Physalopterine nematodes in Australian reptiles: interactions and patterns of infection

Abstract

Abstract. Spirurid nematodes (family Physalopteridae) are widespread as adults or as encysted larvae in many species of Australian reptiles. Fifteen species of physalopterine nematodes (subfamily Physalopterinae) in the genera Kreisiella, Abbreviata and Skrjabinoptera infect more than 40 species of reptile in the five families Agamidae, Varanidae, Gekkonidae, Scincidae and Elapidae. Four species of nematode are host-species specific, six are host-family specific to varanid lizards, and three to agamid lizards. Larger species of reptile support a higher prevalence and abundance of nematodes, and often support multiple infections with more than one species, with the potential for interspecific competition. Geographic distribution of nematodes is partially limited by host distribution, and by climatic factors, mainly precipitation and temperature. There are strong positive and negative associations between several pairs of nematodes. Two species of nematode with the most pronounced muscular development at the anterior end, Abbreviata tumidocapitis and Abbreviata glebopalmae, only occur concurrently, and in low numbers, with species of nematode without these morphological features, suggesting differences in feeding in the hosts' stomachs. A combination of host specificity, geographic distribution and habitat, climatic factors and feeding organ morphology are factors that probably reduce the potential for interspecific competition. There is no evidence that concurrent infections affect either prevalence or abundance of nematodes, or cause discernible pathological changes to their hosts.

The life cycle of the reptile-inhabiting nematode Abbreviata hastaspicula (Spirurida: Physalopteridae: Physalopterinae) in Australia

“…The same species of parasites are more likely to infect the host species that are taxonomically related ( Freeland, 1983 ). In the case of Abbreviata spp., consistent with Jones, 2005 , Jones, 2007 , Jones, 2014 which indicated that A. hastaspicula predominates in Varanidae, all of the eight wild caught V. gouldii in our experiment were naturally infected with A. hastaspicula . Although A. antarctica was recovered at highest prevalence and intensity in V. rosenbergi ( Jones, 2005 , Jones, 2007 , Jones, 2014 ), concurrent infection of both A. hastaspicula and A. antarctica occurred in one of our controls V. gouldii.…”

“…Distribution of the nematode genus Abbreviata is worldwide ( Bain et al., 2015 ), in Australia, nematodes in this genus are widespread. They are most common in the lizard fauna ( Jones, 2014 ), and physalopterid nematodes also occur in birds ( Berger, 2010 ). The arid Australian landscapes support the richest and the most diverse lizard fauna in the world, due to the dry hot climate and the dominant, hummock grasslands ( Triodia spp.…”

“…Factors affecting the geographical pattern of Abbreviata are probably firstly, the distribution of suitable arthropod intermediate hosts; secondly, the ability of the eggs to survive and remain viable outside the final hosts ( Jones, 2014 ); thirdly, the availability of prey for the hosts e.g. small lizards.…”

High infection intensities, but negligible fitness costs, suggest tolerance of gastrointestinal nematodes in a tropical snake

“…; Stearns & Koella ; Poulin ; Schmid‐Hempel ). There are several cross‐sectional studies on the diversity and prevalence of parasites in Australian reptiles (Johnston & Mawson ; Mackerras ; Jones , ; Riley et al . ; Pichelin et al .…”

Wildlife parasitology in Australia: past, present and future

“…The current status of knowledge of the helminth parasites of Australian reptiles has been summarised in a checklist by Pichelin et al (1999). Much of the information available has been assembled through incidental collections, although the extensive ecological and taxonomic studies of Jones (2014), particularly on the parasites of varanids, those on gekkonids (Goldberg and Bursey (2001) and the experimental studies of Sprent (e.g. Sprent and McKeown 1979) on the ascaridoid nematodes of pythons stand out as landmarks in the field.…”