2015 Mlynarek et al - host characterstics and parasitism.pdf (original) (raw)
Related papers
Ecography, 2014
In this study, we tested which host species’ characteristics explain the nature and level of parasitism for host damselfly (Coenagrionidae)–water mite (Arrenuridae) parasite associations. Prevalence and intensity of mite parasites, and mite species richness were examined in relation to geographic range size, regional occurrence, relative local abundance, phenology and body size of host damselfly species. A total of 7107 damselfly individuals were collected representing 16 species from 13 sites in southeastern Ontario and southwestern Quebec, Canada. Using comparative methods, differences in prevalence and intensity of parasitism could be predicted by a host species’ geographic range and phenology. Barcoding based on Cytochrome Oxidase I revealed 15 operational taxonomic units (OTUs) for mite species. The number of mite OTUs known to infest a given host species was explained by a host species’ regional occurrence. Our findings demonstrate the need to measure factors at several ecological scales in order to understand the breadth of evolutionary interactions with host–parasite associations and the selective ‘milieu’ for particular species of both hosts and parasites.
BMC Ecology, 2013
Background: One of the main challenges in evolutionary parasitology is to determine the factors that explain variation among host species in parasitism. In this study, we addressed whether host phylogeny or ecology was important in determining host species use by water mites. Parasitism (prevalence and intensity) by Arrenurus water mites was examined in relation to geographic distribution of host damselflies from sibling species pairs. In addition, the likelihood of putative mite species parasitizing both species of a host species pair was explored. Results: A total of 1162 damselflies were examined for water mites across four sites in Southeastern Ontario. These damselflies represent ten species (five closely related host species pairs) in the Coenagrionidae. Only two of the five species pairs showed near significant or significant differences in prevalence of infection by mites. In one of those species comparisons, it was the less widespread host that had higher water mite prevalence and in the other species comparison, the less widespread host species had lower water mite prevalence. Only one of the five pairs showed a significant difference in intensity of infection; intensity was higher in the species with a smaller geographic distribution. Based on the COI barcode, there were nine water mite clades (OTU) infecting these ten host species. Three Arrenurus OTUs may be host monospecific, four OTUs were specific to a given host species pair, and two OTUs infected at least three host species. Host species in each species pairs tend to share at least one of the Arrenurus OTU. No striking differences in mite species diversity were found among species in any species pair. Finally, the Arrenurus examined in this study appear to be ecological specialists, restricted to a particular type of habitat, parasitizing few to many of the host species present in that site or habitat. Conclusions: Although differences in levels of parasitism by water mites exist for some closely related hosts species, no such differences were found between other related host species. Differences in geographic range of related host species does not reliably explain differential levels of parasitism by water mites.
Background: One of the main challenges in evolutionary parasitology is to determine the factors that explain variation among host species in parasitism. In this study, we addressed whether host phylogeny or ecology was important in determining host species use by water mites. Parasitism (prevalence and intensity) by Arrenurus water mites was examined in relation to geographic distribution of host damselflies from sibling species pairs. In addition, the likelihood of putative mite species parasitizing both species of a host species pair was explored. Results: A total of 1162 damselflies were examined for water mites across four sites in Southeastern Ontario. These damselflies represent ten species (five closely related host species pairs) in the Coenagrionidae. Only two of the five species pairs showed near significant or significant differences in prevalence of infection by mites. In one of those species comparisons, it was the less widespread host that had higher water mite prevalence and in the other species comparison, the less widespread host species had lower water mite prevalence. Only one of the five pairs showed a significant difference in intensity of infection; intensity was higher in the species with a smaller geographic distribution. Based on the COI barcode, there were nine water mite clades (OTU) infecting these ten host species. Three Arrenurus OTUs may be host monospecific, four OTUs were specific to a given host species pair, and two OTUs infected at least three host species. Host species in each species pairs tend to share at least one of the Arrenurus OTU. No striking differences in mite species diversity were found among species in any species pair. Finally, the Arrenurus examined in this study appear to be ecological specialists, restricted to a particular type of habitat, parasitizing few to many of the host species present in that site or habitat. Conclusions: Although differences in levels of parasitism by water mites exist for some closely related hosts species, no such differences were found between other related host species. Differences in geographic range of related host species does not reliably explain differential levels of parasitism by water mites.
Freshwater Biology, 2015
1. The metapopulation theory predicts that the more distant a host population is from other populations, the more challenged will be a parasite to colonise it. We studied parasite prevalence of two parasite taxa across the geographical range of their host in Finland, from more dense host population structure in the south of Finland, towards the northern edge of the host distribution characterised by more isolated populations. 2. We found that prevalence of both water mites and gregarines decreased with increasing latitude towards the distribution edge with more isolated population structure of the host damselfly, Coenagrion hastulatum. Furthermore, the prevalences of the two parasite groups were positively correlated. 3. The results are discussed in the context of three non-mutually exclusive hypotheses, explaining why host species have fewer parasites at the edge of their geographic range: (i) unsuitable host hypothesis, (ii) physiological barrier hypothesis and (iii) metapopulation hypothesis.
Regionally widespread parasitic water mites have relatively broad host species ranges
Canadian Journal of Zoology
Certain parasite species have free-living stages, so habitat range may influence host-species range. We tested whether regional occurrence and habitat use of parasitic water mites were related to their host-species range. We collected 7445 Arrenurus Dugès, 1834 mites from 7107 coenagrionid damselflies, representing 11 host species from 13 sites in southeastern Ontario and southwestern Quebec. Because larval water mites are difficult to identify morphologically to species, we chose to amplify the barcode fragment of cytochrome oxidase subunit I to explore host-species ranges. Fifteen operational taxonomic units or clades were identified based on the amplification from 217 larval mites. The Arrenurus clades that were present in both bog and marsh habitats had a broader host-species range than clades found only in marshes (the comparison with one clade found only in bogs lacked statistical power). As predicted, host-species range increased with the regional occurrence of an Arrenurus clade. Additionally, the most commonly barcoded species also have high host-species ranges. This result could be because species with broader host-species ranges are more common and were more likely to be sampled and barcoded (an explanation we favor), or due to sampling bias. Although this is the first study exploring whether habitat range affects host-species range, further investigation is needed to tease apart which habitat factors influence host-species ranges the most.
PloS one, 2015
Related host species often demonstrate differences in prevalence and/or intensity of infection by particular parasite species, as well as different levels of resistance to those parasites. The mechanisms underlying this interspecific variation in parasitism and resistance expression are not well understood. Surprisingly, few researchers have assessed relations between actual levels of parasitism and resistance to parasites seen in nature across multiple host species. The main goal of this study was to determine whether interspecific variation in resistance against ectoparasitic larval water mites either was predictive of interspecific variation in parasitism for ten closely related species of damselflies (grouped into five "species pairs"), or was predicted by interspecific variation in a commonly used measure of innate immunity (total Phenoloxidase or potential PO activity). Two of five species pairs had interspecific differences in proportions of individuals resisting la...
BMC Ecology, 2010
Background: Insects can resist parasites using the costly process of melanotic encapsulation. This form of physiological resistance has been studied under laboratory conditions, but the abiotic and biotic factors affecting resistance in natural insect populations are not well understood. Mite parasitism of damselflies was studied in a temperate damselfly population over seven seasons to determine if melanotic encapsulation of mite feeding tubes was related to degree of parasitism, host sex, host size, emergence timing, duration of the emergence period, and average daily air temperature. Results: Although parasite prevalence in newly emerged damselflies was > 77% each year, hosts did not resist mites in the early years of study. Resistance began the year that there was a dramatic increase in the number of mites on newly emerged damselflies. Resistance continued to be correlated with mite prevalence and intensity throughout the seven-year study. However, the percentage of hosts resisting only ranged from 0-13% among years and resistance was not sex-biased and was not correlated with host size. Resistance also was not correlated with air temperature or with timing or duration of damselfly emergence. Conclusions: Resistance in host damselflies was weakly and variably expressed over the study period. Factors such as temperature, which have been identified in laboratory studies as contributing to resistance by similar hosts, can be irrelevant in natural populations. This lack of temperature effect may be due to the narrow range in temperatures observed at host emergence among years. Degree of mite parasitism predicted both the appearance and continued expression of resistance among parasitized damselflies.
Ecological Entomology, 2012
1. This study investigated inter-specific variation in parasitism by gregarines (Eugregarinorida: Actinocephalidae), among sibling species of damselflies (Odonata: Zygoptera), in relation to relative size of geographical ranges of host species. 2. Gregarines are considered generalist parasites, particularly for taxonomically related host species collected at the same sites or area. Prevalence and median intensity of gregarine parasitism was obtained for 1338 adult damselflies, representing 14 species (7 sibling species pairs) across 3 families within the suborder Zygoptera. Damselflies were collected at three local sites in Southeastern Ontario, during the same periods over the season. 3. Five out of seven species pairs had significant differences in parasitism between sibling species. The less widespread host species was the more parasitised for three species pairs with significant differences in gregarine prevalence, and for two species pairs with differences in median intensity. The more widespread host had a higher intensity of infection as expected, in two species pairs. 4. Future studies on ecological determinants of parasitism among related species should examine robust measures of abundance of species and representation of species regionally.