An invasive human commensal and a native marsupial maintain tick populations at the urban fringe.

Ticks (Acari: Ixodidae) are major disease vectors globally making it increasingly important to understand how altered vertebrate communities in urban areas shape tick population dynamics. In urban landscapes of Australia, little is known about which native and introduced small mammals maintain tick populations preventing host-targeted tick management and leading to human-wildlife conflict. Here, we determined (1) larval, nymphal, and adult tick burdens on host species and potential drivers, (2) the number of ticks supported by the different host populations, and (3) the proportion of medically significant tick species feeding on the different host species in Northern Sydney. We counted 3551 ticks on 241 mammals at 15 sites and found that long-nosed bandicoots (Perameles nasuta) hosted more ticks of all life stages than other small mammals but introduced black rats (Rattus rattus) were more abundant at most sites (33%-100%) and therefore important in supporting larval and nymphal ticks in our study areas. Black rats and bandicoots hosted a greater proportion of medically significant tick species including Ixodes holocyclus than other hosts. Our results show that an introduced human commensal contributes to maintaining urban tick populations and suggests ticks could be managed by controlling rat populations on urban fringes.

Partnerships, Lawsuits, and Competing Accountabilities in CCAA Agreements.

Private lands are often critical for successful species conservation, and the US Fish and Wildlife Service has increasingly utilized voluntary Candidate Conservation Agreements with Assurances (CCAAs) as a strategy for promoting private land conservation. CCAAs, however, present a challenge where the FWS, with its history as a regulatory entity, must now engage landowners as conservation partners. There is a deep culture of distrust among landowners, who are often suspicious of engaging with the agency, making it necessary for the FWS to build trusting relationships. Furthermore, FWS decisions often face litigation in the courts, where they may be overturned. This creates a challenge for CCAAs, as the agency is pulled between landowner demands for greater flexibility and a court system that emphasizes rigid compliance to established rules and procedures. This study seeks to understand what factors influenced the flexibility of agency staff and officials as they navigate the process of negotiating CCAAs amidst these competing demands for accountability. Three cases of CCAA development are presented, each aiming to protect the habitat for the greater sage-grouse and ease the regulatory burden on ranching communities, should the grouse become a federally protected species. In addition to the well-documented need for trust-building and maintenance, the findings of the study highlight the importance of shared goals, the participation of trusted intermediary organizations, and as well as the meaningful support and investment of senior FWS leadership in exploring creative, innovative solutions.

The bacterial biome of ticks and their wildlife hosts at the urban-wildland interface.

Advances in sequencing technologies have revealed the complex and diverse microbial communities present in ticks (Ixodida). As obligate blood-feeding arthropods, ticks are responsible for a number of infectious diseases that can affect humans, livestock, domestic animals and wildlife. While cases of human tick-borne diseases continue to increase in the northern hemisphere, there has been relatively little recognition of zoonotic tick-borne pathogens in Australia. Over the past 5 years, studies using high-throughput sequencing technologies have shown that Australian ticks harbour unique and diverse bacterial communities. In the present study, free-ranging wildlife (n=203), representing ten mammal species, were sampled from urban and peri-urban areas in New South Wales (NSW), Queensland (QLD) and Western Australia (WA). Bacterial metabarcoding targeting the 16S rRNA locus was used to characterize the microbiomes of three sample types collected from wildlife: blood, ticks and tissue samples. Further sequence information was obtained for selected taxa of interest. Six tick species were identified from wildlife: Amblyomma triguttatum, Ixodes antechini, Ixodes australiensis, Ixodes holocyclus, Ixodes tasmani and Ixodes trichosuri. Bacterial 16S rRNA metabarcoding was performed on 536 samples and 65 controls, generating over 100 million sequences. Alpha diversity was significantly different between the three sample types, with tissue samples displaying the highest alpha diversity (P<0.001). Proteobacteria was the most abundant taxon identified across all sample types (37.3 %). Beta diversity analysis and ordination revealed little overlap between the three sample types (P<0.001). Taxa of interest included Anaplasmataceae, Bartonella, Borrelia, Coxiellaceae, Francisella, Midichloria, Mycoplasma and Rickettsia. Anaplasmataceae bacteria were detected in 17.7% (95/536) of samples and included Anaplasma, Ehrlichia and Neoehrlichia species. In samples from NSW, 'Ca. Neoehrlichia australis', 'Ca. Neoehrlichia arcana', Neoehrlichia sp. and Ehrlichia sp. were identified. A putative novel Ehrlichia sp. was identified from WA and Anaplasma platys was identified from QLD. Nine rodent tissue samples were positive for a novel Borrelia sp. that formed a phylogenetically distinct clade separate from the Lyme Borrelia and relapsing fever groups. This novel clade included recently identified rodent-associated Borrelia genotypes, which were described from Spain and North America. Bartonella was identified in 12.9% (69/536) of samples. Over half of these positive samples were obtained from black rats (Rattus rattus), and the dominant bacterial species identified were Bartonella coopersplainsensis and Bartonella queenslandensis. The results from the present study show the value of using unbiased high-throughput sequencing applied to samples collected from wildlife. In addition to understanding the sylvatic cycle of known vector-associated pathogens, surveillance work is important to ensure preparedness for potential zoonotic spillover events.

Haemoprotozoan surveillance in peri-urban native and introduced wildlife from Australia.

Vector-borne haemoprotozoans comprise a diverse group of eukaryote single-celled organisms transmitted by haematophagous (blood-feeding) invertebrates. They can cause debilitating diseases that impact wildlife, livestock, companion animals and humans. Recent research has shown that Australian wildlife host a diverse range of haemoprotozoan species; however, to date this work has primarily been confined to a few host species or isolated populations in rural habitats. There has been little investigation into the presence of these blood parasites in wildlife inhabiting urban and peri-urban areas. In this study, blood and tissue samples and ticks were collected from wildlife in New South Wales and Western Australia. Extracted DNA samples were screened with pan-specific molecular assays to determine the presence of haemoprotozoans using amplicon metabarcoding and Sanger sequencing approaches. In addition, light microscopy was performed on blood films. Eight haemoprotozoans were identified in the present study, which included species of Babesia, Hepatozoon, Theileria and Trypanosoma. Blood samples were collected from 134 animals; 70 black rats (Rattus), 18 common brush-tailed possums (Trichosurus vulpecula), two bush rats (Rattus fuscipes), 22 chuditch (Dasyurus geoffroii), 20 long-nosed bandicoots (Perameles nasuta), one quenda (Isoodon fusciventer) and one swamp rat (Rattus lutreolus). Molecular screening of DNA extracted from blood samples identified 52.2% (95% CI: 43.8-60.5%) of individuals were positive for at least one haemoprotozoan species, with 19.4% (95% CI: 13.4-26.7%) positive for more than one species. The present study provides the first sequences of Theileria cf. peramelis from black rats and long-nosed bandicoots. Babesia lohae was identified from brush-tailed possums. Two Hepatozoon genotypes were identified from black rats and bush rats. Black rats showed the highest haemoprotozoan diversity, with five species identified. No known human pathogens that have been described in the northern hemisphere were identified in the present study, and future work is required to understand the zoonotic potential of these microbes in Australia. This work represents the first large-scale body of research using molecular tools to investigate haemoprotozoans in animals at the urban-wildland interface. Further research is needed to investigate potential consequences of infection in wildlife, particularly effects of pathogen spillover from invasive black rats to native wildlife.

Invasive rabbits host immature Ixodes ticks at the urban-forest interface.

Introduced wildlife may be important alternative hosts for generalist ticks that cause health issues for humans and companion animals in urban areas, but to date are rarely considered as part of the tick-host community compared to native wildlife. In Australia, European rabbits, Oryctolagus cuniculus, are a widespread and abundant invasive species common to a range of human-modified ecosystems. To understand the potential role of rabbits in the life cycle of Australian ticks, we investigated the seasonal abundance of all tick life stages (larva, nymph, and adult) on rabbits collected from pest control programs in two urban forest remnants in Sydney, Australia. We also recorded whether larvae, nymphs, and adults were attached to the head, body, or limbs of rabbits to reveal patterns of tick attachment. Of the 2426 Ixodes ticks collected from 42 rabbits, larvae were by far the most abundant life stage (2360), peaking in abundance in autumn, while small numbers of nymphs (62) and adults (4) were present in winter and summer respectively. Larvae were found all over the body, whereas adults and nymphs were predominantly attached to the head, suggesting that the mature life stages use the host landscape differently, or that adults or nymphs may be groomed off the body. The most abundant tick species, as determined by morphology and DNA sequencing, was Ixodes holocyclus, a generalist tick responsible for significant human and companion animal health concerns in Australia. Our findings highlight the importance of understanding the role of introduced wildlife in tick dynamics particularly in novel ecosystems where non-native hosts may be more abundant than native hosts.

Molecular identification of the Trypanosoma (Herpetosoma) lewisi clade in black rats (Rattus rattus) from Australia.

Invasive rodent species are known hosts for a diverse range of infectious microorganisms and have long been associated with the spread of disease globally. The present study describes molecular evidence for the presence of a Trypanosoma sp. from black rats (Rattus rattus) in northern Sydney, Australia. Sequences of the 18S ribosomal RNA (rRNA) locus were obtained in two out of eleven (18%) blood samples with subsequent phylogenetic analysis confirming the identity within the Trypanosoma lewisi clade.