Line Blotting. Among the 1500 ticks tested, 29·85% were infected. More low-fat nymphs walked inside the arena than high-fat individuals. When nymphs walked, more low-fat ticks walked towards wetter than drier air, whereas more high-fat individuals walked towards drier than wetter air. Among high-fat nymphs, a lower proportion of Borrelia-infected ticks walked inside the arena compared to uninfected individuals, as though spirochetes manipulated their arthropod vector to stay. However, Borrelia infection had no effect on walking direction towards the dry or the wet end. Hence, it appears that I. ricinus nymphs walk horizontally over short distances within a humidity gradient depending on both energy resources and Borrelia infection.