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Neil B. Chilton – 1st expert on this subject based on the ideXlab platform

  • indirect evidence of density dependent population regulation in Aponomma hydrosauri acari ixodidae an ectoparasite of reptiles
    Austral Ecology, 2003
    Co-Authors: Andrew J Tyre, Michael C Bull, Brigitte Tenhumberg, Neil B. Chilton


    The extent to which density-dependent processes regulate natural populations is the subject of an ongoing debate. We contribute evidence to this debate showing that density-dependent processes influence the population dynamics of the ectoparasite Aponomma hydrosauri (Acari: Ixodidae), a tick species that infests reptiles in Australia. The first piece of evidence comes from an unusually long-term dataset on the distribution of ticks among individual hosts. If density-dependent processes are influencing either host mortality or vital rates of the parasite population, and those distributions can be approximated with negative binomial distributions, then general host-parasite models predict that the aggregation coefficient of the parasite distribution will increase with the average intensity of infections. We fit negative binomial distributions to the frequency distributions of ticks on hosts, and find that the estimated aggregation coefficient k increases with increasing average tick density. This pattern indirectly implies that one or more vital rates of the tick population must be changing with increasing tick density, because mortality rates of the tick’s main host, the sleepy lizard, Tiliqua rugosa, are unaffected by changes in tick burdens. Our second piece of evidence is a re-analysis of experimental data on the attachment success of individual ticks to lizard hosts using generalized linear modelling. The probability of successful engorgement decreases with increasing numbers of ticks attached to a host. This is direct evidence of a density-dependent process that could lead to an increase in the aggregation coefficient of tick distributions described earlier. The population-scale increase in the aggregation coefficient is indirect evidence of a density-dependent process or processes sufficiently strong to produce a population-wide pattern, and thus also likely to influence population regulation. The direct observation of a density-dependent process is evidence of at least part of the responsible mechanism.

  • influence of temperature and relative humidity on the moulting success of amblyomma limbatum and Aponomma hydrosauri acari ixodidae larvae and nymphs
    International Journal for Parasitology, 2000
    Co-Authors: Neil B. Chilton, Ross H. Andrews, Michael C Bull


    This study compared the duration of the moulting periods of engorged larvae and nymphs of the ixodid ticks, Amblyomma limbatum and Aponomma hydrosauri, at different temperature/relative humidity regimes, and examined the relationships between the engorged weight of ticks and their weights after moulting. The results showed that for each species, there was a significant relationship between the weights of unfed nymphs and engorged larvae, and the weights of unfed adults and engorged nymphs. The weight of engorged nymphs was also a good indicator of their sex, with female ticks having heavier weights as engorged nymphs. Temperature and relative humidity had a marked effect on the moulting success of engorged ticks of both species. Aponomma hydrosauri larvae and nymphs were able to moult at lower temperatures than Amb. limbatum but most ticks, except Ap. hydrosauri larvae, failed to moult at 13°C. Additionally, there was a marked decrease in the pre-moult times of ticks at higher temperatures, with larvae taking less time to moult than nymphs. At temperatures greater than 21°C, Amb. limbatum took less time to moult than Ap. hydrosauri but this interspecific difference was less marked for nymphs. The interspecific differences in the responses of engorged larvae and nymphs to different temperatures and relative humidities correlated with interspecific differences in off-host behaviour and with the different climates the two species experience throughout most of their distributional range.

  • Can predators maintain parapatry : Ant distribution across a tick parapatric boundary in South Australia
    Austral Ecology, 1996
    Co-Authors: Neil B. Chilton, C. Michael Bull


    Ants were sampled by pitfall traps at 85 sites, 0.5 or 1.0 km apart, along six transects across a parapatric boundary between the reptile ticks Aponomma hydrosauri and Amblyomma limbatum near Mt Mary in South Australia. There was no tendency for overall ant density, or for the distribution of any single species of ant, to be related to the tick distribution. Thus the survey found no support for the hypothesis that predation by ants was maintaining the boundary. Along transects there were no correlations between ant and tick densities. Thus the survey found no support for the hypothesis that ant predation was a major factor controlling tick densities. These negative results provide further evidence that single, strong ecological processes cannot explain this well-studied parapatric boundary.

C M Bull – 2nd expert on this subject based on the ideXlab platform

  • systematic status of Aponomma tachyglossi roberts acari ixodidae from echidnas tachyglossus aculeatus from queensland australia
    Systematic & Applied Acarology, 2006
    Co-Authors: R H Andrews, C M Bull, Ian Beveridge, N. B. Chilton, Bruce R Dixon, Trevor N Petney


    Abstract Evidence is presented based on morphological, electrophoretic and behavioural data, and on geographical distribution, that Aponomma tachyglossi Roberts is an independent species parasitic primarily on echidnas. Females of A. tachyglossi are distinguishable from the closely related species A. hydrosauri (Denny), parasitic on reptiles, in the shape of the porose areas, and males by the extent of the punctate areas between the scutum and the festoons. Nymphs and larvae of the two species could not be distinguished. In electrophoretic studies, A. tachyglossi was found to differ from A. hydrosauri at 16% of the 18 loci examined. Larvae of A. tachyglossi failed to attach and engorge on lizards, the usual host of A. hydrosauri. Futhermore, A. tachyglossi was found to have a limited geographical range in coastal areas of central Queensland. These data support the hypothesis that A. tachyglossi is a distinct species.

  • The impact of tick parasites on the behaviour of the lizard Tiliqua rugosa.
    Oecologia, 2000
    Co-Authors: A. R. Main, C M Bull


    Populations of the Australian sleepy lizard, Tiliqua rugosa, near Mt. Mary, South Australia carry natural infestations of two tick species Aponomma hydrosauri and Amblyomma limbatum. In field experiments at two sites, 18 km apart, lizards with experimentally increased tick loads had smaller home ranges, moved shorter distances in a day, and were found basking more but moving less often than lizards from which ticks were experimentally removed. The results were consistent for adult lizards in two years, and for sub-adults in a third year. Laboratory trials showed that juvenile lizards that had tick infestations had lower sprint speeds than uninfested siblings, and that adults with tick infestations had less endurance than those that were uninfested. The results contrast with those of a previous survey that showed that lizards with high tick loads had greater body size and remained longer at a site, but indicate that there may be a balance, for lizards, between the fitness advantages in occupying habitats with high-quality resources, and the costs from parasites that also prefer those habitats.

  • Laboratory studies of ant predation on parapatric reptile ticks
    Austral Ecology, 1997
    Co-Authors: Tracy Z. Dawes-gromadzki, C M Bull


    Two reptile tick species, Aponomma hydrosauri and Amblyomma limbatum, have a parapatric distribution in South Australia. Predation may play a role in maintaining the boundary. Laboratory colonies of Rhytidoponera and Iridomyrmex ants were collected from near Mt Mary, South Australia, close to the tick boundary. They were tested as predators of the two tick species. In the experiments, ticks in leaf litter were more protected from predation than those on bare soil. When comparing leaf litter types from the Mt Mary area, mallee litter was more protective than bluebush litter of equivalent depth. Ticks positioned at the base of the litter layer were more protected from predation than those at the litter surface, and Amb.. limbatum ticks were more resistant to predation than Ap. hydrosauri ticks. These results contribute to our understanding of the mechanisms maintaining the abrupt parapatric boundary between the two tick species. Predators may contribute to preventing the more susceptible Ap. hydrosauri from spreading further north, where bluebush litter is more common, and so predation risk is higher. Predators probably have less influence in preventing Amb. limbatum from spreading further south.

Lance A. Durden – 3rd expert on this subject based on the ideXlab platform

  • New Records of Ticks (Acari: Argasidae, Ixodidae) from South Carolina 1
    , 2020
    Co-Authors: Will K. Reeves, Lance A. Durden, William Wills


    Tick-borne diseases are of increasing economic importance. The biogeographical distributions of tick species are important in the distri- bution of tick-borne diseases. The tick fauna of South Carolina was previously known to include 19 species, and the most recent tick checklist focused pri- marily on the coastal counties in the state. We report an additional seven species of ticks from South Carolina, bringing the total number of tick species collected in the state to 26, and provide information on tick species in the foothills and mountainous area of the state. The newly reported species are Aponomma trimaculatum (Lucas), Argas persicus (Oken), Haemaphysalis chordeilis (Packard), Ixodes dentatus Marx, I. muris Bishopp & Smith, Otobius megnini (Duges), and Rhipicephalus appendiculatus Neumann.

  • bothriocroton oudemansi neumann 1910 n comb acari ixodida ixodidae an ectoparasite of the western long beaked echidna in papua new guinea redescription of the male and first description of the female and nymph
    Systematic Parasitology, 2008
    Co-Authors: Lorenza Beati, James E Keirans, Lance A. Durden, Muse D Opiang


    Specimens of Amblyomma oudemansi (Neumann, 1910) were collected in Papua New Guinea from an endangered monotreme, Zaglossus bruijni (Peters & Doria), the western long-beaked echidna. These ticks were compared morphologically and molecularly with species formerly assigned to Aponomma Neumann, 1899 (now included in Bothriocroton Keirans, King, & Sharrad, 1994 or Amblyomma Koch, 1844), and a phylogeny was generated. Based on our results, we reassign this tick to Bothriocroton, as B. oudemansi (Neumann, 1910) n. comb. Original descriptions are provided for the female and the nymph of this species and the male is redescribed. A revised list of all Bothriocroton records and holdings in the US National Tick Collection is also provided.

  • invasion exotic ticks acari argasidae ixodidae imported into the united states a review and new records
    Journal of Medical Entomology, 2001
    Co-Authors: James E Keirans, Lance A. Durden


    A review of the literature and unpublished records from the U.S. National Tick Collection on the importation of ticks from foreign lands reveals that at least 99 exotic tick species assignable to 11 genera have been either detected and destroyed at ports of entry or inadvertently imported into the United States in the past half century. This number includes four argasid and 95 ixodid species, some of which are important vectors of agents that cause disease to both man and animals. If one includes Aponomma sp. and Hyalomma sp. and the subspecies of Rhipicephalus, the total exceeds 100 taxa. It is notable that the number of imported tick species recorded herein exceeds the total number of tick species native to the United States. It appears that the soft tick genera Argas, Antricola and Nothoaspis have not been imported, although at some point in time Argas persicus (Oken) was introduced because it is resident although not often collected. The hard tick genera Anomalohimalaya, Cosmiomma, Margaropus, Nosomma and Rhipicentor, and the nuttalliellid genus Nuttalliella have also not been imported.