Presentation Abstract

Title: Mite associated disease impact on the federally endangered Amargosa vole.
Session Title: Wildlife Disease and Toxicology
Session Number: 16
Session Time: Sunday, Oct 14, 2012, 8:30 AM -12:20 PM
Presentation Time: Sunday, Oct 14, 2012, 9:10 AM - 9:30 AM
Author(s): Caitlin N. Ott-Conn1, Deana Clifford2, Tammy Branston3, Leslie Woods4, Robert Klinger5, Janet Foley1, 1University of California, Davis, Davis, CA, 2Wildlife Investigations Lab, California Department of Fish and Game, Rancho Cordova, CA, 3California Department of Fish and Game, Bishop, CA, 4California Animal Health and Food Safety Laboratory, University of California, Davis, Davis, CA, 5United States Geological Survey, Bishop, CA, Contact: cnottconn@ucdavis.edu
Abstract Body: During re-assessment of the distribution of the federally endangered Amargosa vole (Microtus californicus scirpensis) in 2010 a mite-associated skin disease was discovered in 40% (61/151) of voles at 3 of 16 sites. Infested voles had bright orange mites associated with ulcerative lesions located on the external ear pinnae, genitalia, or mammae. External ear lesions were often associated with pinna deformity and tissue loss. To assess individual and population-level effects of the disease we conducted focused trapping at six 1 hectare grids from December 2011 through March 2012. Biological samples were obtained to assess the extent of disease and associated pathology in infested individuals, and population surveillance was initiated to assess disease prevalence, distribution, and potential impact on vole demographic rates. Anatomical characterization of mites recovered from affected voles performed using light microscopy, scanning electron microscopy and DNA sequencing of the 18S rRNA gene showed that the vole mite shared 92-97% homology with the Trombuculid mite, Leptotrombidium deliense. Histology of necrotic skin lesions of varying severity reported ulcerative inflammatory dermatitis directly associated with mites. Genetically homologous mites collected from a sympatric mouse with orange lesions but no associated necrosis suggests potential species variation in response to the mite. Mite infestation prevalence was 13% (3/22) in January 2012, and 6% (3/50) in March 2012. Preliminary abundance estimates from 219 captures of 97 individuals indicated that 84% (81/97) of the sampled vole population occurred in a single 1 hectare site. This site also had the highest prevalence of mite-associated skin disease. The monthly survival rate was 0.512 (±0.045), but more data are needed to compare survival between mite-affected and unaffected voles. Individual impact from the mite associated disease on overall body condition appears to be limited; however longer-term data is needed for further surveillance and protection of this species.


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