Studies investigating host-parasite systems rarely deal with multispecies interactions, and mostly explore impacts on hosts as individuals. Much less is known about the effects at colony level, when parasitism involves host organisms that form societies. We surveyed the effect of an ectoparasitic fungus, Rickia wasmannii, on kin-discrimination abilities of its host ant, Myrmica scabrinodis, identifying potential consequences at social level and subsequent changes in colony infiltration success of other organisms. Analyses of cuticular hydrocarbons (CHCs), known to be involved in insects’ discrimination processes, revealed variations in chemical profiles correlated with the infection status of the ants, that could not be explained by genetic variation tested by microsatellites. In behavioural assays, fungus-infected workers were less aggressive towards both non-nestmates and unrelated queens, enhancing the probability of polygyny. Likewise, parasitic larvae of Maculinea butterflies had a higher chance of adoption by infected colonies. Our study indicates that pathogens can modify host recognition abilities, making the society more prone to accept both conspecific and allospecific organisms.
a b s t r a c t
29The order Laboulbeniales (Fungi, Ascomycota) is a little-studied group of microscopic ectoparasites of 30 invertebrates, mostly insects. The effects of Laboulbeniales species on their hosts are mostly unknown.
31Rickia wasmannii Cavara, 1899 is a common Laboulbeniales fungus occurring in Europe and is currently 32 known to be a parasite of at least eight Myrmica ant species. R. wasmannii serves as a good model organ- ants. Therefore, it is possible that infected ants must replace the loss of water. Based on these results, R.
42wasmannii substantially decreases the chances and time of survival of infected individuals, at least in 43 resource-limited environments, which suggest that R. wasmannii has a negative effect on its host.
Highlights d Ants overcome complex multidimensional nutritional constraints d Collective homeostasis relies on individual feeding decisions d Feeding decisions are flexible and rely on individual nutritional state d Ants are able to solve nutritional conflicts within the colony Authors Enik} o Csata, Jacques Gautrais,
The ant species Myrmica scabrinodis plays a markedly important ecological role through much of the humid grasslands of Eurasia. It hosts a species-rich community of pathogens and parasites, including Rickia wasmannii, an enigmatic member of entomoparasitic laboulbenialean fungi. This study provides a descriptive ecology of R. wasmannii by characterizing its prevalence and distribution across several hierarchical levels: colonies, individuals, and anatomic body parts. Infections were restricted to a single ant species, Myrmica scabrinodis, and infected colonies occurred predominantly in wet habitats. Infections tended to be highly prevalent within infected colonies, often reaching 100% sample prevalence among workers. Individual infections exhibited an aggregated distribution typical to host-parasite systems. Workers from the aboveground part of nests (presumably older ones acting as foragers) were more infected than those from the belowground part. Fungal thalli could be found all over the body of the hosts, the head and the abdomen being the most infected parts of the body. The fungi's distribution among host body parts statistically differed between low versus high-intensity infections: the initial dominance of the head decreased with advancing infection. These findings may provide baseline data for future comparative or monitoring studies.
Title:Distribution of the myrmecoparasitic fungus Rickiawasmannii (Ascomycota:
Laboulbeniales) across colonies, individuals, and body parts of Myrmicascabrinodis
Running title:Prevalence and distribution of Rickiawasmannii on ants We are grateful for the reviewers" comments, they helped us improving the manuscript considerably. We addressed every question and carried out all the requested corrections. More specifically, we clarified all those aspects that were not addressed by us in the required manner in the previous version of the manuscript (e.g. methodological details in the Materials and Methods), and eliminated one GLMM analysis since the dataset behind it was very unbalanced, and the results of the analysis where anyhow non-significant. We added a more detailed paragraph on host specificity to the discussion and generally corrected all mistakes and errors that were mentioned by the reviewers. In the end the general message of the manuscript has not changed. A detailed list of responses was also prepared further on.
Detailed answers REVIEWER #1:General comments
R:The 'entomopathogenicity' role of Laboulbeniales in the genus Rickia is not clear, so this word should be carefully used in sentences as "an enigmatic member of entomopathogeniclaboulbenialean fungi". Nevertheless, I think that the biological interaction between Laboulbeniales and hosts has scientific relevance for fitting in the scope of Csata et al., 2014;Báthori et al., 2015). Such negative effects are also documented in other Laboulbeniales fungi: according to Riddick (2010) laboulbenian infection reduces the winter survival of Harmonia axyridis, while other Laboulbeniales species could reduce ...
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