Functional similarity affects similarity in partner composition in flea-mammal networks.

Functional signal in an interaction network is a phenomenon in which species resembling each other in their traits interact with similar partners. We tested the functional signal concept in realm-specific and regional flea-host networks from four biogeographic realms and asked whether the species composition of (a) host spectra and (b) flea assemblages is similar between functionally similar flea and host species, respectively. Analogously to testing for phylogenetic signal, we applied Mantel tests to investigate the correlation between flea or host functional distances calculated from functional dendrograms and dissimilarities in sets of interacting partners. In all realm-specific networks, functionally similar fleas tended to exploit similar hosts often belonging to the same genus, whereas functionally similar hosts tended to harbour similar fleas, again often belonging to the same genus. The strength of realm-specific functional signals and the frequency of detecting a significant functional signal in the regional networks differed between realms. The frequency of detecting a significant functional signal in the regional networks correlated positively with the network size for fleas and with the number of hosts in a network for hosts. A functional signal in the regional networks was more frequently found for hosts than for fleas. We discuss the mechanisms behind the functional signal in both fleas and their hosts, relate geographic functional signal patterns to the historic biogeography of fleas and conclude that functional signals in the species composition of host spectra for fleas and of flea assemblages for hosts result from the interplay of evolutionary and ecological processes.

Relationships between functional alpha and beta diversities of flea parasites and their small mammalian hosts.

We studied the relationships between functional alpha and beta diversities of fleas and their small mammalian hosts in 4 biogeographic realms (the Afrotropics, the Nearctic, the Neotropics and the Palearctic), considering 3 components of alpha diversity (functional richness, divergence and regularity). We asked whether (a) flea alpha and beta diversities are driven by host alpha and beta diversities; (b) the variation in the off-host environment affects variation in flea alpha and beta diversities; and (c) the pattern of the relationship between flea and host alpha or beta diversities differs between geographic realms. We analysed alpha diversity using modified phylogenetic generalized least squares and beta diversity using modified phylogenetic generalized dissimilarity modelling. In all realms, flea functional richness and regularity increased with an increase in host functional richness and regularity, respectively, whereas flea functional divergence correlated positively with host functional divergence in the Nearctic only. Environmental effects on the components of flea alpha diversity were found only in the Holarctic realms. Host functional beta diversity was invariantly the best predictor of flea functional beta diversity in all realms, whereas the effects of environmental variables on flea functional beta diversity were much weaker and differed between realms. We conclude that flea functional diversity is mostly driven by host functional diversity, whereas the environmental effects on flea functional diversity vary (a) geographically and (b) between components of functional alpha diversity.

Phenotypic and genotypic characterization of acaricide resistance in Rhipicephalus microplus field isolates from South Africa and Brazil.

Rhipicephalus (Boophilus) microplus is one of the most successful ticks infesting cattle around the world. This highly-invasive species transmits cattle parasites that cause cattle fever leading to a high socio-economic burden. Tick eradication programs have often failed, due to the development of acaricide resistance. Here we characterize acaricide resistance in a large number of tick isolates from regions in South Africa (KwaZulu Natal, Mpumalanga, Western & Eastern Cape provinces) and two Brazilian regions. By means of Larval Packet Tests (LPT's) acaricide resistance was evaluated against five commonly used acaricides (chlorfenvinphos, fipronil, deltamethrin, amitraz, and ivermectin). Furthermore, the coding region containing the knock down resistance (kdr) mutation, known to result in pyrethroid resistance, was sequenced. Resistance to at least one acaricide class was reported in each of the five regions, and a high proportion of tick isolates exhibited multi-resistance to at least two acaricide classes (range: 22.2-80.0%). Furthermore, resistance ratios (RR) showed high spatial variation (intercontinental, as well as regional) but low regional spatial autocorrelation. Previous and current acaricide use correlated with current RR, and several combinations of acaricide RR were positively correlated. Moreover, fipronil resistance tended to be higher in farms with more intense acaricide use. The kdr-mutations provided the ticks a fitness advantage under the selection pressure of synthetic pyrethroids based on population (kdr-allele frequency) and individual level data (genotypes). The data show the threat of acaricide (multi-)resistance is high in Brazil and South Africa, but acaricide specific levels need to be assessed locally. For this purpose, gathering complementary molecular information on mutations that underlie resistance can reduce costs and expedite necessary actions. In an era of human-caused habitat alterations, implementing molecular data-driven programs becomes essential in overcoming tick-induced socio-economic losses.

Environment and traits affect parasite and host species positions but not roles in flea-mammal networks.

We studied spatial variation in the effects of environment and network size on species positions and roles in multiple flea-mammal networks from four biogeographic realms. We asked whether species positions (measured as species strength [SS], the degree of interaction specialization [d'], and the eigenvector centrality [C]) or the roles of fleas and their hosts in the interaction networks: (a) are repeatable/conserved within a flea or a host species; (b) vary in dependence on environmental variables and/or network size; and (c) the effects of environment and network size on species positions or roles in the networks depend on species traits. The repeatability analysis of species position indices for 441 flea and 429 host species, occurring in at least two networks, demonstrated that the repeatability of SS, d', and C within a species was significant, although not especially high, suggesting that the indices' values were affected by local factors. The majority of flea and host species in the majority of networks demonstrated a peripheral role. A value of at least one index of species position was significantly affected by environmental variables or network size in 41 and 36, respectively, of the 52 flea and 52 host species that occurred in multiple networks. In both fleas and hosts, the occurrence of the significant effect of environment or network size on at least one index of species position, but not on a species' role in a network, was associated with some species traits.

Documenting the microbiome diversity and distribution in selected fleas from South Africa with an emphasis on the cat flea, Ctenocephalides f. felis.

The factors that influence parasite associated bacterial microbial diversity and the geographic distributions of bacteria are not fully understood. In an effort to gain a deeper understanding of the relationship between the bacterial diversity of Ctenocephalides fleas and host species and the external environment, we conducted a metagenetic analysis of 107 flea samples collected from 8 distinct sampling sites in South Africa. Pooled DNA samples mostly comprising of 2 or 3 individuals sampled from the same host, and belonging to the same genetic cluster, were sequenced using the Ion PGM™ Hi-Q™ Kit and the Ion 316™ Chip v2. Differences were detected in the microbiome compositions between Ctenocephalides felis, Ctenocephalides canis and Ctenocephalides connatus. Although based on a small sample, C. connatus occurring on wildlife harboured a higher bacterial richness when compared to C. felis on domestic animals. Intraspecific differences in the microbial OTU diversity were detected within C. f. felis that occurred on domestic cats and dogs. Different genetic lineages of C. f. felis were similar in microbial compositions but some differences exist in the presence or absence of rare bacteria. Rickettsia and Bartonella OTU's identified in South African cat fleas differ from those identified in the USA and Australia. Intraspecific microbial compositions also differ across geographic sampling sites. Generalized dissimilarity modelling showed that temperature and humidity are potentially important environmental factors explaining the pattern obtained.

Host phylogeny and ecology, but not host physiology, are the main drivers of (dis)similarity between the host spectra of fleas: application of a novel ordination approach to regional assemblages from four continents.

We investigated the patterns of phylogenetic and functional (dis)similarity in the species composition of host spectra between co-habitating generalist flea species in regional assemblages from four continents (Europe, Asia, North America and Africa) using a recently developed ordination approach (Double Similarity Principal Component Analysis). From the functional perspective, we considered physiological [body mass and basal metabolic rate (BMR)] and ecological (shelter depth and complexity) host traits. We asked (a) whether host phylogeny, physiology or ecology is the main driver of (dis)similarities between flea host spectra and (b) whether the patterns of phylogenetic and functional (dis)similarity in host spectra vary between flea assemblages from different continents. Phylogenetic similarity between the host spectra was highest in Africa, lowest in North America and moderate in Europe and Asia. In each assemblage, phylogenetic clusters of hosts dominating in the host spectra could be distinguished. The functional similarity between the host spectra of co-occurring fleas was low for shelter structure in all assemblages and much higher for body mass and BMR in three of the four assemblages (except North America). We conclude that host phylogeny and shelter structure are the main drivers of (dis)similarity between the host spectra of co-habitating fleas. However, the effects of these factors on the patterns of (dis)similarity varied across continents.

Adaptation to a novel host and performance trade-off in host-generalist and host-specific insect ectoparasites.

We investigated the performance trade-offs of fleas (Siphonaptera) while adapting to a novel host using two host generalists (Xenopsylla conformis and Xenopsylla ramesis) and one host specialist (Parapulex chephrenis) maintained on their principal hosts (Meriones crassus for Xenopsylla and Acomys cahirinus for P. chephrenis). We asked whether, over generations, (i) a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and (ii) a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host. We established an experimental line of each species on a novel host (Acomys russatus for Xenopsylla and M. crassus for P. chephrenis) and maintained this line on this host during 23 generations. We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size, hatching success, offspring production, and offspring size. We found changes in performance over generations in female offspring size only. Xenopsylla conformis demonstrated a tendency to become a host specialist (increased performance on the novel host with a concomitant decreased performance on the original host), whereas P. chephrenis demonstrated a tendency to become a host generalist (increased performance on the novel host without a concomitant decreased performance on the original host). We conclude that the probability of generalist to specialist transition, and vice versa, is context-dependent and varies between species.

Functional and phylogenetic uniqueness of helminth and flea assemblages of two South African rodents.

The loss of a particular species from a community may have different effects on its functioning, depending on the presence or absence of functionally similar or phylogenetically close species in that community (redundancy). Redundancy is thus defined as the fraction of species diversity not expressed by functional or phylogenetic diversity. We assessed functional and phylogenetic alpha- and beta-redundancy in helminth and flea assemblages of two species of South African rodents, Rhabdomys dilectus and Rhabdomys pumilio, using community uniqueness as the inverse indicator of redundancy. We asked whether patterns of functional and phylogenetic alpha- and beta-uniqueness differed between (i) parasite groups (endo- versus ectoparasites), (ii) host species within parasite groups, and (iii) biomes within host species. We found differences between the two hosts in the functional and phylogenetic alpha-uniqueness (but not beta-uniqueness) of flea, but not helminth, assemblages. Significant correlations between the alpha-uniqueness of parasite assemblages and the total parasite prevalence were found only for phylogenetic uniqueness and only in helminths. Pairwise site-by-site dissimilarities in uniqueness (beta-uniqueness) and pairwise dissimilarity in prevalence were significantly associated (positively) in helminths but not in fleas. A between-biome difference in functional (but not phylogenetic) alpha-uniqueness was found in both helminth and flea assemblages harboured by R. pumilio. We conclude that the resilience of parasite assemblages in terms of the effect on hosts depends not only on their transmission strategy but also on traits of host species and environmental factors.

Insecticidal efficacy of afoxolaner against bedbugs, Cimex lectularius, when administered orally to dogs.

The objective of this experimental study was to assess the insecticidal efficacy of afoxolaner (NexGard®) against bedbugs (Cimex lectularius) on dogs. For each challenge, 20 bedbugs were placed in two chambers positioned in contact to the dog's skin for 15 min, after which live fed parasites were counted and incubated for survival evaluations. On Day 0, 7 dogs assigned to the treated group were administered afoxolaner orally at the registered dose. All 14 dogs were challenged on Days 1, 7, 14, 21 and 28, and the collected live fed C. lectularius incubated for 72 h (Day 1), and 72 h and 96 h (Days 7, 14, 21 and 28) for survival evaluation. The percent feeding in the control group ranged from 95% to 98.6% and the percent of live fed bedbugs at 96 h ranged from 99.3% to 100% in the control group, demonstrating the viability of the strain and their capacity to feed on dogs. Significantly fewer live fed bedbugs were counted in the treated group, compared to the control group, at all time-points. The reduction of live fed C. lectularius in the afoxolaner group was 41.4% at 72 h after the Day 1 challenge, and 77.2%, 82.7%, 85.0% and 63.5% at 96 h after the Days 7, 14, 21 and 28 challenges, respectively. It is hypothesized that monthly treatment of dogs with afoxolaner could help in preventing a bed bug population from installing in a household if bedbugs bite dogs in the presence of humans.

TITLE: Efficacité insecticide de l'afoxolaner administré par voie orale à des chiens contre les punaises de lit, Cimex lectularius. ABSTRACT: L'objectif de cette étude expérimentale était de déterminer l'efficacité insecticide de l'afoxolaner (NexGard®) contre les punaises de lit (Cimex lectularius) chez les chiens. Pour chaque exposition, 20 punaises de lit ont été mises dans deux chambres placées en contact avec la peau des chiens pendant 15 minutes. Après cela, les parasites vivants et gorgés ont été comptés et incubés pour évaluer leur survie. Le jour 0, 7 chiens affectés au groupe traité ont reçu de l'afoxolaner (NexGard) par voie orale à la dose commerciale. Les 14 chiens ont été exposés aux punaises aux jours 1, 7, 14, 21 et 28, et les C. lectularius vivants et gorgés, collectés, ont été incubés pendant 72 h (jour 1) et 72 et 96 h (jours 7, 14, 21 et 28) pour l'évaluation de la survie. Le pourcentage d'engorgement dans le groupe témoin variait de 95 % à 98,6 % et le pourcentage de ces punaises vivantes à 96 h variait de 99,3 à 100 %, démontrant la viabilité de la souche et la capacité à se nourrir des chiens. Le nombre de punaises vivantes était significativement plus faible dans le groupe traité, par rapport au groupe témoin, à chaque point de contrôle. La réduction de C. lectularius vivants dans le groupe afoxolaner était de 41,4 % à 72 h après l'exposition du jour 1, et respectivement de 77,2 %, 82,7 %, 85,0 %, et 63,5 % à 96 h après les expositions des jours 7, 14, 21, et 28. On peut donc faire l'hypothèse que le traitement mensuel des chiens avec de l'afoxolaner pourrait empêcher une population de punaises de lit de s'installer dans un foyer, si les punaises piquent les chiens en présence d'humains.

Colonization of a novel host by fleas: changes in egg production and egg size.

We studied the success of fleas, Synosternus cleopatrae and Xenopsylla ramesis, in switching to a novel host by establishing experimental lines maintained on different hosts for 18 generations. Fleas fed on principal (P-line) or novel hosts, either sympatric with (S-line) or allopatric to (A-line) a flea and its principal host, then we assessed their reproductive performance via the number and size of eggs. We compared reproductive performance between hosts within a line and between lines within a host asking: (a) whether fleas adapt to a novel host species after multiple generations; (b) if yes, whether the pattern of adaptation differs between novel host species sympatric with or allopatric to a flea and its principal host; and (c) adaptation to a novel host is accompanied with a loss of success in exploitation of an original host. Fleas from the S- and A-lines increased their egg production on a novel host (except X. ramesis from the S-line). S. cleopatrae from the S-line but not the A-line increased egg size on a novel host, whereas X. ramesis from the A-line but not the S-line produced larger eggs from a novel host. We found no indication of a loss of reproductive performance on the original host while adapting to a novel host. We conclude that fleas are able to switch rapidly to a new host with the pattern of a switch to either sympatric or an allopatric host depending on the identities of both flea and host species.

New taxonomic and evolutionary insights relevant to the cat flea, Ctenocephalides felis: A geographic perspective.

The cat flea, Ctenocephalides felis, is an obligate haematophagous ectoparasite of wildlife and domestic cats and dogs worldwide. Since cat fleas can affect the health of humans and their pets, an uncertain taxonomy of this taxon can greatly inhibit pest and disease management. To address the evolution and taxonomy of the cat flea, we set out to determine 1) how many genetically distinct taxa exist, 2) whether there is morphological support for the genetically distinct taxa, and 3) the role of host range and paleoclimatic events in speciation. We collected a total of 3352 fleas sampled from 576 domestic cats and dogs as well as 10 wildlife species across 30 localities in South Africa. A total of three flea genera, five species, and three of the currently recognized cat flea subspecies, C. f. damarensis, C. f. strongylus and C. f. felis were obtained. Geometric morphometric analyses on head shape were performed on 68 female and 107 male cat flea individuals. Principal component analysis demonstrated large overlap in head shape variation between C. f. strongylus and C. f. felis, rendering this character not useful for phylogenetic inferences. DNA was extracted from 188 Ctenocephalides spp. and mitochondrial COII and nuclear EF1-α sequences were generated. Bayesian and Maximum Likelihood analyses as well as a TCS parsimony haplotype network of the mitochondrial DNA confirmed the presence of three well supported monophyletic clades. These assemblages did not fully corroborate the existence of the three C. felis subspecies. A single well-supported molecular clade included only C. f. damarensis morphotypes that were mostly collected from wildlife. The recognition of this subspecies as a distinct taxon was further corroborated by sequence distances and also the number of plantar spiniform bristles on fore-tarsi V in males. Despite the overall lack of support for the recognition of C. f. damarensis and C. f. strongylus, a geographic trend was visible whereby one genetic lineage corresponded to the western dryer hot subregion, whereas the other was found throughout the region. Bayesian dating suggested that these two clades diverged during the early Pliocene (4.18 mya), a date that corresponds well with the establishment of a dry hot climate in the west of southern Africa. If so, the off-host environment, particularly temperature and humidity, are important factors to consider in the evolution of the cat flea. The present study rejects recent assertions that the three cat flea subspecies are valid entities and rather point to a situation where more sampling is required before the taxonomic status of C. f. damarensis can be resolved.

Compositional turnover in ecto- and endoparasite assemblages of an African bat, Miniopterus natalensis (Chiroptera, Miniopteridae): effects of hierarchical scale and host sex.

We studied the compositional turnover in infracommunities and component communities of ecto- and endoparasites infesting a bat, Miniopterus natalensis (Chiroptera, Miniopteridae), across seven sampling sites using the zeta diversity metric (measuring similarity between multiple communities) and calculating zeta decline and retention rate (both scales) and zeta decay (component communities). We asked whether the patterns of zeta diversity differ between (a) infracommunities and component communities; (b) ecto- and endoparasites and (c) subsets of communities infecting male and female bats. The pattern of compositional turnover differed between infracommunities and component communities in endoparasites only. The shape of zeta decline for infracommunities indicated that there were approximately equal probabilities of ecto- and endoparasitic species to occur on/in any bat individual within a site. The shape of zeta decline for component communities suggested the stochasticity of ectoparasite turnover, whereas the turnover of endoparasites was driven by niche-based processes. Compositional turnover in component communities of ectoparasites was more spatially dependent than that of endoparasites. Spatial independence of compositional turnover in endoparasites was due to subcommunities harboured by female bats. We conclude that the patterns of compositional turnover in infracommunities were similar in ecto- and endoparasites, whereas the patterns of turnover in component communities differed between these groups.

The diversity and distribution of chigger mites associated with rodents in the South African savanna.

Chigger mites (Trombiculidae) are temporary habitat-specific ectoparasites that often occur on rodents. Little ecological data are available on chiggers associated with rodents in South Africa. The study aims were to (1) record the chigger species associated with rodents in the savanna, (2) assess if chigger species display parasitope preference on the rodent body and (3) compare the distribution of chigger species in natural, agricultural and urban habitats. Rodents (n = 314) belonging to eight genera were trapped in the savanna biome during 2014 and 2015. Twelve chigger species, of which five are recently described species, were recorded from 161 rodent hosts. The data include three new country locality records. Microtrombicula mastomyia was the most prevalent species across sampling seasons and habitat types. Significant parasitope preference was recorded for two species, with the ear, face and tail base some of the preferred attachment sites. Sampling season and habitat type had a significant effect on chigger communities with summer and agricultural habitats recording the highest species richness, while the highest species diversity was recorded in natural habitats. The study contributes to our current knowledge regarding rodent-associated chigger diversity and distribution in South Africa and further highlights the importance of environmental characteristics in shaping chigger communities.

Drivers of compositional turnover are related to species' commonness in flea assemblages from four biogeographic realms: zeta diversity and multi-site generalised dissimilarity modelling.

We investigated drivers of species turnover in fleas parasitic on small mammals in four biogeographic realms using novel methodology (zeta diversity, and Multi-Site Generalised Dissimilarity Modelling). We asked whether (i) flea turnover was better explained by host turnover or environmental variables; (ii) different factors drive the turnover of rare and widespread fleas; (iii) the factors affecting the turnover of rare or widespread fleas differ between realms; and (iv) environmental variables drive flea turnover directly or via their effects on hosts. Dissimilarity in host species composition was the most important factor affecting flea turnover in all realms. In the Afrotropics, the Nearctic, and the Neotropics, this was true mainly for rare species, whereas the zeta diversity of the Palearctic hosts exerted a strong effect on the turnover of both rare and widespread fleas. Dissimilarity in temperature contributed the most to the turnover of rare fleas in the Neotropics and the Palearctic, whereas the turnover of widespread species in these realms was strongly affected by dissimilarity in precipitation. In the Nearctic, dissimilarity in precipitation or temperature mostly affected the turnover of rare fleas or common species, respectively. In the Afrotropics, dissimilarity in the Normalised Difference Vegetation Index and temperature affected the turnover of all species, independently of their level of commonness, while dissimilarity in rainfall was important for the turnover of rare fleas. The responses of flea assemblages to environmental factors represented a combination of direct responses and responses mediated via effects on host turnover. We conclude that host turnover is a more important factor than environmental dissimilarity in its effect on flea species turnover. However, the relative effects of host composition and environment, as well as those of temperature, precipitation and the amount of vegetation, on flea turnover differ (i) between realms and (ii) between rare and common fleas.

Feeding performance on a novel host: no adaptation over generations and differential patterns in two flea species.

To model the colonization of a novel host by fleas, Synosternus cleopatrae and Xenopsylla ramesis, we established experimental lines maintained for 15 generations on a principal or a novel host (either co-occurring with a flea or not). We compared the blood meal size and the energy expended for digestion by fleas from the 15th generation of each line on these hosts between hosts within a line and between lines within a host asking (a) whether fleas adapt to a novel host (increased blood consumption/decreased energy expended for digestion); (b) if yes, whether this adaptation leads to the loss of ability to exploit an original host, and (c) whether the success of adaptation to a novel host depends on its ecological co-occurrence with a flea. The blood consumption and digestion energetics of fleas fed on the principal host differed from those on other hosts. The effect of the principal host on feeding performance differed between fleas, with S. cleopatrae consuming less blood and expending more energy for digestion on the principal than on any other host, whereas the opposite was true for X. ramesis. No changes in feeding performance on a novel host over generations were found. We propose several explanations for the lack of adaptation to a novel host over time. We explain the poor performance of S. cleopatrae on its principal host via its immune response mounting pattern. We argue that the principal host of a parasite is not necessarily the host on which the parasite demonstrates the best performance.

Flea infestation, social contact, and stress in a gregarious rodent species: minimizing the potential parasitic costs of group-living.

Both parasitism and social contact are common sources of stress that many gregarious species encounter in nature. Upon encountering such stressors, individuals secrete glucocorticoids and although short-term elevation of glucocorticoids is adaptive, long-term increases are correlated with higher mortality and deleterious reproductive effects. Here, we used an experimental host-parasite system, social rodents Acomys cahirinus and their characteristic fleas Parapulex chephrenis, in a fully-crossed design to test the effects of social contact and parasitism on stress during pregnancy. By analysing faecal glucocorticoid metabolites, we found that social hierarchy did not have a significant effect on glucocorticoid concentration. Rather, solitary females had significantly higher glucocorticoid levels than females housed in pairs. We found a significant interaction between the stressors of parasitism and social contact with solitary, uninfested females having the highest faecal glucocorticoid metabolite levels suggesting that both social contact and infestation mitigate allostatic load in pregnant rodents. Therefore, the increased risk of infestation that accompanies group-living could be outweighed by positive aspects of social contact within A. cahirinus colonies in nature.

Beta diversity of gastrointestinal helminths in two closely related South African rodents: species and site contributions.

A fundamental aim of parasite ecology is to understand the mechanisms behind spatial variation in diversity and structure of parasite assemblages. To understand the contribution of individual parasite species and their assemblages to spatial variation in parasite communities, we examined species contributions to beta diversity (SCBD) and local contributions to beta diversity (LCBD) of parasitic gastrointestinal helminths (nematodes and cestodes) in two closely related rodents, Rhabdomys dilectus and Rhabdomys pumilio, from 20 localities across South Africa. Although the two Rhabdomys spp. are morphologically similar, they differ substantially in body size, habitat preference, and sociality. We asked whether the variation in life history traits and infection parameters are associated with SCBD of helminths and whether variation in environmental factors, host population density, and species richness of host communities are associated with LCBD of component assemblages of helminths. We also considered spatial factors to test whether LCBD of helminth assemblages demonstrate geographic structure. We found that the contribution of helminth species parasitic in both hosts to beta diversity significantly increased with characteristic prevalence of these species, whereas mean abundance, type of life cycle, and location in the host's gut had no effect on SCBD. The LCBD of helminth assemblages showed a significant positive correlation with environmental factors in both host species. Our results suggest that predictors of variation in SCBD and LCBD may substantially differ between parasites with different infection parameters and/or parasite communities at different hierarchical scales.

Reproductive performance in generalist haematophagous ectoparasites: maternal environment, rearing conditions or both?

We tested whether and how the maternal environment (i.e. host species exploited by a mother), rearing conditions (i.e. host species exploited by her offspring) or both (i.e. matches and mismatches in host species exploited by a mother and her offspring) affect reproductive performance in the offspring. We experimentally manipulated maternal and rearing environments in two generalist fleas (Xenopsylla conformis and Xenopsylla ramesis) implementing a factorial cross-rearing design. Mothers exploited either the principal host (PH) or auxiliary hosts that were either closely (CAH) or distantly related (DAH) to the PH. After six generations of infesting a given host species, we cross-reared fleas within and between host species. These fleas reproduced and we measured their reproductive performance both quantitatively (i.e. egg number) and qualitatively (i.e. egg size, development time, body size of the next generation). We found that identity of the host a flea was reared on (=actual host) had the strongest effect on its performance. Individuals reared on the PH performed considerably better than those reared on either auxiliary host. Moreover, fleas reared on a CAH performed better than those reared on a DAH. Actual host identity also had a stronger effect on reproductive performance in X. ramesis than in X. conformis. Nevertheless, there was no difference in performance between match and mismatch maternal and actual host identities. We conclude that rearing environment has the strongest effect on fitness in generalist parasites. Moreover, phylogenetic distance between an auxiliary host and the PH determines the level of suitability of the former.

Effects of maternal and grandmaternal flea infestation on offspring quality and quantity in a desert rodent: evidence for parasite-mediated transgenerational phenotypic plasticity.

Parasites can cause a broad range of sublethal fitness effects across a wide variety of host taxa. However, a host's efforts to compensate for possible parasite-induced fitness effects are less well-known. Parental effects may beneficially alter the offspring phenotype if parental environments sufficiently predict the offspring environment. Parasitism is a common stressor across generations; therefore, parental infestation could reliably predict the likelihood of infestation for offspring. However, little is known about relationships between parasitism and transgenerational phenotypic plasticity. Thus, we investigated how maternal and grandmaternal infestation with fleas (Xenopsylla ramesis) affected offspring quality and quantity in a desert rodent (Meriones crassus). We used a fully-crossed design with control and infested treatments to examine litter size, pup body mass at birth, and pup mass gain before weaning for combinations of maternal and grandmaternal infestation status. No effect of treatment on litter size or pup body mass at birth was found. However, maternal and grandmaternal infestation status significantly affected pre-weaning body mass gain, a proxy for the rate of maturation, in male pups. Pups gained significantly more weight before weaning if maternal and grandmaternal infestation statuses matched, regardless of the treatment. Thus, pups whose mothers and grandmothers experienced similar risks of parasitism, either both non-parasitized or both infested, would reach sexual maturity more quickly than those pups whose mothers' infestation status did not match that of their grandmothers. These results support the contention that parents can receive external cues such as the risk of parasitism, that prompt them to alter offspring provisioning. Therefore, parasites could be a mediator of environmentally-induced maternal effects and could affect host reproductive fitness across multiple generations.

Do the pattern and strength of species associations in ectoparasite communities conform to biogeographic rules?

We tested whether biogeographic patterns characteristic of species diversity and composition may also apply to community assembly by investigating geographic variation in the pattern (PSA) (aggregation versus segregation) and strength of species associations (SSA) in flea and mite communities harbored by small mammalian hosts in Western Siberia. We asked whether (a) there is a relationship between latitude and PSA or SSA and (b) similarities in PSA or SSA follow a distance decay pattern or if they are better explained by variation in environmental factors (altitude, amount of vegetation, precipitation, and air temperature). We used a sign of a co-occurrence metric (the C-score) as an indicator of PSA and its absolute standardized value as a measure of SSA. We analyzed data using logistic and linear models, generalized dissimilarity modeling (GDM), and a logistic version of the multiple regression on distance matrices (MRM). The majority of the C-scores of the observed presence/absence matrices indicated a tendency to species aggregation rather than segregation. No effect of latitude on PSA or SSA was found. The dissimilarity in PSA was affected by environmental dissimilarity in mite compound communities only. A relatively large proportion of the deviance of spatial variation in SSA was explained by the GDMs in infracommunities, but not component communities, and in only three (of seven) and two (of eight) host species of fleas and mites, respectively. The best predictors of dissimilarity in SSA in fleas differed between host species, whereas the same factor (precipitation) was the best predictor of dissimilarity in SSA in mites. We conclude that PSA and SSA in parasite communities rarely conform to biogeographic rules. However, when a biogeographic pattern is detected, its manifestation differs among hosts and between ectoparasite taxa.