Notes on fleas (Siphonaptera) in plague foci on the Tay Nguyen plateau (Vietnam)]

The fleas of wild and commensal small mammals, domestic animals (dogs, cats) and free-living flea forms in houses have been collected in plague nidi of Tay Nguyen plate, Dak-Lak province, Vietnam. Pulex irritans, Ctenocephalides felis felis, Ct. felis orientis were found in the houses on dogs, cats and on the ground floor. Commensal rats in populated areas were infested by Xenopsylla cheopis and rarely by Lentistivalius klossi. The agricultural zone was inhabited by both home and wild animals such as commensal, savannah and forest-dwelling small mammals. The flea fauna of this zone is presented by X. cheopis and L. klossi. In the tropical forest surrounding villages four of the flea species were found: X. vexabilis, a specific parasite of the forest-dwelling rat Berylmys berdmorei, L. klossi found on six species of forest small mammals, Acropsylla girshami from Berylmys bowersii and Pariodontis subjugis from Hystrix brachyura. The agricultural zone is the most possible place of commensal and forest-dwelling small mammals contact, where the latter can get plague microbe.     

Habitat variation in species composition of flea assemblages on small mammals in central Europe

We studied patterns of variation in species composition of flea assemblages on small mammals across different habitats of Slovakia and compared flea species composition within and across host species among habitats. We asked (1) how variable the composition of flea assemblages is among different populations of the same host occurring in different habitats and (2) whether the composition of flea assemblages in a habitat is affected either by species composition of hosts or by environmental affinities of this habitat. Between-habitat similarity in flea species composition increased with an increase in the similarity in host species composition. Species richness of flea assemblages of a host species correlated positively with mean number of cohabitating host species but not with the number of habitats occupied by a host species. Results of the ordination of flea collections from each individual host demonstrated that the first five principal components explained most of the variance in species composition of flea assemblages. The segregation between rodent and insectivore flea assemblages was easily discerned from the ordination diagram when flea assemblages were plotted according to their hosts. When flea assemblages were plotted according to their habitat affinities, the distinction of habitats based on variation in flea composition was not as clear. The results of ANOVA of each principal component showed the significant effect of both host species and habitat type. The variation in each principal component was explained better by the factor of host species compared with the factor of habitat type. Multidimensional scaling of flea assemblages within host species across habitats demonstrated that among-habitat variation in flea composition was manifested differently in different hosts.     

Aggregation and species coexistence in fleas parasitic on small mammals

The aggregation model of coexistence states that species coexistence is facilitated if interspecific aggregation is reduced relative to intraspecific aggregation. We investigated the relationship between intraspecific and interspecific aggregation in 17 component communities (the flea assemblage of a host population) of fleas parasitic on small mammals and hypothesized that interspecific interactions should be reduced relative to intraspecific interactions, facilitating species coexistence. We predicted that the reduction of the level of interspecific aggregation in relation to the level of intraspecific aggregation would be positively correlated with total flea abundance and species richness of flea assemblages. We also expected that the higher degree of facilitation of flea coexistence would be affected by host parameters such as body mass, basal metabolic rate (BMR) and depth and complexity of burrows. Results of this study supported the aggregation model of coexistence and demonstrated that, in general, a) conspecific fleas were aggregated across their hosts; b) flea assemblages were not dominated by negative interspecific interactions; and c) the level of interspecific aggregation in flea assemblages was reduced in relation to the level of intraspecific aggregation. Intraspecific aggregation tended to be correlated positively to body mass, burrow complexity and mass-independent BMR of a host. Positive interspecific associations of fleas tended to occur more frequently in species-rich flea assemblages and/or in larger hosts possessing deep complex burrows. Intraspecific aggregation increased relative to interspecific aggregation when species richness of flea infracommunities (the flea assemblage of a host individual) and component communities increased. We conclude that the pattern of flea coexistence is related both to the structure of flea communities and affinities of host species.     

黄鼠洞干蚤和宿主密度的年间动态关系

根据内蒙古自治区正镶白旗乌宁巴图苏木1981～1993年达乌尔黄鼠Citellus dauriCUS密度和洞干蚤指数监测资料进行分析,得到如下结果。共检洞干蚤9种,其中方形黄鼠蚤蒙古亚种Citellophilus tesquorum mongolicus (66.0%)为优势蚤种,光亮额蚤Frontopsylla lu-culenta(23.6%)为次优势蚤种,阿巴盖新蚤Neopsylla abagaitui和二齿新蚤N。Bidentatifor-mis为常见种,余为少见种。鼠密度与洞干蚤指数关系显著(PPP<0.05),关系为洞干蚤指数=0.2709+0.0504体蚤指数。洞干蚤和巢蚤指数的关系是显著的(P<0.07),关系为洞干蚤指数＝0.27652+0.00348巢蚤指数。三种蚤指数之间有如下近似 关系：巢蚤指数：体蚤指数：洞干蚤指数：100：10：1。     

Epizootological role of fleas in the Gorno-Altai natural plague focus (a review)

Epizootological role of fleas in the Gorno-Altai natural plague focus (Sailugemsk focus) and numerous data on the flea viability are analyzed and generalized. Information concerning the flea natural infectivity with Yersinia pestis altaica is represented. Ecological peculiarities of some flea species parasitizing the main host, Mongolian pika Ochotona pallasi, and nature of their interrelations with Y. pestis are investigated. It is shown that the flea taxocenosis provides the permanent all year-round circulation of Y. pestis in the Gorno-Altai natural focus. Certain combinations of structural elements of the flea taxocenosis have a dominant significance in determination the circulation process at different phases of the annual epizootic cycle.     

Host specificity and geographic range in haematophagous ectoparasites

A negative interspecific correlation between the degree of habitat specialization and the size of a species' geographic range has been documented for several free living groups of organisms, providing support for the niche breadth hypothesis. In contrast, practically nothing is known about the geographic range sizes of parasitic organisms and their determinants. In the context of the niche breadth hypothesis, parasites represent ideal study systems, because of the well documented variation in host specificity among parasite species. Here, we investigated the relationship between host specificity (a measure of niche breadth) and geographic range size among flea species parasitic on small mammals, using data from seven distinct geographical regions. Two measures of host specificity were used: the number of host species used by a flea species, and a measure of the average taxonomic distance between the host species used by a flea; the latter index provides an evolutionary perspective on host specificity. After correcting for phylogenetic influences, and using either of our two measures of host specificity, the degree of host specificity of fleas was negatively correlated with the size of their geographic range in all seven regions studied here, with only one minor exception. Overall, these results provide strong support for the niche breadth hypothesis, although other explanations cannot be ruled out.     

Host associations and origin in the formation of the Caucasian fauna of fleas (Siphonaptera)

Results of analysis of the Caucasian fauna of fleas and their association with mammal and avian hosts are reported. The Caucasian fauna of potential flea hosts comprises about 130 species of mammals and about 470 species of birds. Most of the flea species in the Caucasian fauna (88 out of 155) parasitize rodents, 51 species of which are permanent hosts of different flea species; 13 flea species occur on 11 species of insectivores; 13 flea species, on 13 species of chiropterans; 14 flea species, on 20 species of carnivores. Only 2 flea species parasitize artiodactyles. 54 species of birds are permanent hosts of 23 species of fleas from 4 genera in the Caucasus. Ten types of ranges of flea species are distinguished; host associations of the Caucasian flea species from these groups are discussed. The greatest numbers of hosts from the families Cricetidae, Muridae, and Sciuridae are associated with fleas with Euro-Asian (extra-Siberian), European, Turanian, and Iranian ranges. Soricidae are known as hosts of flea species with European and Euro-Turanian ranges. Four major groups of flea taxa are represented in the Caucasian fauna. The distribution of the first group is determined by the influence of the palaeofauna of the ancient European continent in the early Cenozoic; that of the second group, by the influence of the fauna of the ancient Asian continent during the Paleogene and part of the Neogene; the third, by the influence of the fauna of southern Europe starting with the Miocene. The fourth group comprises the species which immigrated from northern Europe and Asia in the Late Neogene (2–3 mln years ago).     

Geographical variation in the 'bottom-up' control of diversity: fleas and their small mammalian hosts

Aim We searched for signs of the ‘bottom‐up’ diversity effect in the association between fleas (Siphonaptera) and their small mammalian hosts (Rodentia, Insectivora and Lagomorpha). We asked (1) whether a strong dependence of flea species richness on host species richness is characteristic for both Palaeoarctic and Nearctic realms; (2) if yes, whether the ratio of host species per flea species along the host diversity gradient is similar between the Palaeoarctic and Nearctic; and (3) whether factors other than host species richness (i.e. geographical position, climate and landscape) might better explain variation in flea species richness than host species richness. Location The study used previously published data on species richness of fleas and their small mammalian hosts from 26 Palaeoarctic and 19 Nearctic regions. Methods We regressed the number of flea species on the number of small mammal species across regions, separately for Palaeoarctic and Nearctic realms, using both non‐transformed data as well as data corrected for the confounding effects of host sampling effort and sampling area. To test whether flea species richness is determined by external factors unrelated to the host, we used stepwise multiple regressions of flea species richness against host species richness and parameters describing the geographical position, climate and relief of a region. Results When non‐transformed data were analysed, flea species richness was positively correlated with host species richness in both the Palaeoarctic and Nearctic, although the slopes of the two regressions differed significantly. After removal of the confounding effects of host sampling effort and sampling area, Palaeoarctic flea species richness remained strongly positively correlated with host species richness, whereas in the Nearctic, flea species richness appeared to be completely independent of host species richness. Results of the multiple regressions using corrected data demonstrated that in the Palaeoarctic, flea species richness was correlated with both the number of host species and the mean altitude of the region, whereas in the Nearctic, flea species richness only tended to be weakly correlated with latitude (however, this correlation turned out to be non‐significant after Bonferroni correction). Main conclusions We found evidence of bottom‐up control of flea diversity in the Palaeoarctic regions only, and not in the Nearctic. We explore several potential explanations for the different patterns observed in the two biogeographical realms, including differences in (1) levels of host specialization, (2) history of host–parasite associations and (3) landscape effects on flea diversification. We conclude that these factors combine to create different macroecological patterns in different biogeographical realms, and that diversity is not governed by the same forces everywhere.     

Benefits, Costs and Constraints of Anti-Parasitic Grooming in Adult and Juvenile Rodents

Grooming behaviour plays various roles in the health care, reproduction, and social life of an individual vertebrate. However, the reasons for the variability in time spent grooming amongst species, populations and individuals are not fully understood. We tested the hypothesis that the main role of grooming is ectoparasite removal and thus that time spent grooming by an animal reflects the costs of parasite infestation offset against the costs of grooming. The test was conducted on a rodent, Meriones crassus, that is parasitised by a flea, Xenopsylla conformis. We monitored behaviour of juvenile and adult rodents before and after flea infestation and quantified the probability of mortality of fleas with respect to the time spent grooming in adults compared with juvenile rodents. We predicted that: (1) increased costs of flea infestation (e.g. in parasitised as opposed to flea‐free rodents and in juveniles as opposed to adults) increases time spent grooming and (2) mortality probability per flea increases with increasing time spent grooming and is higher for fleas on juveniles than for fleas on adult rodents. We were interested to discover at the expense of which activity grooming is increased. Our findings established that the major role of grooming is in flea removal, as exposure to fleas evoked grooming activity in all rodents and grooming activity explained 57–70% of the variation in flea mortality. Furthermore, we showed that the rise in grooming activity was at the expense of resting. However, we found only partial support for the predicted increase in grooming time with increasing costs of flea infestation. Flea infestation did indeed increase the time spent grooming by rodents. Nevertheless, juvenile rodents who incur higher costs of flea infestation spent less time grooming than adults and sustained similar flea densities, suggesting that these hosts are constrained by some other factors, such as feeding time.     

黄鼠巢和宿主密度的年间动态关系

根据内蒙古自治区正镶白旗乌宁巴图苏木1981～1993年达乌尔黄鼠Citellus dauricus密度和巢蚤指数监测资料进行分析,得到如下结果。共检巢蚤10种,其中方形黄鼠蚤蒙古亚种Citellophilus tesquorum mongolicus(45.4%)为优势蚤种,光亮额蚤Frontopsylla lucu lenta(25.0%)和阿巴盖新蚤Neopsylla abagaitui(21.3%)为次优势蚤种。二齿新蚤N.Bidentatiformis和角尖眼蚤Ophthalmopsylla praefecta为常见种,余为少见种。鼠密度与巢蚤指数 的关系不显著(p>0.10)、与巢染蚤率关系显著(p<0.05),不同年份的蚤类多样性和均匀性比较稳定。巢蚤和体蚤指数的关系是显著的(PP<0.005)。     

Consumption of flea faeces and eggs by larvae of the cat flea,Ctenocephalides felis

The effects of the consumption of flea faeces and non-viable eggs on larval development in the cat flea Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae) were investigated. Only 13.3% of larvae developed into adults when fed a diet of male or female flea faeces alone; however, 90% of larvae developed into adults when fed on flea faeces supplemented with non-viable flea eggs. When fed with non-viable eggs alone, larvae did not develop into adults. Nevertheless, non-viable eggs may provide critical supplemental nutrients, lacking in flea faeces and required for larval development. None of the larvae fed on flea faeces or non-viable eggs alone formed a cocoon. A diet of flea faeces alone significantly extended the second as well as third larval stadia compared to larvae fed on diets containing non-viable eggs. It is suggested that the cannibalism of fertile eggs may limit population growth in the cat flea.     

Age-dependent flea (Siphonaptera) parasitism in rodents: a host's life history matters

We studied age-dependent patterns of flea infestation in 7 species of rodents from Slovakia (Apodemus agrarius, A. flavicollis, A. sylvaticus, A. uralensis, Clethrionomys glareolus, Microtus arvalis, and M. subterraneus). We estimated the age of the host from its body mass and expected the host age-dependent pattern of flea abundance, the level of aggregation, and prevalence to be in agreement with theoretical predictions. We expected that the mean abundance and the level of aggregation of fleas would be lowest in hosts of smallest and largest size classes and highest in hosts of medium size classes, whereas pattern of variation of prevalence with host age would be either convex or asymptotic. In general, mean abundance and species richness of fleas increased with an increase in host age, although the pressure of flea parasitism in terms of number of fleas per unit host body surface decreased with host age. We found 2 clear patterns of the change in flea aggregation and prevalence with host age. The first pattern demonstrated a peak of flea aggregation and a trough of flea prevalence in animals of middle age classes (Apodemus species and C. glareolus). The second pattern was an increase of both flea aggregation and flea prevalence with host age (both Microtus species). Consequently, we did not find unequivocal evidence for the main role of either parasite-induced host mortality or acquired resistance in host age-dependent pattern of flea parasitism. Our results suggest that this pattern can be generated by various processes and is strongly affected by natural history parameters of a host species such as dispersal pattern, spatial distribution, and structure of shelters.     

哈尔滨郊区人为鼠疫疫源地蚤类种群动态分析

1982～1999年对黑龙江省哈尔滨郊区人为鼠疫疫源地达乌尔黄鼠Spermophilus dauricus巢蚤、体蚤、洞干蚤指数和染蚤率进行了调查和分析。共获蚤9种,其中方形黄鼠蚤松江亚种Citellophius tesquorum sungaris是优势种(89.39%),其次为二齿新蚤Neopsylla bidentatiformis (10.37%)。3类蚤指数、染蚤率的均值差异均显著(P<0.01)。巢蚤与体蚤指数相关显著(P<0.05)。巢蚤指数∶体蚤指数∶洞干蚤指数≈650∶140∶1; 巢染蚤率∶体染蚤率∶洞干染蚤率≈165∶88∶1。     

黄鼠体蚤和宿主密度的年间动态关系

根据内蒙古自治区正镶白旗乌宁巴图苏木1981-1993年达乌尔黄鼠Citellus dauricus密度和体蚤指数监测资料进行分析,得到如下结果。共检体蚤10种,其中方形黄鼠蚤蒙古亚种Citelloilus tesquorum mongoJicus(72.38%)和光亮额蚤Fronto Psylla luculenta(18.03%)分别为优势和次优势蚤种,阿巴盖新蚤Neopsylla abagaitui、二齿新蚤Neopsylla bidentatifor-mis为常见种,余为少见种。宿主密度与蚤指数均呈指数增长,鼠密度与蚤指数的关系是极为显著的(P<0.0001),关系为鼠密度＝exp(-0.6206十0.1989t),蚤指数＝1.6109+0.8997(鼠密度)。方形黄鼠蚤蒙古亚种比例的高低显著地影响体蚤的多样性和均匀性.宿主 密度与染蚤率呈正相关关系(P相似文献   

Abundance patterns and coexistence processes in communities of fleas parasitic on small mammals

The abundance of a given species in a community is likely to depend on both the total abundance and diversity of other species making up that community. A large number of co-occurring individuals or co-occurring species may decrease the abundance of any given species via diffuse competition; however, indirect interactions among many co-occurring species can have positive effects on a focal species. The existence of diffuse competition and facilitation remain difficult to demonstrate in natural communities. Here, we use data on communities of fleas ectoparasitic on small mammals from 27 distinct geographical regions to test whether the abundance of any given flea species in a community is affected by either the total abundance of all other co-occurring flea species, or the species richness and/or taxonomic diversity of the flea community. At all scales of analysis, i.e. whether we compared the same flea species on different host species, or different flea species, two consistent results emerged. First, the abundance of a given flea species correlates positively with the total abundance of all other co-occurring flea species in the community. Second, the abundance of any given flea species correlates negatively with either the species richness or taxonomic diversity of the flea community. The results do not support the existence of diffuse competition in these assemblages, because the more individuals of other flea species are present on a host population, the more individuals of the focal species are there as well. Instead, we propose explanations involving either apparent facilitation among flea species via suppression of host immune defenses, or niche filtering processes acting to restrict the taxonomic composition and abundance of flea assemblages.     

Flea (Siphonaptera) species richness in the Great Basin Desert and island biogeography theory

Numbers of flea (Siphonaptera) species (flea species richness) on individual mammals should be higher on large mammals, mammals with dense populations, and mammals with large geographic ranges, if mammals are islands for fleas. I tested the first two predictions with regressions of H. J. Egoscue's trapping data on flea species richness collected from individual mammals against mammal size and population density from the literature. Mammal size and population density did not correlate with flea species richness. Mammal geographic range did, in earlier studies. The intermediate‐sized (31 g), moderately dense (0.004 individuals/m²) Peromyscus truei (Shufeldt) had the highest richness with eight flea species on one individual. Overall, island biogeography theory does not describe the distribution of flea species on mammals in the Great Basin Desert, based on H. J. Egoscue's collections. Alternatively, epidemiological or metapopulation theories may explain flea species richness.     

Interaction frequency across the geographical range as a determinant of host specialisation in generalist fleas

The strength of interspecific interactions varies over geographical scales, and can influence patterns of resource specialisation. Even with gene flow preventing local adaptation of a consumer to particular resources, we might expect that across its entire range, the consumer would show some specialisation for the resource types most likely to be encountered across the localities where it occurs. We tested the hypothesis that generalist fleas are more successful at exploiting small mammalian host species with which they co-occur frequently across their geographical range than host species that, though suitable, are encountered less frequently. This hypothesis was tested with data on 121 flea species compiled from field surveys across 35 regions of the Palaearctic. Using abundance (mean number of individual fleas per individual host) as a measure of flea success on a particular host species, positive correlations between flea abundance and the frequency of co-occurrence of a flea with each of its hosts amongst all regions surveyed were found in all but two of the flea species investigated, with one-fifth of these being significant. If overlap in geographical range between flea and host is used as a measure of frequency of encounters instead of the actual proportion of regions where they both occur, similar patterns are observed, though they are much weaker. In a comparative analysis across all flea species, there were significant relationships between the average abundance of fleas and average values of both measures of frequency of encounters (proportion of sites where they co-occur and range overlap), even when correcting for potential phylogenetic influences. The results suggest that for any given flea species, host species more commonly encountered throughout the spatial range of the flea are generally those on which the flea does best. Interaction frequency may be a key determinant of specialisation and abundance in host-parasite systems.     

Contrasting seasonal dynamics in fleas of the Siberian flying squirrel (Pteromys volans) in Finland

Abstract.  1. The seasonal and spatial variation of the adult flea fauna (Siphonaptera) was examined in connection with live-trapping studies of the Siberian flying squirrel ( Pteromys volans ) in three study areas in southern Finland between 1997 and 2005.
2. The numerically dominant flea species of the Siberian flying squirrel were Tarsopsylla octodecimdentata octodecimdentata and Ceratophyllus (Monopsyllus) indages indages (Ceratophyllidae); the latter being a host specialist of the Siberian flying squirrel. Tarsopsylla octodecimdentata , which also commonly occurs on the red squirrel ( Sciurus vulgaris ), infected a large proportion of the host population throughout the winter, whereas C. indages occurred predominantly during the summer and autumn, being practically the only flea species in nests during the flying squirrels' breeding season and on juveniles still inhabiting their natal nest.
3. The use of nest boxes by flying squirrels did not have any positive effects on flea populations, but it may have had a negative impact on T.   octodecimdentata .
4. The potentially vulnerable C.   i.   indages is a predictable, widespread component in the flea fauna of the Siberian flying squirrel at various spatial scales, and it is likely to occur in most of the permanent flying squirrel populations in Finland.     

Geographical variation in host specificity of fleas (Siphonaptera) parasitic on small mammals: the influence of phylogeny and local environmental conditions

The evolution of host specificity remains a central issue in the study of host‐parasite relationships. Here we tackle three basic questions about host specificity using data on host use by fleas (Siphonaptera) from 21 geographical regions. First, are the host species exploited by a flea species no more than a random draw from the locally available host species, or do they form a taxonomically distinct subset? Using randomization tests, we showed that in the majority of cases, the taxonomic distinctness (measured as the average taxonomic distances among host species) of the hosts exploited by a flea is no different from that of random subsets of hosts taken from the regional pool. In the several cases where a difference was found, the taxonomic distinctness of the hosts used by a flea was almost always lower than that of the random subsets, suggesting that the parasites use hosts within a narrower taxonomic spectrum than what is available to them. Second, given the variation in host specificity among populations of the same flea species, is host specificity truly a species character? We found that host specificity measures are repeatable among different populations of the same flea species: host specificity varies significantly more among flea species than within flea species. This was true for both measures of host specificity used in the analyses: the number of host species exploited, and the index measuring the average taxonomic distinctness of the host species and its variance. Third, what causes geographical variation in host specificity among populations of the same flea species? In the vast majority of flea species, neither of our two measures of host specificity correlated with either the regional number of potential host species or their taxonomic distinctness, or the distance between the sampled region and the center of the flea's geographical range. However, in most flea species host specificity correlated with measures of the deviation in climatic conditions (precipitation and temperature) between the sampled region and the average conditions computed across the flea's entire range. Overall, these results suggest that host specificity in fleas is to a large extent phylogenetically constrained, while still strongly influenced by local environmental conditions.     

Ctenopllhaimus (Ethioctrvophthalmus) kemmelberg n. sp. (Insecta: Siphonaptera: Ctenophthalmidae), a new flea from Tanzania and description of unknown small structures in the mecopteroids

We recently described two new taxa of Siphonaptera (Ctenophthalmus (Ethioctenophthalmus) teucqoe teucqaoe et C. (E.) teucqae shumeensis Laudisoit & Beaucournu, 2007) from Lushoto plague focus (West Usambara mountains, Tanzania). A new taxa is here being studied, Ctenophthalmus kemmelberg, an original flea, not only for its genitalia, but also for original structures appearing, and that have not been described yet, at our knowledge, in any Mecopteroid. These are visible in females only. We suggest the name "Teucq's organs" for those remarkable structures.