The impact of parasites during range expansion of an invasive gecko

Abstract

Host-parasite dynamics can play a fundamental role in both the establishment success of invasive species and their impact on native wildlife. The net impact of parasites depends on their capacity to switch effectively between native and invasive hosts. Here we explore host-switching, spatial patterns and simple fitness measures in a slow-expanding invasion: the invasion of Asian house geckos (Hemidactylus frenatus) from urban areas into bushland in Northeast Australia. In bushland close to urban edges, H. frenatus co-occurs with, and at many sites now greatly out-numbers, native geckos. We measured prevalence and intensity of Geckobia mites (introduced with H. frenatus), and Waddycephalus (a native pentastome). We recorded a new invasive mite species, and several new host associations for native mites and geckos, but we found no evidence of mite transmission between native and invasive geckos. In contrast, native Waddycephalus nymphs were commonly present in H. frenatus, demonstrating this parasite's capacity to utilize H. frenatus as a novel host. Prevalence of mites on H. frenatus decreased with distance from the urban edge, suggesting parasite release towards the invasion front; however, we found no evidence that mites affect H. frenatus body condition or lifespan. Waddycephalus was present at low prevalence in bushland sites and, although its presence did not affect host body condition, our data suggest that it may reduce host survival. The high relative density of H. frenatus at our sites, and their capacity to harbour Waddycephalus, suggests that there may be impacts on native geckos and snakes through parasite spillback.

Morphological divergence and reduced ectoparasite prevalence in an introduced population of a Caribbean anole

“…What is not always clear is how or if reduced ectoparasite prevalence contributes to the success of an introduced species (Colautti et al, 2004;Prenter et al, 2004). In the case of A. maynardi, mite infestation had a negligible effect on body condition (Table 2), other studies have also highlighted an asymptomatic effect of ectoparasites in a range of reptile species based on body condition indices (Conover et al, 2015;Mayer et al, 2015; Barnett et al, 2018). However, body condition indices can only detect major differences in energy reserves between infested and non-infested individuals (Peig & Green, 2009).…”

Parasite in peril? A new species of mite in the genus Ophiomegistus Banks (Parasitiformes: Paramegistidae) on an endangered host, the pygmy bluetongue lizard Tiliqua adelaidensis (Peters) (Squamata: Scincidae)

“…Sorci & Clobert ; Main & Bull ; Schlaepfer ; Barnett et al . ). Fitness costs of parasites may not be evident unless measured in a specific way, and in a large enough proportion of the population (Scott ).…”

How epidemiological patterns shift across populations in an exotic lizard

“…Barnett et al . (2018) found a native parasite that may reduce the survival of individuals of the congeneric host Hemidactylus frenatus in an Asian house gecko that had been accidentally introduced to many tropical and subtropical areas. In some places, such as Northern Australia, H. frenatus are spreading from urban areas into bushland (Hoskin, 2011).…”