Experiment in semi-natural conditions did not confirm the influence of malaria infection on bird attractiveness to mosquitoes.

7 pagesInternational audienceBackground Changes in host phenotype following parasite infection are often considered as host manipulation when they seem advantageous for the parasite. However, putative cases of host manipulation by parasites are rarely tested in field-realistic conditions. Infection-induced phenotypic change cannot be conclusively considered as host manipulation if no evidence shows that this trait is adaptive for the parasite in the wild. Plasmodium sp., the parasites causing malaria in vertebrates, are hypothesized to “manipulate” their host by making their odour more attractive to mosquitoes, their vector and final host. While this is fairly well supported by studies on mice and humans, studies focusing on avian malaria give contradictory results. Methods In the present study, genotyped birds at different stages (uninfected, acute and chronic) of Plasmodium relictum infection were exposed, in a large outdoor aviary, to their natural vector, the mosquito Culex pipiens . Results After genotyping the blood meals of more than 650 mosquitoes, we found that mosquitoes did not bite infected birds more than they bit them before infection, nor more than they bit uninfected hosts. Conclusions Our study highlights the importance of testing ecological behaviours under natural conditions and suggests that different processes might be at play in mammals and birds regarding potential manipulation of attractiveness by malaria parasites

Impact of host stress on the replication rate of Plasmodium: Take it easy to avoid malaria recurrence

This dataset is associated with a study where we explored the impact of increasing the concentration of corticosterone in the blood of birds on the within-host infection dynamic of malaria parasite (i.e. Plasmodium relictum). The birds were in a chronic stage of infection. We manipulated the corticosterone concentration of the birds either artificially (corticosterone ingestion, experiment 1) or naturally (handling stress, experiment 2). We also exposed treated and controlled birds to mosquitoes to determine if increased stress hormone levels in vertebrate hosts impacted Plasmodium transmission. We conducted a third experiment to study the impact of mosquito bites on stress hormone levels in vertebrate hosts. </div

Determinants of haemosporidian single- and co-infection risks in western palearctic birds

Understanding the drivers of infection risk helps us to detect the most at-risk species in a community and identify species whose intrinsic characteristics could act as potential reservoirs of pathogens. This knowledge is crucial if we are to predict the emergence and evolution of infectious diseases. To date, most studies have only focused on infections caused by a single parasite, leaving out co-infections. Yet, co-infections are of paramount importance in understanding the ecology and evolution of host-parasite interactions due to the wide range of effects they can have on host fitness and on the evolutionary trajectories of parasites. Here, we used a multinomial Bayesian phylogenetic modelling framework to explore the extent to which bird ecology and phylogeny impact the probability of being infected by one genus (hereafter single infection) or by multiple genera (hereafter co-infection) of haemosporidian parasites. We show that while nesting and migration behaviours influenced both the probability of being single- and co-infected, species position along the slow-fast life-history continuum and geographic range size were only pertinent in explaining variation in co-infection risk. We also found evidence for a phylogenetic conservatism regarding both single- and co-infections, indicating that phylogenetically related bird species tend to have similar infection patterns. This phylogenetic signal was four times stronger for co-infections than for single infections, suggesting that co-infections may act as a stronger selective pressure than single infections. Overall, our study underscores the combined influence of hosts’ evolutionary history and attributes in determining infection risk in avian host communities. These results also suggest that co-infection risk might be under stronger deterministic control than single infection risk, potentially paving the way toward a better understanding of the emergence and evolution of infectious diseases

Raw sequencing data and ngsfilters for snow track eDNA samples

&lt;p&gt;Continued advancements in environmental DNA (eDNA) research have made it possible to access intraspecific variation from eDNA samples, opening new opportunities to expand non-invasive genetic studies of wildlife populations. However, the use of eDNA samples for individual genotyping, as typically performed in non-invasive genetics, still remains elusive. We present the first successful individual genotyping of eDNA obtained from snow tracks of three large carnivores: brown bear (&lt;em&gt;Ursus&lt;/em&gt; &lt;em&gt;arctos&lt;/em&gt;), European lynx (&lt;em&gt;Lynx&lt;/em&gt; &lt;em&gt;lynx&lt;/em&gt;) and wolf (&lt;em&gt;Canis&lt;/em&gt; &lt;em&gt;lupus&lt;/em&gt;). DNA was extracted using a protocol for isolating water eDNA and genotyped using amplicon sequencing of short tandem repeats (STR) and, for brown bear, a sex marker, on a high-throughput sequencing platform. Individual genotypes were obtained for all species, but genotyping performance differed among samples and species. The proportion of samples genotyped to individuals was higher for brown bear samples (5/7) than for wolf (7/10) and lynx (4/9), but locus genotyping success was greater for brown bear (0.88). Results for three species show that reliable individual genotyping, including sex identification, is now possible from eDNA in snow tracks, underlining its vast potential to complement the non-invasive genetic methods used for wildlife. To fully leverage the application of snow track eDNA, improved understanding of the ideal species- and site-specific sampling conditions, as well as laboratory methods promoting genotyping success are needed. This will also inform efforts to retrieve and type nuclear DNA from other eDNA samples, thereby advancing eDNA–based individual and population-level studies.&lt;/p&gt;&lt;p&gt;Funding provided by: European Commission&lt;br&gt;Crossref Funder Registry ID: https://ror.org/00k4n6c32&lt;br&gt;Award Number: LIFE16 NAT/SI/000634&lt;/p&gt;&lt;p&gt;Funding provided by: European Commission&lt;br&gt;Crossref Funder Registry ID: https://ror.org/00k4n6c32&lt;br&gt;Award Number: LIFE18 NAT/IT/000972&lt;/p&gt;&lt;p&gt;Funding provided by: Slovenian Research Agency&lt;br&gt;Crossref Funder Registry ID: https://ror.org/059bp8k51&lt;br&gt;Award Number: P1-0184&lt;/p&gt;&lt;p&gt;Funding provided by: Federal Office for the Environment&lt;br&gt;Crossref Funder Registry ID: https://ror.org/04t48sm91&lt;br&gt;Award Number: &lt;/p&gt;&lt;p&gt;Snow tracks of brown bear, lynx and wolf were collected opportunistically during winter in 2019, 2020 and 2022 in the Slovenian Alps and Dinaric Mountains (seven brown bear samples and nine lynx samples) and in the French Alps (ten wolf samples). For genotyping of each species, we used a set of STR markers designed for optimal multiplex amplification and HTS genotyping. The brown bear set includes 13 STR recently described and used for individual profiling from fecal DNA, with the addition of a sex-specific marker. For wolf and lynx, we used 13 new STRs. We performed sequencing on a NovaSeq platform (2x150 bp) (libraries with id DIVJA088, DIVJA089, DAB074) and on a Miniseq platform (2x150 bp) (library LF22). Amplicons were sequenced in multiplexes, and necessary information for demultiplexing is in .ngsfilter files.&lt;/p&gt