Monitoring of questing tick species distribution in Galicia, north-western Spain, over a period of 5.5 years

Abstract

An active survey was performed by the Galician Vector Surveillance Network (ReGaViVec) to determine the distribution of questing tick species in the Autonomous Community of Galicia Galicia, north-western Spain. Monitoring of tick populations involved drag/flag sampling at 533 locations over a period of 5.5 years. The identification of tick species, sex, and stage was carried out according to morphological keys, and the results were analyzed considering three Köppen climate regions, i.e. Cfb (marine west coast climate), Csb (warm-summer Mediterranean climate), and Csa (hot-summer Mediterranean climate), season, environment (forest, rural, or urban), vegetation height (≤ 15 cm, 16–40 cm, and > 40 cm); and altitude (< 300 m, 301–500 m, 501–1000 m, and >1000 m). A total of 1378 ticks were collected at 260 locations: 62.92% in Csb, 24.38% in Cfb, and 12.70% in Csa. Of these, 2% were larvae, 45.2% were nymphs, and 52.8% were adults (58.3% females and 41.7% males). Six species were recorded, i.e. Ixodes ricinus (57.90%), Rhipicephalus sanguineus (sensu lato) (26.05%), Dermacentor reticulatus (10.95%), Dermacentor marginatus (2.10%), Haemaphysalis sp. (2.61%), and Rhipicephalus bursa (0.36%). A seasonal pattern was recorded, with the relative abundance of I. ricinus and R. sanguineus (s.l.) peaking in spring-summer, and that of Dermacentor spp. and Haemaphysalis sp. peaking in autumn-winter. Significant differences were demonstrated in the species abundance distribution according to climate region, season, environment, and altitude. The highest tick abundance was recorded in summer, in rural areas, and at altitudes of < 300 m. Because most of the tick species present in the environment of Galicia have vectorial competence for emerging tick-borne pathogens, it is important to maintain research and coordination of tick surveillance practices in the region.