Unlocking the Neural Basis of Tick Sensory Processing

• Applicant: Dr. Carola Staedele
• Subject Area: Cognitive, Systems and Behavioural Neurobiology ; Sensory and Behavioural Biology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 553030864

Ticks are major disease vectors that pose significant threats to human and animal health by transmitting numerous pathogens, including bacteria, viruses, and protozoa. Their ability to locate hosts, engage in feeding behaviors, and navigate environments is intricately linked to their sensory processing capabilities. However, the neuronal mechanisms underlying sensory processing in these ectoparasites are poorly understood, and we do not understand what makes a tick tick. The current project will significantly advance our understanding of tick chemosensation. By delving into the neuroanatomical basis of sensory processing in the central nervous system (synganglion) of the castor bean tick, Ixodes ricinus, the primary vector of Lyme disease and tick-borne encephalitis in Europe, we aim to shed light on the mechanisms that drive tick sensory processing. I. ricinus, with its relatively large size and genomic and transcriptomic resources, provides an ideal model for anatomical studies, enabling us to comprehensively understand the tick nervous system and its role in host-seeking and disease transmission. Three complementary objectives will be pursued. First, a comprehensive, high-resolution three-dimensional atlas of the adult male and female I. ricinus synganglion will be generated using immunohistochemistry combined with advanced confocal imaging. This atlas will be a vital resource for researching the complex tick nervous system, allowing the mapping of individual neurons within the standard neuropils of male and female ticks. Second, the spatial distribution and organization of sensory projections within the synganglion will be determined, focusing on olfaction and gustation - two critical sensory modalities for tick survival and reproduction. Axonal projections from the forelegs, bearing the multi-sensory Haller’s organ, and the mouthparts will be retrogradely labeled to visualize their paths within the synganglion. Third, the neuronal circuit architecture of the Ixodes olfactory system, from sensory input to output, will be deciphered. Local interneurons, modulatory neurons, and projection neurons connecting within the olfactory lobe and its glomeruli will be identified based on their neurochemical fingerprints, laying the foundation for subsequent functional studies. This study will elevate our understanding of tick neurobiology, with far-reaching implications for public health and disease ecology.

• DFG Programme: Research Grants