SEASONAL INCIDENCE OF IXODES-RICINUS TICKS (ACARI, IXODIDAE) ON RODENTS IN WESTERN FRANCE

Data collected from a longitudinal survey carried out over 2 years on four farms in western France were used to assess the incidence and inf estation of Ixodes ricinus on rodents. Once a month, on each farm, 25 Sherman live traps were set in hedges bordering selected pastures. A t otal of 799 micromammals were examined, including Apodemus sylvaticus, Clethrionomys glareolus, Microtus agrestis, Microtus arvalis, and Cro cidura spp. Larvae and nymphs of I. ricinus were found. Small numbers of Ixodes (Exopalpiger) trianguliceps were also recovered from each fa rm. The mean infestation rate of the I. ricinus larvae (1.6-5.9) among all animals examined varied between farms Most animals were infested by only a single tick, but one M. agrestis harboured 43 I. ricinus lar vae. Larvae or nymphs were found throughout the year, with peaks from March to October.