Eero J. Vesterinen

Bats as Reservoir Hosts of Human Bacterial Pathogen, Bartonella mayotimonensis

Bats can be potent reservoirs of human bacterial pathogens.

Exposing the structure of an Arctic food web.

How food webs are structured has major implications for their stability and dynamics. While poorly studied to date, arctic food webs are commonly assumed to be simple in structure, with few links per species. If this is the case, then different parts of the web may be weakly connected to each other, with populations and species united by only a low number of links. We provide the first highly resolved description of trophic link structure for a large part of a high-arctic food web. For this purpose, we apply a combination of recent techniques to describing the links between three predator guilds (insectivorous birds, spiders, and lepidopteran parasitoids) and their two dominant prey orders (Diptera and Lepidoptera). The resultant web shows a dense link structure and no compartmentalization or modularity across the three predator guilds. Thus, both individual predators and predator guilds tap heavily into the prey community of each other, offering versatile scope for indirect interactions across different parts of the web. The current description of a first but single arctic web may serve as a benchmark toward which to gauge future webs resolved by similar techniques. Targeting an unusual breadth of predator guilds, and relying on techniques with a high resolution, it suggests that species in this web are closely connected. Thus, our findings call for similar explorations of link structure across multiple guilds in both arctic and other webs. From an applied perspective, our description of an arctic web suggests new avenues for understanding how arctic food webs are built and function and of how they respond to current climate change. It suggests that to comprehend the community-level consequences of rapid arctic warming, we should turn from analyses of populations, population pairs, and isolated predator–prey interactions to considering the full set of interacting species.

Next generation sequencing of fecal DNA reveals the dietary diversity of the widespread insectivorous predator Daubenton's Bat (Myotis daubentonii) in Southwestern Finland.

Understanding predator-prey dynamics is a fundamental task in the evaluation of the adaptive capacities of species. However, direct observations or morphological identification of fecal remains do not offer an effective way to study the dietary ecology of elusive species, such as nocturnal insectivorous bats. However, recent advances in molecular techniques have opened a new method for identifying prey species from fecal samples. In this study, we amplified species-specific mitochondrial COI fragments from fecal DNA extractions from 34 individual Daubenton’s bats (Myotis daubentonii) collected between 2008 and 2010 from southwestern Finland. Altogether, 128 different species of prey were identified based on a comprehensive local DNA reference library. In our study area, Daubenton’s bats feed most frequently on insects of the orders Diptera (found in the diet of 94% individuals), Trichoptera (69%) and Lepidoptera (63%). The most frequent dipteran family in the diet was Chironomidae, which was found in 31 of 34 individuals. Most common prey species were chironomids Microtendipes pedellus (found in 50% of bats), Glyptotendipes cauliginellus (44%), and Procladius ferrugineus (41%). For the first time, an accurate species level list of the diet of the insectivorous Daubenton’s bat (Myotis daubentonii) in Finland is presented. We report a generally applicable method for describing the arthropod diet of vertebrate predators. We compare public databases to a national database to highlight the importance of a local reference database.

What you need is what you eat? Prey selection by the bat Myotis daubentonii.

Optimal foraging theory predicts that predators are selective when faced with abundant prey, but become less picky when prey gets sparse. Insectivorous bats in temperate regions are faced with the challenge of building up fat reserves vital for hibernation during a period of decreasing arthropod abundances. According to optimal foraging theory, prehibernating bats should adopt a less selective feeding behaviour – yet empirical studies have revealed many apparently generalized species to be composed of specialist individuals. Targeting the diet of the bat Myotis daubentonii, we used a combination of molecular techniques to test for seasonal changes in prey selectivity and individual‐level variation in prey preferences. DNA metabarcoding was used to characterize both the prey contents of bat droppings and the insect community available as prey. To test for dietary differences among M. daubentonii individuals, we used ten microsatellite loci to assign droppings to individual bats. The comparison between consumed and available prey revealed a preference for certain prey items regardless of availability. Nonbiting midges (Chironomidae) remained the most highly consumed prey at all times, despite a significant increase in the availability of black flies (Simuliidae) towards the end of the season. The bats sampled showed no evidence of individual specialization in dietary preferences. Overall, our approach offers little support for optimal foraging theory. Thus, it shows how novel combinations of genetic markers can be used to test general theory, targeting patterns at both the level of prey communities and individual predators.

Assessing the abundance, seasonal questing activity, and Borrelia and tick-borne encephalitis virus (TBEV) prevalence of Ixodes ricinus ticks in a Lyme borreliosis endemic area in Southwest Finland

Studies have revealed that Ixodes ricinus (Acari: Ixodidae) have become more abundant and their geographical distribution extended northwards in some Nordic countries during the past few decades. However, ecological data of tick populations in Finland are sparse. In the current study, I. ricinus abundance, seasonal questing activity, and their Borrelia spp. and tick-borne encephalitis virus (TBEV) prevalence were evaluated in a Lyme borreliosis endemic area in Southwest Finland, Seili Island, where a previous study mapping tick densities was conducted 12 years earlier. A total of 1940 ticks were collected from five different biotopes by cloth dragging during May-September 2012. The overall tick density observed was 5.2 ticks/100m(2) for nymphs and adults. Seasonal questing activity of ticks differed between biotopes and life stages: bimodal occurrences were observed especially for nymphal and adult ticks in forested biotopes, while larvae in pastures exhibited mostly unimodal occurrence. Prevalence of Borrelia and TBEV in ticks was evaluated using conventional and real-time PCR. All samples were negative for TBEV. Borrelia prevalence was 25.0% for adults (n=44) and the minimum infection rate (MIR) 5.6% for pooled nymph samples (191 samples, 1-14 individuals per sample; 30/191 positive). No Borrelia were detected in pooled larval samples (63 samples, 1-139 individuals per sample). Five species of Borrelia were identified from the samples: B. afzelii, B. burgdorferi s.s., B. garinii, B. valaisiana and B. miyamotoi. In Finland, B. valaisiana and B. miyamotoi have previously been reported from the Åland Islands but not from the mainland or inner archipelago. The results of the present study suggest an increase in I. ricinus abundance on the island.

Sediment organic tin contamination promotes impoverishment of non-biting midge species communities in the Archipelago Sea, S-W Finland

Chironomid species are a vital component in many benthic and terrestrial food webs; they have an important role in the detritus cycle, and are an important source of food for many species. We studied how tributyltin (TBT) in brackish water sediments affect the composition of chironomid species communities. Emergence traps were used at selected sites on a TBT gradient in the Archipelago Sea, S-W Finland. Increased sediment TBT concentration was associated with significant chironomid species turnover, which in turn was related to decreased species diversity (number of species and genera). However, the overall number of individuals did not decrease markedly with increasing TBT contamination. This suggests that the ecological role of chironomids in the food web may be preserved even under severe impoverishment of the chironomid community due to organic tin contamination. The increased prevalence of more TBT tolerant species can potentially lead to a transport of organic tin compounds between aquatic and terrestrial food webs. Furthermore, the reduced diversity of an ecologically influential group might lower the resistance of the entire food web to other environmental hazards and perturbations.

Pellets of proof: First glimpse of the dietary composition of adult odonates as revealed by metabarcoding of feces

Abstract Recent advances in molecular techniques allow us to resolve the diet of unstudied taxa. Odonates are potentially important top‐down regulators of many insects. Yet, to date, our knowledge of odonate prey use is based mainly on limited observations of odonates catching or eating their prey. In this study, we examine the potential use of metabarcoding in establishing the diet of three adult odonate species (Lestes sponsa, Enallagma cyathigerum, and Sympetrum danae) at a site in southwestern Finland. To this purpose, we compared three different methods for extracting DNA from fecal samples: the Macherey‐Nagel Nucleospin XS kit, a traditional salt extraction, and the Zymo Research Fecal Microprep kit. From these extracts, we amplified group‐specific mitochondrial markers (COI and 16S rRNA) from altogether 72 odonate individuals, and compared them to comprehensive reference libraries. The three odonate species show major overlap in diet, with no significant differences between individuals of different size and/or gender, reflecting opportunistic foraging of adult odonates. Of a total of 41 different prey species detected, the most frequently consumed ones were Diptera, with additional records of six other orders. Based on our data, the best DNA extraction method is the traditional salt extraction, as it provides the most information on prey content while also being the most economical. To our knowledge, this is the first study to resolve the species‐level diet of adult odonates. Armed with the appropriate methodological caveats, we are ready to examine the ecological role of odonates in both terrestrial and aquatic food webs, and in transferring subsidies between these two realms.

REED BEDS MAY FACILITATE TRANSFER OF TRIBUTYLTIN FROM AQUATIC TO TERRESTRIAL ECOSYSTEMS THROUGH INSECT VECTORS IN THE ARCHIPELAGO SEA, SW FINLAND

Due to their adsorptive behavior, organotin compounds (OTCs), such as tributyltin (TBT), are accumulated in aquatic sediments. They resist biodegradation and, despite a ban in 2008, are a potential source for future exposure. Sediment OTCs have mostly been measured from sites of known high concentrations such as ports, shipping lanes, and marine dredging waste sites. The possible flow of OTCs from marine to terrestrial ecosystems, however, has not been studied. In the present study, the authors assessed whether sediments in common reed beds (Phragmites australis) accumulate TBT and whether chironomid (Diptera: Chironomidae) communities developing in reed-bed sediments act as vectors in the transfer of TBT from aquatic to terrestrial ecosystems in the Airisto channel, Archipelago Sea. The authors also investigated whether distance from the only known source and depth and TBT concentration of the adjacent shipping lane affect reed-bed concentrations. Thirty-six sites along the Airisto channel were sampled at 2-km intervals with triplicate samples from reed beds and the adjacent shipping lane for sediment and seven reed-bed sites for chironomids, and these were analyzed with an solid phase extraction liquid chromatography tamdem mass spectrometry method. The closer to the source the sample site was, the higher the measured TBT concentrations were; and the deeper the shipping lane, the lower the concentration of TBT in reed-bed sediments. The chironomid TBT concentrations correlated with reed-bed sediment TBT concentrations and showed evidence of accumulation. Therefore, TBT may be transferred, through the food web, from aquatic to terrestrial ecosystems relatively close to a source through ecosystem boundaries, such as common reed beds, which are areas of high insect biomass production in the Archipelago Sea.

Crowdsourcing-based nationwide tick collection reveals the distribution of Ixodes ricinus and I. persulcatus and associated pathogens in Finland

A national crowdsourcing-based tick collection campaign was organized in 2015 with the objective of producing novel data on tick distribution and tick-borne pathogens in Finland. Nearly 20 000 Ixodes ticks were collected. The collected material revealed the nationwide distribution of I. persulcatus for the first time and a shift northwards in the distribution of I. ricinus in Finland. A subset of 2038 tick samples containing both species was screened for Borrelia burgdorferi sensu lato (the prevalence was 14.2% for I. ricinus and 19.8% for I. persulcatus), B. miyamotoi (0.2% and 0.4%, respectively) and tick-borne encephalitis virus (TBEV; 0.2% and 3.0%, respectively). We also report new risk areas for TBEV in Finland and, for the first time, the presence of B. miyamotoi in ticks from mainland Finland. Most importantly, our study demonstrates the overwhelming power of citizen science in accomplishing a collection effort that would have been impossible with the scientific community alone. Emerging Microbes & Infections (2017) 6, e31; doi:10.1038/emi.2017.17; published online 10 May 2017

Chlamydia-Like Organisms (CLOs) in Finnish Ixodes ricinus Ticks and Human Skin.

Ticks carry several human pathogenic microbes including Borreliae and Flavivirus causing tick-born encephalitis. Ticks can also carry DNA of Chlamydia-like organisms (CLOs). The purpose of this study was to investigate the occurrence of CLOs in ticks and skin biopsies taken from individuals with suspected tick bite. DNA from CLOs was detected by pan-Chlamydiales-PCR in 40% of adult ticks from southwestern Finland. The estimated minimal infection rate for nymphs and larvae (studied in pools) was 6% and 2%, respectively. For the first time, we show CLO DNA also in human skin as 68% of all skin biopsies studied contained CLO DNA as determined through pan-Chlamydiales-PCR. Sequence analyses based on the 16S rRNA gene fragment indicated that the sequences detected in ticks were heterogeneous, representing various CLO families; whereas the majority of the sequences from human skin remained “unclassified Chlamydiales” and might represent a new family-level lineage. CLO sequences detected in four skin biopsies were most closely related to “uncultured Chlamydial bacterium clones from Ixodes ricinus ticks” and two of them were very similar to CLO sequences from Finnish ticks. These results suggest that CLO DNA is present in human skin; ticks carry CLOs and could potentially transmit CLOs to humans.