Nation-wide surveillance of ticks (Acari: Argasidae) on bats (Chiroptera) in Singapore

Bats and ticks are important sources of zoonotic pathogens. Therefore, understanding the diversity, distribution, and ecology of both groups is crucial for public health preparedness. Soft ticks (Argasidae) are a major group of ectoparasites commonly associated with bats. The multi-host life cycle of many argasids make them important vectors of pathogens. Over nine years (2011-2020), surveillance was undertaken to identify the ticks associated with common bats in Singapore. During this period, the bat tick Ornithodoros batuensis was detected within populations of two cave roosting bat species: Eonycteris spelaea and Penthetor lucasi. We examined the relationship between bat species, roosting behaviour, and probability of O. batuensis infestation. We also estimated the relationship between bat life history variables (body condition index, sex, and age) on the probability of infestation and tick count. This represents the first detection of O. batuensis and the genus Ornithodoros within Singapore. We also provide evidence of the continued persistence of Argas pusillus in Singapore with the second local record.

The East Indies reptile tick Amblyomma helvolum Koch, 1844 (Acari: Ixodidae), taxonomy, biology and new host records, including the first record of human infestation

Amblyomma helvolum is a widespread, generalist ectoparasite of reptiles in the oriental region, and has the potential to become highly invasive should it be inadvertently introduced outside its native range through the exotic pet trade. All life stages of A. helvolum are re-characterised morphologically and the first examples of nanism (dwarfism) and gynandromorphy (male and female tissue in one animal) for the species are described. Eighteen new hosts records are presented for A. helvolum, including the first case of human infestation. The taxonomy, distribution, ecology, phenology, disease associations, and invasion biology of the species are also discussed.

Host, season, habitat and climatic factors as drivers of Asian rodent tick (Ixodes granulatus) (Acari: Ixodidae) occurrence and abundance in Southeast Asia

The Asian rodent tick (Ixodes granulatus) occurs throughout much of Asia, it frequently bites humans, and zoonotic pathogens, such as Borrelia burgdorferi (sensu lato) and Rickettsia honei, have been detected within it. Unfortunately, the ecology of I. granulatus remains poorly known, including drivers of its abundance and the interaction ecology with its sylvatic hosts. To elucidate the ecology of this medically important species, the habitat preferences of I. granulatus were assessed in Singapore and Malaysia. Ixodes granulatus showed strong associations with old forest habitats, though across different age classes of old forest there was limited variation in abundance. Ixodes granulatus was absent from other habitats including young forest, scrubland, and parks/gardens. Within its sylvatic rodent hosts, a range of factors were found to be statistically significant predictors of I. granulatus load and/or infestation risk, including sex and body condition index. Male rodents were significantly more likely to be infested and to have higher loads than females, similarly, animals with a lower body condition index were significantly more likely to be infested. Proactive public health efforts targeted at preventing bites by this tick should carefully consider its ecology to minimise ecological overlap between humans and I. granulatus.

Human-biting ticks and zoonotic tick-borne pathogens in North Africa: diversity, distribution, and trans-Mediterranean public health challenges

North Africa is home to more than 200 million people living across five developing economies (Egypt, Libya, Tunisia, Algeria, and Morocco) and two Spanish exclaves (Ceuta and Melilla), many of whom are impacted by ticks and tick-borne zoonoses. Populations in Europe are also increasingly vulnerable to North African ticks and tick-borne zoonoses due to a combination of climate change and the movement of ticks across the Mediterranean on migratory birds, human travellers, and trafficked wildlife. The human-biting ticks and tick-borne zoonoses in North Africa are reviewed along with their distribution in the region. We also assess present and future challenges associated with ticks and tick-borne zoonoses in North African and highlight opportunities for collaboration and coordination between governments in Europe and North Africa to address public health challenges posed by North African ticks and tick-borne zoonoses.

Habitat impacts the abundance and network structure within tick (Acari: Ixodidae) communities on tropical small mammals

Ticks of small mammals pose a significant risk to public health but these hazards are poorly understood in the tropics due to the paucity of information on the disease ecology of ticks in these regions. Mapping and quantifying the diversity of small mammal/tick networks and the effects of habitat on these medically important systems is key to disease prevention. Singapore represents a microcosm of much of tropical Asia as it has a diverse, though poorly studied, community of ticks and small mammals. Singapore also has a range of terrestrial habitats exhibiting a gradient of degradation. Small mammals and their ticks were sampled across the island in four main habitat types (old secondary forest, young secondary forest, scrubland, urban) across 4.5 years. Four tick species were collected (Amblyomma helvolum, Dermacentor auratus, Haemaphysalis semermis, Ixodes granulatus) from 10 small mammal species. Habitat was found to have a significant effect on both the abundance and structure of tick communities on small mammals. Old secondary forest communities had the highest tick abundance, comparatively high connectance, niche overlap (among ticks), linkage density, and were the preferred habitat of the zoonotic tick I. granulatus. Therefore, future disease spillover is likely to emerge from small mammal-tick communities in old secondary forests.

Emergence of the zoonotic tick Dermacentor (Indocentor) auratus Supino, 1897 (Acari: Ixodidae) in Singapore

Though ticks pose a significant public health risk, until recently, little research had focused on the diversity of ticks and tick-borne diseases in Singapore. To date, only fourteen tick species in five genera have been recorded there. For the first time, Dermacentor auratus is recorded from Singapore from a range of hosts, including humans. DNA sequences are provided at 2 loci, for D. auratus, the cytochrome c oxidase I (COI) for DNA barcoding and the 16S large subunit ribosomal RNA (16S lsu rRNA). The health risk posed by D. auratus in Singapore is discussed.

A checklist and key to the tick fauna (Acari: Ixodidae, Argasidae) of Pulau Tioman, Malaysia

Pulau Tioman is a popular tourist island off the east coast of Peninsula Malaysia, known for its vast areas of intact vegetation. Six tick species have been recorded on the island but little is known about their local ecology or public health importance. To facilitate studies of the tick fauna of Pulau Tioman, a checklist of all species and host associations is presented with the first host records, from Pulau Tioman, of Amblyomma helvolum from the Asian water monitor (Varanus salvator) and Amblyomma varanense from the keeled rat snake (Ptyas carinata). A pictorial key is also presented for all tick species known from the island.

Tick-crocodilian interactions: a review, with the first record of tick (Acari: Ixodidae) infestation in the saltwater crocodile (Crocodylus porosus), and a concise host-parasite index

Interactions between ticks and crocodilians (crocodiles, alligators, caiman, and gharials) are poorly studied but may have significant bearing on the ecology and health of these reptiles. The first record of tick infestation of the saltwater crocodile (Crocodylus porosus) is reported along with the first case of infestation by Amblyomma cordiferum on Cuvier's dwarf caiman (Paleosuchus palpebrosus). A review is also provided of tick-crocodilian interactions with a concise host-parasite index.

Correction to: The first authenticated record of the pangolin tick Amblyomma javanense (Acari: Ixodidae) in Singapore, with notes on its biology and conservation

Due to an unfortunate turn of events, the surname of the third author appeared incorrectly in the original publication as it should have read Douay. The original article has been corrected, and the proper representation of the authors' names and their affiliation is also listed here.

The first authenticated record of the pangolin tick Amblyomma javanense (Acari: Ixodidae) in Singapore, with notes on its biology and conservation

The first authenticated record of the co-endangered pangolin tick (Amblyomma javanense) is reported from the Republic of Singapore, based on specimens of males and females collected from the Sunda pangolin (Manis javanica). The biology of the species is reviewed and steps for its conservation are outlined to ensure its continued survival across its range.

Ixodes heathi n. sp. (Acari: Ixodidae), a co-endangered tick from the critically endangered mountain pygmy possum (Burramys parvus), with notes on its biology and conservation

A new species of co-endangered tick, Ixodes heathi n. sp., is described from specimens of the nymph collected on the critically endangered mountain pygmy possum (Burramys parvus Broom) from the alpine region of Victoria, Australia. Its biology is discussed along with strategies for its conservation.

Ticks in the Lion City: a preliminary review of the tick fauna of Singapore

To this day, the tick fauna of Singapore remains poorly known. Although several studies of select species have been undertaken within Singapore, much of the information regarding Singaporean ticks is fragmentary. To facilitate future study of this group, the scattered information on Singaporean ticks is synthesised in the present work and includes a preliminary checklist of species reported to occur in Singapore, which comprised 14 species in 5 genera, with confirmed records of Argas pusillus, Amblyomma nitidum, Amblyomma varanense, Haemaphysalis doenitzi, Haemaphysalis nadchatrami, Haemaphysalis semermis, Ixodes granulatus, Rhipicephalus microplus, and Rhipicephalus sanguineus, and unconfirmed reports of Amblyomma cordiferum, Amblyomma geoemydae, Amblyomma helvolum, Amblyomma javanense and Amblyomma testudinarium.

A checklist of the ticks (Acari: Argasidae, Ixodidae) of Japan

Ticks significantly affect the health of humans and animals in Japan. However, no complete checklist has been produced for the Japanese tick fauna in English, and even recent checklists in Japanese do not include all presently known tick species found on the Japanese islands. Here, a complete species list of all tick taxa known to occur within Japan is presented. The status of several controversial Japanese tick species is also discussed.

The introduction and subsequent extinction of the camel tick Hyalomma (Euhyalomma) dromedarii (Acari, Ixodidae) in Australia, with a review of the introduction of foreign ticks to Australia

Historically, several tick taxonomists have reported Hyalomma aegyptium within Australia due to misidentifications. This has resulted in confusion relating to the occurrence of the genus Hyalomma within Australia. Based on the recent discovery of museum specimens of Hyalomma dromedarii, misidentified as H. aegyptium, the historical occurrence of H. dromedarii is reported for the first time within Australia, along with its apparent subsequent extinction. The introduction and naturalisation of foreign tick species into Australia is also reviewed.

Redescription of the kiwi tick Ixodes anatis (Acari: Ixodidae) from New Zealand, with notes on its biology

Ixodes anatis Chilton is of veterinary and conservation importance in New Zealand due to its association with the threatened kiwi (Aves: Apterygidae: Apteryx spp.). Since the tick's description in 1904, there has been debate regarding its correct taxonomic position and nomenclature. Herein all life stages of this species are redescribed and accompanied by electron micrographs and drawings. The systematics, host preferences, distribution, disease relationships and conservation biology of the species are also discussed.

The first records of human infestation by the hard tick Ixodes (Endopalpiger) australiensis (Acari: Ixodidae), with a review of human infestation by ticks in Australia

The first record of human infestation and feeding by the native tick species Ixodes australiensis is reported in Australia based on a specimen collected from an adult male. Human infestation by ticks in Australia is reviewed and a concise list of anthropophagic ticks occurring in Australia is presented.

A survey of ticks (Acari: Ixodidae) from an over-abundant koala (Phascolarctos cinereus) population in south eastern Australia, with an overview of the ticks and mites of koalas

Within Australia, koala over-abundance has become a serious problem in some areas resulting in significant damage to native forests through defoliation. An over-abundant Victorian koala population was surveyed for ticks in the autumn of 2016. During the survey 1036 ticks were collected from 158 koalas. All ticks collected were identified as Ixodes tasmani. Tick prevalence, infestation intensity and on-host sex ratios were calculated for the population. An overview of the ticks and mites associated with koalas in Australia is also presented.

The first record of infestation by a native tick (Acari: Ixodidae) on the Australian emu (Dromaius novaehollandiae) and a review of tick paralysis in Australian birds

For the first time, infestation of the Australian emu by a native tick is recorded based on an engorged adult female specimen of the southern paralysis tick (Ixodes cornuatus) taken from a captive emu at Healesville sanctuary, Victoria, Australia. Tick paralysis in Australian birds is discussed.

Redescription of the numbat tick Ixodes (Sternalixodes) myrmecobii Roberts, 1962 (Acari: Ixodidae) with descriptions of the male and nymph, and new host records

Limited knowledge regarding the biology and identification of the Australian tick Ixodes myrmecobii exists with only the female described to date. Here we provide a description of the male and nymph as well as a redescription of the female. All described stages are molecularly characterised using the cytochrome c oxidase subunit 1 (CO1) and internal transcribed spacer 2 (ITS2) loci. An updated list of hosts is presented including the first records from humans, cattle and several native species. Information on the distribution and conservation status of this species is also included.

Phylogenetic analysis of the Australasian paralysis ticks and their relatives (Ixodidae: Ixodes: Sternalixodes)

Background

The Australasian paralysis ticks and their relatives, Ixodes Latrielle, subgenus Sternalixodes Schulze, are some of the most important ticks in the region. However, very little is known about their phylogenetic relationships. The aim of this study was to elucidate the evolutionary relationships of members of the subgenus Sternalixodes by undertaking phylogenetic analyses of morphological and molecular datasets.

Methods

Adult females (n = 64) of Sternalixodes, including Ixodes anatis Chilton, 1904, Ixodes confusus Roberts, 1960, Ixodes cornuatus Roberts, 1960, Ixodes cordifer Neumann, 1908, Ixodes dendrolagi Wilson, 1967, Ixodes hirsti Hassall, 1931, Ixodes holocyclus Neumann, 1899, Ixodes myrmecobii Roberts, 1962 and Ixodes trichosuri Roberts, 1960, were examined morphologically. Subsequently, these Ixodes spp. were genetically characterised using cytochrome c oxidase subunit 1 (cox1) gene and the internal transcribed spacer 2 (ITS-2) of the rRNA. Both morphological and molecular datasets were analysed using various phylogenetic methods to assess the evolutionary relationship of various members of the subgenus Sternalixodes.

Results

Phylogenetic analyses of the cox1 sequences and morphological characters datasets revealed that the Australian and Papuan Sternalixodes formed a distinct clade with the New Zealand member of the group I. anatis positioned basally, in a separate clade. Ixodes holocyclus, I. cornuatus and I. myrmecobii formed a distinctive clade in both the cox1 and morphological phylogenies. However, based on phylogenetic analysis of the ITS-2 data, I. holocyclus formed a separate clade whereas I. cornuatus and I. myrmecobii grouped in a different clade.

Conclusions

The cox1 and morphological data suggest that the subgenus Sternalixodes is paraphyletic, and I. anatis is not a sternalixodid tick; hence, it should not be included in the subgenus. Based on the phylogenetic analyses of cox1 and ITS-2 sequences, it appears that I. myrmecobii and I. cornuatus are not subspecies of I. holocyclus. Although this study provided better insights into the taxonomic status of the subgenus Sternalixodes, a complete morphological and molecular (using multiple markers) phylogenetic analysis including all members of the subgenus would be required to more accurately elucidate the evolutionary relationships within the subgenus.

The tick (Acari: Ixodidae) fauna of Herald's Beacon Islet, Australia

A rare opportunity to travel to Herald's Beacon Islet with permission from the Australian government to collect ticks allowed for a survey of the tick fauna of the island to be undertaken for the first time. The avian fauna of the island, which serve as hosts, was also recorded and includes one new species record for the island. The seabird soft tick Ornithodoros capensis Neumann and the seabird hard tick Amblyomma loculosum Neumann were found to be present on the island. Images of the ticks present on the island are presented along with morphological characters for their identification.

A revision of the Australian genus Trachylestes with the description of two new species (Hemiptera: Heteroptera: Reduviidae: Harpactorinae)

Two new species, Trachylestes barrowensis sp. nov. from Barrow Island, Western Australia and T. queenslandensis sp. nov. from southeastern Queensland are described, and a key for their separation from other known species of the Australian endemic genus Trachylestes Stål, 1868 (Hemiptera: Heteroptera: Reduviidae: Harpactorinae) is given.