Testing Mechanisms of the Dilution Effect: Deer Mice Encounter Rates, Sin Nombre Virus Prevalence and Species Diversity

Abstract

Species diversity has been shown to decrease prevalence of disease in a variety of host-pathogen systems, in a phenomenon termed the Dilution Effect. Several mechanisms have been proposed by which diversity may decrease prevalence, though few have been tested in natural host-pathogen systems. We investigated the mechanisms by which diversity influenced the prevalence of Sin Nombre virus (SNV), a directly transmitted virus in deer mice (Peromyscus maniculatus). We monitored both intra and interspecific encounters of deer mice using foraging arenas at five sites in the Great Basin Desert with disparate levels of species diversity to examine two potential mechanisms which may contribute to the dilution of SNV prevalence: (1) reduced frequency of encounters between deer mice, or (2) reduced duration of contacts between deer mice. We also investigated the relationship between deer mouse density and these mechanisms, as density is often predicted to influence both inter and intraspecific encounters. Results of our study indicate that frequency of intraspecific interactions between deer mice was reduced with increased diversity. Species diversity did not impact average duration of encounters. Density was correlated with absolute, but not relative rates of encounters between deer mice, suggesting that encounters may be influenced by factors other than density. Our study indicates that species diversity influences the dynamics of SNV by reducing encounters between deer mice in a trade-off between intra and interspecific interactions.

Effect of Forest Fragmentation on Tick Infestations of Birds and Tick Infection Rates by Rickettsia in the Atlantic Forest of Brazil

“…Since then, several studies using simulation models, and experimental and empirical data, have revealed details of this mechanism of disease regulation (Ostfeld and Keesing 2000;Ostfeld and LoGiudice 2003;Keesing et al 2010). More recently, this effect was also confirmed to explain the prevalence of other diseases, such as the West Nile virus (Ezenwa et al 2006;Swaddle and Calos 2008;Allan et al 2009), hantavirus (Clay et al 2009;Suzán et al 2009), and schistosomiasis (Johnson et al 2009). …”

Diversity and abundance of mosquitoes (Diptera:Culicidae) in an urban park: Larval habitats and temporal variation

“…16 The change in ecological processes as a result of anthropogenic actions puts pressure on the natural environment, increasing the risk of human contact with pathogens, many of which can be transmitted by mosquitoes (Bradley and Altizer, 2007). It has been demonstrated that loss of diversity tends to increase pathogens transmission incidence of diseases such as malaria, West Nile Fever (WNF), schistossomose, Lyme disease and hantavirus (Ezenwa et al, 2006;LoGuidice et al, 2008;Clay et al, 2009;Johnson et al, 2009, Laporta et al, 2013. Therefore,the policy makers should propose the creation and maintenance of green areas aimed mainly at conserving ecosystems and natural communities, thus reducing the risk of pathogen transmission.…”

Effects of Land Use on Plague (Yersinia pestis) Activity in Rodents in Tanzania

“…All of these metrics are routinely used in examining diversity-disease relationships, but multiple metrics are rarely reported. 10,18,22,[67][68][69] An important area for future research that will help extend the reach of these observations will be learning more about interactions between rodent communities in agricultural and conserved sites. All of the rodent species found in agricultural sites were also detected in paired conserved sites.…”