Nestedness of Ectoparasite-Vertebrate Host Networks

Abstract

Determining the structure of ectoparasite-host networks will enable disease ecologists to better understand and predict the spread of vector-borne diseases. If these networks have consistent properties, then studying the structure of well-understood networks could lead to extrapolation of these properties to others, including those that support emerging pathogens. Borrowing a quantitative measure of network structure from studies of mutualistic relationships between plants and their pollinators, we analyzed 29 ectoparasite-vertebrate host networks—including three derived from molecular bloodmeal analysis of mosquito feeding patterns—using measures of nestedness to identify non-random interactions among species. We found significant nestedness in ectoparasite-vertebrate host lists for habitats ranging from tropical rainforests to polar environments. These networks showed non-random patterns of nesting, and did not differ significantly from published estimates of nestedness from mutualistic networks. Mutualistic and antagonistic networks appear to be organized similarly, with generalized ectoparasites interacting with hosts that attract many ectoparasites and more specialized ectoparasites usually interacting with these same “generalized” hosts. This finding has implications for understanding the network dynamics of vector-born pathogens. We suggest that nestedness (rather than random ectoparasite-host associations) can allow rapid transfer of pathogens throughout a network, and expand upon such concepts as the dilution effect, bridge vectors, and host switching in the context of nested ectoparasite-vertebrate host networks.

Phylogenetic Analysis of Eastern Equine Encephalitis Virus Isolates from Florida

“…With the exception of the southeastern region of Florida, multiple archived viral samples collected over a relatively long period were available. In addition to these four regions in Florida, three isolates of EEEV from pools of mosquitoes collected at a well-characterized study site in the Tuskegee National Forest 5,21,22 were included in the study. Descriptions of these isolates are shown in Table 1 .…”

Serosurveillance of Eastern Equine Encephalitis Virus in Amphibians and Reptiles from Alabama, USA

“…25 This study area has been thoroughly investigated as a focus for EEEV zoonotic transmission. [23][24][25][26][27] Field sampling. During April-October 2007-2009, a herpetofaunal census was conducted in Tuskegee National Forest wetlands.…”

“…[23][24][25][26] This finding indicates that arboviruses can potentially navigate through entire ecto-parasite-vertebrate host communities, an observation supported by a network analysis, which demonstrated that these communities have nested structure and are highly centralized. 27 We report the results of a three-year surveillance for EEEV in amphibians and reptiles from our study site in Tuskegee National Forest in Alabama, USA. A total of 351 animals individuals representing 9 amphibian and 18 reptile species were tested for antibodies against EEEV.…”

Host compatibility rather than vector–host-encounter rate determines the host range of avian Plasmodium parasites

“…Expansions in host range can result when changes in vector-host contact rates introduce parasites to novel hosts [17]. However, numerous studies have revealed an important interplay between host compatibility and the encounter rate in driving pathogen transmission dynamics over time [3], space [5] and between ecological communities that differ in structure [4,67].…”