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Highlights • Microplastics affected the toxicity of chlorpyrifos to two soil arthropod species. fibers. • Chlorpyrifos lethality to arthropods decreased by tire particles but not by • Fibers and tire particles affected chlorpyrifos-induced biomarker changes in woodlice. • Tire particles changed chlorpyrifos effects on woodlice more than polyester fibers. • Microplastics did not affect chlorpyrifos toxicity to springtail reproduction. Abstract Synthetic fibers released from sewage sludge and tire particles released from traffic are among the most common types of microplastics in soil. In soil, microplastics may interact with chemicals, such as plant protection products used in agriculture. Most studies on the interactions of microplastics and chemicals focused on aquatic environments and only few addressed soil arthropods. To increase the understanding of the combined effects of microplastics and chemicals on soil arthropods, we studied the effects of polyester fibers and tire particles on the toxicity of the insecticide chlorpyrifos. Springtails (Folsomia candida) and woodlice (Porcellio scaber) were exposed in Lufa 2.2 soil to a range of chlorpyrifos concentrations (0.0088–0.8 and 0.2–3.9 mg kg−1 dry soil, respectively) without or with 0.05 % w/w (“low”) or 0.5 % w/w (“high”) of microplastics. Tire particles reduced the lethality of chlorpyrifos to springtails (LC50 = 0.13–0.14 mg kg−1 dry soil) and isopods (LC50 = 1.6 mg kg−1 dry soil) by a factor of 2- > 2.5 and the chlorpyrifos-induced inhibition of acetylcholinesterase (AChE) activity and changes in electron transfer system (ETS) activity in P. scaber by a factor of 2–4. Polyester fibers reduced the chlorpyrifos-induced inhibition of AChE activity by a factor of 2 and increased (ETS) activity in P. scaber by a factor of >3. The fibers did not affect the toxicity of chlorpyrifos to the survival of P. scaber or the survival and reproduction of F. candida. These results indicate that the bioavailability of chlorpyrifos may be decreased by microplastics, especially by tire particles. This study shows the importance of applying a mixture toxicity approach for understanding the threats of microplastics to soil, but also suggests that the organism and the endpoints chosen are crucial for the interpretation of the effects of combined exposures to microplastics and chemicals.

Interactions among fungi and insects involve hundreds of thousands of species. While insect communities on plants have formed some of the classic model systems in ecology, fungus-based communities and the forces structuring them remain poorly studied by comparison. We characterize the arthropod communities associated with fruiting bodies of eight mycorrhizal basidiomycete fungus species from three different orders along a 1200-km latitudinal gradient in northern Europe. We hypothesized that, matching the pattern seen for most insect taxa on plants, we would observe a general decrease in fungal-associated species with latitude. Against this backdrop, we expected local communities to be structured by host identity and phylogeny, with more closely related fungal species sharing more similar communities of associated organisms. As a more unique dimension added by the ephemeral nature of fungal fruiting bodies, we expected further imprints generated by successional change, with younger fruiting bodies harboring communities different from older ones. Using DNA metabarcoding to identify arthropod communities from fungal fruiting bodies, we found that latitude left a clear imprint on fungus-associated arthropod community composition, with host phylogeny and decay stage of fruiting bodies leaving lesser but still-detectable effects. The main latitudinal imprint was on a high arthropod species turnover, with no detectable pattern in overall species richness. Overall, these findings paint a new picture of the drivers of fungus-associated arthropod communities, suggesting that latitude will not affect how many arthropod species inhabit a fruiting body but, rather, what species will occur in it and at what relative abundances (as measured by sequence read counts). These patterns upset simplistic predictions regarding latitudinal gradients in species richness and in the strength of biotic interactions.

Species interactions are known to structure ecological communities. Still, the influence of climate change on biodiversity has primarily been evaluated by correlating individual species distributions with local climatic descriptors, then extrapolating into future climate scenarios. We ask whether predictions on arctic arthropod response to climate change can be improved by accounting for species interactions. For this, we use a 14-year-long, weekly time series from Greenland, resolved to the species level by mitogenome mapping. During the study period, temperature increased by 2 degrees C and arthropod species richness halved. We show that with abiotic variables alone, we are essentially unable to predict species responses, but with species interactions included, the predictive power of the models improves considerably. Cascading trophic effects thereby emerge as important in structuring biodiversity response to climate change. Given the need to scale up from species-level to community-level projections of biodiversity change, these results represent a major step forward for predictive ecology.

Monitoring of arthropods focuses typically on changes in population and range size over time. Yet, there are a myriad of other aspects that could and should be monitored under the ongoing global and local environmental change. Stable isotope analysis, widely employed in short-term ecological studies, has potential in long-term monitoring of arthropods. Here we discuss the use of stable isotopes in monitoring terrestrial arthropods, provide some empirical examples of the use of bulk tissue samples in stable isotope analysis, and outline future directions in using compound-specific stable isotope analysis in monitoring. We performed a literature search for 2012–2021 to see if stable isotopes have been specifically used in monitoring of terrestrial arthropods. The literature shows that stable isotopes have been successfully used to reveal ecological phenomena (dispersal, trophic interactions, resource use) that would have been difficult or impossible to detect by other means. Yet, stable isotopes have been underused in arthropod monitoring programs, but the growing number of basic studies on stable isotope ecology and methodology provides crucial basis needed for developing monitoring programs. Stable isotopes provide technically, economically and ecologically feasible addition to the traditional monitoring methods of terrestrial arthropods. peerReviewed

Publisher Copyright: © 2021 The Authors. Molecular Ecology Resources published by John Wiley & Sons Ltd. To associate specimens identified by molecular characters to other biological knowledge, we need reference sequences annotated by Linnaean taxonomy. In this study, we (1) report the creation of a comprehensive reference library of DNA barcodes for the arthropods of an entire country (Finland), (2) publish this library, and (3) deliver a new identification tool for insects and spiders, as based on this resource. The reference library contains mtDNA COI barcodes for 11,275 (43%) of 26,437 arthropod species known from Finland, including 10,811 (45%) of 23,956 insect species. To quantify the improvement in identification accuracy enabled by the current reference library, we ran 1000 Finnish insect and spider species through the Barcode of Life Data system (BOLD) identification engine. Of these, 91% were correctly assigned to a unique species when compared to the new reference library alone, 85% were correctly identified when compared to BOLD with the new material included, and 75% with the new material excluded. To capitalize on this resource, we used the new reference material to train a probabilistic taxonomic assignment tool, FinPROTAX, scoring high success. For the full-length barcode region, the accuracy of taxonomic assignments at the level of classes, orders, families, subfamilies, tribes, genera, and species reached 99.9%, 99.9%, 99.8%, 99.7%, 99.4%, 96.8%, and 88.5%, respectively. The FinBOL arthropod reference library and FinPROTAX are available through the Finnish Biodiversity Information Facility (www.laji.fi) at https://laji.fi/en/theme/protax. Overall, the FinBOL investment represents a massive capacity-transfer from the taxonomic community of Finland to all sectors of society.

Merkittävä osa kasvien yhteyttämästä hiilestä päätyy maan alle joko kasvibiomassana, symbionttisten sienten biomassana tai juurten erittäminä hiiliyhdisteinä. Maaperäeläimille ja mikrobeille juurista maahan erittyneet hiiliyhdisteet ovat tärkeä energianlähde. Puiden juurieritys vaikuttaa siten myös maaperän eliöyhteisön rakenteeseen ja sitä kautta mahdollisesti kaikkiin maaperän mikrobiologisiin prosesseihin. Tässä tutkimuksessa selvitettiin kuinka puiden juurierityksen estäminen vaikuttaa maaperäeläimien runsauteen sekä tiettyihin maaperän ominaisuuksiin. Tutkimusalueena oli suomalainen mäntymetsä, johon oli perustettu koealoja, joissa luonnollisia ravinne- ja energiavirtoja oli manipuloitu eristämällä koealat maaperään asetetuilla verkoilla. Näitä ns. trenching-käsittelyjä oli kaikkiaan kolme: 1) kontrollina toimivat koealat oli jätetty eristämättä ympäristöstä, 2) 50 μm silmäkoon verkko eristi koealat ympäröivästä maaperästä muilta paitsi sienijuurilta ja sienirihmalta sekä 3) 1 μm silmäkoon verkolla eristettyihin koealoihin eivät kasvien juuret, sienijuuret eivätkä sienirihmat päässeet koealan ympäriltä. Koealoilta kerättiin maaperäkairalla maanäytteitä kesällä ja syksyllä 2016, ja niistä eroteltiin maaperäeläimiä. Tutkimuskohteina olivat änkyrimadot (Enchytraeidae), sukkulamadot (Nematoda) sekä mikroniveljalkaiset (Arthropoda), esimerkiksi punkit (Acari) ja hyppyhäntäiset (Collembola). Koealoilta selvitettiin myös maaperän ominaisuuksista pH, kosteus ja orgaanisen aineen määrä. Änkyri- ja sukkulamatojen sekä mikroniveljalkaisten runsaudessa ei ollut eroja käsittelyjen välillä, mutta änkyrimatoja ja eräitä mikroniveljalkaisia oli syksyllä enemmän. Koealat oli eristetty ympäröivästä maaperästä 3 vuotta ennen maaperänäytteiden ottamista, joten koealojen pintakasvillisuus oli mahdollisesti kompensoinut puiden juurien erittämän hiilisyötteen, ja koealoille jääneet puiden juuret olivat hajotessaan tuottaneet maaperäeläimille ravintoresurssin, joka vaikutti maaperäeläinten runsauteen. Significant part of the carbon allocated by forest trees ends up in the soil as biomass of plant or symbiotic fungi, or as excretion by the roots. Carbon, which is allocated belowground is a major energy source for the soil fauna and microbes. Therefore, the carbon allocation of the forest trees affects soil organism community structure and thereby all microbiological processes in the soil. In this study, the effects of exlusion of tree roots exudation on specific soil properties and abundance of soil animals was examined. The study was performed in a Scots pine (Pinus sylvestris) stand in central Finland where several different plots were established and where the natural nutrient and energy flows were manipulated by trenching. The study included three different treatments: control plots left intact and two differently trenched plots, in which soil had been trenched either with 50 μm or 1 μm nets to ca. 40 cm depth belowground. 50 μm net allowed fungi to enter the plot and 1 μm net excluded both fungal hyphae and roots. Data of this study was collected twice during the growing season 2016, in the summer and in the autumn. Soil samples were taken with soil corer and soil animals, enchytraeids (Enchytraeidae), nematodes (Nematoda) and microarthropods (Arthropoda), mainly mites (Acari) and springtails (Collembola), were extracted from the samples and soil properties (pH, moisture and organic matter contents) were measured. The trenching treatment did not affect the abundance of enchytraeids, nematodes or microarthropods nor the soil properties. The abundances of enchytraeids and some microarthropods were higher in the autumn than in the summer. The plots were established 3 years before the sampling and thus the ground vegetation may have compensated the carbon excreted by the trees or the dead roots of the trees left in the soil could have offered resources for the soil animals, and therefore, affected the abundance of the soil fauna.

Large scale photovoltaic (PV) solar power plants are gaining popularity in Chile. Solar energy potential in northern Chile is one of the best worldwide and true deserts are considered ideal environments for solar power plant projects. Atacama Desert is one of the driest places on earth. Nevertheless, northern Chile is home for many endemic species with 40 different vegetation types. The thesis presents studies of ecological effects (I-II) and location optimization of PV solar power plants in northern Chile (III). For ecological impacts two types of PV solar power plant technologies were studied: fixed mount solar plant and solar- tracking mounts. Study units were placed below the mounts or between the panels. Reference area was outside the panel area. Arthropod species composition was altered between shade and sun conditions at fixed mount power plant and, for example, dipterans were more common in shade conditions. Fixed mount solar power plants’ shade conditions can act as refuge to some arthropod groups, but for vegetation, shade conditions can disturb their florescence. Abiotic conditions limited local spider species habitat selection, but invasive spider species Lactrodectus geometricus could colonize mount legs of entire plant. Precaution should be taken when planning PV projects in areas with sensitive nature. Northern Chile is an ideal place for solar power plant projects because of its high solar energy potential but environmental and social aspects of site selection should be considered. Ideal places with low environmental and landscape value are in the absolute desert situated in the central valley starting from Arica and reaching until the northern part of Atacama region. Nevertheless, cities and historical sites should be avoided. The results of this thesis provide new information about ecological environment of PV plants and gives alternatives to multidisciplinary site selection.

FM Minna-Liisa Rantalainen osoittaa väitöskirjatyössään, että metsämaaperän eliöyhteisöt sietävät suhteellisen hyvin elinympäristönsä pirstaloitumista. Yhtenä harvoista aiheesta tehdyistä tutkimuksista työ luo myös pohjaa mallille siitä, miten maaperäeliöillä saatuja tuloksia voidaan hyödyntää, kun halutaan ennustaa luonnonsuojelun kannalta tärkeiden eliöiden selviytymismahdollisuuksia elinympäristön pirstaloituessa.Yhtenäisen elinympäristön pirstaloitumisen pienemmiksi saarekkeiksi tiedetään johtavan lajien häviämisiin ja/tai pienempiin populaatioihin. Maaperän hajottajaeliöyhteisön vasteita pirstaloitumiseen on aiemmin tutkittu varsin vähän. Tämä on yllättävää, koska hajottajilla on tärkeä merkitys maaperän toiminnassa ja viime kädessä metsän kasvussa.Rantalaisen tutkimukset osoittavat, että kokonaisuutena maaperän eliöyhteisöt sietävät suhteellisen hyvin pirstaloitumisesta aiheutuvia elinympäristön muutoksia: kokeissa luoduista maaperäpirstaleista hävisi vain vähän lajeja. Aiemmissa tutkimuksissa on todettu maaperän eliöiden sietävän hyvin erilaisten metsänkäsittelytoimenpiteiden aiheuttamia muutoksia elinympäristössään. Rantalaisen tulokset viittaavat siihen, ettei elinympäristön pirstaloituminenkaan ole vakava uhka maaperän monimuotoisuudelle eikä siten hajottajayhteisön toiminnalle. On kuitenkin huomattava, että tämä tulos koskee maaperän erityisoloissa eläviä eliöyhteisöjä, eikä sen perusteella voi suoraviivaisesti ennustaa muiden, toisenlaisiin olosuhteisiin sopeutuneiden eliöyhteisöjen herkkyyttä pirstaloitumiselle.Tutkimuksissa saatiin kuitenkin selkeitä viitteitä siitä, että eräät harvinaiset ja vähälukuiset hyppyhäntäislajit kärsivät pirstaloitumisesta. Lisäksi tutkittujen maaperän huippupedot, kuten petopunkit, osoittautuivat herkemmiksi elinympäristön pienelle koolle kuin muut maaperäeliöt. Useat aiemmat kokeet maanpäällisissä eliöyhteisöissä ovat osoittaneet harvinaisten ja korkealla ravintoketjussa olevien eliöiden olevan erityisen herkkiä elinympäristön pirstaloitumiselle. The objectives of this thesis were (i) to experimentally investigate the effects of habitat fragmentation on soil decomposers, and (ii) to examine whether such studies of soil decomposer communities can be used as a tool to provide generally applicable information on the consequences of habitat fragmentation. Special emphasis was put on testing the utility of habitat corridors in mitigating the expected negative effects of fragmentation.The experiments were conducted both in the laboratory and in the field. The results show that the soil decomposer organisms are, in general, relatively insensitive to habitat fragmentation. However, some predatory and rare, non-predatory microarthropod species were an exception to this rule, being negatively affected by restricted habitat size.The functioning of corridors in alleviating fragmentation-induced effects was practically undetected. Despite this, corridors were shown to facilitate the colonisation of new habitats by both soil fauna and microbes, suggesting that the corridors may benefit a whole community instead of only one or a few species. It was also shown that resource quality is a fundamental factor in determining the abundance of soil decomposers in fragmented habitats. The present studies were novel in the sense that they investigated the responses of a wide variety of organisms, from basal resources to top predators.Although it is unlikely that the results can be straightforwardly extrapolated to larger scales, they nevertheless suggest that not all communities, and species therein, unanimously suffer from habitat fragmentation. On the other hand, the fragmentation responses of soil microarthropods may not differ that much from those of aboveground organisms operating at larger scales. The results of this thesis support the applicability of studying soil food webs as a tool for solving questions related to both applied and theoretical ecology.