Ecology and Dynamics of the Blood Parasite, Hepatozoon Tuatarae (Apicomplexa), in Tuatara (Sphenodon Punctatus) on Stephens Island, New Zealand

Abstract

ABSTRACT:We explored infection patterns and temporal dynamics of the protozoan blood parasite Hepatozoon tuatarae (Apicomplexa) infecting the tuatara (Sphenodon punctatus), a protected reptile living on Stephens Island, New Zealand. In March 2006, we surveyed tuatara in five study sites to examine spatial variation in infection prevalence, and four times, from May 2005 to November 2006, we recaptured marked individuals within three study sites to examine the temporal dynamics of infection. We also examined how blood-parasite infection patterns were influenced by host sex, body size, and host infestation with ticks (Amblyomma sphenodonti) and mites (Neotrombicula spp.), which are potential vectors of the blood parasite. Infection prevalence (16.9-24% infected) and intensity (,0.01-0.1% blood cells infected) were low in all samples. Infection intensity varied among the five sampled sites in March 2006, but prevalence did not. Neither infection prevalence nor intensity varied with time, and infections were detected in consecutive samples from recaptured individuals for up to 18 mo. Neither survey showed an influence of host sex on infection, but both surveys showed infection intensity declined with increasing host body size, as did infection prevalence in the spatial survey. In the temporal survey, we found a positive relationship between the tick numbers on hosts and blood-parasite infection intensity, which were stronger in two of the sampling periods and among larger hosts. These data suggest that exposure and susceptibility to infection decreases with host size and that ticks, but not mites, are probably the vectors in this ancient host-parasite association of a long-lived (.50 yr) host.

Relationships between parasitic infection and natural antibodies, age, and sex in a long‐lived vertebrate

“…For example, in the spiny‐tailed iguana ( Ctenosaura melansterna ), whose lifespan is estimated around 20 years, prevalence and parasitemias of blood parasites declined with increasing host age (Davis et al., ). A similar result was found regarding blood parasites in the tuatara, which have life spans of over 50 years (Godfrey, Nelson, & Bull, ).…”

A Comparison of Multiple Methods for Estimating Parasitemia of Hemogregarine Hemoparasites (Apicomplexa: Adeleorina) and Its Application for Studying Infection in Natural Populations

“…However, this pattern is not linear among hemogregarine infections, especially when considering long-lived reptile species. Studies conducted on snakes [35], [36], [95] and tuataras [96] have found an inverse association to that reported here, with larger individuals having lower intensities. These contrasting infestation patterns may be related to differences in the pathogenesis of hemogregarine infections between short- and long-lived reptiles.…”

Searching Before It Is Too Late: A Survey of Blood Parasites in Ctenosaura melanosterna, a Critically Endangered Reptile of Honduras

“…Furthermore, a literature review on the subject of age-related effects on blood parasites in lizards (including genus Lacerta , Sceloporus , and Tiliqua ) indicated that higher prevalence in adults is the dominant pattern [ 26 ]. A recent exception to this was a study of parasites in tuatara ( Sphenodon punctatus ), which, like our investigation, found infections with Hepatozoon tuatarae decreased in frequency and severity with host size [ 27 ]. The reasons for these variable findings are unknown but could be related to the biology of the hosts, including overall size and longevity.…”