Threats from the air: Damselfly predation on diverse prey taxa.

To understand the diversity and strength of predation in natural communities, researchers must quantify the total amount of prey species in the diet of predators. Metabarcoding approaches have allowed widespread characterization of predator diets with high taxonomic resolution. To determine the wider impacts of predators, researchers should combine DNA techniques with estimates of population size of predators using mark-release-recapture (MRR) methods, and with accurate metrics of food consumption by individuals. Herein, we estimate the scale of predation exerted by four damselfly species on diverse prey taxa within a well-defined 12-ha study area, resolving the prey species of individual damselflies, to what extent the diets of predatory species overlap, and which fraction of the main prey populations are consumed. We identify the taxonomic composition of diets using DNA metabarcoding and quantify damselfly population sizes by MRR. We also use predator-specific estimates of consumption rates, and independent data on prey emergence rates to estimate the collective predation pressure summed over all prey taxa and specific to their main prey (non-biting midges or chironomids) of the four damselfly species. The four damselfly species collectively consumed a prey mass equivalent to roughly 870 (95% CL 410-1,800) g, over 2 months. Each individual consumed 29%-66% (95% CL 9.4-123) of its body weight during its relatively short life span (2.1-4.7 days; 95% CL 0.74-7.9) in the focal population. This predation pressure was widely distributed across the local invertebrate prey community, including 4 classes, 19 orders and c. 140 genera. Different predator species showed extensive overlap in diets, with an average of 30% of prey shared by at least two predator species. Of the available prey individuals in the widely consumed family Chironomidae, only a relatively small proportion (0.76%; 95% CL 0.35%-1.61%) were consumed. Our synthesis of population sizes, per-capita consumption rates and taxonomic distribution of diets identifies damselflies as a comparatively minor predator group of aerial insects. As the next step, we should add estimates of predation by larger odonate species, and experimental removal of odonates, thereby establishing the full impact of odonate predation on prey communities.

Negative covariance between water mite and gregarine parasitism for adult dragonflies, Leucorrhinia intacta (Hagen): an age-related pattern?

Studies on parasite-mediated selection often focus on single parasite taxa infecting single species of hosts. However, host populations experience infections by multiple parasite taxa simultaneously; coinfection is expected to influence how host- and/or parasite-related factors affect host exposure and susceptibility to various parasites, and the resulting patterns of infection. We sampled adult dragonflies from a population of Leucorrhinia intacta (Hagen) in eastern Ontario, Canada. Dragonflies were exposed to parasitism by both water mites (Arrenuridae) and gregarines (Eugregarinidae). We tested for covariation between these ecto- and endoparasites, while considering potential sex and age biases in host sampling and patterns of infection. Mite parasitism differed dramatically between host sexes: nearly all collected males were parasitized, whereas only half of females were infested. This was likely due to differences in age distributions between sexes in sampled dragonflies. Water mite and gregarine parasitism showed strong, negative covariation, and coinfection occurred far less often than expected by chance, although these patterns were restricted to samples of females which, unlike male samples, likely included many old and young dragonflies. We report the first observation of negative covariation between internal and external parasite taxa in an anisopteran host and suggest this relationship between water mites and gregarines may be more widespread among Odonata and perhaps other insects than previously surmised. We advance hypotheses based on host age-parasitism relationships as well as variable parasite-mediated selection to help explain the sex specificity of observed coinfection patterns in our samples.

Parasite burden and the insect immune response: interpopulation comparison.

The immune response affects host's survival and reproductive success. Insurmountable immune function has not evolved because it is costly and there is a trade-off between other life-history traits. In previous studies several factors such as diet and temperature have been proposed to cause interpopulation differences in immune response. Moreover, the insect immune system may be functionally more protective upon secondary exposure, thus infection history may associate with the immune response. Here we measured how geographical location and parasite burden is related to variation in immune response between populations. We included 13 populations of the Northern Damselfly Coenagrion hastulatum (Odonata: Coenagrionidae) in Finland over a latitudinal range of 880 km to this study. We found that water mites associated strongly with the immune response at interpopulation level: the more the mites, the higher the immune response. Also, in an alternative model based on AIC, latitude and individual size associated with the immune response. In turn, endoparasitic gregarines did not affect the immune response. To conclude, a positive interpopulation association between the immune response and the rate of water mite infection may indicate (i) local adaptation to chronic parasite stress, (ii) effective 'induced' immune response against parasites, or (iii) a combined effect of both of these.

Capitojoppa, a new genus of Ichneumoninae (Hymenoptera, Ichneumonidae) from Peruvian Amazonia.

A new monotypic genus of ichneumonine parasitoid wasps (Hymenoptera, Ichneumonidae, Ichneumoninae) is described from Peru; Capitojoppagen. nov. is described to accommodate Capitojoppaamazonicasp. nov. The new genus is morphologically very distinctive and can be easily separated from all known ichneumonine genera. By describing Capitojoppa from the lowland rain forests of Peru, we aim to draw attention to the considerable diversity and morphological variation of the Amazonian ichneumonine fauna.

Wing shape and its influence on the outcome of territorial contests in the damselfly Calopteryx virgo.

Male mating success is often determined by territory ownership and traits associated with successful territory defense. Empirical studies have shown that the territory owner wins the majority of fights with challenging males. Several physical and physiological traits have been found to correlate with resource holding potential. In addition, in aerial insects, wing design may also have a strong influence on resource holding potential, since it determines efficiency and precision during flight. However, this possibility has not yet been thoroughly evaluated using the modern technique of geometric morphometrics to analyze shape. Therefore, this study examined whether wing shape affects the outcome of male-male contests in the territorial damselfly, Calopteryx virgo (L.) (Odonata: Calopterygidae). Wing shape and also traditional flight-related morphological measures were compared between 27 pairs of winners and losers from experimental territorial contests. Contrary to expectations, there were no differences between winners and losers in all studied wing traits (shape, length, width, total surface, aspect ratio, and wing loading). However, highly significant differences in wing shape and size were detected between the fore- and hindwing. It is currently not known how these differences relate to flight performance, since previous biomechanical studies in damselflies assumed fore- and hindwings to have an identical planform.

Cryptic biodiversity of tropical hesperiid caterpillar-attacking parasitoid wasps: three new species of Creagrura Townes (Hymenoptera, Ichneumonidae, Cremastinae) from Costa Rica and Perú.

Background: We describe three new species of the previously monotypic genus Creagrura Townes from Central and South America: C.alejandromasisi sp. n. and C.rogerblancoi sp. n. from Costa Rica and C.allpahuaya sp. n. from Peru, all of which emphasise the unknown parasitoid insect diversity yet to be revealed in the tropics. New information: Host relationships of the two Costa Rican species are described in detail. In addition, it is inferred that the Creagrura wasps find and oviposit in the caterpillar when it is exposed at night, rather than when it is concealed during daylight hours.

A review of the spider-attacking Polysphinctadizardi species-group (Hymenoptera, Ichneumonidae, Pimplinae), with descriptions of seven new species from South America.

The Neotropical Polysphinctadizardi species-group is revised. We describe seven new species from South America: P.bonita sp. nov., P.cosnipata sp. nov., P.inca sp. nov., P.macroepomia sp. nov., P.organensis sp. nov., P.pichincha sp. nov., and P.teresa sp. nov. In addition, we provide a diagnosis and an identification key to all species of the group.

Metabarcoding prey DNA from fecal samples of adult dragonflies shows no predicted sex differences, and substantial inter-individual variation, in diets.

Sexes often differ in foraging and diet, which is associated with sex differences in size, trophic morphology, use of habitats, and/or life history tactics. Herein, strikingly similar diets were found for adult sexes of a dragonfly (Leucorrhinia intacta), based on comparing 141 dietary taxa identified from the metabarcoding of mitochondrial DNA archived in feces. Arthropods in > 5% of samples included five species of dipterans, two hemipterans, two spider species and one parasitic mite. The mite was not traditional prey as its presence was likely due to DNA contamination of samples arising through parasitism or possibly via accidental consumption during grooming, and therefore the mite was excluded from diet characterizations. Common prey species were found with statistically indistinguishable frequencies in male and female diets, with one exception of an aphid more often found in male diets, although this pattern was not robust to corrections for multiple statistical tests. While rare prey species were often found in diets of only one sex, instances of this were more frequent in the more oft-sampled females, suggesting sampling artefact. Sexes did not differ in the mean prey species richness in their diets. Overall, sexes showed statistically indistinguishable diets both on a prey species-by-species basis and in terms of multivariate characterizations of diet composition, derived from presence-absence data of prey species analyzed via PERMANOVA and accumulation curves. Males and females may have similar diets by being both opportunistic and generalist predators of arthropods, using the same foraging habitats and having similar sizes and flight agilities. Notably, similarities in diet between sexes occur alongside large interindividual differences in diet, within sexes. Researchers intending on explaining adaptive sex differences in diet should consider characteristics of species whose sexes show similar diets.

A global class reunion with multiple groups feasting on the declining insect smorgasbord.

We report a detection of a surprising similarity in the diet of predators across distant phyla. Though just a first glimpse into the subject, our discovery contradicts traditional aspects of biology, as the earliest notions in ecology have linked the most severe competition of resources with evolutionary relatedness. We argue that our finding deserves more research, and propose a plan to reveal more information on the current biodiversity loss around the world. While doing so, we expand the recently proposed conservation roadmaps into a parallel study of global interaction networks.

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

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.

New and poorly known Holarctic species of Boletina Staeger, 1840 (Diptera, Mycetophilidae).

BACKGROUND: The genus Boletina is a species rich group of fungus gnats. Members of the genus are mainly known from temperate, boreal and arctic biomes. Phylogeny of the genus is still poorly resolved, dozens of species are insufficiently described and undescribed species are often discovered, especially from samples taken from the boreal zone. NEW INFORMATION: Four new species are described. Boletina valteri Salmela sp.n. (Finland), Boletina kullervoi Salmela sp.n. (Finland), B. hyperborea Salmela sp.n. (Finland, Norway, Sweden, Canada) and B. nuortti Salmela sp.n. (Finland). Boletina arctica Holmgren is redescribed and reported for the first time from the Canadian high arctic zone. Boletina borealis Zetterstedt and B. birulai Lundström are reported for the first time from Canada. Boletina subnitidula Sasakawa (syn. n.) is proposed as a junior synonym of B. pallidula Edwards.

Additions to the list of Finnish Bibionomorpha (Diptera, Nematocera).

A total of 12 gnat species are reported for the first time from Finland (3 Cecidomyiidae, 1 Keroplatidae, 8 Mycetophilidae), and the occurrence of Macroceranigropicea Lundström in Finland is verified. All material was collected from the Finnish Lapland, mainly from the north boreal ecoregion. Two of the recorded species are likely to be pyrophilous, associated with forest fire sites. A photo of the ventral appendage of the gonocoxite of Brevicornusetigerum Zaitzev is provided for the first time. The male hypopygium of Mycetophilaharuspica Plassmann is redescribed.

Expression and localization of the Na+/H+ exchanger isoform NHE3 in the rat efferent ducts.

The efferent ducts reabsorb most of the fluid released with spermatozoa from the testis. This absorptive capacity results in a severalfold increase in sperm concentration in the proximal epididymis and is partly responsible for maintenance of the optimal microenvironment for the sperm maturation. The fluid absorption is coupled to active Na+ transport and is inhibitable by amiloride, both of which suggest a role for a Na+/H+ exchanger (NHE). NHE3 is an apical membrane NHE responsible for sodium absorption in renal proximal tubule and intestinal epithelium. In the present study, we examined the expression of NHE3 messenger RNA (mRNA) and protein in the rat efferent ducts by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting and the localization of NHE3 by indirect immunofluoresce. RT-PCR indicated the expression of NHE3 mRNA, and Western blotting showed an NHE3 protein in the efferent duct membrane homogenate. By immunofluorescence, NHE3 was localized to the apical membrane of the nonciliated cells in the efferent duct epithelium, which also expressed aquaporin-1 water channel protein. These results suggest that NHE3 potentially plays an important role in the fluid reabsorption in the efferent ducts.

Unveiling of a cryptic Dicranomyia (Idiopyga) from northern Finland using integrative approach (Diptera, Limoniidae).

The subgenus Idiopyga Savchenko, 1987 is a northern hemisphere group of short-palped crane flies (Diptera, Limoniidae). In the current article we describe a new species, Dicranomyia (I.) boreobaltica Salmela sp.n., and redescribe the male and female post-abdomen of a closely related species, D. (I.) intricata Alexander. A standard DNA barcoding fragment of 5' region of the cytochrome c oxidase I (COI) gene of the new species is presented, whilst the K2P minimum distances between the new species and 10 other species of the subgenus were found to range from 5.1 to 15.7 % (mean 11.2 %). Phylogenetic analyses (parsimony and maximum likelihood) based on COI sequences support the identity of the new species and its close relationship with D. (I.) intricata and D. (I.) esbeni (Nielsen). The new species is known from the northern Baltic area of Finland. The new species has been mostly collected from Baltic coastal meadows but an additional relict population is known from a calcareous rich fen that was estimated to have been at sea level circa 600-700 years ago. Dicranomyia (I.) intricata (syn. D.suecica Nielsen) is a Holarctic species, occurring in the north boreal and subarctic vegetation zones in Fennoscandia.