PARENT SESSION
Symposium 3: Emerging Diseases: Stressing the Union of Community Ecology and Epidemiology
Organized by: S Collinge and C Ray
Monday, August 4. 8:00 AM to 11:30 AM, SITCC Chatham Ballroom C.
Community ecology meets epidemiology: biodiversity loss and elevated Lyme disease risk in fragmented landscapes.
Ostfeld, Richard *,1, Keesing, Felicia1, 2, LoGiudice, Kathleen1, 3, 1 Institute of Ecosystem Studies, Millbrook, NY2 Biology Department, Annandale, NY3 Biology Department, Schenechtady, NY
ABSTRACT- Lyme disease is a tick-borne bacterial zoonosis in which the white-footed mouse (Peromyscus leucopus) serves as the primary source (or reservoir) from which ticks acquire the disease agent, Borrelia burgdorferi. Previous research using both field data and modeling has shown that high species richness within the vertebrate community results in decreased risk of human exposure to Lyme disease. High vertebrate diversity: (1) dilutes the impact of white-footed mice by providing ticks with blood meal sources that are unlikely to result in infection; and (2) appears to directly reduce the abundance of mice via both predation and competition. We used an empirically based simulation model to assess the degree to which the sequence of species loss from vertebrate communities influences the proportion of ticks infected with the etiological agent, an important risk factor. We observed marked differences in the shapes of curves relating vertebrate biodiversity to disease risk. All potentially realistic disassembly rules resulted in increases in disease risk with decreasing biodiversity, although shapes of the curves varied dramatically. We extend these results by allowing species to interact with one another within foodwebs. For example, the loss of grey squirrels can result not only in the loss of blood meals for ticks, but also in the increased abundance of rodent competitors, which themselves serve as blood meal sources. Greater interaction strengths within the foodweb result in stronger indirect effects of species loss on tick infection. To understand how biodiversity loss affects Lyme disease (and similar vector-borne diseases), it will be necessary to determine: (1) the order by which species are lost in human-impacted ecosystems (i.e. disassembly rules); and (2) the direct and indirect effects of the loss of key host species on tick abundance and infection.
Key words: ecosystem function, biodiversity, disease ecology, Lyme disease