Spatial and Temporal Patterns of Ixodes scapularis (Acari: Ixodidae) in Southeastern Connecticut

Abstract

The spatial distribution and abundance of host-seeking Ixodes scapularis Say (formerly I. dammini) were studied in 10 residential sites in woodlands during 1989-1991. In total, 7,385 larval, 2,202 nymphal, 164 female, and 248 male I. scapularis were collected in Old Lyme, Lyme, East Haddam, and Chester, CT. The majority of host-seeking I. scapularis larvae (84.2%) and nymphs (73.5%) were collected within the woodland plots, whereas a large proportion of the adults were recovered from lawn (36.4%) and transitional areas between lawns and forest (20.9%). The majority (71.1% of 1,244) of all stages of I. scapularis on the lawn were recovered within 1 m of the lawn edge, particularly along woods and stone walls. In contrast, most of the I. scapularis (60.0% of 3,065) collected in the woods were > 3 m from any defined edge and ticks were recovered throughout the forested plots. The abundance of nymphs on the lawns (1.0-29.4 nymphs per ha per sample) and in the woods (17.3-271.5 nymphs per ha per sample) varied significantly among the 10 residences during June and July. The average rate of infection by Borrelia burgdorferi, the causal agent of Lyme disease, in the nymphs was 14.2, 14.1, and 15.5% for 1989, 1990, and 1991, respectively. The abundance of I. scapularis nymphs in the forest was significantly higher in June 1991, than in 1989 or 1990. The risk of exposure to infected nymphs of I. scapularis varied spatially with the landscape and individual residence, and temporally.