Dung beetles (Insecta: Coleoptera) as disseminators of viable Cryptosporidium parvum in a multispecies agricultural complex

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Tenth International Workshop on Opportunistic Protists

Dung Beetles (Insecta: Coleoptera) as Disseminators of Viable Cryptosporidium parvum in a Multispecies Agricultural Complex. D.B. CONN,1 S. NESLUND,2 R. NIEMEYER,3 L. TAMANG,4 T.K. GRACZYK4 1 Berry College, Mount Berry, GA, USA 2 Lee University, Cleveland, TN, USA 3 Whitworth University, Spokane, WA, USA 4 Johns Hopkins University, Baltimore, MD, USA. Dung beetles (Coleoptera: Scarabaeidae) are abundant and widespread coprophagous insects, and are responsible for ingesting and/or burying large amounts of fecal material from numerous species of wild and domestic mammals and birds. Despite the ubiquitous occurrence of dung beetles in association with known wild and domestic hosts of zoonotic Cryptosporidium parvum, few studies have examined the occurrence of this opportunistic protistan pathogen in the beetles or their edaphic tunnels. We established study sites at diverse locations throughout a multispecies agricultural complex on the 26,500-acre campus of Berry College in northwest Georgia, USA. Sites included facilities and pastures housing domestic sheep, dairy cattle, beef cattle, and horses, as well as fields frequented by populations of Canada Geese (Branta canadensis) and White-tailed Deer (Odocoileus virginianus). Fecal samples of all these vertebrate species were examined for the presence of Cryptosporidium by acid-fast staining. Within the sites occupied by each vertebrate species, dung beetles of the genera Onthophagus, Ataenius, and Aphodius were collected by baited pitfall trapping and recovery from soil cores. Sixteen beetles were homogenized and examined for C. parvum using fluorescent in-situ hybridization (FISH) and immunofluorescent antibody (IFA) techniques. All host species were positive for fecal oocysts of Cryptosporidium. Prevalence varied between dairy cattle (80%), beef cattle (70%), geese (40%), deer (37.5%), horses (22.2%), and sheep (20%). Intensity (oocysts/fecal sample) varied between dairy cattle (23.4), beef cattle (6.9), deer (3.5), geese (3.4), horses (1.33), and sheep (0.6). Dung beetles were distributed non-randomly across the sites, with highest numbers in cattle areas. All of the 16 beetles examined by FISH/IFA contained viable oocysts of C. parvum (oocysts/beetle, mean = 93.31; range = 3-321). These data demonstrate that dung beetles are competent disseminators of viable C. parvum within multispecies agricultural ecosystems, both above and below ground. (Supported by U.S. National Science Foundation NSF-REU grant DEB0354017). 54

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