Ecology of the common marsupial tick (Ixodes tasmani Neumann) (Acarina : Ixodidae), in eastern Australia

Abstract

Ixodes tasmani is one of the most common and widespread of the Australian species of Ixodes and a vector of zoonotic rickettsial diseases. The tick was reared successfully in the laboratory; the entire life cycle was completed in 4 months. A diurnal rhythm of detachment from captive hosts (laboratory Rattus norvegicus) was observed for all stages and, combined with other evidence, suggests that I. tasmani is nidicolous. The prevalence and intensity of tick infestation on wild-caught, common brushtail possums (Trichosurus vulpecula), was least during the summer months. To investigate questing activity, laboratory-reared nymphs were held in enclosures in one sheltered (tree hollows) and three exposed (vegetation) microhabitats. Questing was continuous but at low intensity in tree hollows, and nocturnal and at an increased (higher) intensity in vegetation. The observed questing activity appeared to maximise host contact with T. vulpecula, which is nocturnal but retires by day to tree hollows. Field and laboratory observations suggest that the risk for humans of tick-bite from I. tasmani and consequent transmission of zoonotic diseases may be low compared with the risk from other tick species.

Bartonella-Like DNA Detected inIxodes tasmaniTicks (Acari: Ixodida) Infesting Koalas (Phascolarctos cinereus) in Victoria, Australia

“…It is the first detection of a Bartonella-related organism in the Ixodid tick I. tasmani, a species known for its competency as a vector of Queensland tick typhus (Rickettsia australis) and Flinders Island spotted fever (R. honei) (Dyer et al 2005, Murdoch andSpratt 2005). The partial sequences obtained for the gltA definitively groups the genotypes obtained in this study with the family Bartonellaceae rather than Rickettsiaceae.…”

“…Of the 52 known Australian tick species (Roberts 1970), I. tasmani are the most abundant and parasitize the greatest range of species (Murdoch andSpratt 2005, Roberts 1970) making them an ideal vector for pathogen transmission (Roberts 1970). Parasitization of the koala by I. tasmani has been previously reported, with heavy tick burdens being common and known to cause anemia (Spencer and Canfield 1994).…”

“…The fastidious nature of Bartonella has made isolation of recognized species difficult or impossible (La Scola and Raoult, 1999), and molecular methods have proven ideal for both detection and genetic characterization of new and existing species (Birtles and Raoult 1996, Houpikian and Raoult 2001, Boulouis et al 2005. Although a number of different target genes have been used, including 16S rRNA, groEL, rpoB, ftsZ, and ITS (Scoles 2004, Murdoch andSpratt 2005), the gltA (citrate synthase) gene is the most widely used and deemed effective for phylogenetic analysis (Birtles and Raoult 1996, Scoles 2004, Maggi et al 2005. It has been shown of particular value in estimating the phylogenetic relationship between members of both the ␣1 and ␣2 proteobacteria (Maggi et al 2005) and differentiating between all species of Rickettsia and Bartonella (Birtles andRaoult 1996, Murdoch andSpratt 2005).…”

“…Although a number of different target genes have been used, including 16S rRNA, groEL, rpoB, ftsZ, and ITS (Scoles 2004, Murdoch andSpratt 2005), the gltA (citrate synthase) gene is the most widely used and deemed effective for phylogenetic analysis (Birtles and Raoult 1996, Scoles 2004, Maggi et al 2005. It has been shown of particular value in estimating the phylogenetic relationship between members of both the ␣1 and ␣2 proteobacteria (Maggi et al 2005) and differentiating between all species of Rickettsia and Bartonella (Birtles andRaoult 1996, Murdoch andSpratt 2005).…”

Molecular detection of Rickettsia, Coxiella and Rickettsiella DNA in three native Australian tick species

“…Known as the marsupial tick, due to its low host specificity and Australia-wide distribution (Roberts 1970;Murdoch and Spratt 2005), it is a vector for both R. australis (Queensland tick typhus) and R. honei (Flinders Island spotted fever) (Murdoch and Spratt 2005;Unsworth et al 2007a). Efforts to detect Rickettsia species in the Phillip Island koala I. tasmani samples were unsuccessful, however, 16S rRNA gene sequences for three male tick samples identified the presence of three Rickettsiella genotypes.…”