Patterns of diversity and abundance of fleas and mites in the Neotropics: host-related, parasite-related and environment-related factors

Ectoparasites of wild rodents in forest sites invaded and uninvaded by Maesopsis eminii in Amani nature forest reserve, Tanzania

Parasites are important component of communities in a forest ecosystem with profound effects on trophic interactions such as food web. Modification of the forest structure (e.g. changes in species composition and abundance of key species) can have a strong impact on the occurrence, diversity, and abundance of parasites, with subsequent repercussions for ecosystem functioning. In this study, we compared the occurrence and abundance of wild rodents' ectoparasites from forest sites invaded and uninvaded by an invasive tree, Maesopsis eminii in Amani Nature Forest Reserve, Tanzania. Three large plots (40 m × 100 m) were randomly established in each forest sites invaded and uninvaded by M. eminii. In each plot, 50 Sherman traps were systematically placed at 10 m interval for capturing wild rodents through a capture-mark-recapture technique. Wilcox rank sum test was used to compare for differences in the abundance of infested rodents and ectoparasites between the invaded and uninvaded forest sites. A total of 297 individual rodents were captured and screened for ectoparasites, including 174 rodents from uninvaded forest site and 123 rodents from invaded forest site. The number of infested rodents were significantly (W = 8592, P < 0.001) greater in uninvaded forest site (66.27%) than in the invaded forest site (36.2%). Furthermore, a significant greater number of Echinolaelaps echidninus (W = 1849, P < 0.01) and Dinopsyllus ellobius (W = 2800.5, P < 0.05) ectoparasites were found in uninvaded as compared to the invaded forest sites. The results of this study suggest that the invasion and dominance by, M. eminii in Amani Nature Reserve has created unfavorable conditions for rodents and ectoparasites and therefore impacting the diversity and function of the forest ecosystem. We recommend prevention of further introduction of the M. eminii outside their natural range and mitigating the impact of the established M. eminii in Amani Forest Nature Reserve.

Explorational analysis of the abundance and prevalence of chigger and gamasid mites parasitic on small mammals in Vietnam

We studied chigger and gamasid mite loads on small mammals during the dry season in Vietnam and used both our field data and museum collections to estimate the influence of environmental factors on mite abundance and prevalence. Generalized linear (mixed effect) models were used to analyze the data. We examined 1,239 small mammal individuals, which were obtained from field expeditions and museum collections belonging to 59 species. In different localities, Rattus Fischer (Rodentia: Muridae), Niviventer Marshall (Rodentia: Muridae), and Maxomys Sody (Rodentia: Muridae) were the most common animals captured. The prevalence of chigger and gamasid mites in our expedition data was high: 72% and 62%, respectively. We found differences in the abundance of chigger mites between different populations of the same species of small mammals. Season and locality were the main factors that influenced chigger mite abundance and prevalence. The best model that predicted the abundance and prevalence of chigger mites included geography (province) as a predictor and host species and season as random effects. For the first time, we analyzed factors connected with climate and weather affecting chigger mites of small mammals in Vietnam.

Repeated Cross-Sectional Survey of Ectoparasites in Sheep from Central Tunisia: Does Low Prevalence Indicate Good Hygiene or Resistance to Ectoparasites?

Sheep ectoparasites such as chewing lice, fleas and ticks are serious constraints to sheep productivity and are the cause of skin lesions in animals that decrease their market value. This study aims at investigating the ectoparasite fauna infesting small ruminants in the district of Sidi Bouzid (central Tunisia). A total of 1243 Barbarine and Queue Fine de l'Ouest (QFO) sheep were examined every two months for one year. Of the total animals examined, 74 were infested by at least 1 parasite group (5.95%). Three ectoparasite groups were identified as Psoroptes ovis (0.48%; 6/1243), ticks (5.3%; n = 66/1243) and one specimen of Ctenocephalides canis (0.08%; n = 1/1243). The most abundant tick among the 358 specimens was Rhipicephalus sanguineus sensu lato (n = 337; 94.1%), followed by Hyalomma impeltatum (n = 7/358; 1.9%), H. dromedarii (n = 7/358; 1.9%), H. excavatum (n = 5/358; 1.4%) and only two specimens of H. scupense (n = 2/358; 0.55%). The sheep herds showed low infestation prevalence by ectoparasite over the year, with a significant difference according to the seasons (p < 0.05). A higher infestation prevalence was recorded in March (14.36%). Barbarine sheep breed showed significantly higher infestation prevalence (16.8%) compared to QFO (0.8%) (p < 0.01). There were no differences in infestation prevalence according to sex of the animal or age groups. Knowledge of the ectoparasite population harboured by sheep, its activity dynamics and risk factors is required to develop effective ectoparasite control options. The low prevalence of ectoparasite infestation in sheep reported here may be due to possible genetic resistance or simply to successful hygiene measures implemented by farmers.

Influence of biotic and abiotic factors on flea species population dynamics on Lasiopodomys brandtii

Brandt's Vole (Lasiopodomys brandtii) is one of the most abundant rodent species in the grasslands of Inner Mongolia, China, and one of the main carriers of Yersinia pestis, the plague bacterium. There have been several instances of plague transmission among L. brandtii, and all of their dominant flea species are known carriers of plague. Little work has been done to understand the regulation of flea abundance on L. brandtii by biotic and abiotic factors. Here, we examine the impacts of host and climate variation on flea abundance on L. brandtii in May, July, and September of 2021 in the East Ujumqin Banner, Xilinhot City, Inner Mongolia Autonomous Region. We arrived at the following conclusions: 1) There were 8 flea species representing 2 families and 5 genera collected from L. brandtii, and Frontopsylla luculenta, Neopsylla pleskei orientalis, and Amphipsylla primaris mitis were most common. 2) Host body weight, host age, season, temperature, and humidity are key factors influencing flea abundance on L. brandtii. 3) Flea species vary in their respective responses to factors.

Host species and environment drivers of ectoparasite community of rodents in a Mojave Desert wetlands

Drivers of patterns of ectoparasitism in rodents in patchy Mojave Desert wetlands were investigated. A total of 1,571 ectoparasites in Mesostigmata, Trombidiformes, Siphonaptera and Ixodida were collected from 341 rodents (Microtus californicus scirpensis, Mus musculus, Reithrodontomys megalotis, Peromyscus eremicus, and Neotoma lepida) at eleven marshes. Trombiculids accounted for 82.5% of mites, followed by the mesostigmatid Ornithonyssus bacoti (17.5%), with chiggers predominating on voles and harvest mice. There were at least three genera of chiggers (Eutrombicula alfreddugesi, Euschoengastia sp. novel, and Blankaartia sp. novel). Fleas included Orchopeas leucopus (90.3% of all fleas) and O. sexdentatus (9.7%), and ticks were the novel endemic Ixodes mojavensis (82.1% of ticks) and Dermacentor similis (17.9%). On all hosts and at all marshes, coverage-based rarefaction sampling was over 96%, indicating coverage sufficient for analysis. Dissimilarities in ectoparasite community structure were driven mainly by chiggers, I. mojavensis and O. leucopus. Northern marshes were dominated by chiggers; central marshes by I. mojavensis; and southern marshes by O. leucopus. Primary determinants of ectoparasite community structure were host species, patch size, and parasite interspecific interactions. Host species richness and environmental factors such as patch distance and water and plant availability were not significantly associated with patterns of ectoparasitism. There were nine (60%) significant negative pairwise associations between ectoparasite taxa and no significant positive relationships. Ixodes mojavensis had the highest number of negative associations (with five other species), followed by chiggers and O. bacoti with two negative associations each. The study area is among the most arid in North America and supports numerous rare and endemic species in increasingly isolated wetland habitat patches; knowledge of ectoparasite ecology in this region identifies potential ectoparasite vectors, and provides information needed to design and implement programs to manage vector-borne diseases for purposes of wildlife conservation.

Effects of host factors on the dynamics of fleas (Siphonaptera) in Sigmodontinae rodents (Cricetidae) from El Espinal Ecoregion, Argentina

We investigated the patterns of flea infestation in wild populations of eight Sigmodontinae rodent species: Akodon azarae, Calomys callidus, Calomys venustus, Holochilus chacarius, Necromys lasiurus, Oligoryzomys flavescens, Oligoryzomys nigripes and Oxymycterus rufus. Rodents were captured in systematic trapping sessions carried out along 2 years at two localities from El Espinal Ecoregion, Argentina. Mean flea intensity, occurrence (presence/absence) of flea infestation, richness and diversity were compared for different ages, body condition, sex and rodent tribes (Akodontini, Oryzomyini and Phyllotini). A total of 376 fleas of the following species and subspecies were collected: Craneopsylla minerva wolffhuegeli, Polygenis (Neopolygenis) pradoi, Polygenis (Polygenis) axius axius, and Polygenis (Polygenis) byturus. The most important factor driving flea infestation was the rodent tribe, with Phyllotini showing the highest values of occurrence, abundance and species richness. Only C. m. wolffhuegeli was affected by the sex of the host. Age and body condition of the hosts did not affect flea infestation. Our results contribute to knowledge of the ecology of fleas on rodent hosts in El Espinal Ecoregion. The relevance of host taxonomy as driver of flea dynamics highlight the importance of considering host community structures at the time of studying the ecology of parasites.

Small mammals, ticks and rickettsiae in natural and human-modified landscapes: Diversity and occurrence of Brazilian spotted fever in Brazil

We studied communities of small mammals and their ticks in endemic (E) and non-endemic (NE) areas for Brazilian spotted fever (BSF), aiming to infer if diversity parameters of parasites and hosts could be related to occurrence and prevalence of rickettsial infection, especially Rickettsia rickettsii. We compared E and NE areas in human-modified landscapes (HMLs) and natural areas (BIO) with no report of BSF cases. Composition and equitability were important components of diversity explaining differences among areas. The marsupial Didelphis albiventris was dominant in HMLs, but not in natural areas, and this opossum was the main host for the tick Amblyomma sculptum, principal vector of R. rickettsii, especially in E areas. Communities of ticks were dominated by A. sculptum, followed by Amblyomma dubitatum in E areas. In NE areas, this dominance was inverted, with more A. dubitatum than A. sculptum infesting small mammals, but the numbers of ticks were much lower than in E areas. Composition and abundance of ticks in natural areas were very dissimilar from HMLs, with the lowest tick burdens. Didelphis albiventris in E areas presented higher seroprevalence and endpoint titres against R. rickettsii than in other areas. At least three Rickettsia species, non-pathogenic to humans, were detected in natural areas (Rickettsia bellii, Rickettsia amblyommatis and 'Candidatus Rickettsia andeanae'), and only one non-pathogenic species in HMLs (R. bellii). Our results suggest that higher diversity of ticks, hosts and rickettsiae could be relevant factors in buffering the effect in BSF occurrence. Particularly for D. albiventris, its importance has to be quantified in further studies considering the epidemiological scenario of BSF.

Detection of Bartonella sp. and a novel spotted fever group Rickettsia sp. in Neotropical fleas of wild rodents (Cricetidae) from Southern Brazil

The Neotropical region shows a great diversity of fleas, comprising more than 50 genera. The importance of the study of fleas is linked to their potential role as disease vectors. The aim of this study is to investigate the presence of Rickettsia spp. and Bartonella spp. in Neotropical fleas collected from wild rodents in Southern Brazil. From 350 rodents captured, 30 were parasitized by fleas. A total of 61 fleas belonging to two genera and six different species were collected (Craneopsylla minerva minerva, Polygenis occidentalis occidentalis, Polygenis platensis, Polygenis pradoi, Polygenis rimatus, and Polygenis roberti roberti). In 13 % of fleas of three different species (C. minerva, P. platensis, and P. pradoi) Rickettsia sp. DNA was found. Phylogenetic analysis of concatenated sequences of gltA, htrA, and ompA genes showed that Rickettsia sp. found in rodent fleas (referred as strain Taim) grouped together with Spotted Fever Group Rickettsia. In reference to Bartonella spp., five genotypes were identified in seven fleas of two species (C. minerva and P. platensis) and in five rodent spleens. Also, 207 frozen samples of wild rodents were screened for these pathogens: while none was positive for Rickettsia spp.; five rodent spleens were PCR-positive for Bartonella spp.. Herein, we show the detection of potential novel variants of Bartonella sp. and Rickettsia sp. in fleas collected of wild rodents from Southern Brazil. Further studies are needed to fully characterize these microorganisms, as well as to improve the knowledge on the potential role of Neotropical flea species as diseases vectors.

Parasite species co-occurrence patterns on Peromyscus: Joint species distribution modelling

Hosts are often infested by multiple parasite species, but it is often unclear whether patterns of parasite co-occurrence are driven by parasite habitat requirements or parasite species interactions. Using data on infestation patterns of ectoparasitic arthropods (fleas, trombiculid mites, cuterebrid botflies) from deer mice (Peromyscus maniculatus), we analyzed species associations using joint species distribution modelling. We also experimentally removed a flea (Orchopeas leucopus) from a subset of deer mice to examine the effect on other common ectoparasite species. We found that the mite (Neotrombicula microti) and botfly (Cuterebra sp.) had a negative relationship that is likely a true biotic species interaction. The flea had a negative association with the mite and a positive association with the botfly species, both of which appeared to be influenced by host traits or parasite life-history traits. Furthermore, experimental removal of the flea did not have a significant effect on ectoparasite prevalence of another species. Overall, these findings suggest that complex parasite species associations can be present among multiple parasite taxa, and that aggregation is not always the rule for ectoparasite communities of small mammals.

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A negative species interaction was identified between a mite and botfly species.

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Additional parasite associations appear to be influenced by host traits or parasite life-history traits.

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Removal of the flea species did not have an effect on prevalence of another species.

Drivers of community turnover differ between avian hemoparasite genera along a North American latitudinal gradient

The latitudinal diversity gradient (LDG) is an established macroecological pattern, but is poorly studied in microbial organisms, particularly parasites. In this study, we tested whether latitude, elevation, and host species predicted patterns of prevalence, alpha diversity, and community turnover of hemosporidian parasites. We expected parasite diversity to decrease with latitude, alongside the diversity of their hosts and vectors. Similarly, we expected infection prevalence to decrease with latitude as vector abundances decrease. Lastly, we expected parasite community turnover to increase with latitudinal distance and to be higher between rather than within host species. We tested these hypotheses by screening blood and tissue samples of three closely related avian species in a clade of North American songbirds (Turdidae: Catharus, n = 466) across 17.5° of latitude. We used a nested PCR approach to identify parasites in hemosporidian genera that are transmitted by different dipteran vectors. Then, we implemented linear-mixed effects and generalized dissimilarity models to evaluate the effects of latitude, elevation, and host species on parasite metrics. We found high diversity of hemosporidian parasites in Catharus thrushes (n = 44 lineages) but no evidence of latitudinal gradients in alpha diversity or prevalence. Parasites in the genus Leucocytozoon were most prevalent and lineage rich in this study system; however, there was limited turnover with latitude and host species. Contrastingly, Plasmodium parasites were less prevalent and diverse than Leucocytozoon parasites, yet communities turned over at a higher rate with latitude and host species. Leucocytozoon communities were skewed by the dominance of one or two highly prevalent lineages with broad latitudinal distributions. The few studies that evaluate the hemosporidian LDG do not find consistent patterns of prevalence and diversity, which makes it challenging to predict how they will respond to global climate change.

Norway rat (Rattus norvegicus) ectoparasites in livestock production systems from central Argentina: Influencing factors on parasitism

Haematophagous ectoparasites are worldwide vectors of many zoonotic bacterial diseases, both emerging and re-emerging, whose incidences are rising. Livestock development alters different environmental characteristics such as the microclimate of a site, changing the availability, density and susceptibility of the hosts to pathogens and vectors, indirectly influencing the spread and persistence of a disease within an ecosystem. The Norway rat (Rattus norvegicus), the most abundant vertebrate pest species found on livestock farms from Argentina, is a reservoir for several important zoonotic bacteria and may harbor ectoparasite species, which act as their vectors. Even though the Norway rat is widely known for its role as an ectoparasite host, the ecological characteristics of their ectoparasite communities and the related factors with parasitism on livestock farms have never been described. In the present study, we describe the ectoparasite community in Norway rats from central Argentina livestock farms, while also depicting the influencing factors on both ectoparasite occurrence and abundance. Ectoparasites were collected from rats captured in 20 sites from Buenos Aires province, between the winter of 2016 and the summer of 2018. A total of 1441 ectoparasite individuals were collected from 159 Norway rat individuals [Total ectoparasite prevalence = 69.2%; Mean ectoparasite specimen abundance (± CI) = 9.06 ± 2.32 ectoparasite individuals per rat; Mean ectoparasite specimen intensity (±CI) = 13.10 ± 3.08 ectoparasite individuals per infested rat found]. Ectoparasite assemblage consisted of four cosmopolitan species, recognized for their sanitary relevance: mites (Laelapidae: Laelaps nuttalli and Laelaps echidninus), lice (Polyplacidae: Polyplax spinulosa) and fleas (Pulicidae: Xenopsylla cheopis). We observed higher Norway rat abundance in sites related to higher ectoparasite occurrence and abundance frequencies on the rats. Additionally, ectoparasites were more abundant on rats in warm seasons and on male individuals, over female rats. Moreover, the geographical location of the studied sites influenced the ectoparasite assemblage structure observed on the rats. This study broadens the knowledge on the role of Norway rats as zoonotic ectoparasites hosts and analyzes the drivers influencing ectoparasite occurrence and abundance on the most populated region of Argentina, which is also the region with the most intensive livestock farming. Therefore, this survey may assist in evaluating potential risks for humans and generate effective sanitary control strategies for ectoparasite-borne infectious diseases.

Multi-driver and multi-scale assessment of vine community structure and composition across a complex tropical environmental matrix

Ecological communities are structured by multiple processes operating at multiple scales yet understanding the scale-dependency of these processes remains an open challenge. This might be particularly true for parasites, for which biotic rather than abiotic processes may play a primary role in structuring communities. Focusing on vines, a group of structural parasites that gain access to the canopy using different climbing mechanisms, we examined the influence of abiotic factors in tandem with host-parasite and parasite-parasite interactions in the assembly of tropical vine communities. Two synthetic variables, namely Climate1 and landscape Variety, were consistently important in explaining variation in species richness and diversity, as well as species composition, but their importance varied with scale. Whereas Climate1 summarizes the largest variability among climatic variables, landscape Variety expresses landscape heterogeneity within a neighborhood. Significant patterns of species co-occurrences suggest that vine-vine interactions also contribute to vine community assembly. Our results may be critical to understand vine proliferation and help design management strategies for their control.

Assessing the natural circulation of canine vector-borne pathogens in foxes, ticks and fleas in protected areas of Argentine Patagonia with negligible dog participation

We collected blood and/or ectoparasites from 49 South American grey foxes (Lycalopex griseus) and two Andean foxes (L. culpaeus) caught in two National Parks of southern Argentine Patagonia (Bosques Petrificados, BPNP; and Monte León, MLNP) where dogs are nearly absent (density < 0.01 dog/km2). Common ectoparasites were the flea Pulex irritans (88% prevalence) and the tick Amblyomma tigrinum (29%). Conventional PCR and sequencing of 49 blood samples, 299 fleas analysed in 78 pools, and 21 ticks revealed the presence of DNA of the following canine vector-borne pathogens: in grey foxes, Rickettsia sp. (3%), hemoplasmas (8%), including Mycoplasma haemocanis, and Hepatozoon sp. (50%); in P. irritans, Bartonella spp. (72% of flea pools from 76% of foxes), mostly B. vinsonii subsp. berkhoffii but also B. rochalimae, Anaplasmataceae (Wolbachia sp.; 60% and 54%), and M. haemocanis/haemofelis (29% and 18%); and in A. tigrinum, Hepatozoon sp. (33% of ticks in 4 of 7 foxes). No piroplasmid DNA was detected in any sample. Andean foxes were negative for all tested pathogens. Two different Hepatozoon haplotypes were detected: the most prevalent was phylogenetically associated with H. felis, and the other with H. americanum and related sequences. Amblyomma tigrinum and Hepatozoon sp. were more abundant and/or prevalent in BPNP than in colder MLNP, 300 km southwards, perhaps located close to the limit for tick suitability. Bartonella v. berkhoffii was also significantly more prevalent in fleas of foxes in BPNP than in MLNP. This study provides novel information about natural host-pathogen associations in wildlife, markedly extends the distribution area in South America of arthropods and vector-borne pathogens of veterinary and public health interest, and contributes preliminary evidence about the potential role of A. tigrinum and P. irritans as vectors, respectively, for potentially new species of Hepatozoon from Lycalopex spp. and for M. haemocanis that should be further investigated.

Diversity, distribution and parasitism rates of fleas (Insecta: Siphonaptera) on sigmodontine rodents (Cricetidae) from Argentinian Patagonia

Fleas have great medical relevance as vectors of the causative agents of several diseases in animals and humans and rodents are the principal reservoirs for these pathogens. Argentinian Patagonia has the highest diversity of rodent fleas in South America. However, parasitism rates of rodents by fleas, the factors that influence them and the ecological aspects that modulate geographical distributions of flea-host association remain unknown for this region. This is the first study to record the diversity, prevalence, abundance, geographical distributions and host ranges of fleas in Argentinian Patagonia. It also compares parasitism rates among Patagonian ecoregions and host species. We captured 438 rodents belonging to 13 species, which harboured 624 fleas from 11 species and subspecies (P = 46%; mean abundance = 1.44). The high parasitism rates obtained were consistent with previous records for other arid regions, suggesting that Patagonia favours the survival and development of Siphonaptera. Host geographic range and abundance were related to the parasitological indexes: host species with high-density populations had the highest mean flea abundance and prevalence, whereas widely distributed hosts had the highest richness and diversity of flea species. Our results contribute to the knowledge of the flea-host-environment complex. Our analysis of flea distributions and parasitism rate in Central Patagonia may be useful in epidemiological studies of flea-borne diseases and provide a basis for implementing surveillance systems for better risk assessment of emerging zoonoses in the region.

Host species influence on flea (Siphonaptera) infection parameters of terrestrial micromammals in a temperate forest of Mexico

Studies of abundance and distribution of organisms are fundamental to ecology. The identity of host species is known to be one of the major factors influencing ectoparasitic flea abundance, but explanations are still needed regarding how host taxa influence abundance parameters of different flea species. This study was carried out at La Malinche National Park (LMNP), Tlaxcala, Mexico, where previously 11 flea species had been recorded on 8 host species. Our aims were to list micromammal flea species, to determine flea infection parameters [flea prevalence (FP) and flea mean abundance (FMA)] and to analyse the influence of host species on these parameters. A total of 16 species of fleas were identified from 1178 fleas collected from 14 species of 1274 micromammals captured with Sherman® traps from March 2014 to December 2015 in 18 sites at LMNP. Some host species influence FP and FMA, in particular, Microtus mexicanus and Peromyscus melanotis showed particularly higher infection values than other host species. Plusaetis aztecus and Plusaetis sibynus were identified as the most abundant flea species.

Drivers of flea (Siphonaptera) community structure in sympatric wild carnivores in northwestern Mexico

Host identity, habitat type, season, and interspecific interactions were investigated as determinants of the community structure of fleas on wild carnivores in northwestern Mexico. A total of 540 fleas belonging to seven species was collected from 64 wild carnivores belonging to eight species. We found that the abundances of some flea species are explained by season and host identity. Pulex irritans and Echidnophaga gallinacea abundances were significantly higher in spring than in fall season. Flea communities on carnivore hosts revealed three clusters with a high degree of similarity within each group that was explained by the flea dominance of E. gallinacea, P. simulans, and P. irritans across host identity. Flea abundances did not differ statistically among habitat types. Finally, we found a negative correlation between the abundances of three flea species within wild carnivore hosts. Individual hosts with high loads of P. simulans males usually had significantly lower loads of P. irritans males or tend to have lower loads of E. gallinacea fleas and vice-versa. Additionally, the logistic regression model showed that the presence of P. simulans males is more likely to occur in wild carnivore hosts in which P. irritans males are absent and vice-versa. These results suggest that there is an apparent competitive exclusion among fleas on wild carnivores. The study of flea community structure on wild carnivores is important to identify the potential flea vectors for infectious diseases and provide information needed to design programs for human health and wildlife conservation.

Ectoparasites of small-mammals: determinants of community structure in South American savannah

This study aimed to assess the contribution of hosts characteristics (rodents and marsupials) in the organization of ectoparasite communities present in woodland patches in western central Brazil. We verified the effect of host species, sex, body mass and vertical strata in addition to the role of seasonality on the ectoparasite composition, richness and abundance. The total sampling effort was 22 032 trap-nights equally distributed in 54 woodland patches. Variance partition and principal coordinate analysis were used to verify the existence of significant relationships between response variables and predictors. As expected, host species was the most important variable in ectoparasite community assembly. The composition, richness and abundance of mites and lice were highly influenced by host species, although higher for mites than for lice. Host body mass had a determining role on the richness and abundance of tick species. Vertical stratification and seasonality had weak influence, while the sex of the host had no influence on the organization of these communities. The results are closely related to the evolutionary characteristics of the species involved, as well as with local environmental characteristics of the study area.

Community assembly and coexistence in communities of arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi are asexual, obligately symbiotic fungi with unique morphology and genomic structure, which occupy a dual niche, that is, the soil and the host root. Consequently, the direct adoption of models for community assembly developed for other organism groups is not evident. In this paper we adapted modern coexistence and assembly theory to arbuscular mycorrhizal fungi. We review research on the elements of community assembly and coexistence of arbuscular mycorrhizal fungi, highlighting recent studies using molecular methods. By addressing several points from the individual to the community level where the application of modern community ecology terms runs into problems when arbuscular mycorrhizal fungi are concerned, we aim to account for these special circumstances from a mycocentric point of view. We suggest that hierarchical spatial structure of arbuscular mycorrhizal fungal communities should be explicitly taken into account in future studies. The conceptual framework we develop here for arbuscular mycorrhizal fungi is also adaptable for other host-associated microbial communities.

Environment-related and host-related factors affecting the occurrence of lice on rodents in Central Europe

We studied the effects of environment- (habitat, season) and host-related (sex, body mass) factors on the occurrence of four species of lice (Insecta:Phthiraptera:Anoplura) on six rodent species (Rodentia:Muridae). We asked how these factors influence the occurrence of lice on an individual host and whether different rodent–louse associations demonstrate consistent trends in these effects. We found significant effects of at least one environment-related and at least one host-related factor on the louse occurrence in five of six host–louse associations. The effect of habitat was significant in two associations with the occurrence of lice being more frequent in lowland than in mountain habitats. The effect of season was significant in five associations with a higher occurrence of infestation during the warm season in four associations and the cold season in one association. Host sex affected significantly the infestation by lice in three associations with a higher frequency of infestation in males. Host body mass affected the occurrence of lice in all five associations, being negative in wood mice and positive in voles. In conclusion, lice were influenced not only by the host- but also by environment-related factors. The effects of the latter could be mediated via life history parameters of a host.

Drivers of Intensity and Prevalence of Flea Parasitism on Small Mammals in East African Savanna Ecosystems

The relative importance of environmental factors and host factors in explaining variation in prevalence and intensity of flea parasitism in small mammal communities is poorly established. We examined these relationships in an East African savanna landscape, considering multiple host levels: across individuals within a local population, across populations within species, and across species within a landscape. We sampled fleas from 2,672 small mammals of 27 species. This included a total of 8,283 fleas, with 5 genera and 12 species identified. Across individual hosts within a site, both rodent body mass and season affected total intensity of flea infestation, although the explanatory power of these factors was generally modest (<10%). Across host populations in the landscape, we found consistently positive effects of host density and negative effects of vegetation cover on the intensity of flea infestation. Other factors explored (host diversity, annual rainfall, anthropogenic disturbance, and soil properties) tended to have lower and less consistent explanatory power. Across host species in the landscape, we found that host body mass was strongly positively correlated with both prevalence and intensity of flea parasitism, while average robustness of a host species to disturbance was not correlated with flea parasitism. Cumulatively, these results provide insight into the intricate roles of both host and environmental factors in explaining complex patterns of flea parasitism across landscape mosaics.

Neosomes of tungid fleas on wild and domestic animals

Tunga is the most specialized genus among the Siphonaptera because adult females penetrate into the skin of their hosts and, after mating and fertilization, undergo hypertrophy, forming an enlarged structure known as the neosome. In humans and other warm-blooded animals, neosomes cause tungiasis, which arises due to the action of opportunistic agents. Although its effects on humans and domestic animals are well described in the literature, little is known about the impact of tungiasis on wild animals. This review focuses on the morphology, taxonomy, geographical distribution, hosts, prevalence, sites of attachment, and impact of tungid neosomes on wild and domestic animals. Because neosomes are the most characteristic form of the genus Tunga and also the form most frequently found in hosts, they are here differentiated and illustrated to aid in the identification of the 13 currently known species. Perspectives for future studies regarding the possibility of discovering other sand flea species, adaptation to new hosts, and the transfer of tungids between hosts in natural and modified habitats are also presented.