A poorly known high-latitude parasitoid wasp community: unexpected diversity and dramatic changes through time

Parasitoids indicate major climate-induced shifts in arctic communities

Climatic impacts are especially pronounced in the Arctic, which as a region is warming twice as fast as the rest of the globe. Here, we investigate how mean climatic conditions and rates of climatic change impact parasitoid insect communities in 16 localities across the Arctic. We focus on parasitoids in a widespread habitat, Dryas heathlands, and describe parasitoid community composition in terms of larval host use (i.e., parasitoid use of herbivorous Lepidoptera vs. pollinating Diptera) and functional groups differing in their closeness of host associations (koinobionts vs. idiobionts). Of the latter, we expect idiobionts-as being less fine-tuned to host development-to be generally less tolerant to cold temperatures, since they are confined to attacking hosts pupating and overwintering in relatively exposed locations. To further test our findings, we assess whether similar climatic variables are associated with host abundances in a 22 year time series from Northeast Greenland. We find sites which have experienced a temperature rise in summer while retaining cold winters to be dominated by parasitoids of Lepidoptera, with the reverse being true for the parasitoids of Diptera. The rate of summer temperature rise is further associated with higher levels of herbivory, suggesting higher availability of lepidopteran hosts and changes in ecosystem functioning. We also detect a matching signal over time, as higher summer temperatures, coupled with cold early winter soils, are related to high herbivory by lepidopteran larvae, and to declines in the abundance of dipteran pollinators. Collectively, our results suggest that in parts of the warming Arctic, Dryas is being simultaneously exposed to increased herbivory and reduced pollination. Our findings point to potential drastic and rapid consequences of climate change on multitrophic-level community structure and on ecosystem functioning and highlight the value of collaborative, systematic sampling effort.

A DNA Barcoding Survey of an Arctic Arthropod Community: Implications for Future Monitoring

Accurate and cost-effective methods for tracking changes in arthropod communities are needed to develop integrative environmental monitoring programs in the Arctic. To date, even baseline data on their species composition at established ecological monitoring sites are severely lacking. We present the results of a pilot assessment of non-marine arthropod diversity in a middle arctic tundra area near Ikaluktutiak (Cambridge Bay), Victoria Island, Nunavut, undertaken in 2018 using DNA barcodes. A total of 1264 Barcode Index Number (BIN) clusters, used as a proxy for species, were recorded. The efficacy of widely used sampling methods was assessed. Yellow pan traps captured 62% of the entire BIN diversity at the study sites. When complemented with soil and leaf litter sifting, the coverage rose up to 74.6%. Combining community-based data collection with high-throughput DNA barcoding has the potential to overcome many of the logistic, financial, and taxonomic obstacles for large-scale monitoring of the Arctic arthropod fauna.

Quantifying the unquantifiable: why Hymenoptera, not Coleoptera, is the most speciose animal order

BACKGROUND

We challenge the oft-repeated claim that the beetles (Coleoptera) are the most species-rich order of animals. Instead, we assert that another order of insects, the Hymenoptera, is more speciose, due in large part to the massively diverse but relatively poorly known parasitoid wasps. The idea that the beetles have more species than other orders is primarily based on their respective collection histories and the relative availability of taxonomic resources, which both disfavor parasitoid wasps. Though it is unreasonable to directly compare numbers of described species in each order, the ecology of parasitic wasps-specifically, their intimate interactions with their hosts-allows for estimation of relative richness.

RESULTS

We present a simple logical model that shows how the specialization of many parasitic wasps on their hosts suggests few scenarios in which there would be more beetle species than parasitic wasp species. We couple this model with an accounting of what we call the "genus-specific parasitoid-host ratio" from four well-studied genera of insect hosts, a metric by which to generate extremely conservative estimates of the average number of parasitic wasp species attacking a given beetle or other insect host species.

CONCLUSIONS

Synthesis of our model with data from real host systems suggests that the Hymenoptera may have 2.5-3.2× more species than the Coleoptera. While there are more described species of beetles than all other animals, the Hymenoptera are almost certainly the larger order.

Systematics, Biology, and Evolution of Microgastrine Parasitoid Wasps

The braconid parasitoid wasp subfamily Microgastrinae is perhaps the most species-rich subfamily of animals on Earth. Despite their small size, they are familiar to agriculturalists and field ecologists alike as one of the principal groups of natural enemies of caterpillars feeding on plants. Their abundance and nearly ubiquitous terrestrial distribution, their intricate interactions with host insects, and their historical association with mutualistic polydnaviruses have all contributed to Microgastrinae becoming a key group of organisms for studying parasitism, parasitoid genomics, and mating biology. However, these rich sources of data have not yet led to a robust genus-level classification of the group, and some taxonomic confusion persists as a result. We present the current status of understanding of the general biology, taxonomic history, diversity, geographical patterns, host relationships, and phylogeny of Microgastrinae as a stimulus and foundation for further study. Current progress in elucidating the biology and taxonomy of this important group is rapid and promises a revolution in the classification of these wasps in the near future.

Diversity of parasitoid and parasitic wasps across a latitudinal gradient: Using public DNA records to work within a taxonomic impediment

The diversity of insect parasitoids (Hymenoptera) has long been thought to be anomalous because it doesn’t appear to increase rapidly with decreasing latitude. However, due to the presence of undiscovered cryptic species and the under-sampling of hyper-diverse tropical areas, such apparently anomalous gradients may, in fact, be artifacts of limited geographic and taxonomic sampling. We attempted to circumvent such taxonomic impediments by elucidating a diversity/latitude relationship for parasitoid wasps, using publicly available DNA sequences to quantify diversity (via a species proxy molecular operational taxonomic unit (the DNA Barcode Index Number) and phylogenetic diversity) across a latitudinal gradient of ∼5000 km. We compared these diversity values to the abiotic factors (temperature and precipitation) that may drive the diversity/latitude relationship. We found no significant relationship between either diversity measure with latitude or with the environmental variables. Although ours is the first work to enumerate different DNA-based measures of parasitoid diversity across this geographic scale in a standardized fashion using publicly available sequences, further standardized collections over long time periods and a rapid movement of sequences into the public arena are needed to facilitate the further testing of macroecological trends elucidated with public DNA sequence libraries.

An annotated and illustrated checklist of Microgastrinae wasps (Hymenoptera, Braconidae) from the Canadian Arctic Archipelago and Greenland

The Microgastrinae (Hymenoptera: Braconidae) from ten islands of the Canadian Arctic Archipelago (CAA) and Greenland were studied based on 2,183 specimens deposited in collections. We report a total of 33 species in six genera, more than doubling the totals previously known. Most of the species (75.7%) have a distribution restricted to the Nearctic, with nine of those (27.3%) confirmed to be High Arctic endemics and another 10 species considered very likely to be High Arctic endemics as well – accounting for all of those, more than half of all species found are endemic to the region. The most diverse genera were Cotesia (10 species), Glyptapanteles (9 species), and Microplitis (7 species), representing 78.8% of the overall species diversity in the region. The six most frequently collected species comprised 84.7% of all examined specimens. The flight period for Microgastrinae in the High Arctic encompasses only two months, with activity peaking during the first half of July, when almost 40% of all available specimens were collected, and then plummeting in the first half to the end of August. Microgastrinae wasps from the High Arctic are currently known to parasitize eight species within four families of Lepidoptera: three species of Noctuidae, two each of Lymantridae and Nymphalidae, and one species of Pterophoridae. However, that information is very preliminary, as only six of the 33 species of microgastrines currently have associated host data. An annotated checklist, including photographs for 24 of the 33 species, is provided, as well as a key to all Microgastrinae genera present in the region.

A biodiversity hotspot for Microgastrinae (Hymenoptera, Braconidae) in North America: annotated species checklist for Ottawa, Canada

Microgastrinae wasps (Hymenoptera, Braconidae) from the city of Ottawa and its surroundings (a 50-km radius circle, ~7,800 km2) were studied based on 1,928 specimens collected between 1894 and 2010, and housed in the Canadian National Collection of Insects. A total of 158 species from 21 genera were identified, which is by far the highest number of species ever recorded for a locality in North America. An annotated checklist of species is provided.Choerasparasitellae(Bouché, 1834) andPholetesornanus(Reinhard, 1880) are recorded for the first time in the Nearctic (previously only known from the Palearctic region),Cotesiadepressa(Viereck, 1912) is recorded for the first time in Canada (previously only known from the United States), andCotesiahemileucae(Riley, 1881) andProtapantelesphlyctaeniae(Muesebeck, 1929) are recorded for the first time in the province of Ontario. In Ottawa the most diverse genera areCotesia,Apanteles,Microplitis,Pholetesor,Microgaster, andDolichogenidea, altogether comprising 77% of the species found in the area. A total of 73 species (46%) were represented by only one or two specimens, suggesting that the inventory for Ottawa is still relatively incomplete. Seasonal distribution showed several peaks of activity, in spring, summer, and early fall. That general pattern varied for individual species, with some showing a single peak of abundance either in the summer or towards the end of the season, others species attaining two peaks, in late spring and late summer, or in early summer and early fall, and yet others attaining up to three different peaks, in spring, summer and fall. At least 72 of the Microgastrinae species from Ottawa have been previously associated with 554 species of Lepidoptera as hosts – but those historical literature records are not always reliable and in many cases are based on data from areas beyond Ottawa. Thus, our knowledge of the associations between the 158 species of microgastrine parasitoids and the caterpillars of the 2,064 species of Lepidoptera recorded from Ottawa is still very incomplete.

A biodiversity hotspot for Microgastrinae (Hymenoptera, Braconidae) in North America: annotated species checklist for Ottawa, Canada

Microgastrinae wasps (Hymenoptera, Braconidae) from the city of Ottawa and its surroundings (a 50-km radius circle, ~7,800 km²) were studied based on 1,928 specimens collected between 1894 and 2010, and housed in the Canadian National Collection of Insects. A total of 158 species from 21 genera were identified, which is by far the highest number of species ever recorded for a locality in North America. An annotated checklist of species is provided. Choerasparasitellae (Bouché, 1834) and Pholetesornanus (Reinhard, 1880) are recorded for the first time in the Nearctic (previously only known from the Palearctic region), Cotesiadepressa (Viereck, 1912) is recorded for the first time in Canada (previously only known from the United States), and Cotesiahemileucae (Riley, 1881) and Protapantelesphlyctaeniae (Muesebeck, 1929) are recorded for the first time in the province of Ontario. In Ottawa the most diverse genera are Cotesia, Apanteles, Microplitis, Pholetesor, Microgaster, and Dolichogenidea, altogether comprising 77% of the species found in the area. A total of 73 species (46%) were represented by only one or two specimens, suggesting that the inventory for Ottawa is still relatively incomplete. Seasonal distribution showed several peaks of activity, in spring, summer, and early fall. That general pattern varied for individual species, with some showing a single peak of abundance either in the summer or towards the end of the season, others species attaining two peaks, in late spring and late summer, or in early summer and early fall, and yet others attaining up to three different peaks, in spring, summer and fall. At least 72 of the Microgastrinae species from Ottawa have been previously associated with 554 species of Lepidoptera as hosts – but those historical literature records are not always reliable and in many cases are based on data from areas beyond Ottawa. Thus, our knowledge of the associations between the 158 species of microgastrine parasitoids and the caterpillars of the 2,064 species of Lepidoptera recorded from Ottawa is still very incomplete.

Establishing a community-wide DNA barcode library as a new tool for arctic research

DNA sequences offer powerful tools for describing the members and interactions of natural communities. In this study, we establish the to-date most comprehensive library of DNA barcodes for a terrestrial site, including all known macroscopic animals and vascular plants of an intensively studied area of the High Arctic, the Zackenberg Valley in Northeast Greenland. To demonstrate its utility, we apply the library to identify nearly 20 000 arthropod individuals from two Malaise traps, each operated for two summers. Drawing on this material, we estimate the coverage of previous morphology-based species inventories, derive a snapshot of faunal turnover in space and time and describe the abundance and phenology of species in the rapidly changing arctic environment. Overall, 403 terrestrial animal and 160 vascular plant species were recorded by morphology-based techniques. DNA barcodes (CO1) offered high resolution in discriminating among the local animal taxa, with 92% of morphologically distinguishable taxa assigned to unique Barcode Index Numbers (BINs) and 93% to monophyletic clusters. For vascular plants, resolution was lower, with 54% of species forming monophyletic clusters based on barcode regions rbcLa and ITS2. Malaise catches revealed 122 BINs not detected by previous sampling and DNA barcoding. The insect community was dominated by a few highly abundant taxa. Even closely related taxa differed in phenology, emphasizing the need for species-level resolution when describing ongoing shifts in arctic communities and ecosystems. The DNA barcode library now established for Zackenberg offers new scope for such explorations, and for the detailed dissection of interspecific interactions throughout the community.

Influences of extreme weather, climate and pesticide use on invertebrates in cereal fields over 42 years

Cereal fields are central to balancing food production and environmental health in the face of climate change. Within them, invertebrates provide key ecosystem services. Using 42 years of monitoring data collected in southern England, we investigated the sensitivity and resilience of invertebrates in cereal fields to extreme weather events and examined the effect of long-term changes in temperature, rainfall and pesticide use on invertebrate abundance. Of the 26 invertebrate groups examined, eleven proved sensitive to extreme weather events. Average abundance increased in hot/dry years and decreased in cold/wet years for Araneae, Cicadellidae, adult Heteroptera, Thysanoptera, Braconidae, Enicmus and Lathridiidae. The average abundance of Delphacidae, Cryptophagidae and Mycetophilidae increased in both hot/dry and cold/wet years relative to other years. The abundance of all 10 groups usually returned to their long-term trend within a year after the extreme event. For five of them, sensitivity to cold/wet events was lowest (translating into higher abundances) at locations with a westerly aspect. Some long-term trends in invertebrate abundance correlated with temperature and rainfall, indicating that climate change may affect them. However, pesticide use was more important in explaining the trends, suggesting that reduced pesticide use would mitigate the effects of climate change.

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.

Comparison of five methods for delimitating species in Ophion Fabricius, a diverse genus of parasitoid wasps (Hymenoptera, Ichneumonidae)

DNA taxonomy has been proposed as a method to quickly assess diversity and species limits in highly diverse, understudied taxa. Here we use five methods for species delimitation and two genetic markers (COI and ITS2) to assess species diversity within the parasitoid genus, Ophion. We searched for compensatory base changes (CBC's) in ITS2, and determined that they are too rare to be of practical use in delimiting species in this genus. The other four methods used both COI and ITS2, and included distance-based (threshold analysis and ABGD) and tree-based (GMYC and PTP) models. We compared the results of these analyses to each other under various parameters and tested their performance with respect to 11 Nearctic species/morphospecies and 15 described Palearctic species. We also computed barcode accumulation curves of COI sequences to assess the completeness of sampling. The species count was highly variable depending on the method and parameters used, ranging from 47 to 168 species, with more conservative estimates of 89-121 species. Despite this range, many of the Nearctic test species were fairly robust with respect to method. We concluded that while there was often good congruence between methods, GMYC and PTP were less reliant on arbitrary parameters than the other two methods and more easily applied to genetic markers other than COI. However, PTP was less successful at delimiting test species than was GMYC. All methods, as well as the barcode accumulation curves, indicate that several Palearctic species remain undescribed and that we have scarcely begun to appreciate the Nearctic diversity within this genus.

A Linnaeus NG (TM) interactive key to the Lithocolletinae of North-West Europe aimed at accelerating the accumulation of reliable biodiversity data (Lepidoptera, Gracillariidae)

We present an interactive key that is available online through any web browser without the need to install any additional software, making it an easily accessible tool for the larger public. The key can be found at http://identify.naturalis.nl/lithocolletinae. The key includes all 86 North-West European Lithocolletinae, a subfamily of smaller moths (“micro-moths”) that is commonly not treated in field guides. The user can input data on several external morphological character systems in addition to distribution, host plant and even characteristics of the larval feeding traces to reach an identification. We expect that this will enable more people to contribute with reliable observation data on this group of moths and alleviate the workload of taxonomic specialists, allowing them to focus on other new keys or taxonomic work.

New records of Microgasterdeductor Nixon, 1968 (Hymenoptera: Braconidae: Microgastrinae) for the Holarctic region, with comments on its historical distribution

Four new localities for the species Microgasterdeductor Nixon (1968) are recorded from the Nearctic (Canada and the United States) and the Palaearctic (Sweden), expanding significantly the range of the species. Microgasterdeductor seems to be widely distributed in boreal areas of the Holarctic, and it is characterized by unique morphological (tarsal claw structure) and molecular (COI) traits. Preliminary evidence, to be corroborated when more data is available, suggests that the species might have shifted northwards between 1950 and the present day.

Review of Apanteles sensu stricto (Hymenoptera, Braconidae, Microgastrinae) from Area de Conservación Guanacaste, northwestern Costa Rica, with keys to all described species from Mesoamerica

More than half a million specimens of wild-caught Lepidoptera caterpillars have been reared for their parasitoids, identified, and DNA barcoded over a period of 34 years (and ongoing) from Area de Conservación de Guanacaste (ACG), northwestern Costa Rica. This provides the world's best location-based dataset for studying the taxonomy and host relationships of caterpillar parasitoids. Among Hymenoptera, Microgastrinae (Braconidae) is the most diverse and commonly encountered parasitoid subfamily, with many hundreds of species delineated to date, almost all undescribed. Here, we reassess the limits of the genus Apanteles sensu stricto, describe 186 new species from 3,200+ parasitized caterpillars of hundreds of ACG Lepidoptera species, and provide keys to all 205 described Apanteles from Mesoamerica - including 19 previously described species in addition to the new species. The Mesoamerican Apanteles are assigned to 32 species-groups, all but two of which are newly defined. Taxonomic keys are presented in two formats: traditional dichotomous print versions and links to electronic interactive versions (software Lucid 3.5). Numerous illustrations, computer-generated descriptions, distributional information, wasp biology, and DNA barcodes (where available) are presented for every species. All morphological terms are detailed and linked to the Hymenoptera Anatomy Ontology website. DNA barcodes (a standard fragment of the cytochrome c oxidase I (COI) mitochondrial gene), information on wasp biology (host records, solitary/gregariousness of wasp larvae), ratios of morphological features, and wasp microecological distributions were used to help clarify boundaries between morphologically cryptic species within species-complexes. Because of the high accuracy of host identification for about 80% of the wasp species studied, it was possible to analyze host relationships at a regional level. The ACG species of Apanteles attack mainly species of Hesperiidae, Elachistidae and Crambidae (Lepidoptera). About 90% of the wasp species with known host records seem to be monophagous or oligophagous at some level, parasitizing just one host family and commonly, just one species of caterpillar. Only 15 species (9%) parasitize species in more than one family, and some of these cases are likely to be found to be species complexes. We have used several information sources and techniques (traditional taxonomy, molecular, software-based, biology, and geography) to accelerate the process of finding and describing these new species in a hyperdiverse group such as Apanteles. The following new taxonomic and nomenclatural acts are proposed. Four species previously considered to be Apanteles are transferred to other microgastrine genera: Dolichogenidea hedyleptae (Muesebeck, 1958), comb. n., Dolichogenidea politiventris (Muesebeck, 1958), comb. n., Rhygoplitis sanctivincenti (Ashmead, 1900), comb. n., and Illidops scutellaris (Muesebeck, 1921), comb. rev. One European species that is a secondary homonym to a Mesoamerican species is removed from Apanteles and transferred to another genus: Iconella albinervis (Tobias, 1964), stat. rev. The name Apanteles albinervican Shenefelt, 1972, is an invalid replacement name for Apanteles albinervis (Cameron, 1904), stat. rev., and thus the later name is reinstated as valid. The following 186 species, all in Apanteles and all authored by Fernández-Triana, are described as species nova: adelinamoralesae, adrianachavarriae, adrianaguilarae, adrianguadamuzi, aichagirardae, aidalopezae, albanjimenezi, alejandromasisi, alejandromorai, minorcarmonai, alvarougaldei, federicomatarritai, anabellecordobae, rostermoragai, anamarencoae, anamartinesae, anapiedrae, anariasae, andreacalvoae, angelsolisi, arielopezi, bernardoespinozai, bernyapui, bettymarchenae, bienvenidachavarriae, calixtomoragai, carloscastilloi, carlosguadamuzi, eliethcantillanoae, carlosrodriguezi, carlosviquezi, carloszunigai, carolinacanoae, christianzunigai, cinthiabarrantesae, ciriloumanai, cristianalemani, cynthiacorderoae, deifiliadavilae, dickyui, didiguadamuzi, diegoalpizari, diegotorresi, diniamartinezae, duniagarciae, duvalierbricenoi, edgarjimenezi, edithlopezae, eduardoramirezi, edwinapui, eldarayae, erickduartei, esthercentenoae, eugeniaphilipsae, eulogiosequeira, felipechavarriai, felixcarmonai, fernandochavarriai, flormoralesae, franciscopizarroi, franciscoramirezi, freddyquesadai, freddysalazari, gabrielagutierrezae, garygibsoni, gerardobandoi, gerardosandovali, gladysrojasae, glenriverai, gloriasihezarae, guadaluperodriguezae, guillermopereirai, juanmatai, harryramirezi, hectorsolisi, humbertolopezi, inesolisae, irenecarrilloae, isaacbermudezi, isidrochaconi, isidrovillegasi, ivonnetranae, jairomoyai, javiercontrerasi, javierobandoi, javiersihezari, jesusbrenesi, jesusugaldei, jimmychevezi, johanvargasi, jorgecortesi, jorgehernandezi, josecalvoi, josecortesi, josediazi, josejaramilloi, josemonteroi, joseperezi, joserasi, juanapui, juancarrilloi, juangazoi, juanhernandezi, juanlopezi, juanvictori, juliodiazi, juniorlopezi, keineraragoni, laurahuberae, laurenmoralesae, leninguadamuzi, leonelgarayi, lilliammenae, lisabearssae, luciariosae, luisbrizuelai, luiscanalesi, luiscantillanoi, luisgarciai, luisgaritai, luishernandezi, luislopezi, luisvargasi, manuelarayai, manuelpereirai, manuelriosi, manuelzumbadoi, marcobustosi, marcogonzalezi, marcovenicioi, mariachavarriae mariaguevarae, marialuisariasae, mariamendezae, marianopereirai, mariatorrentesae, sigifredomarini, marisolarroyoae, marisolnavarroae, marvinmendozai, mauriciogurdiani, milenagutierrezae, monicachavarriae, oscarchavesi, osvaldoespinozai, pablotranai, pabloumanai, pablovasquezi, paulaixcamparijae, luzmariaromeroae, petronariosae, randallgarciai, randallmartinezi, raulacevedoi, raulsolorsanoi, wadyobandoi, ricardocaleroi, robertmontanoi, robertoespinozai, robertovargasi, rodrigogamezi, rogerblancoi, rolandoramosi, rolandovegai, ronaldcastroi, ronaldgutierrezi, ronaldmurilloi, ronaldnavarroi, ronaldquirosi, ronaldzunigai, rosibelelizondoae, ruthfrancoae, sergiocascantei, sergioriosi, tiboshartae, vannesabrenesae, minornavarroi, victorbarrantesi, waldymedinai, wilbertharayai, williamcamposi, yeissonchavesi, yilbertalvaradoi, yolandarojasae, hazelcambroneroae, zeneidabolanosae.

Spiders (Araneae) of Churchill, Manitoba: DNA barcodes and morphology reveal high species diversity and new Canadian records

BACKGROUND

Arctic ecosystems, especially those near transition zones, are expected to be strongly impacted by climate change. Because it is positioned on the ecotone between tundra and boreal forest, the Churchill area is a strategic locality for the analysis of shifts in faunal composition. This fact has motivated the effort to develop a comprehensive biodiversity inventory for the Churchill region by coupling DNA barcoding with morphological studies. The present study represents one element of this effort; it focuses on analysis of the spider fauna at Churchill.

RESULTS

198 species were detected among 2704 spiders analyzed, tripling the count for the Churchill region. Estimates of overall diversity suggest that another 10-20 species await detection. Most species displayed little intraspecific sequence variation (maximum <1%) in the barcode region of the cytochrome c oxidase subunit I (COI) gene, but four species showed considerably higher values (maximum = 4.1-6.2%), suggesting cryptic species. All recognized species possessed a distinct haplotype array at COI with nearest-neighbour interspecific distances averaging 8.57%. Three species new to Canada were detected: Robertus lyrifer (Theridiidae), Baryphyma trifrons (Linyphiidae), and Satilatlas monticola (Linyphiidae). The first two species may represent human-mediated introductions linked to the port in Churchill, but the other species represents a range extension from the USA. The first description of the female of S. monticola was also presented. As well, one probable new species of Alopecosa (Lycosidae) was recognized.

CONCLUSIONS

This study provides the first comprehensive DNA barcode reference library for the spider fauna of any region. Few cryptic species of spiders were detected, a result contrasting with the prevalence of undescribed species in several other terrestrial arthropod groups at Churchill. Because most (97.5%) sequence clusters at COI corresponded with a named taxon, DNA barcoding reliably identifies spiders in the Churchill fauna. The capacity of DNA barcoding to enable the identification of otherwise taxonomically ambiguous specimens (juveniles, females) also represents a major advance for future monitoring efforts on this group.

The diversity and biogeography of the Coleoptera of Churchill: insights from DNA barcoding

BACKGROUND

Coleoptera is the most diverse order of insects (>300,000 described species), but its richness diminishes at increasing latitudes (e.g., ca. 7400 species recorded in Canada), particularly of phytophagous and detritivorous species. However, incomplete sampling of northern habitats and a lack of taxonomic study of some families limits our understanding of biodiversity patterns in the Coleoptera. We conducted an intensive biodiversity survey from 2006-2010 at Churchill, Manitoba, Canada in order to quantify beetle species diversity in this model region, and to prepare a barcode library of beetles for sub-arctic biodiversity and ecological research. We employed DNA barcoding to provide estimates of provisional species diversity, including for families currently lacking taxonomic expertise, and to examine the guild structure, habitat distribution, and biogeography of beetles in the Churchill region.

RESULTS

We obtained DNA barcodes from 3203 specimens representing 302 species or provisional species (the latter quantitatively defined on the basis of Molecular Operational Taxonomic Units, MOTUs) in 31 families of Coleoptera. Of the 184 taxa identified to the level of a Linnaean species name, 170 (92.4%) corresponded to a single MOTU, four (2.2%) represented closely related sibling species pairs within a single MOTU, and ten (5.4%) were divided into two or more MOTUs suggestive of cryptic species. The most diverse families were the Dytiscidae (63 spp.), Staphylinidae (54 spp.), and Carabidae (52 spp.), although the accumulation curve for Staphylinidae suggests that considerable additional diversity remains to be sampled in this family. Most of the species present are predatory, with phytophagous, mycophagous, and saprophagous guilds being represented by fewer species. Most named species of Carabidae and Dytiscidae showed a significant bias toward open habitats (wet or dry). Forest habitats, particularly dry boreal forest, although limited in extent in the region, were undersampled.

CONCLUSIONS

We present an updated species list for this region as well as a species-level DNA barcode reference library. This resource will facilitate future work, such as biomonitoring and the study of the ecology and distribution of larvae.

Climate change and infectious diseases: from evidence to a predictive framework

Scientists have long predicted large-scale responses of infectious diseases to climate change, giving rise to a polarizing debate, especially concerning human pathogens for which socioeconomic drivers and control measures can limit the detection of climate-mediated changes. Climate change has already increased the occurrence of diseases in some natural and agricultural systems, but in many cases, outcomes depend on the form of climate change and details of the host-pathogen system. In this review, we highlight research progress and gaps that have emerged during the past decade and develop a predictive framework that integrates knowledge from ecophysiology and community ecology with modeling approaches. Future work must continue to anticipate and monitor pathogen biodiversity and disease trends in natural ecosystems and identify opportunities to mitigate the impacts of climate-driven disease emergence.

A review of the New World species of the parasitoid wasp Iconella (Hymenoptera, Braconidae, Microgastrinae)

The New World species of Iconella (Hymenoptera: Braconidae, Microgastrinae) are revised. Iconella andydeansi Fernández-Triana, sp. n., Iconella canadensis Fernández-Triana, sp. n., and Iconella jayjayrodriguezae Fernández-Triana, sp. n., are described as new. Iconella isolata (Muesebeck, 1955), stat. r., previously considered as a subspecies of Iconella etiellae (Viereck, 1911), is here elevated to species rank. All species have different, well defined geographic distributions and hosts. Taxonomic keys are presented in two formats: traditional dichotomous hardcopy versions and links to electronic interactive versions (software Lucid 3.5). Numerous illustrations, computer-generated descriptions, distributional information, host records (mostly Lepidoptera: Crambidae and Pyralidae), and DNA barcodes (where available) are presented for every species. Phylogenetic analyses of the barcoding region of COI indicate the possibility that Iconella is not monophyletic and that the New World species may not form a monophyletic group; more data is needed to resolve this issue.

Advancing the long view of ecological change in tundra systems. Introduction

Despite uncertainties related to sustained funding, ideological rivalries and the turnover of research personnel, long-term studies and studies espousing a long-term perspective in ecology have a history of contributing landmark insights into fundamental topics, such as population- and community dynamics, species interactions and ecosystem function. They also have the potential to reveal surprises related to unforeseen events and non-stationary dynamics that unfold over the course of ongoing observation and experimentation. The unprecedented rate and magnitude of current and expected abiotic changes in tundra environments calls for a synthetic overview of the scope of ecological responses these changes have elicited. In this special issue, we present a series of contributions that advance the long view of ecological change in tundra systems, either through sustained long-term research, or through retrospective or prospective modelling. Beyond highlighting the value of long-term research in tundra systems, the insights derived herein should also find application to the study of ecological responses to environmental change in other biomes as well.

Indirect interactions in the High Arctic

Indirect interactions as mediated by higher and lower trophic levels have been advanced as key forces structuring herbivorous arthropod communities around the globe. Here, we present a first quantification of the interaction structure of a herbivore-centered food web from the High Arctic. Targeting the Lepidoptera of Northeast Greenland, we introduce generalized overlap indices as a novel tool for comparing different types of indirect interactions. First, we quantify the scope for top-down-up interactions as the probability that a herbivore attacking plant species i itself fed as a larva on species j. Second, we gauge this herbivore overlap against the potential for bottom-up-down interactions, quantified as the probability that a parasitoid attacking herbivore species i itself developed as a larva on species j. Third, we assess the impact of interactions with other food web modules, by extending the core web around the key herbivore Sympistis nigrita to other predator guilds (birds and spiders). We find the host specificity of both herbivores and parasitoids to be variable, with broad generalists occurring in both trophic layers. Indirect links through shared resources and through shared natural enemies both emerge as forces with a potential for shaping the herbivore community. The structure of the host-parasitoid submodule of the food web suggests scope for classic apparent competition. Yet, based on predation experiments, we estimate that birds kill as many (8%) larvae of S. nigrita as do parasitoids (8%), and that spiders kill many more (38%). Interactions between these predator guilds may result in further complexities. Our results caution against broad generalizations from studies of limited food web modules, and show the potential for interactions within and between guilds of extended webs. They also add a data point from the northernmost insect communities on Earth, and describe the baseline structure of a food web facing imminent climate change.

DNA barcoding reveals diversity of Hymenoptera and the dominance of parasitoids in a sub-arctic environment

Background

Insect diversity typically declines with increasing latitude, but previous studies have shown conflicting latitude-richness gradients for some hymenopteran parasitoids. However, historical estimates of insect diversity and species richness can be difficult to confirm or compare, because they may be based upon dissimilar methods. As a proxy for species identification, we used DNA barcoding to identify molecular operational taxonomic units (MOTUs) for 7870 Hymenoptera specimens collected near Churchill, Manitoba, from 2004 through 2010.

Results

We resolved 1630 MOTUs for this collection, of which 75% (1228) were ichneumonoids (Ichneumonidae + Braconidae) and 91% (1484) were parasitoids. We estimate the total number of Hymenoptera MOTUs in this region at 2624-2840.

Conclusions

The diversity of parasitoids in this sub-Arctic environment implies a high diversity of potential host species throughout the same range. We discuss these results in the contexts of resolving interspecific interactions that may include cryptic species, and developing reproducible methods to estimate and compare species richness across sites and between surveys, especially when morphological specialists are not available to identify every specimen.

More than just records: analysing natural history collections for biodiversity planning

Natural History Collections (NHCs) play a central role as sources of data for biodiversity and conservation. Yet, few NHCs have examined whether the data they contain is adequately representative of local biodiversity. I examined over 15,000 databased records of Hymenoptera from 1435 locations across New Zealand collected over the past 90 years. These records are assessed in terms of their geographical, temporal, and environmental coverage across New Zealand. Results showed that the spatial coverage of records was significantly biased, with the top four areas contributing over 51% of all records. Temporal biases were also evident, with a large proportion (40%) of records collected within a short time period. The lack of repeat visits to specific locations indicated that the current set of NHC records would be of limited use for long-term ecological research. Consequently, analyses and interpretation of historical data, for example, shifts in community composition, would be limited. However, in general, NHC records provided good coverage of the diversity of New Zealand habitats and climatic environments, although fewer NHC records were represented at cooler temperatures (<5°C) and the highest rainfalls (>5000 mm/yr). Analyses of NHCs can be greatly enhanced by using simple techniques that examine collection records in terms of environmental and geographical space. NHCs that initiate a systematic sampling strategy will provide higher quality data for biodiversity research than ad hoc or point samples, as is currently the norm. Although NHCs provide a rich source of information they could be far better utilised in a range of large-scale ecological and conservation studies.

Unprecedented ichneumonid parasitoid wasp diversity in tropical forests

The megadiverse parasitoid wasp family Ichneumonidae (Hymenoptera) is classically considered an exception to the extensively studied latitudinal diversity gradient: the majority of ichneumonid species are described from temperate regions. The gradient has been hypothesized to be dependent on the biology of the wasps, but recently questions of sampling and description biases have been raised. Here, we show with primary data that the species richness of Ichneumonidae is markedly underestimated in tropical areas and that latitudinal diversity patterns in the family remain uncharacterized. We discovered a startling 177 likely undescribed orthocentrine species with relatively low sampling effort in the forests of Central America and Amazonian Ecuador, over three times the previously known orthocentrine diversity in the world's tropics. Species accumulation curves reveal that we are just beginning to unveil the true extent of tropical orthocentrine diversity. We also found evidence for cryptic species; our DNA analysis revealed additional species not easily distinguishable using morphological characteristics. The difficulty in establishing species richness patterns of Ichneumonidae probably follows from the relative lack of taxonomic expertise and the low density of ichneumonid species throughout the landscape.

Wolbachia and DNA barcoding insects: patterns, potential, and problems

Wolbachia is a genus of bacterial endosymbionts that impacts the breeding systems of their hosts. Wolbachia can confuse the patterns of mitochondrial variation, including DNA barcodes, because it influences the pathways through which mitochondria are inherited. We examined the extent to which these endosymbionts are detected in routine DNA barcoding, assessed their impact upon the insect sequence divergence and identification accuracy, and considered the variation present in Wolbachia COI. Using both standard PCR assays (Wolbachia surface coding protein – wsp), and bacterial COI fragments we found evidence of Wolbachia in insect total genomic extracts created for DNA barcoding library construction. When >2 million insect COI trace files were examined on the Barcode of Life Datasystem (BOLD) Wolbachia COI was present in 0.16% of the cases. It is possible to generate Wolbachia COI using standard insect primers; however, that amplicon was never confused with the COI of the host. Wolbachia alleles recovered were predominantly Supergroup A and were broadly distributed geographically and phylogenetically. We conclude that the presence of the Wolbachia DNA in total genomic extracts made from insects is unlikely to compromise the accuracy of the DNA barcode library; in fact, the ability to query this DNA library (the database and the extracts) for endosymbionts is one of the ancillary benefits of such a large scale endeavor – for which we provide several examples. It is our conclusion that regular assays for Wolbachia presence and type can, and should, be adopted by large scale insect barcoding initiatives. While COI is one of the five multi-locus sequence typing (MLST) genes used for categorizing Wolbachia, there is limited overlap with the eukaryotic DNA barcode region.