title: Habitat-related variation in infestation of lizards and rodents with Ixodes ticks in dense woodlands in Mendocino County, California.
abstract: During the spring and early summer of 2002, we examined the relative importance of Borrelia-refractory lizards (Sceloporus occidentalis, Elgaria spp.) versus potential Borrelia burgdorferi sensu lato (s.l.)-reservoirs (rodents) as hosts for Ixodes pacificus immatures in 14 woodland areas (six oak, five mixed oak/Douglas fir, and three redwood/tanoak areas) distributed throughout Mendocino County, California. Lizards were estimated to serve as hosts for 93-98% of all larvae and > or =99.6% of all nymphs infesting lizards or rodents in oak woodlands and oak/Douglas fir sites in the southern part of the county. In redwood/tanoak woodlands and oak/Douglas fir sites in northern Mendocino County, the contribution of rodents to larval feedings reached 36-69% but lizards still accounted for 94-100% of nymphal bloodmeals. From late April to mid-June, I. pacificus larvae were recovered from 95 to 96% of lizards and dusky-footed woodrats (Neotoma fuscipes) and from 59% of Peromyscus spp. mice. In contrast, 99% of lizards but few woodrats (15%) and none of the mice were infested by nymphs. Comparisons of tick loads for 19 lizard-Peromyscus spp. mouse pairings, where the lizard and mouse were captured within 10m of each other, revealed that the lizards harbored 36 times more larvae and >190 times more nymphs than the mice. In oak woodlands, loads of I. pacificus larvae decreased from late April/early May to late June for S. occidentalis lizards but increased for Peromyscus spp. mice. We conclude that the relative utilization of Borrelia-refractory lizards, as compared to rodents, by I. pacificus larvae was far higher in dry oak woodlands than in moister habitats such as redwood/tanoak and oak/Douglas fir woodlands in northern Mendocino County. Non-lizard-infesting potential enzootic vectors of B. burgdorferi s.l. (I. angustus and I. spinipalpis) were recorded from rodents in three of six oak woodland areas, two of five oak/Douglas fir woodland areas, and two of three redwood/tanoak woodland areas.
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, USA. reisen@nature.berkeley.edu
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Eisen
authors.forename: Lars
authors.initials: L
authors.lastname: Eisen
authors.forename: Robert S
authors.initials: RS
authors.lastname: Lane
mesh_terms: D000818:Animals; D025065:Borrelia burgdorferi / Q000254:growth & development; D002140:California; D004197:Disease Reservoirs; D004777:Environment; D018884:Ixodes / Q000254:growth & development* / Q000382:microbiology; D008116:Lizards / Q000469:parasitology*; D012377:Rodentia / Q000469:parasitology*; D012621:Seasons; D013984:Tick Infestations / Q000382:microbiology