Life cycle and behavior of Amblyomma rotundatum (Acari: Ixodidae) under laboratory conditions and remarks on parasitism of toads in Brazil

Ticks parasitizing cold-blooded animals from three different Brazilian biomes; with note for males of Amblyomma rotundatum

Ticks parasitize a wide variety of wild animals, including amphibians and reptiles. In addition to the possibility of microorganism transmission to these hosts, ticks can also cause severe bleeding, and high parasitism can lead to death. Therefore, knowing the diversity of ticks parasitizing amphibians and reptiles is important for conservation and preservation measures for these vertebrates. In the present study, we report parasitism by ticks in amphibians and reptiles from different Brazilian biomes (Amazon, Caatinga, Cerrado and Atlantic Forest). Ticks were collected from amphibians and reptiles deposited from the Herpetological Collection of the Federal University of Maranhão (UFMA), São Luís (Maranhão State), the State University Santa Cruz (UESC), Ilhéus (Bahia State), and the Federal University of São Francisco Valley (Univasf), Petrolina (Pernambuco State). Additionally, ticks were collected from amphibians and reptiles captured and road-killed in the Amazon biome, at Maranhão and Amapá States. Specimens of ticks were photographed under a Zeiss stereomicroscope (5.1 zoom). Map with the locations were made using the Qgis program. Overall, 1973 specimens of amphibians and reptiles were examined. A total of 927 ticks were collected: 98 larvae, 421 nymphs and 408 adults. Six species of ticks were identified: Amblyomma rotundatum and Amblyomma dissimile the most frequent, and Amblyomma cajennense sensu stricto, Amblyomma sculptum, Amblyomma nodosum and Amblyomma humerale, occasionally. Surprisingly, a total of twelve males of A. rotundatum were collected. Here we report new records of association between cold-blooded animals and ticks and reinforce the absence of A. dissimile in the Caatinga, Cerrado and Atlantic Forest biomes. Additionally, we report new records of A. rotundatum males on reptiles in the Amazon biome. This last record allows us to speculate about a possible association of A. rotundatum males with reptiles and the Amazon biome.

Molecular survey of Rickettsia spp. in ticks infesting wild animals in six departments in Colombia

Ticks are a globally distributed group of hematophagous ectoparasites that parasitize terrestrial vertebrates such as amphibians, reptiles, birds, and mammals. Ticks are vectors and reservoirs of pathogens that play an important role in wildlife and human health. Rickettsia is one of the bacteria transmitted by ticks, which some pathogenic species can cause rickettsiosis, a zoonotic disease that can cause serious harm to humans and animals. More information is necessary on the interactions between ticks and wildlife despite the fifty-seven ticks species already identified in Colombia. The objective of the present study was to determine the associations between ticks parasitizing wildlife and bacteria of the genus Rickettsia in six departments of Colombia. One hundred eighty-five ticks (80 larvae, 78 nymphs, and 27 adults) were collected from 55 wildlife species (amphibians, birds, mammals, and reptiles). Nine tick species were identified, and Rickettsia bellii, Rickettsia felis, 'Candidatus Rickettsia colombianensi' and Rickettsia parkeri were detected. Our results contribute to the current knowledge of tick-associated rickettsiae and the role of wildlife in their transmission dynamics.

Spatially limited pathogen pollution in an invasive tick and host system

Expansion of global commerce has facilitated pathogen pollution via the transportation and translocation of invasive species and their associated parasites and pathogens. In Florida, imported cane toads (Rhinella horribilis) were accidentally and intentionally released on multiple occasions. Early populations were found to be infested with the invasive tick, Amblyomma rotundatum, yet it is unknown if these ticks dispersed with their hosts as cane toads spread throughout much of the state. The objectives of our investigation were to (1) determine if there are fewer tick infestations on toads at the periphery than at the core of their distribution as predicted by founder effect events, and (2) identify if ticks were infected with exotic pathogens. We captured toads from 10 populations across Florida. We collected ticks, vent tissue, and tick attachment site tissue from each toad, then tested samples for bacteria in the genus, Rickettsia. We found that 3/10 populations had toads that were infested with A. rotundatum, and infested individuals were in the earliest introduced populations at the core of their distribution. Pathogen testing confirmed Rickettisa bellii in ticks, but not in toad tissues. Haplotype networks could not clearly distinguish if R. bellii in Florida was more closely related to North or South American strains, but host-tick associations suggest that the pathogen was exotic to Florida. Our investigation demonstrated that an invasive species facilitated the introduction of parasites and pathogens into Florida, yet the invasive tick species encountered limitations to dispersal on this host species.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10530-024-03291-9.

Parasitism by Amblyomma rotundatum Koch, 1844 (Acari: Ixodidae) associated with blefaritis on a red-footed tortoise (Chelonoidis carbonarius) in Rio de Janeiro state - case report

Amblyomma rotundatum is a tick species commonly found on reptiles and amphibians. In Brazil, investigations of this ectoparasite have indicated its distribution across all Brazilian biomes, although it is concentrated in certain locations. In this context, the objective of the present study was to describe a case of parasitism by A. rotundatum in a red-footed tortoise (Chelonoidis carbonarius) in the state of Rio de Janeiro. A female red-footed tortoise (C. carbonarius), seized by the environmental police, was parasitized by a tick in the left periocular region. The tick was manually removed, preserved in 70º GL ethanol, and sent for identification at the Federal Rural University of Rio de Janeiro (UFRRJ). Based on the morphological evaluation Dantas-Torres et al. (2019), Barros-Battesti et al. (2006) and Lampo et al. (1997), a diagnosis of a female specimen of A. rotundatum was made. In conclusion, this study reports the first case of A. rotundatum parasitizing C. carbonarius in the state of Rio de Janeiro, highlighting the presence of periocular blepharitis associated with this parasitism.

Distribution modeling of Amblyomma rotundatum and Amblyomma dissimile in Brazil: estimates of environmental suitability

The number of reports of tick parasitism in amphibians and reptiles has increased over the past few years, including new host and location records for Amblyomma rotundatum and Amblyomma dissimile. However, knowledge of the geographical distribution remains incomplete, and in many regions of Brazil, the presence of these vectors has not been investigated. Several candidate models were built using a correlative maximum entropy approach, and best-fitting models were selected based on statistical significance, predictive ability, and complexity based on current climatic trends and future projected climate changes. Final models showed a good ability to discriminate A. rotundatum and A. dissimile current and future potential distributions. The entire country had higher predicted suitability for A. rotundatum while A. dissimile was mainly restricted to the Amazon and Pantanal biomes. A. rotundatum is a species with enormous potential for dissemination in the next decades, potentially through the legal and illegal transport of reptiles and amphibians. The proposed model is useful for targeting surveillance efforts increasing the efficiency and accuracy of future ecological research and tick management efforts.

Mites and ticks of reptiles and amphibians in Brazil

This study focuses on the parasitic associations of mites and ticks infesting reptiles and amphibians through a multifocal approach. Herein, reptiles (n= 3,596) and amphibians (n= 919) were examined to ensure representativeness of the Brazilian herpetofauna megadiversity. The overall prevalence was calculated to better understand which were the preferred hosts for each order of Acari (Trombidiformes, Mesostigmata and Ixodida), as well as to determine which orders frequently parasitize reptiles and amphibians in Brazil, and their host specificity. Infestation rates were calculated [prevalence, mean intensity (MI) and mean abundance (MA)] for each order and species, determining which mites and ticks are more likely to be found parasitizing the ectothermic tetrapod fauna. Parasitic niches and preferred locations were recorded to help identify specific places exploited by different Acari, and to determine the host-parasite adaptations, specificity, and relationships in terms of co-evolution. In total 4,515 reptiles and amphibians were examined, of which 170 specimens were infested by mites and ticks (overall prevalence of 3.8%). Trombidiformes mites were prevalent in lizards (55.3%), followed by Ixodida on snakes (24.7%). Mesostigmata mites were the less prevalent, being identified only on Squamata reptiles (4.3% on snakes, 2.4% on lizards). In amphibians, Ixodida ticks were the most prevalent (63.2%), followed by Trombidiformes (34.6%), and lastly Oribatida (2%). From the 13 species of Trombidiformes identified, Eutrombicula alfreddugesi (19.9%) was the most abundant in terms of number of host species and infested individuals. Specimens of Ixodida, yet more common, showed low preferred locations and different values of infestation rates. Co-infestations were recorded only on snakes. Lizard mites generally adhered to the ventral celomatic area (Pterygosomatidae), and some species to the pocket-like structures (Trombiculidae). Lizards, at variance from snakes, have adapted to endure high parasitic loads with minimum effects on their health. The high number of mites recorded in the digits of toads (Cycloramphus boraceiensis, Corythomantis greening, Cycloramphus dubius, Leptodactylus latrans, Melanophryniscus admirabilis) could lead to avascular necrosis. Frogs were often infested by Hannemania larvae, while Rhinella toads were likely to be infested by Amblyomma ticks. Of note, Rhinella major toad was found infested by an oribatid mite, implying first a new parasitic relationship. The effect of high parasitic loads on critically endangered species of anurans deserves further investigation. Our results add basic knowledge to host association of mites and ticks to Brazilian reptiles and amphibians, highlighting that routine ectoparasite examination is needed in cases of quarantine as well as when for managing reptiles and amphibians in captivity given the wide diversity of Acari on the Brazilian ectothermic tetrapod fauna.

Lack of seasonality of Amblyomma rotundatum (Acari: Ixodidade) on Rhinella jimi (Anura: Bufonidae) in a semi-arid region of northeastern Brazil

Amblyomma rotundatum is an ixodid tick strictly associated with cold-blooded animals, among them the toad Rhinella jimi. This work aimed to evaluate the seasonal dynamics of larvae, nymphs, and adults of A. rotundatum parasitizing R. jimi in an area within the semi-arid Caatinga Biome of northeastern Brazil. Monthly sampling from February 2014 to January 2016 resulted in a total of 592 R. jimi toads captured and inspected for infestation by ticks, which were counted and identified. After the procedure, the toads were released with their ticks at the same capture site. During the study period, a total of 658 A. rotundatum were counted, comprising 497 larvae, 110 nymphs, and 51 females. The two-year mean abundances of larvae, nymphs, and adults were 0.84, 0.19, and 0.09, respectively. The two-year mean infestation intensities of larvae, nymphs, and adults were 3.65, 1.45, and 1.34, respectively. Comparing the monthly values of prevalence, mean abundance, and mean infestation intensity of A. rotundatum life stages, differences were observed between the first and second year of study; however, with no clear seasonal pattern.

Manual for maintenance of multi-host ixodid ticks in the laboratory

Use of laboratory animals as hosts for blood-sucking arthropods remains a time-proven and the most efficient method for establishment and propagation of slowly feeding ixodid ticks, despite introduction of techniques involving artificial feeding on either animal skins or synthetic membranes. New Zealand White rabbits are usually the most accessible and most suitable hosts routinely used for establishment and maintenance of a large variety of multi-host tick species. Here we describe standard procedures for maintaining colonies of multi-host ixodid ticks by feeding all developmental stages (larvae, nymphs, and adults) upon New Zealand White rabbits. When needed, the same procedures can be easily adapted to other species of laboratory or domestic animals from mice to dogs and goats. A summary of our experience in maintaining laboratory colonies of Ixodes scapularis, Ixodes pacificus, Amblyomma americanum, Dermacentor variabilis, Dermacentor occidentalis, Haemaphysalis leporispalustris, and Rhipicephalus sanguineus with descriptions of the complete laboratory life cycles and reliable production of uninfected ticks under standardized conditions has been published by Troughton and Levin (J Med Entomol 44:732-740, 2007). Here we provide step-by-step recommendations for various procedures used in the maintenance of ixodid tick colonies based on over 20 years of experience.

Patterns of parasitism by Amblyomma rotundatum (Ixodidae) on Rhinella schneideri (Bufonidae) in islands of São Francisco River, Minas Gerais, Brazil

Abstract: We sampled ticks from specimens of the rococo toad Rhinella schneideriby flannel dragging on two Islands located in the São Francisco River near the Três Marias hydroelectric dam, southeastern Brazil. A total of 120 toads was examined, of which 63 (52.5%) were parasitized only by Amblyomma rotundatumtotaling 96 larvae, 163 nymphs and 134 females. The burden of parasitism ranged from one to 43 ticks, with a mean intensity of infestation of 6.2±5.5 ticks per host. The tick A. rotundatumexhibited highly aggregated distribution. Peak abundance of larvae and nymphs occurred in the dry season (May to September), whereas peak abundance of females occurred in the wet season (October to April). We collected most ticks near the head and hind limbs of R. schneideri. The finding of two engorged A. rotundatumnymphs in the same resting places of two toads and the absence of this species in the dragged areas suggest a nidicolous behavior at the studied site.