Hans Petter Leinaas

• Konestabo, Heidi Sjursen; Leinaas, Hans Petter; Gestel, Cornelis A.M. van & Borgå, Katrine (2026). Prior pesticide exposure reduces drought tolerance in Arctic and temperate springtails—Effects of sequential stressors. Environmental Toxicology and Chemistry. ISSN 0730-7268. 45(6), s. 1460–1469. doi: 10.1093/etojnl/vgag046. Fulltekst i vitenarkiv
• Kristiansen, Silje Marie; Leinaas, Hans Petter; Gestel, Cornelis A.M. van & Borgå, Katrine (2024). Thermal adaptation affects the temperature-dependent toxicity of the insecticide imidacloprid to soil invertebrates. Science of the Total Environment. ISSN 0048-9697. 944. doi: 10.1016/j.scitotenv.2024.173845. Fulltekst i vitenarkiv Vis sammendrag

  Terrestrial ectotherms are vulnerable to climate change since their biological rates depend on the ambient temperature. As temperature may interact with toxicant exposure, climate change may cause unpredictable responses to toxic stress. A population's thermal adaptation will impact its response to temperature change, but also to interactive effects from temperature and toxicants, but these effects are still not fully understood. Here, we assessed the combined effects of exposure to the insecticide imidacloprid across the temperatures 10–25 °C of two populations of the Collembola Hypogastrura viatica (Tullberg, 1872), by determining their responses in multiple life history traits. The con-specific populations differ considerably in thermal adaptations; one (arctic) is a temperature generalist, while the other (temperate) is a warm-adapted specialist. For both populations, the sub-lethal concentrations of imidacloprid became lethal with increasing temperature. Although the thermal maximum is higher for the warm-adapted population, the reduction in survival was stronger. Growth was reduced by imidacloprid in a temperature-dependent manner, but only at the adult life stage. The decrease in adult body size combined with the absence of an effect on the age at first reproduction suggests a selection on the timing of maturation. Egg production was reduced by imidacloprid in both populations, but the negative effect was only dependent on temperature in the warm-adapted population, with no effect at 10 °C, and decreases of 41 % at 15 °C, and 74 % at 20 °C. For several key traits, the population best adapted to utilize high temperatures was also the most sensitive to toxic stress at higher temperatures. It could be that by allocating more energy to faster growth, development, and reproduction at higher temperatures, the population had less energy for maintenance, making it more sensitive to toxic stress. Our findings demonstrate the need to take into account a population's thermal adaptation when assessing the interactive effects between temperature and other stressors.

• Möllerke, Anton; Vidal, Diogo Montes; Leinaas, Hans Petter & Schulz, Stefan (2024). Socialane, a Nonaprenyl Terpene Hydrocarbon Surface Lipid from the Collembola Hypogastrura socialis. Chemistry - A European Journal. ISSN 0947-6539. 30(27). doi: 10.1002/chem.202400272. Fulltekst i vitenarkiv Vis sammendrag

  Springtails use unique compounds for their outermost epicuticular wax layer, often of terpenoid origin. We report here the structure and synthesis of socialane, the major cuticular constituent of the Collembola Hypogastrura socialis. Socialane is also the first regular nonaprenyl terpene with a cyclic head group. The saturated side chain has seven stereogenic centers, making the determination of the configuration difficult. We describe here the identification of socialane and a synthetic approach using the building blocks farnesol and phytol, enantioselective hydrogenation, and α-alkylation of sulfones for the synthesis of various stereoisomers. NMR experiments showed the presence of an anti-configuration of the methyl groups closest to the benzene ring and that the other methyl groups of the polyprenyl side-chain are not uniformly configured. Furthermore, socialane is structurally different from [6+2]-terpene viaticene of the closely related H. viatica, showing species specificity of the epicuticular lipids of this genus and hinting at a possible role of surface lipids in the communication of these gregarious arthropods.

• Möllerke, Anton; Brasse, Gregor; Bello, Jan; Vidal, Diogo Montes; Dettner, Konrad & Zettel, Jürg [Vis alle 10 forfattere av denne artikkelen] (2024). The unique epicuticular chemistry of Collembola – A cross-species analysis. iScience. 27(8). doi: 10.1016/j.isci.2024.110416. Fulltekst i vitenarkiv Vis sammendrag

  Springtails (Collembola), tiny hexapod arthropods, are abundant in the soil of most ecosystems, but our knowledge of their secondary metabolites is limited, in contrast to that of insects. In insects, the outer cuticle is usually covered by mixtures of long-chain hydrocarbons serving different functions, such as water regulation or chemical communication. In contrast, the knowledge of the epicuticular chemistry of springtails is scarce. We analyzed the cuticular lipids of 23 species covering different lineages. The often complicated structures were elucidated using gas chromatography/mass spectrometry, microderivatization, and synthesis. In contrast to insects, the terpene biosynthetic pathway is used for many of these lipids, producing unprecedented higher terpenes. In addition, evidence for de novo cholesterol biosynthesis in springtails was found, which is absent in insects. Finally, diverse non-insect linear compounds originating from the fatty acid biosynthetic pathway were identified. Our comparative analysis showed clear differences compared to insects and shed light on phylogenetic relationships.

• Sengupta, Sagnik & Leinaas, Hans Petter (2024). Phenotypic plasticity and thermal efficiency of temperature responses in two conspecific springtail populations from contrasting climates. Journal of Thermal Biology. ISSN 0306-4565. 123, s. 1–10. doi: 10.1016/j.jtherbio.2024.103914. Fulltekst i vitenarkiv Vis sammendrag

  Temperature drives adaptation in life-history traits through direct effects on physiological processes. However, multiple life-history traits co-evolve as a life-history strategy. Therefore, physiological limitations constraining the evolution of trait means and phenotypic plasticity can be larger for some traits than the others. Comparisons of thermal responses across life-history traits can improve our understanding of the mechanisms determining the life-history strategies. In the present study, we focused on a soil microarthropod species abundant across the Northern Hemisphere, Folsomia quadrioculata (Collembola), with previously known effects of macroclimate. We selected an arctic and a temperate population from areas with highly contrasting climates — the arctic tundra and a coniferous forest floor, respectively — and compared them for thermal plasticity and thermal efficiency in growth, development, fecundity, and survival across four temperatures for a major part of their life cycle. We intended to understand the mechanisms by which temperature drives the evolution of life-history strategies. We found that the temperate population maximized performance at 10–15 °C, whereas the arctic population maintained its thermal efficiency across a wider temperature range (10–20 °C). Thermal plasticity varied in a trait-specific manner, and when considered together with differences in thermal efficiency, indicated that stochasticity in temperature conditions may be important in shaping the life-history strategies. Our study suggests that adopting a whole-organism approach and including physiological time considerations while analysing thermal adaptation will markedly improve our understanding of plausible links between thermal adaptation and responses to global climate change.

• Möllerke, Anton; Stell, Matthew; Schlawis, Christian; Trauer-Kizilelma, Ute; Herrmann, Jennifer & Leinaas, Hans Petter [Vis alle 8 forfattere av denne artikkelen] (2024). Identification of unique highly hetero-substituted benzenes as chemical weapons of springtails by a combination of trace analytical methods with DFT calculations and synthesis. Chemical Science. ISSN 2041-6520. 15, s. 15332–15338. doi: 10.1039/d4sc03182b. Fulltekst i vitenarkiv Vis sammendrag

  Springtails (Collembola) are important members of the soil mesofauna. They are small, often less than 1–2 mm in length. A typical escape response of most surface-living species is to jump, using their furca. However, some species also use chemical defence against predators. While the defence chemistry of higher insects has been well studied, reports from the basal Collembola are rare, linked to the difficulties in obtaining enough biomass. We herein report on the identification and repellent activity of compounds detected in Ceratophysella denticulata. Extracts with various solvents obtained from only 50 individuals were sufficient for analysis by GC/MS, GC/HR-MS, and GC/IR. The large number of candidate structures of the major components were then prioritised by DFT calculations of IR spectra. Finally, the total synthesis of the top candidates confirmed the structures of the three major compounds to be 4-methoxy-5-(methylthio)benzo-1,3-dioxolane, 5,6,7-trimethoxybenzo-1,3-oxathiolane, and 8-amino-5,6,7-trimethoxybenzo-1,3-oxathiolane, the latter being the first naturally occurring fully hetero-substituted benzene. These highly substituted benzenes have no precedence in nature and carry structural motifs rare in nature, such as the benzo-1,3-oxathiolane ring system or the occurrence of O-, N-, and S-substituents at the same benzene core. Another novel natural compound, 2-methyl-1H-imidazo[4,5-b]pyridine, is used by Hypogastrura viatica. 4-Methoxy-5-(methylthio)benzo-1,3-dioxolane showed significant activity in deterrence assays with the ant Lasius niger. The data indicate that the title compounds are used in the chemical defence of these springtails, thus adding a new compound class to the known antipredator defences of arthropods. The results underline the difference in defence chemistry between Collembola and insects.

• Möllerke, Anton; Bello, Jan; Leinaas, Hans Petter & Schulz, Stefan (2023). Cyclopropane Hydrocarbons from the Springtail Vertagopus sarekensis─A New Class of Cuticular Lipids from Arthropods. Journal of natural products. ISSN 0163-3864. 87(1), s. 85–97. doi: 10.1021/acs.jnatprod.3c00789. Fulltekst i vitenarkiv Vis sammendrag

  The epicuticle of insects is usually coated with a complex mixture of hydrocarbons, primarily straight-chain and methyl-branched alkanes and alkenes. We were interested in whether springtails (Collembola), a sister class of the insects, also use such compounds. We focused here on Vertagopus sarekensis, an abundant Isotomidae species in European high alpine regions, exhibiting coordinated group behavior and migration. This coordination, suggesting chemical communication, made the species interesting for our study on epicuticular hydrocarbons in springtails with different degrees of group behavior. We isolated a single hydrocarbon from its surface, which is the major epicuticular lipid. The structure was deduced by NMR analysis and GC/MS including derivatization. Total synthesis confirmed the structure as cis,cis-3,4,13,14-bismethylene-24-methyldotriacontane (4, sarekensane). The GC/MS analyses of some other cyclopropane hydrocarbons also synthesized showed the close similarity of both mass spectra and gas chromatographic retention indices of alkenes and cyclopropanes. Therefore, analyses of cuticular alkenes must be performed with appropriate derivatization to distinguish these two types of cuticular hydrocarbons. Sarekensane (4) is the first nonterpenoid cuticular hydrocarbon from Collembola that is biosynthesized via the fatty acid pathway, as are insect hydrocarbons, and contains unprecedented cyclopropane rings in the chain, not previously reported from arthropods.

• Silva, Andreia Sofia Jorge; Kristiansen, Silje Marie; Sengupta, Sagnik; Gestel, Cornelis A. M. van; Leinaas, Hans Petter & Borgå, Katrine (2023). Using dietary exposure to determine sub-lethal effects from imidacloprid in two springtail (Collembola) species. Ecotoxicology. ISSN 0963-9292. 32, s. 1209–1220. doi: 10.1007/s10646-023-02715-x. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Standard toxicity tests expose springtails (Collembola) through soil, while dietary exposure tests with animals visible on a surface are less commonly applied. We refined a method for dietary chemical exposure for two widely distributed and abundant Collembola species: Folsomia quadrioculata and Hypogastrura viatica as existing methods were sub-optimal. Newly hatched Collembola were offered bark with a natural layer of Cyanobacteria that was either moistened with a solution of the neonicotinoid insecticide imidacloprid using a micropipette or soaked in the solution overnight. The first method was superior in producing a measured concentration close to the nominal (0.21 and 0.13 mg/kg dry bark, respectively), and resulting in sub-lethal effects as expected. The adult body size was reduced by 8% for both species, but egg production only in H. viatica . Contrastingly, soaked bark resulted in a measured concentration of 8 mg/kg dry bark, causing high mortality and no egg production in either species. Next, we identified the sub-lethal concentration-range by moistening the bark to expose H. viatica to 0, 0.01, 0.04, 0.13, 0.43 and 1.2 mg imidacloprid/kg dry bark. Only the highest concentration affected survival, causing a mortality of 77%. Imidacloprid reduced moulting rate and the body size at first reproduction. The age at first reproduction appeared delayed as some replicates did not reproduce within the experiment duration. The method of moistened bark for dietary exposure proved optimal to continuously study life history traits, such as growth and reproductive outcomes, which are important to understand effects on key events crucial for population viability and growth.

• Sengupta, Sagnik; Leinaas, Hans Petter; Gestel, Cornelis A.M. van; Jager, Tjalling; Rundberget, Thomas & Borgå, Katrine (2023). High sensitivity to dietary imidacloprid exposure in early life stages of Folsomia quadrioculata (Collembola) populations from contrasting climates. Agriculture, Ecosystems & Environment. Applied Soil Ecology. ISSN 0929-1393. 187. doi: 10.1016/j.apsoil.2023.104880. Fulltekst i vitenarkiv Vis sammendrag

  Survival of early life stages is critical for population growth. Understanding the vulnerability of these sensitive stages can therefore improve ecological risk predictions. The globally-used neonicotinoid insecticide imidacloprid does not degrade easily in soil and occurs at concentrations potentially toxic to non-target soil organisms, such as Collembola. Here, we studied the effects of dietary exposure to imidacloprid on the survival of juveniles in an arctic and a temperate population of Folsomia quadrioculata (Collembola), a commonly-occurring litter-dwelling species in the Northern Hemisphere. The exposure lasted from <24 h to 30 days since hatching at 15 °C. We assessed whether (1) the arctic population of the test species with faster development rates could be more vulnerable than the temperate population, (2) cumulative mortality could increase substantially with exposure time, and (3) the mortality risk experienced during the juvenile stage could be greater than that experienced by the adults. We found a strong concentration-dependent decline in survival in both populations, with small but significantly different LC50s, despite large differences in multiple life-history traits. Applying a General Unified Threshold model for Survival (GUTS) showed a low threshold for effects, slow damage dynamics, a 6–11-fold decrease in LC50 from 14 to 30 days of exposure, and saturation of damage at the three highest concentrations. In addition, exposure starting soon after hatching caused much more mortality than that starting in the adult stages. Our findings suggest that toxicity tests not emphasizing the neonate stages or not lasting long enough can underestimate the implications for populations of naturally abundant non-target organisms.

• Konestabo, Heidi Sjursen; Birkemoe, Tone; Leinaas, Hans Petter; Gestel, Cornelis A.M. van; Sengupta, Sagnik & Borgå, Katrine (2022). Pesticide effects on the abundance of springtails and mites in field mesocosms at an agricultural site. Ecotoxicology. ISSN 0963-9292. 31(9), s. 1450–1461. doi: 10.1007/s10646-022-02599-3. Fulltekst i vitenarkiv Vis sammendrag

  Abstract The use of pesticides to protect crops often affects non-target organisms vital to ecosystem functioning. A functional soil mesofauna is important for decomposition and nutrient cycling processes in agricultural soils, which generally have low biodiversity. To assess pesticide effects on natural soil communities we enclosed intact soil cores in situ in an agricultural field in 5 cm wide mesocosms. We used two types of mesh lids on the mesocosms, allowing or preventing migration of mesofauna. The mesocosms were exposed to the insecticide imidacloprid (0, 0.1, 1, and 10 mg/kg dry soil) and left in the field for 20 days. Overall, regardless of lid type, mesocosm enclosure did not affect springtail or mite abundances during the experiment when compared with undisturbed soil. Imidacloprid exposure reduced the abundance of both surface- and soil-living springtails in a concentration-dependent manner, by 65–90% at the two highest concentrations, and 21–23% at 0.1 mg/kg, a concentration found in some agricultural soils after pesticide application. Surface-living springtails were more affected by imidacloprid exposure than soil-living ones. In contrast, neither predatory nor saprotrophic mites showed imidacloprid-dependent changes in abundance, concurring with previous findings indicating that mites are generally less sensitive to neonicotinoids than other soil organisms. The possibility to migrate did not affect the springtail or mite abundance responses to imidacloprid. We show that under realistic exposure concentrations in the field, soil arthropod community composition and abundance can be substantially altered in an organism-dependent manner, thus affecting the soil community diversity.

• Kristiansen, Silje Marie; Borgå, Katrine; Rundberget, Jan Thomas & Leinaas, Hans Petter (2021). Effects on Life-History Traits of Hypogastrura viatica (Collembola) Exposed to Imidacloprid Through Soil or Diet. Environmental Toxicology and Chemistry. ISSN 0730-7268. 40(11), s. 3111–3122. doi: 10.1002/etc.5187. Fulltekst i vitenarkiv Vis sammendrag

  Collembola (springtails) are important members of soil communities worldwide by contributing to degradation of organic matter. In nature, Collembola might be exposed to the neonicotinoid insecticide imidacloprid, which is fairly persistent in soil. We exposed the widespread Hypogastrura viatica to imidacloprid through soil or food and monitored the animals during exposure and a post exposure period. We recorded effects on life-history traits affecting individual fitness, that is, mortality, behavioral activity, several reproduction traits, and molting frequency. Exposure through soil led to a concentration-dependent mortality, while the mortality from dietary exposure possibly reflected reduced feeding activity. The body burden of imidacloprid in the Collembola did not differ between treatments. We found no sign of recovery in behavioral activity following exposure in either experiment. The egg production of H. viatica was not significantly affected by imidacloprid at 0.01 mg/kg dry soil but showed a tendency to reduce number of eggs per batch and reduced hatching success. At higher concentrations, reproduction was close to, or completely, stopped. The molting frequency decreased during exposure, while in the post exposure period, we saw milder effects at the highest concentrations, suggesting elimination through molting or reduced toxic response as a result of reduced feeding activity. Overall, H. viatica was more sensitive to imidacloprid than previously studied Collembola, which highlights the importance of considering species sensitivities when risk-assessing soil environments.

• Hasle, Gunnar; Leinaas, Hans Petter; Heier, Lise; Garcia, Aïda Lopez & Røed, Knut (2021). Mitochondrial DNA in Ixodus ricinus (Acari: Ixodidae) on birds reflects ticks’ transportation routes to Lista, Norway. Ticks and Tick-borne Diseases. ISSN 1877-959X. 12(1), s. 1–7. doi: 10.1016/j.ttbdis.2020.101553. Fulltekst i vitenarkiv
• Poli, Pedro; Lenoir, Jonathan; Plantard, Olivier; Ehrmann, Steffen; Røed, Knut & Leinaas, Hans Petter [Vis alle 8 forfattere av denne artikkelen] (2020). Strong genetic structure among populations of the tick Ixodes ricinus across its range. Ticks and Tick-borne Diseases. ISSN 1877-959X. 11(6), s. 1–10. doi: 10.1016/j.ttbdis.2020.101509. Fulltekst i vitenarkiv Vis sammendrag

  Ixodes ricinus is the most common and widely distributed tick species in Europe, responsible for several zoonotic diseases, including Lyme borreliosis. Population genetics of disease vectors is a useful tool for understanding the spread of pathogens and infection risks. Despite the threat to the public health due to the climate-driven distribution changes of I. ricinus, the genetic structure of tick populations, though essential for understanding epidemiology, remains unclear. Previous studies have demonstrated weak to no apparent spatial pattern of genetic differentiation between European populations. Here, we analysed the population genetic structure of 497 individuals from 28 tick populations sampled from 20 countries across Europe, the Middle-East, and northern Africa. We analysed 125 SNPs loci after quality control. We ran Bayesian and multivariate hierarchical clustering analyses to identify and describe clusters of genetically related individuals. Both clustering methods support the identification of three spatially-structured clusters. Individuals from the south and north-western parts of Eurasia form a separated cluster from northern European populations, while central European populations are a mix between the two groups. Our findings have important implications for understanding the dispersal processes that shape the spread of zoonotic diseases under anthropogenic global changes.

• Sengupta, Sagnik; Leinaas, Hans Petter; Gestel, Cornelis A.M. van; Rundberget, Jan Thomas & Borgå, Katrine (2020). A Multiple Life‐History Trait–Based and Time‐Resolved Assessment of Imidacloprid Effects and Recovery in the Widely Distributed Collembolan Folsomia quadrioculata. Environmental Toxicology and Chemistry. ISSN 0730-7268. 40(1), s. 139–147. doi: 10.1002/etc.4897. Fulltekst i vitenarkiv Vis sammendrag

  Life history traits determine individual fitness and the fate of populations. Imidacloprid, a widely used neonicotinoid insecticide, which persists in soil for more than 100 d at biologically relevant levels, may affect non‐target and ecologically important species, such as collembolans. In the present study, we determined the sublethal effects of short‐term imidacloprid exposure and post‐exposure recovery in the collembolan Folsomia quadrioculata, which occurs abundantly across the northern hemisphere. We assessed survival, egg production, and hatching success in adult springtails exposed for 14 d through the diet to imidacloprid followed by a 28 d post‐exposure phase. Survival and hatching success were high throughout the experiment in all the treatments, with no clear concentration dependency. However, egg production declined during the exposure phase and nearly stopped between 8 and 14 d in all the treatments (except the control), but resumed during the post‐exposure phase. Moreover, the resumption of egg production showed a concentration‐dependent delay. Our findings suggest that low imidacloprid exposures can restrict reproduction, with potentially severe consequences for the population, notwithstanding the partial recovery in egg production.

• Janion-Scheepers, Charlene; Bengtsson, Jan; Duffy, Grant A.; Deharveng, Louis; Leinaas, Hans Petter & Chown, Steven L. (2020). High spatial turnover in springtails of the Cape Floristic Region. Journal of Biogeography. ISSN 0305-0270. 47(5), s. 1007–1018. doi: 10.1111/jbi.13801. Fulltekst i vitenarkiv Vis sammendrag

  Aim The extraordinary diversity of plants across the Cape Floristic Region is characterized by considerable species turnover among sites. Phytophagous insects show similarly high turnover, but their patterns are closely coupled to those of their hosts. If the mechanisms underlying high plant turnover are not unique to plants, similar patterns of turnover should also be seen in non‐herbivorous arthropod groups. We tested this hypothesis using new data for the Collembola fauna of the Fynbos biome. Location The south‐western Cape, South Africa. Taxon Springtails (Hexapoda: Collembola). Methods We sampled springtails from six sites over two seasons. Species richness was compared with expected values from other studies worldwide given the environmental characteristics of the sites sampled. Nestedness and turnover components of beta diversity were calculated and compared against beta diversity patterns of springtails across Europe. Results A total of 114 morphospecies from 14 families was collected. Species richness of Fynbos sites ranged from 14 to 31 species, which was not significantly different to that previously reported for non‐Fynbos locations and generally within expectations given the temperature, rainfall and productive energy of each site. Beta diversity was high across all pairwise comparisons of Fynbos sites and dominated by species replacement rather than assemblage nestedness. Relative to the distance between sites, Fynbos assemblages, with a median inter‐site distance of 140 km, showed beta diversity substantially higher than in European assemblages, which had a median inter‐site distance of 1,270 km. Main conclusions Alpha diversity of Fynbos Collembola assemblages is in keeping with species richness expectations. By contrast, beta diversity is high given the small distances among sites and is characterized predominantly by species turnover. These patterns of unremarkable alpha diversity, but high turnover among sites are comparable to many Fynbos plant groups. The mechanisms giving rise to high beta diversity of the plants may also have led to high diversity in other taxa.

• Bello, Jan E; Stamm, Patrick; Leinaas, Hans Petter & Schulz, Stefan (2019). Viaticene A - An Unusual Tetraterpene Cuticular Lipid Isolated from the Springtail Hypogastrura viatica. European Journal of Organic Chemistry. ISSN 1434-193X. 2019(11), s. 2158–2162. doi: 10.1002/ejoc.201900224. Fulltekst i vitenarkiv
• Kristiansen, Silje Marie; Leinaas, Hans Petter; Herzke, Dorte; Hylland, Ketil; Gabrielsen, Geir W. & Harju, Mikael [Vis alle 7 forfattere av denne artikkelen] (2019). Seabird-transported contaminants are reflected in the Arctic tundra, but not in its soil-dwelling springtails (Collembola). Environmental Science and Technology. ISSN 0013-936X. 53(21), s. 12835–12845. doi: 10.1021/acs.est.9b05316. Fulltekst i vitenarkiv Vis sammendrag

  Arctic-breeding seabirds contain high levels of many anthropogenic contaminants, which they deposit through guano to the tundra near their colonies. Nutrient-rich soil in vicinity to seabird colonies are favorable habitats for soil invertebrates, such as springtails (Collembola), which may result in exposure to seabird-derived contaminants. We quantified a wide range of lipid-soluble and protein-associated environmental contaminants in two springtail species (Megaphorura arctica and Hypogastrura viatica) and their respective habitats (soil/moss) collected underneath seabird cliffs. Although springtails are commonly used in laboratory toxicity tests, this is the first study to measure concentrations of persistent organic pollutants (POPs) and mercury (Hg) in springtails from the field, and to study biotransportation of contaminants by seabirds to soil fauna. We categorized the sites a priori as of low, medium, or high seabird influence, based on the seabird abundance and species composition. This ranking was reflected in increasing δ15N values in soil/moss and springtails with increasing seabird influence. We found clear indications of seabirds impacting the terrestrial soil environments with organic contaminants, and that concentrations were higher in soil and moss close to the bird cliff, compared to farther away. However, we did not find a relationship between contaminant concentration in springtails and the concentrations in soil/moss, or with level of seabird influence. Our study indicates a low uptake of contaminants in the soil fauna, despite seabird-derived contamination of their habitat.

• Widenfalk, Lina A.; Leinaas, Hans Petter; Bengtsson, Jan & Birkemoe, Tone (2018). Age and level of self-organization affect the small-scale distribution of springtails (Collembola). Ecosphere. 9(1). doi: 10.1002/ecs2.2058. Fulltekst i vitenarkiv Vis sammendrag

  In studies of community assembly, species are often assumed to have similar spatial distributions and responses to the environment regardless of age or size. Under this assumption, it is possible to use species and species‐level traits in community composition studies. Here, we test this assumption for two species of soil‐living arthropods (springtails: Collembola) with direct development but assumed differences in self‐organizing behavior. We expected that the species with more pronounced social interactions (Hypogastrura tullbergi) should be less influenced by environmental factors and species interactions across all age classes, than Folsomia quadrioculata that is not known to exhibit social behavior. We used variance partitioning to examine the relative contributions of soil variables, vegetation composition, and other Collembola, vs. spatial variables (as a proxy for intraspecific interactions, i.e., self‐organization), on the distribution of the two species and three of their age classes. We show that two coexisting species with clear aggregation patterns greatly differ in how much the environment contributes to affecting the species’ spatial structure. Local F. quadrioculata abundance was explained by different spatial and environmental variables depending on age class. In contrast, for H. tullbergi, spatial variables explained more of the abundance variation in all age classes. These differences have implications for the general predictability of changes in spatial structuring of species, as self‐organized species may be less likely to respond to changes in environmental factors. Our results show that because age classes may be differentially affected by environmental conditions, caution should be taken when assuming that species traits can be applied to all developmental stages in a species.

• Gundersen, Håkon A Holm; Leinaas, Hans Petter & Thaulow, Christian (2017). Collembola cuticles and the three-phase line tension. Beilstein Journal of Nanotechnology. ISSN 2190-4286. 8(1), s. 1714–1722. doi: 10.3762/bjnano.8.172. Fulltekst i vitenarkiv Vis sammendrag

  The cuticles of most springtails (Collembola) are superhydrophobic, but the mechanism has not been described in detail. Previous studies have suggested that overhanging surface structures play an important role, but such structures are not a universal trait among springtails with superhydrophobic cuticles. A novel wetting experiment with a fluorescent dye revealed the extent of wetting on exposed surface structures. Using simple wetting models to describe the composite wetting of the cuticular surface structures results in underestimating the contact angles of water. Including the three-phase line tension allows for a prediction of contact angles in the observed range. The discrepancy between the contact angle predicted by simple models and those observed is especially large in the springtail Cryptopygus clavatus which changes, seasonally, from superhydrophobic to wetting without a large change in surface structure; C. clavatus does not have overhanging surface structures. This large change in observed contact angles can be explained with a modest change of the three-phase line tension.

• Eisenhauer, Nico; Antunes, Pedro; Bennett, Alison E; Birkhofer, Klaus; Bissett, Andrew & Bowker, Matthew A [Vis alle 32 forfattere av denne artikkelen] (2017). Priorities for research in soil ecology. Pedobiologia. ISSN 0031-4056. 63, s. 1–7. doi: 10.1016/j.pedobi.2017.05.003. Fulltekst i vitenarkiv
• Sengupta, Sagnik; Ergon, Torbjørn & Leinaas, Hans Petter (2017). Thermal plasticity in postembryonic life history traits of a widely distributed Collembola: Effects of macroclimate and microhabitat on genotypic differences. Ecology and Evolution. 7(19), s. 8100–8112. doi: 10.1002/ece3.3333. Fulltekst i vitenarkiv Vis sammendrag

  Life history traits in many ectotherms show complex patterns of variation among conspecific populations sampled along wide latitudinal or climatic gradients. However, few studies have assessed whether these patterns can be explained better by thermal reaction norms of multiple life history traits, covering major aspects of the life cycle. In this study, we compared five populations of a Holarctic, numerically dominant soil microarthropod species, Folsomia quadrioculata, sampled from a wide latitudinal gradient (56–81°N), for growth, development, fecundity, and survival across four temperatures (10, 15, 20, and 25°C) in common garden experiments. We evaluated the extent to which macroclimate could explain differences in thermal adaptation and life history strategies among populations. The common garden experiments revealed large genotypic differences among populations in all the traits, which were little explained by latitude and macroclimate. In addition, the life history strategies (traits combined) hardly revealed any systematic difference related to latitude and macroclimate. The overall performance of the northernmost population from the most stochastic microclimate and the southernmost population, which remains active throughout the year, was least sensitive to the temperature treatments. In contrast, performance of the population from the most predictable microclimate peaked within a narrow temperature range (around 15°C). Our findings revealed limited support for macroclimate‐based predictions, and indicated that local soil habitat conditions related to predictability and seasonality might have considerable influence on the evolution of life history strategies of F. quadrioculata. This study highlights the need to combine knowledge on microhabitat characteristics, and demography, with findings from common garden experiments, for identifying the key drivers of life history evolution across large spatial scales, and wide climate gradients. We believe that similar approaches may substantially improve the understanding of adaptation in many terrestrial ectotherms with low dispersal ability.

• Alfsnes, Kristian; Leinaas, Hans Petter & Hessen, Dag Olav (2017). Genome size in arthropods; different roles of phylogeny, habitat and life history in insects and crustaceans. Ecology and Evolution. 7(15), s. 5939–5947. doi: 10.1002/ece3.3163. Fulltekst i vitenarkiv Vis sammendrag

  Despite the major role of genome size for physiology, ecology, and evolution, there is still mixed evidence with regard to proximate and ultimate drivers. The main causes of large genome size are proliferation of noncoding elements and/or duplication events. The relative role and interplay between these proximate causes and the evolutionary patterns shaped by phylogeny, life history traits or environment are largely unknown for the arthropods. Genome size shows a tremendous variability in this group, and it has a major impact on a range of fitness-related parameters such as growth, metabolism, life history traits, and for many species also body size. In this study, we compared genome size in two major arthropod groups, insects and crustaceans, and related this to phylogenetic patterns and parameters affecting ambient temperature (latitude, depth, or altitude), insect developmental mode, as well as crustacean body size and habitat, for species where data were available. For the insects, the genome size is clearly phylogeny-dependent, reflecting primarily their life history and mode of development, while for crustaceans there was a weaker association between genome size and phylogeny, suggesting life cycle strategies and habitat as more important determinants. Maximum observed latitude and depth, and their combined effect, showed positive, and possibly phylogenetic independent, correlations with genome size for crustaceans. This study illustrate the striking difference in genome sizes both between and within these two major groups of arthropods, and that while living in the cold with low developmental rates may promote large genomes in marine crustaceans, there is a multitude of proximate and ultimate drivers of genome size.

• Leinaas, Hans Petter; Jalal, Marwa; Gabrielsen, Tove M. & Hessen, Dag Olav (2016). Inter- and intraspecific variation in body- and genome size in calanoid copepods from temperate and arctic waters. Ecology and Evolution. 6(16), s. 5585–5595. doi: 10.1002/ece3.2302. Fulltekst i vitenarkiv Vis sammendrag

  The tendency of ectotherms to get larger in the cold (Bergmann clines) has potentially great implications for individual performance and food web dynamics. The mechanistic drivers of this trend are not well understood, however. One fundamental question is to which extent variation in body size is attributed to variation in cell size, which again is related to genome size. In this study, we analyzed body and genome size in four species of marine calanoid copepods, Calanus finmarchicus, C. glacialis, C. hyperboreus and Paraeuchaeta norvegica, with populations from both south Norwegian fjords and the High Arctic. The Calanus species showed typical interspecific Bergmann clines, and we assessed whether they also displayed similar intraspecific variations—and if correlation between genome size and body size differed between species. There were considerable inter- as well as intraspecific variations in body size and genome size, with the northernmost populations having the largest values of both variables within each species. Positive intraspecific relationships suggest a functional link between body and genome size, although its adaptiveness has not been settled. Impact of additional drivers like phylogeny or specific adaptations, however, was suggested by striking divergences in body size – genome size ratios among species. Thus, C. glacialis and C. hyperboreus, had fairly similar genome size despite very different body size, while P. norvegica, of similar body size as C. hyperboreus, had the largest genome sizes ever recorded from copepods. The inter- and intraspecific latitudinal body size clines suggest that climate change may have major impact on body size composition of keystone species in marine planktonic food webs.

• Janion-Scheepers, Charlene; Bengtsson, Jan; Leinaas, Hans Petter; Deharveng, Louis & Chown, Steven L. (2016). The response of springtails to fire in the fynbos of the Western Cape, South Africa. Agriculture, Ecosystems & Environment. Applied Soil Ecology. ISSN 0929-1393. 108, s. 165–175. doi: 10.1016/j.apsoil.2016.08.001. Fulltekst i vitenarkiv
• Røed, Knut; Kvie, Kjersti; Hasle, Gunnar; Gilbert, Lucy & Leinaas, Hans Petter (2016). Phylogenetic Lineages and Postglacial Dispersal Dynamics Characterize the Genetic Structure of the Tick, Ixodes ricinus, in Northwest Europe. PLOS ONE. 11(12). doi: 10.1371/journal.pone.0167450. Fulltekst i vitenarkiv Vis sammendrag

  Dispersal and gene flow are important mechanisms affecting the dynamics of vectors and their pathogens. Here, patterns of genetic diversity were analyzed in many North European populations of the tick, Ixodes ricinus. Population sites were selected within and between areas separated by geographical barriers in order to evaluate the importance of tick transportation by birds in producing genetic connectivity across open sea and mountain ranges. The phylogenetic analyses of the mitochondrial control region and the cytochrome b gene revealed two distinct clades with supported sub-clades, with three genetic lineages: GB and WNo associated with Great Britain and western Norway respectively, and Eu with a wider distribution across continental Europe in agreement with much lower efficiency of tick dispersal by birds than by large mammals. The results suggest different ancestry of I. ricinus colonizing Britain and the rest of northern Europe, possibly from different glacial refuges, while ticks from western Norway and continental Europe share a more recent common ancestry. Demographic history modeling suggests a period of strong increase in tick abundance coincident with progression of the European Neolithic culture, long after their post-glacial colonization of NW Europe.

• Sengupta, Sagnik; Ergon, Torbjørn & Leinaas, Hans Petter (2016). Genotypic differences in embryonic life history traits of Folsomia quadrioculata (Collembola: Isotomidae) across a wide geographical range. Ecological Entomology. ISSN 0307-6946. 41(1), s. 72–84. doi: 10.1111/een.12270. Fulltekst i vitenarkiv
• Gundersen, Håkon A Holm; Thaulow, Christian & Leinaas, Hans Petter (2015). Seasonal change in the wetting characteristics of the cuticle of the Collembola Cryptopygus clavatus (Schött, 1893). Zoomorphology. ISSN 0720-213X. 134(2), s. 211–218. doi: 10.1007/s00435-015-0254-y. Fulltekst i vitenarkiv Vis sammendrag

  The littoral Collembola Cryptopygus clavatus spends the summer submerged, grazing on algae under water, and the winter on dry land. The cuticles of Collembola are, in general, highly water repellent, often superhydrophobic; the cuticle of C. clavatus has, in contrast, been described as not water repellent. Wetting properties are closely tied to surface structuring, and previous studies of Collembola cuticles have used the pattern of cuticular granules to explain the superhydrophobic properties of these cuticles. The wetting properties of the cuticles of C. clavatus were measured on animals acclimated to summer and winter. A significant difference in wetting performance was observed. Animals acclimated to winter conditions showed superhydrophobic non-wetting properties. Animals acclimated to summer conditions were not superhydrophobic, water droplets readily adhered to their cuticles. This large change in wetting behavior of the cuticle could not be explained by changes in the cuticular surface structure, which were very limited. Instead, we suggest a change in the epicuticular wax layer could explain the differences.

• Leinaas, Hans Petter; Bengtsson, Jan; Janion-Scheepers, Charlene & Chown, Steven L. (2015). Indirect effects of habitat disturbance on invasion: Nutritious litter from a grazing resistant plant favors alien over native Collembola. Ecology and Evolution. 5(16), s. 3462–3471. doi: 10.1002/ece3.1483. Fulltekst i vitenarkiv Vis sammendrag

  Biological invasions are major threats to biodiversity, with impacts that may be compounded by other forms of environmental change. Observations of high density of the invasive springtail (Collembola), Hypogastrura manubrialis in heavily grazed renosterveld vegetation in the Western Cape, South Africa, raised the question of whether the invasion was favored by changes in plant litter quality associated with habitat disturbance in this vegetation type. To examine the likely mechanisms underlying the high abundance of H. manubrialis, cages with three types of naturally occurring litter with different nutrient content were placed out in the area and collected after different periods of time. Hypogastrura manubrialis was mainly found in the nutrient-rich litter of the yellowbush (Galenia africana), which responds positively to disturbance in the form of overgrazing. This suggests that invasion may have been facilitated by a positive interaction with this grazing resistant plant. By contrast, indigenous Collembola were least abundant in yellowbush litter. Negative correlations between high abundance of H. manubrialis and the abundance and diversity of other species suggest that competitive interactions might underlie low abundance of these other species at the patch level. Group behavior enables H. manubrialis to utilize efficiently this ephemeral, high quality resource, and might improve its competitive ability. The results suggest that interactions among environmental change drivers may lead to unforeseen invasion effects. H. manubrialis is not likely to be very successful in un-grazed renosterveld, but in combination with grazing, favoring the nutrient-rich yellowbush, it may become highly invasive. Field manipulations are required to fully verify these conclusions.

• Schnug, Lisbeth; Ergon, Torbjørn; Jakob, Lena; Scott-Fordsmand, Janeck J; Joner, Erik & Leinaas, Hans Petter (2015). Responses of earthworms to repeated exposure to three biocides Applied singly and as a mixture in an agricultural field. Science of the Total Environment. ISSN 0048-9697. 505, s. 223–235. doi: 10.1016/j.scitotenv.2014.09.089. Fulltekst i vitenarkiv
• Schnug, Lisbeth; Leinaas, Hans Petter & Jensen, John (2014). Synergistic sub-lethal effects of a biocide mixture on the springtail Folsomia fimetaria. Environmental Pollution (1987). ISSN 0269-7491. 186, s. 158–164. doi: 10.1016/j.envpol.2013.12.004. Fulltekst i vitenarkiv
• Schnug, Lisbeth; Jensen, John; Scott-Fordsmand, Janeck J & Leinaas, Hans Petter (2014). Toxicity of three biocides to springtails and earthworms in a soil multi-species (SMS) test system. Soil Biology and Biochemistry. ISSN 0038-0717. 74, s. 115–126. doi: 10.1016/j.soilbio.2014.03.007. Fulltekst i vitenarkiv
• Røed, Knut H.; Birkemoe, Tone; Sverdrup-Thygeson, Anne; Horak, Jakub; Midthjell, Liv & Leinaas, Hans Petter (2014). Isolation and characterization of ten microsatellite loci for the wood-living and threatened beetle Cucujus cinnaberinus (Coleoptera: Cucujidae). Conservation Genetics Resources. ISSN 1877-7252. 6(3), s. 641–643. doi: 10.1007/s12686-014-0164-1. Fulltekst i vitenarkiv
• Gundersen, Håkon A Holm; Leinaas, Hans Petter & Thaulow, Christian (2014). Surface structure and wetting characteristics of Collembola cuticles. PLOS ONE. 9(2), s. 1–11. doi: 10.1371/journal.pone.0086783. Fulltekst i vitenarkiv Vis sammendrag

  The cuticles of the arthropods Collembola (springtails) are known to be superhydrophobic, displaying such properties as water-repellence and plastron formation; overhanging surface structures have been suggested as the source of these properties. Superhydrophobicity is closely related to surface structuring and other surfaces with overhanging structures have been shown to possess robust superhydrophobic properties. In effort to correlate the wetting performance and surface structuring of the cuticles, from both a technical and evolutionary point of view, we investigated a selection of Collembola species including species from several families and covering habitats ranging from aquatic to very dry. The observed contact angles of wetting was in general larger than those predicted by the conventional models. Not all the studied Collembola were found to have superhydrophobic properties, indicating that superhydrophobicity is common, but not a universal trait in Collembola. Overhanging structures were found in some, but not all Collembola species with superhydrophobic cuticles; which leads to the conclusion that there is no direct link between overhanging surface structures and superhydrophobicity in Collembola.

• Hessen, Dag Olav; Daufresne, Martin & Leinaas, Hans Petter (2013). Temperature-size relations from the cellular-genomic perspective. Biological Reviews. ISSN 1464-7931. 88(2), s. 476–489. doi: 10.1111/brv.12006. Fulltekst i vitenarkiv
• Bengtsson, Jan; Janion, Charlene; Chown, Steven L. & Leinaas, Hans Petter (2012). Litter decomposition in fynbos vegetation, South Africa. Soil Biology and Biochemistry. ISSN 0038-0717. 47, s. 100–105. doi: 10.1016/j.soilbio.2011.11.023. Fulltekst i vitenarkiv
• Bengtsson, Jan; Janion, Charlene; Chown, Steven L. & Leinaas, Hans Petter (2011). Variation in decomposition rates in the fynbos biome, South Africa: the role of plant species and plant stoichiometry. Oecologia. ISSN 0029-8549. 165(1), s. 225–235. doi: 10.1007/s00442-010-1753-7. Fulltekst i vitenarkiv
• Hasle, Gunnar; Leinaas, Hans Petter; Røed, Knut H. & Oines, Oivind (2011). Transport of Babesia venatorum-infected Ixodes ricinus to Norway by northward migrating passerine birds. Acta Veterinaria Scandinavica (AVS). ISSN 0044-605X. 53(41). doi: 10.1186/1751-0147-53-41. Fulltekst i vitenarkiv Vis sammendrag

  Background Bovine babesiosis is regarded as a limited health problem for Norwegian cows, and the incidence has decreased markedly since the 1930s. Rare cases of babesiosis in splenectomised humans from infection with Babesia divergens and B.venatorum have been described. The objective of this study was to determine whether birds can introduce Babesia-infected ticks. There are between 30 and 85 million passerine birds that migrate to Norway every spring. Methods Passerine birds were examined for ticks at four bird observatories along the southern Norwegian coast during the spring migrations of 2003, 2004 and 2005. The presence of Babesia was detected in the nymphs of Ixodes ricinus by real-time PCR. Positive samples were confirmed using PCR, cloning and phylogenetic analyses. Results Of 512 ticks examined, real-time PCR revealed five to be positive (1.0%). Of these, four generated products that indicated the presence of Babesia spp.; each of these were confirmed to be from Babesia venatorum (EU1). Two of the four B. venatorum-positive ticks were caught from birds having an eastern migratory route (P< 0.001). Conclusions Birds transport millions of ticks across the North Sea, the Skagerrak and the Kattegat every year. Thus, even with the low prevalence of Babesia-infected ticks, a substantial number of infected ticks will be transported into Norway each year. Therefore, there is a continuous risk for introduction of new Babesia spp. into areas where I. ricinus can survive.

• Aak, Anders; Birkemoe, Tone & Leinaas, Hans Petter (2011). Phenology and life history of the blowfly Calliphora vicina in stockfish production areas. Entomologia Experimentalis et Applicata. ISSN 0013-8703. 139(1), s. 35–46. doi: 10.1111/j.1570-7458.2011.01105.x. Fulltekst i vitenarkiv
• Janion, Charlene; Bedos, Anne; Bengtsson, Jan; Deharveng, Louis; Vuuren, Bettine Jansen van & Leinaas, Hans Petter [Vis alle 10 forfattere av denne artikkelen] (2011). Springtail diversity in South Africa. South African Journal of Science. ISSN 0038-2353. 107(11-12), s. 75–81. doi: 10.4102/sajs.v107i11/12.582. Fulltekst i vitenarkiv
• Wojewodzic, Marcin; Rachamim, Tamar; Andersen, Tom; Leinaas, Hans Petter & Hessen, Dag Olav (2011). Effect of temperature and dietary elemental composition on RNA/protein ratio in a rotifer. Functional Ecology. ISSN 0269-8463. 25(5), s. 1154–1160. doi: 10.1111/j.1365-2435.2011.01864.x. Fulltekst i vitenarkiv
• Hasle, Gunnar; Bjune, Gunnar Aksel; Midthjell, Liv; Røed, Knut H. & Leinaas, Hans Petter (2011). Transport of Ixodes ricinus infected with Borrelia species to Norway by northward-migrating passerine birds. Ticks and Tick-borne Diseases. ISSN 1877-959X. 2(1), s. 37–43. doi: 10.1016/j.ttbdis.2010.10.004. Fulltekst i vitenarkiv
• Hobæk, Thor Christian; Leinan, Kristian Greger; Leinaas, Hans Petter & Thaulow, Christian (2011). Surface Nanoengineering Inspired by Evolution. BioNanoScience. ISSN 2191-1630. 1(3), s. 63–77. doi: 10.1007/s12668-011-0014-5. Fulltekst i vitenarkiv
• Janion, Charlene; Leinaas, Hans Petter; Terblanche, John s. & Chown, Steven L. (2010). Trait means and reaction norms: the consequences of climate change/invasion interactions at the organism level. Evolutionary Ecology. ISSN 0269-7653. 24(6), s. 1365–1380. doi: 10.1007/s10682-010-9405-2. Fulltekst i vitenarkiv
• Hasle, Gunnar; Bjune, Gunnar Aksel; Christensson, Dan; Røed, Knut H.; Whist, Anne Cathrine & Leinaas, Hans Petter (2010). Detection of Babesia divergens in southern Norway by using an immunofluorescence antibody test in cow sera. Acta Veterinaria Scandinavica (AVS). ISSN 0044-605X. 52. doi: 10.1186/1751-0147-52-55. Fulltekst i vitenarkiv Vis sammendrag

  Background The incidence of bovine babesiosis, caused by Babesia divergens (Apicomplexa: Piroplasmida) has decreased markedly since the 1930 s, but may re-emerge as a consequence of climate change and changes in legislation and pasturing practices. This is a potentially serious disease, with both economical and animal welfare consequences. Therefore, there is a need to survey the distribution of B. divergens. Methods We tested sera from 306 healthy pastured cows from 24 farms along the southern Norwegian coast by using an indirect immunofluorescence IgG antibody test (IFAT). Fractions of seropositive cows were compared by calculating 95% CI. Results The results of this test showed that 27% of the sera were positive for B. divergens antibodies. The fraction of antibody-positive sera that we detected showed a two-humped distribution, with a high fraction of positives being found in municipalities in the western and eastern parts of the study area, while the municipalities between these areas had few or no positive serum samples. Conclusions Neither the farmers' observations nor the Norwegian Dairy Herd Recording System give an adequate picture of the distribution of bovine babesiosis. Serological testing of cows by using IFAT is a convenient way of screening for the presence of B. divergens in an area.

• Leinaas, Hans Petter; Slabber, Sarette & Chown, Steven L. (2009). Effects of thermal acclimation on water loss rate and tolerance in the collembolan Pogonognathellus flavescens. Physiological entomology (Print). ISSN 0307-6962. 34, s. 325–332. doi: 10.1111/j.1365-3032.2009.00693.x. Fulltekst i vitenarkiv
• Hasle, Gunnar; Horak, I.g.; Grieve, G.; Leinaas, Hans Petter & Clarke, F. (2009). Ticks collected from birds in the northern provinces of South Africa, 2004-2006. Onderstepoort Journal of Veterinary Research. ISSN 0030-2465. 76(2), s. 167–175. Fulltekst i vitenarkiv
• Hasle, Gunnar; Bjune, Gunnar Aksel; Edvardsen, Erik; Jakobsen, Christer; Linnehol, Bjørn & Røer, Jan Erik [Vis alle 10 forfattere av denne artikkelen] (2009). Transport of ticks by migratory passerine birds to Norway. Journal of Parasitology. ISSN 0022-3395. 95(6), s. 1342–1351. doi: 10.1645/GE-2146.1. Fulltekst i vitenarkiv
• Hasle, Arne Gunnar; Roed, KH & Leinaas, Hans Petter (2008). Multiple paternity in Ixodes ricinus (Acari : Ixodidae), assessed by microsatellite markers. Journal of Parasitology. ISSN 0022-3395. 94, s. 345–347. Fulltekst i vitenarkiv
• Chown, Steven L.; Slabber, S; McGeoch, Melodie A; Janion, Charlene & Leinaas, Hans Petter (2007). Phenotypic plasticity mediates climate change responses among invasive and indigenous arthropods. Proceedings of the Royal Society of London. Biological Sciences. ISSN 0962-8452. 274, s. 2531–2537. doi: 10.1098/rspb.2007.0772. Fulltekst i vitenarkiv
• Slabber, S; Worland, MR; Leinaas, Hans Petter & Chown, SL (2007). Acclimation effects on thermal tolerances of springtails from sub-Antarctic Marion Island: Indigenous and invasive species. Journal of insect physiology. ISSN 0022-1910. 53. doi: 10.1016/j.jinsphys.2006.10.010. Fulltekst i vitenarkiv
• Worland, M. Roger; Leinaas, Hans Petter & Chown, Steven L. (2006). Supercooling point frequency distributions in Collembola are affected by moulting. Functional Ecology. ISSN 0269-8463. 20, s. 323–329. Fulltekst i vitenarkiv
• Røed, Knut H.; Hasle, Gunnar; Midthjell, V.; Skretting, Grethe & Leinaas, Hans Petter (2006). Identification and characterization of 17 microsatellite primers for the tick, Ixodes ricinus, using enriched genomic libraries. Molecular Ecology Notes. ISSN 1471-8278. 6, s. 1165–1167. Fulltekst i vitenarkiv
• Jensen, Thomas Correll; Leinaas, Hans Petter & Hessen, Dag Olav (2006). Age-dependent shift in response to food element composition in Collembola: contrasting effects of dietary nitrogen. Oecologia. ISSN 0029-8549. 149, s. 583–592. Fulltekst i vitenarkiv
• Chown, Steven L.; Sinclair, Brent J.; Leinaas, Hans Petter & Gaston, Kevin J. (2004). Hemispheric Asymmetries in Biodiversity - A Serious Matter for Ecology. PLoS Biology. ISSN 1544-9173. 2(11), s. 1701–1707. doi: 10.1371/journal.pbio.0020406. Fulltekst i vitenarkiv
• Ims, Rolf Anker; Leinaas, Hans Petter & Coulson, Stephen J (2004). Spatial and temporal variation in patch occupancy and population density in a model system of an arctic Collembola species assemblage. Oikos. ISSN 0030-1299. 105, s. 89–100. Fulltekst i vitenarkiv
• Søvik, Guldborg; Leinaas, Hans Petter; Ims, Rolf Anker & Solhøy, Torstein (2003). Population dynamics and life history of the oribatid mite Ameronothrue lineatus (Thorell 1871) (Oribatida, Acari) on the high arctic archipelago of Svalbard; a field study. Pedobiologia. ISSN 0031-4056. 47, s. 257–271. Fulltekst i vitenarkiv
• Søvik, Guldborg & Leinaas, Hans Petter (2003). Experimental field studies on development and survival in the arctic mite, Ameronothrus lineatus (Acari, Oribatidae) on a cyanobacteria surface in the High Arctic. Polar Biology. ISSN 0722-4060. 26, s. 500–508. Fulltekst i vitenarkiv
• Søvik, Guldborg & Leinaas, Hans Petter (2003). Adult survival and reproduction in an arctic mite, Ameronothrus lineatus (Acari, Oribatidae): effects of temperature and winter cold. Canadian Journal of Zoology. ISSN 0008-4301. 81, s. 1579–1588. Fulltekst i vitenarkiv
• Hagen, Snorre B.; Leinaas, Hans Petter & Lampe, Helene Marie (2003). Response of great tits (Parus major) to small tortoiseshells (Agelais urticae) in feeding trials; evidence of aposematism. Ecological Entomology. ISSN 0307-6946. 28, s. 503–509. Fulltekst i vitenarkiv
• Søvik, Guldborg & Leinaas, Hans Petter (2002). Variation in extraction efficiency between juvenile and adult oribatid mites: Ameronothrus lineatus (Oribatida, Acari) in a Macfadyen high-gradient canister extractor. Pedobiologia. ISSN 0031-4056. 46, s. 34–41. Fulltekst i vitenarkiv
• Birkemoe, Tone & Leinaas, Hans Petter (2001). Growth and development in a high Arctic Collembola: adaptive variation in local populations living in contrasting thermal environments. Ecological Entomology. ISSN 0307-6946. 26, s. 100–105. doi: 10.1046/j.1365-2311.2001.00292.x. Fulltekst i vitenarkiv Vis sammendrag

  1. Terrestrial polar invertebrates with wide geographical distribution must complete their life cycle at sites with large differences in thermal regimes. Here we test whether local adaptation of growth and development to temperature has taken place in the Arctic Collembola Hypogastrura tullbergi. 2. Growth and development of two populations from sites with very different climatic regimes (e.g. from different latitudes) are compared at 5, 10 and 15°C. These temperatures are encountered in the daily fluctuations in the habitat of the southern population. 3. Individuals from the northern population grew and developed faster than individuals from the southern population at the highest temperatures (10 and 15°C), whereas the rates remained similar at the lowest temperature (5°C). Individuals of the northern population also became larger than the southern specimens at 10 and 15°C. Despite of increased growth, development rate and size of the northern animals compared to the southern, the specimens from the two populations lived equally long. 4. We argue that the higher growth and development rates in the northern individuals relative to the southern are due to a stronger selection for fast development at the northern site. The increase in rates at high rather than at low temperatures is explained by a large relative contribution of high temperatures to the total thermal sum of the soil microclimate.

• Leinaas, Hans Petter (2001). UV-tolerance, pigmentation and life forms in high arctic Collembola. I Hessen, Dag Olav (Red.), UV Radiation and Arctic Ecosystems, Ecological Studies 153. Springer. ISSN 9783540421061. s. 123–134. Fulltekst i vitenarkiv Vis sammendrag

  Very little information exists on effects of UV-radiation on terrestrial invertebrates, and nothing from the Arctic. In this region the Collembola (springtails) is a dominant group of terrestrial invertebrates and therefore interesting to study in relation to effects of high latitude increase in UV-radiation. Most collembolan families show similar, convergent patterns in pigmentation and vertical distribution: Surface dwelling species in exposed habitats are generally very dark, which is regarded as a primitive trait. Species living below vegetation and litter are paler, and typical soil species are unpigmented. Three species often coexisting on Svalbard, but with differential vertical distribution, showed strong negative relation between UV-B tolerance and degree of reduced pigmentation. A fourth species, belonging to an originally unpigmented soil dwelling collembolan subfamily, was included in the test because it has occupied a more surface near habitat than most of its relatives. It has attained a pale pigmentation that appeared to have a surprisingly strong photo protective effect. Only the unpigmented species were seriously affected by UV-A radiation. The results indicate that UV-protection might be important also for species associated with habitats not exposed to direct sunlight. A steep gradient in UV-exposure close to the surface may potentially have an impact on structuring species assemblages both vertically and horizontally, and most likely in patchy habitats with differential vegetation cover. Increased UV-radiation due to ozone degradation at high latitude may further affect the population dynamics and occurrence of species, but any effect will probably depend on life form. Increased mortality for several days after experimental radiation shows that irreversible damages may occur long before detected by direct measurements of survival during exposure.

• Coulson, Stephen J.; Leinaas, Hans Petter; Ims, Rolf Anker & Søvik, Guldborg (2000). Experimental manipulation of the winter surface ice layer: the effects on a High Arctic soil microarthropod community. Ecography. ISSN 0906-7590. 23, s. 299–306. Fulltekst i vitenarkiv Vis sammendrag

  The effect of patch size on the tolerance of the soil microarthropod population to an experimentally induced environmental catastrophe, a thick surface ice layer, was studied at a high arctic site. Such an ice layer currently occurs infrequently; however, climatic change models suggest that the occurrence of such an ice layer is likely to increase in frequency. The experimental approach was a factorial design with two patch sizes, an icing treatment and controls. A thin layer of natural ice was present even in the controls and this was treated as a covariate in the analysis. The soil microarthropod fauna at the experimental site consisted of five species of Collembola and seven species of oribatid mites. The experimental surface ice layer reduced the total number of the soil microarthropods studied by 50%; however, mortality differed between mites and Collembola. Mites were very resistant and showed no significant change, while Collembola were more sensitive with a reduction of more than 50% in the ice treatment plots. The thin annual surface ice layer seemed to have an additional effect. This unexpected additional effect could play an important role in determing the extreme patchy distribution of arctic soil animals.

• Birkemoe, Tone & Leinaas, Hans Petter (2000). Effects of temperature on the development of an arctic Collembola (Hypogastrura tullbergi). Functional Ecology. ISSN 0269-8463. 14, s. 693–700. doi: 10.1046/j.1365-2435.2000.00478.x. Fulltekst i vitenarkiv Vis sammendrag

  1. Embryonic development, juvenile moulting and growth-rates, and maximum size of the arctic collembolan Hypogastrura tullbergi were investigated at 5, 10 and 15°C in laboratory experiments. The embryonic development was also investigated at 21°C. 2. The lower temperature threshold of the embryonic development (t0) was -1.3°C, possibly reflecting a slight cold adaptation. The temperature of maximum development rate exceeded 21°C. 3. Instar duration rate was linearly related to temperature. Growth per instar, however, was thermally dependent, giving an overall non-linear correlation between growth and temperature. This emphasises the importance of studying growth and moulting as separate processes in Collembola. 4. Development of genital area (number of hairs) over succeeding instars was affected by the temperature, suggesting that a higher proportion of individuals reached the adult stage in an earlier instar at 15 than at 10°C. 5. Contrary to the general pattern in ectotherms of increasing size at lower temperatures, adult H. tullbergi reached a larger maximum size at 15 than at 10°C. 6. No aspects of post embryonic development in H. tullbergi showed any signs of cold-adaptation, probably because it is more important to be able to efficiently utilise high temperatures frequently occurring in the micro habitat during sunny periods in summer.

• Coulson, Stephen J.; Leinaas, Hans Petter; Ims, Rolf Anker & Søvik, Guldborg (2000). Experimental manipulation of winter surface ice layer: The effects on a high arctic soil microarthropod community. Ecography. ISSN 0906-7590. 23, s. 299–306. Fulltekst i vitenarkiv
• Hertzberg, karine; Yoccoz, Nigel; Ims, Rolf Anker & Leinaas, Hans Petter (2000). The effects of spatial habitat configuration on recruitment, growth and population structure in arctic Collembola. Oecologia. ISSN 0029-8549. 124, s. 381–390. Fulltekst i vitenarkiv
• Gjøsæter, Jacob; Lekve, Kyrre; Stenseth, Nils Christian; Leinaas, Hans Petter; Christie, Hartvig & Dahl, Einar [Vis alle 11 forfattere av denne artikkelen] (2000). A long-term perspective on the Chrysochromulina bloom on the Norwegian Skagerrak coast 1988: a catastrophe or an innocent incident? Marine Ecology Progress Series. ISSN 0171-8630. 207, s. 201–218. Fulltekst i vitenarkiv
• Birkemoe, Tone & Leinaas, Hans Petter (1999). Reproductive biology of the Arctic collembolan Hypogastrura tullbergi. Ecography. ISSN 0906-7590. 22, s. 31–39. doi: 10.1111/j.1600-0587.1999.tb00452.x. Fulltekst i vitenarkiv
• Leinaas, Hans Petter & Ambrose, William (1999). Decision between small and large prey: reduced energy acquisition by pre-migratory purple sandpipers, Calidris maritima, on Svalbard. Polar Biology. ISSN 0722-4060. 22, s. 264–270. Fulltekst i vitenarkiv Vis sammendrag

  On Svalbard, purple sandpipers forage on the shores when preparing autumn migration to the European continent after a period of food shortage on the tundra in summer. Their food choice was studied on a beach when they were faced with the choice between two abundant prey species; a small Collembola (springtail) and a much larger amphipod. In spite of several times higher gain of energy when foraging on amphipopds, the birds did not show distinct preference for either of the two prey species in this situation. Alternative explanations for this behaviour are discussed. We suggest that this could be a consequence of adaptations to their summer diet on Svalbard, when they rely on Collembola as food to a considerable extent. Higher variance in energy gain rate when foraging on amphipods might also be important. Collembolan densities high enough to trigger predation from birds occurred only on some days, with cloudy, calm weather. This, together with the possible existence of a dietary bottleneck may reduce the cost associated with the switching to Collembola.

• Leinaas, Hans Petter & Sømme, Lauritz Sverdrup (1999). Feature species: The springtail Hypogastrura tullbergi. Arctic Insect News. 10. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (1999). Spredning og kolonisering. Betydning av habitatheterogenitet og populasjonsdynamikk. I Bengtson, Sven-Axel; Mehlum, Fridtjof & Severinsen, Torbjørn (Red.), Terrestrisk økologisk forskningsprogram på Svalbard. Svalbardtundraens økologi. Norsk Polarinstitutt Meddelelser, Tromsø. ISSN 9788276661392. s. 175–180. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (1999). Collemboler i arktis. Tilpasninger til og konsekvenser av miljøvariasjoner. I Bengtson, Sven-Axel; Mehlum, Fridtjof & Severinsen, Torbjørn (Red.), Terrestrisk økologisk forskningsprogram på Svalbard. Svalbardtundraens Økologi. Norsk Polarinstitutt Meddelelser, Tromsø. ISSN 9788276661392. s. 55–66. Fulltekst i vitenarkiv

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• Sengupta, Sagnik; Leinaas, Hans Petter; Gestel, Cornelis A.M. van & Borgå, Katrine (2022). Interaction of neonicotinoid exposure and temperature on the life-history traits of the widely distributed Collembola Folsomia quadrioculata. Fulltekst i vitenarkiv
• Konestabo, Heidi Sjursen; Birkemoe, Tone; Leinaas, Hans Petter; Gestel, Cornelis A.M. van & Borgå, Katrine (2020). How does a widely used neonicotinoid affect the soil fauna under natural field conditions? Fulltekst i vitenarkiv
• Kristiansen, Silje Marie; Leinaas, Hans Petter; Herzke, Dorte; Hylland, Ketil; Gabrielsen, Geir W. & Harju, Mikael [Vis alle 7 forfattere av denne artikkelen] (2019). The Arctic tundra and its soil-dwelling springtails (Collembola) reflect nitrogen and contaminants biotransported by seabirds. Fulltekst i vitenarkiv
• Hylland, Ketil; Skei, Bjørn Borge; Gilmore, Erik Howard; Fredriksen, Lene; Keilen, Ellen Kristine & Kristiansen, Silje Marie [Vis alle 11 forfattere av denne artikkelen] (2018). Er det en sammenheng mellom miljøgift-eksponering og DNA-skade i spretthaler, hoppekreps, blåskjell, fisk, fugl og isbjørn? Fulltekst i vitenarkiv
• Bengtsson, Jan; Leinaas, Hans Petter; Janion, Charlene & Chown, Steven L. (2014). Effect of plant species on springtail diversity and species composition in remnant renosterveld patches of the Fynbos biome, South Africa. Fulltekst i vitenarkiv
• Gundersen, Håkon A Holm; Thaulow, Christian & Leinaas, Hans Petter (2013). Springtail Cuticles as a Model for Biomimetic Superhydrophobic Surfaces. Fulltekst i vitenarkiv
• Schnug, Lisbeth; Chen, Kun; Sverdrup, Line Emilie; Hylland, Ketil & Leinaas, Hans Petter (2013). Ecotoxicological studies on Collembola. Fulltekst i vitenarkiv
• Janion, Charlene; Bengtsson, Jan; Leinaas, Hans Petter; Deharveng, Louis & Chown, Steven L. (2012). Collembola diversity in the fynbos of South Africa: the effects of fire. Fulltekst i vitenarkiv
• Sengupta, Sagnik & Leinaas, Hans Petter (2012). Adaptations to contrasting environments in Folsomia quadrioculata: acclimation effects on hatchling size and egg developmental arrest. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (2012). Collembola as model organisms in ecological research; potential for integrative approaches to environmental change effects. Fulltekst i vitenarkiv
• Bengtsson, Jan; Janion, Charlene; Chown, Steven L. & Leinaas, Hans Petter (2011). Springtail diversity and plant decomposition in the fynbos biome, South Africa. Fulltekst i vitenarkiv
• Hylland, Ketil; Skei, Bjørn Borge; Nerland, Inger Lise; Leinaas, Hans Petter & Brunborg, Gunnar (2011). Using comet with blood cells from terrestrial and aquatic organisms. Fulltekst i vitenarkiv
• Bengtsson, Jan; Leinaas, Hans Petter; Janion, Charlene & Chown, Steven L. (2011). Springtail diversity and plant decomposition in the Fynbos Biome, South Africa. Fulltekst i vitenarkiv
• Bengtsson, Jan & Leinaas, Hans Petter (2011). Springtail communities and plant decomposition in renosterveld, South Africa. How (some)plants can favour an invasive springtail, or Where has all the litter gone? Fulltekst i vitenarkiv
• Janion, Charlene; Bengtsson, Jan; Leinaas, Hans Petter & Chown, Steven L. (2010). Landscape conversion and soil biodiversity in the fynbos biome: springtails as exemplars. Fulltekst i vitenarkiv
• Leinaas, Hans Petter & Chown, Steven L. (2010). Springtail responses to changing environments. Fulltekst i vitenarkiv
• Janion, Charlene; Bengtsson, Jan; Leinaas, Hans Petter & Chown, Steven L. (2009). Landscape conversion and soil biodiversity in the Fynbos: springtails as exemplars. Fulltekst i vitenarkiv
• Chown, Steven L. & Leinaas, Hans Petter (2009). Springtail responses to a changing environment. Fulltekst i vitenarkiv
• Leinaas, Hans Petter & Chown, Steven L. (2007). Environmental Responses in Collembola (Springtails): Implications for climate change. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (2006). Stoichiometry for the collembologist, or time constraints, growth rate and response on food nutrient elements in arctic Collembola. Fulltekst i vitenarkiv
• Janion, Charlene; Chown, Steven L. & Leinaas, Hans Petter (2006). The effect of temperature on the egg development of Collembola from Marion Island: indigenous vs. invasive species. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (2004). Dynamics of Collembola in a landscape of small habitat patches; an experimental model system approach. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (2004). Temperature adaptation in Arctic Collembola; thermal reaction norms of egg development. Fulltekst i vitenarkiv
• Hasle, Gunnar; Mehl, Reidar; Bjune, Gunnar & Leinaas, Hans Petter (2004). Transport of ticks by migratory birds in Norway. Fulltekst i vitenarkiv
• Hasle, Gunnar; Mehl, Reidar; Bjune, Gunnar & Leinaas, Hans Petter (2004). : Transport of ticks by migratory birds. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (2002). Habitat heterogeneity and climatic change; Collembola as model organisms in studies on adaptation to and consequences of variations in space and time. Fulltekst i vitenarkiv
• Coulson, Stephen J. & Leinaas, Hans Petter (1999). Intergrated field and fytotron studies of the interaction of spatial and temporal environmental heterogeneity on the population dynamics of Arctic Collembola species assemblages. Fulltekst i vitenarkiv
• Leinaas, Hans Petter (1999). The role of spatial and temporal environmental variation in shaping diversity and dynamics in Collembola species assemblages. Fulltekst i vitenarkiv

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