Development of magnetic attraction systems to mark and recapture a medically important vector, Haemaphysalis longicornis (Acari: Ixodidae)

Abstract

Although Haemaphysalis longicornis Neumann (Acari: Ixodidae) is an important disease vector, its small size limits methods applicable for studying its behavior. We developed a magnetic attraction and retrieval system consisting of magnetic label and magnetic sweeper for mark and recapture of the ticks in field conditions. First, among four magnetic materials (Fe powder, Ni powder, Fe3O4 powder, and commercially available magnetic paint), Fe powder showed the highest potential as a labelling material. We then assessed the effect of ferrous label (1.67 mg) on H. longicornis adults. Fe-labelling did not affect survivorship and horizontal movement of these adults. However, it significantly reduced their vertical movement. Hence, ferrous labels were modified to be lighter (0.12 mg) for further experiments, which did not adversely affect vertical movement of H. longicornis. To test the efficacy of this system, we first measured the detection rate of dead individuals from various detection heights. The detection rate was significantly reduced from 3 cm away compared to shorter distances. Finally, on a grassland, we assessed the detection efficacy. On average, 74% of ticks were detected and retrieved. Our study demonstrates the potential of the system as a promising tool to study H. longicornis.