Evaluation of Permethrin-Impregnated Cotton Balls as Potential Nesting Material To Control Ectoparasites of Woodrats in California

Abstract

The dusky-footed woodrat, Neotoma fuscipes Baird is a natural reservoir of the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, in California. To investigate the potential of host-targeted insecticide to control the tick vectors of B. burgdorferi, permethrin-impregnated or untreated cotton balls were distributed in metal cylinders as potential nesting material adjacent to 95 woodrat houses in chaparral-covered rangeland. Laboratory experiments demonstrated that adult woodrats would enter the cylinders and construct nests from permethrin-treated or untreated cotton. The residual concentration of permethrin did not vary significantly during an 11-mo period and remained > 60% of the registered insecticidal formulation (7.5% [AI] by cotton weight). The abundance of 4 species of ticks (Ixodes neotomae Cooley; the western blacklegged tick I. pacificus Cooley & Kohls; I. woodi Bishopp; and the Pacific Coast tick, Dermacentor occidentalis Marx) infesting woodrats was similar in the treatment and control areas. Although > 90% of the cotton disappeared from the metal cylinders in both areas, examination of 8 active woodrat houses revealed that small amounts of cotton had been incorporated into the nest cups of only 25%. In contrast, the abundance of the flea Orchopeas sexdentatus (Baker) decreased significantly in the treatment area only. Spirochetes were not detected in 168 adult O. sexdentatus fleas that had fed on spirochetemic woodrats, which demonstrates that this flea is an inefficient host of B. burgdorferi. We conclude that the use of permethrin-impregnated cotton as potential nesting material is ineffective for controlling ticks associated with the dusky-footed woodrat in brushlands, but this methodology may be useful for reducing populations of sylvatic fleas.

Detection and Characterization ofBorrelia bissettiiin Rodents from the Central California Coast

“…For example, although all stages of I. spinipalpis feed on rodents, in north coastal California, an average of only one or two ticks of each life stage were recovered from N. fuscipes during the winter, when all stages tend to be most abundant on hosts (Brown and Lane 1992). Habitat associations also seem to relate to numbers of I. spinipalpis found on rodents, with a maximum of 0.8 larvae and 0.3 nymphs found per host on chaparral-dwelling rodents, and even fewer from rodents in certain woodland grass and dense woodland habitats (Leprince and Lane 1996, Peavey et al 1997, Wright et al 2000, Casher et al 2002. Habitat associations for I. spinipalpis in coastal scrub and prickly pear habitats are unclear; more frequent sampling of rodents during the fall and winter may be necessary to successfully recover Ixodes spp.…”

Lyme borreliosis in Europe and North America

“…One of the reasons suggested for its varied success was the importance of white-footed mice vs. other reservoir hosts in different locations. Permethrin-treated cotton balls were also ineffective when tested against I. pacificus (Leprince & Lane, 1996). Other rodenttargeted methods involve the use of bait stations for applying acaricides to various rodent species (Sonenshine & Haines, 1985 ;Gage et al 1997 ;Lane et al 1998).…”

Control of Immature <I>Ixodes scapularis</I> (Acari: Ixodidae) on Rodent Reservoirs of <I>Borrelia burgdorferi</I> in a Residential Community of Southeastern Connecticut

“…For example, several studies were carried out using permethrin-treated cotton nesting material to control ticks and ßeas on rodent hosts. This method has been used to take advantage of nest-building behaviors of white-footed mice, Peromyscus leucopus (Mather et al , 1988Deblinger et al 1991;Stafford 1991b), woodrats, and/or other species of Peromyscus (Sonenshine and Haines 1985, Beard et al 1992, Leprince and Lane 1996. Gage et al (1997) developed a rodent-targeted bait tube approach for controlling ectoparasitic disease vectors by passive application of liquid permethrin.…”