1. Laboratory of Biomedical Science, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-0880, Japan
2. Gyotoku Nature Conservation Club NPO, 4-22-11 Fukuei, Ichikawa, Chiba 272-0137, Japan
3. Department of Medical Entomology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku, Tokyo 162-8640, Japan