Third-year evaluation of host-targeted permethrin for the control of Ixodes dammini (Acari: Ixodidae) in southeastern Connecticut.

The impact of commercially available permethrin-treated cotton balls targeted at Ixodes dammini Spielman, Clifford, Piesman & Corwin on white-footed mice, Peromyscus leucopus, was evaluated for a third year at five residential sites in south-central Connecticut. Each site had been treated twice each year from 1989 through 1991 with sufficient product to treat 0.4 ha of mouse habitat, and results were compared with five untreated sites. There were no significant differences in the number of host-seeking nymphs or adults of I. dammini, the vector of the Lyme disease spirochete, Borrelia burgdorferi, in 1991 between the treated and untreated sites. The rate of infection in host-seeking nymphs by B. burgdorferi at the treated sites (15.3% of 600) was comparable with that at the untreated sites (16.5% of 454). Only 16.3% of 86 P. leucopus captured at the treated sites were infested with I. dammini subadults compared with 66.9% of 118 from the mice at the untreated sites. The impact of permethrin-treated cotton during the third year of treatment was similar to that observed for the first 2 yr and did not reduce the risk of exposure to spirochete-infected, host-seeking nymphs and adults of I. dammini.