Projects

Return to Main Entomology, Parasitology & Disease

Category	Entomology, Parasitology & Disease
Project	67-84 - Tick-borne disease agents in the Pacific Coast
Project Leader	Lane
Affiliation	UC Berkeley ESPM Insect Biology
Objective	This research is intended to clarify the role of the western gray squirrel (Sciurus griseus) as a keystone species for maintaining enzootic foci of the Lyme disease (LD) spirochete Borrelia burgdorferi sensu stricto (Bb ss) in the far-western USA; and to investigate the host-seeking behavior of Ixodes pacificus (Ip) nymphs in relation to environmental parameters and to risk of human exposure to Bb ss at the Hopland Research and Extension Center (HREC). The reservoir competence of S. griseus for Bb ss will be evaluated by determining the infectivity of naturally infected squirrels for uninfected Ip larvae; the capacity of fed larvae to pass the infection transstadially; the ability of infected nymphs to transmit infection to naïve squirrels; and the duration of infectivity in experimentally infected squirrels. Previous research has established that dense woodlands are primary biotopes of Ip nymphs, and that contact with either leaf litter and wood, but especially wood (e.g., logs), can elevate the risk of human exposure to nymphal ticks. Therefore, host-seeking activities of Ip nymphs in relation to biotic and abiotic factors will be investigated quantitatively in oak/madrone woodlands. These will include the diurnal questing cycle; the densities of host-seeking nymphs, and of Bb ss-infected nymphs, on logs and tree trunks versus adjacent leaf litter; and the movements of marked nymphal ticks.