Conference Agenda

Haemaphysalis longicornis is a parthenogenetic three-host tick of increasing veterinary and public health importance and is the principal vector of Theileria orientalis in Australasia. Experimental research on this species has been constrained by reliance on live vertebrate hosts, limiting scalability, standardisation and ethical feasibility. This study established a reproducible, host-free in vitro membrane feeding system for adult and nymphal stages. Ticks were fed using a silicone membrane-based system under controlled laboratory conditions. Field-collected adult females were evaluated across six independent experiments for attachment, engorgement, oviposition, egg hatchability and bloodmeal-to-egg conversion efficiency. Nymphal feeding performance was assessed across five experiments. Adult feeding was robust, with 67% (35/52) attachment and 74.3% (26/35) engorgement. Engorged females reached a mean weight of 161 mg and produced a mean egg mass of 67 mg (40% conversion efficiency), with >92% hatchability. Nymphs showed consistently high performance, with 88.4% (76/86) attachment, 97.4% (74/76) engorgement and 90.5% (67/74) moulting success. Engorgement typically occurred within 3–5 days post-attachment, and moulting within 2–4 weeks post-detachment. This system enables controlled, ethical and scalable experimentation and provides a powerful platform for studies of tick physiology, vector competence, acaricide screening and pathogen–vector interactions.

Ticks are obligate haematophagous ectoparasites, and species within the Rhipicephalus microplus complex are responsible for substantial economic losses to the cattle industry. Traditionally, laboratory rearing of ticks has relied on live animal hosts; however, increasing animal welfare concerns have driven the development of artificial tick feeding systems (ATFS). Here, we report the first successful consecutive artificial feeding of all life stages of the Australian cattle tick, Rhipicephalus australis, using a silicone membrane-based system. Success was achieved through optimisation of membrane thickness, incorporation of olfactory stimuli and strict contamination control, enabling continuous in vitro feeding of this one-host tick species. Using larvae aged 2-13.5 weeks, all developmental stages demonstrated good attachment and engorgement rates. This study represents the first demonstration of consecutive feeding of all life stages of R. australis without the use of live animal hosts. The developed ATFS provides a good platform for further investigating tick biology and tick–pathogen interactions under controlled conditions, as well as for evaluating acaricides/vaccine candidates. However, the limitations of this system include reduced oviposition and increased mortality indicating the need for further optimisation. Overall, this system supports the principles of the 3Rs (Replacement, Reduction and Refinement) in tick and tick-borne disease research.

Ticks are among the most important vectors of pathogens affecting livestock. Rhipicephalus australis (the Australian cattle tick) transmits several economically significant pathogens, including Anaplasma and Babesia spp. Increasing evidence suggests that the tick microbiome influences pathogen acquisition, persistence and transmission, thereby shaping vectorial capacity. This study characterised bacterial communities across larval, nymphal and adult stages of R. australis collected from cattle farms in Queensland, Australia. Following surface decontamination and DNA extraction, 16S rRNA gene sequencing was performed using the Illumina NextSeq 1000 platform, with downstream analyses conducted in QIIME 2 and R. A diverse bacterial community was identified, including Arsenophonus, Acinetobacter, Brevibacterium, Coxiella, Corynebacterium, Serratia, Stenotrophomonas, Escherichia–Shigella and Staphylococcus. Several taxa were consistently detected across all life stages, suggesting conserved or potentially symbiotic associations while others were stage-specific, indicating dynamic shifts in microbial community composition during tick development. Microbial network analyses further revealed distinct, stage-specific interaction patterns. These findings provide the first comprehensive insights into life stage-associated microbiome variation in R. australis and highlight the potential role of microbial communities in tick biology and pathogen transmission. This work establishes a foundation for microbiome-informed strategies to improve Australian cattle tick control and enhance livestock health and productivity.

Ticks are important vectors of pathogens affecting both humans and animals. For example, cattle ticks transmit Anaplasma and Babesia spp., causing substantial economic losses to the global cattle industry. Artificial tick feeding systems (ATFS) are increasingly used as alternatives to animal-based feeding to study tick biology, pathogen transmission and control strategies. However, their impact on the tick microbiome remains poorly understood. This study investigated the microbiome and microbial co-occurrence networks of the Australian cattle tick (Rhipicephalus australis) reared under ATFS conditions to establish baseline insights. Ticks were collected across multiple life stages, from larvae to engorged females, surface decontaminated, and processed for DNA extraction. Microbial profiling was conducted using 16S rRNA gene sequencing on the Illumina NextSeq 1000 platform, with downstream analyses performed in QIIME 2 and R. Artificially fed ticks harboured diverse microbial communities, with variation observed across life stages. Network analyses revealed distinct microbial interaction patterns, suggesting structured community dynamics under in vitro conditions. These findings indicate that ATFS environments, including the blood meal, membrane system, and absence of host-derived immune factors, may influence microbial community composition. Such effects should be considered when interpreting biological processes and vector competence in artificially fed ticks.

Theileria orientalis Ikeda has been a significant cause of disease in the Australian cattle industry for over a decade. To investigate how widespread T. orientalis Ikeda is across Australia, particularly in regions in and outside of known ranges of the vectors and in the absence of clinical disease, we conducted testing on herds of homebred adult cattle in New South Wales and Queensland. Molecular testing of 526 blood samples from 49 properties was performed to detect and quantify different T. orientalis genotypes present within these herds. Previous studies have shown that in clinical cases of theileriosis, the Ikeda genotype is detected in 88% of samples.

Preliminary findings suggest that T. orientalis Ikeda may be more widespread than previously thought, including in areas outside the known ranges of the tick vectors. These detections in herds that have not experienced clinical disease indicate that presence of the organism may be a necessary but not sufficient cause of disease on its own. These results help build a clearer understanding of clinical theileriosis in Australia and highlight the value of ongoing active surveillance. Future work to include additional Australian states is planned.