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.