Dispersal of Blacklegged Tick (Acari: Ixodidae) Nymphs and Adults at the Woods–Pasture Interface

Abstract

Marked nymphal and adult blacklegged ticks, Ixodes scapularis Say, were released in 4 host-exclusion cages and 4 similar control areas, all straddling the woods-pasture interface. Both nymphs and adults were recaptured by flagging at regular intervals outside the cages, having therefore actively dispersed > 4.5 m (i.e., without involvement of vertebrates). Nymphs were recaptured much more often ( > 90%) in the woods than pastures, whereas 62.8% of recaptured adults were taken in pastures. Females were recaptured in equal numbers in pastures and woods, but 75.4% of recaptured males were in pastures. Adults that dispersed into pastures were recaptured an average of 1.6 and 3.7 m from the woods edge in 1992 and 1993, respectively, and as far as 7-8 m from the woods edge. Nymphs dispersed shorter distances than adults with 66% of the recaptured nymphs found 2-3 m from their release points, and > 46% of recaptured adults found > 5 m from their release points. Twice as many nymphs were recaptured from the caged than uncaged sites. The lower numbers of nymphs recaptured from control sites compared with caged sites are probably the result of host acquisition; the absence of this discrepancy with the adults may reflect by their ability to move relatively quickly from the host-exclusion cages and become available for host contact.