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Diel activity patterns in an arable collebolan community
Abstract
Diel patterns of activity and abundance among soil-surface Collembola in a wheat crop in southern England were investigated in summer using pitfall trapping, suction sampling and sweep-net sampling. The multivariate technique principal response curves (PRC) analysis was used to investigate changes in the overall community composition within and between sampling dates. Catches of Collembola obtained using all three sampling methods were generally highest from 12.00 to 00.00 h and lowest from 00.00 to 06.00 h, but diel patterns varied among species and were more variable for pitfall than suction samples. Pitfall catches of Lepidocyrtus cyaneus and also of the total Collembola were correlated positively with soil-surface temperature. The above-ground abundance of Arthropleona estimated by suction sampling varied by ca. 870 m−2 in a 24-h period, suggesting that availability of Collembola to predatory arthropods could change considerably in a short time. These findings have implications for arthropod sampling strategies, exposure of Collembola to agrochemicals and predation of Collembola in agroecosystems.
... Species weights can be interpreted quantitatively to give the fitted relative abundance of a taxon relative to the reference treatment. [25][26][27][28][29][30] In the current work, values of c dt and b k were obtained for the comparison of the two field halves by performing PRC analyses with the software program CANOCO 4, 31 using ln(x þ 1)transformed suction or pitfall counts, x, (n = 4 per field half) for up to 24 sampling dates ( Table 2). Three PRC analyses were performed: (1) field suction-captured Collembola (16 taxa); (2) field pitfall-captured Collembola (23 taxa); and (3) field-edge pitfall-captured Collembola (23 taxa). ...
... For each analysis, the null hypothesis that the PRC diagram does not display the treatment variance (ie T dtk = 0 for all t, d and k) was tested using an F-type statistic obtained by permuting whole time series in the partial RDA from which that PRC was obtained. 31 Permutation tests were also performed among samples within each sampling date as described previously [25][26][27][28][29][30] to test the null hypothesis that on each date the principal response c dt did not differ significantly between the treatments (here, east and west halves of the field). Notable differences between field and field-edge catches were that, in all years, Orchesella cincta (L) and Tomocerus spp were found only in field-edge samples. ...
... Pitfall traps provide a combined measure of activity and abundance, hence their catches can be influenced by micro-climatic conditions and, at least over short time periods, the catches do not accurately reflect abundance of Collembola in the field. 30 The remarkable similarity of pitfall and suction catches of Collembola in this study suggests that pitfall trapping may in fact be a reliable means of estimating changes in collembolan abundance at longer time scales, at least where effects of intensive agricultural management practices are concerned. ...
During a 6-year study, effects of two contrasting regimes of pesticide use on pitfall and suction catches of Collembola were monitored in an arable field under a rotation of grass and winter wheat. Current farm practice (CFP) represented conventional fungicide and herbicide use plus applications of organophosphorus (OP) insecticides, whereas reduced input approach (RIA) utilised minimum inputs of fungicides and herbicides and excluded any use of insecticides. Compared with RIA, the CFP regime caused a substantial decline in the abundance and diversity of Collembola in the field, including the local disappearance of one species, without recovery during the study. At the field edge, which was protected during OP applications by a 6-m unsprayed buffer zone, effects of the CFP regime were less severe, and were not persistent in the long term. Some Collembola species occurred only in field-edge samples. Pitfall and suction sampling yielded remarkably similar patterns of catches, indicating that pitfall trapping may be appropriate for detecting long-term changes in collembolan abundance caused by intensive agricultural management practices.
... Several studies indicated the effects of abiotic factors on the abundance, distribution and activity of Collembola in sitespecific ecosystems. Many of these studies included effects of combinations of edaphic and meteorological factors such as soil moisture (Choi et al., 2002;Choi et al., 2006;Schultz et al., 2006;Abbas and Parwez, 2012), soil temperature (Frampton et al., 2001;Karoline et al., 2010;Kardol et al., 2011;Begum et al., 2011), soil organic matter (Mussury et al., 2002;Muturi et al., 2009;Karoline et al., 2010), relative humidity (Loring, 1981;Gope and Ray, 2012), soil pH (Ke et al., 2004;Begum et al., 2014), rainfall (Ferguson and Joly, 2002;Lensing et al., 2005), vegetation cover (Hansen, 2000;Bandyopadhyaya et al., 2002;Abbas, 2012) and crop type (Kanal, 2004) on Collembola. These studies also suggest that there is ample scope of investigation on these abiotic factors in context of Collembola to envisage the challenges of climatic changes. ...
... Soil temperature was negatively correlated with the abundance of Collembola (Bandyopadhyaya et al., 2002;Parwez and Sharma, 2004;Kardol et al., 2011). These finding are contradictory to that of Frampton et al. (2001) and Karoline et al. (2010) who have reported that the abundance of Collembola was positively correlated with the soil temperature. The low soil temperature in wheat may be responsible for the low abundance of Collembola and strong positive correlation was found. ...
In the present studies, Collembola populations were followed for one year in multiple crops agroecosystem of Faisalabad, Pakistan. Four crops, viz., sugarcane, cotton, clover and wheat were selected. Sampling was done fortnightly by installing pitfall traps in each crop area. The results revealed that maximum mean abundance of Collembola was found in clover (36.74) followed by sugarcane (29.15), cotton (20.79) and wheat (16.52). Four species of Collembola (Isotoma decorata, Xenylla indus, Seira indra and Sminthurus mime) were abundant in cotton followed by three (Xenylla indus, Seira indra and Sminthurus mime) in sugarcane and two (Xenylla indus and Seira indra) each in clover and wheat. The proportionate percentage of the abundance of Xenylla indus was 65% followed by 20% of Seira indra, 13% of Isotoma decorata and 2% of Sminthurus mime throughout the sampling period taking together all the crops. The principal component analysis showed significant effect of soil moisture and soil pH on the abundance of Collembola while the effect of soil temperature, relative humidity and organic matter was non-significant. The abundance of Collembola was positively correlated with soil moisture and organic matter in all the crops, soil temperature in wheat, relative humidity in sugarcane and cotton, soil pH in cotton while negatively correlated with soil temperature in sugarcane, cotton and clover, relative humidity in clover and wheat, soil pH in sugarcane, clover and wheat.
... Mites feed either on dead plant material or on soil microflora, while springtails are mostly fungivorous, although they can also feed on decomposing plant or animal residue, live plant parts, bacteria or algae (Endlweber et al., 2009; Scheu et al., 2005). Some epedaphic collembolans can also use the aerial parts of plants in certain moments of their life cycle (Frampton et al., 2001; Peterson et al., 2010), as it happens in the case of entomobryid springtails on maize (Dively, 2005). Both groups have been used as indicators of soil quality (Behan-Pelletier, 1999; van Straalen, 1998); however, collembolans can respond more rapidly than oribatids to ecosystem disturbance as they are primarily " r-selected " detritivorous organisms (Behan-Pelletier, 2003 ). ...
... collembolan genus in our soil samples, collected from the husk leaves of ears, where they were very abundant at the end of the maize season. These species have been described mainly as saprophagous and fungal feeders, so their presence in mature maize plants just prior to harvest might be either to exploit the decaying organic matter and fungi accumulated among maize foliage in the final stage of development of the crop or to avoid adverse environmental conditions (Frampton et al., 2001). Collembolans, and specifically Entomobrya spp., seem to be an important source of food for spiders (McNabb et al., 2001; Peterson et al., 2010) and for epigeic generalist predators in agricultural soils, such as carabids (Bilde et al., 2000). ...
The impact of Cry1Ab-expressing Bt maize (event MON810) on non-target fauna has been a major
concern since its deployment in Europe. In this paper, we have assessed the levels of Cry1Ab in
rhizosphere soil samples from a Bt maize crop and evaluated the potential effects of Bt maize on soil
microarthropods by a three-year trial in an experimental farm-scale field in Central Spain. The Cry1Ab
toxin was detected in decaying soil organic matter (OM) from Bt maize plots up to three months after
harvest, with values ranging between 0.10 and 0.18 ng Cry1Ab/mg OM, but it showed low insecticidal
activity. The study focused on Acari and Collembola, the two major components of the soil
microarthropod community. They accounted for 88% of the total specimens collected, and they were
identified at the suborder and species level, respectively. Interestingly, Cry1Ab was detected for the
first time in field collected collembolans, Entomobrya spp., demonstrating their exposure to the toxin. The
abundance of mites and collembolans and the frequency of occurrence of the main collembolan species
did not rely on the type of maize except for Parisotoma notabilis, more abundant and frequent in Bt maize
plots. However, significant differences among years were common in both groups. Noticeably, we found
higher values of species richness and diversity of collembolans in Cry1Ab-expressing Bt maize than in
non-Bt plots, which could be explained under different scenarios. Our results suggest that continuous
cultivation of Bt maize does not negatively affect soil microarthropods, indicating that Bt maize could be
compatible with this community.
... 106 In the ecosystem, disturbances also affect the soil arthropod community. 107,108 The structural characteristics of the soil arthropod community are relatively stable in an environment with fewer disturbances. However, when a natural or human disturbance considerably changes the soil environment, the structure of the soil fauna community will generally change significantly. ...
Background:
Pine wood nematode disease is a major plant quarantine object in the world. Trunk injection is an effective method for controlling pests that cause disease. To evaluate the ecological safety of trunk injection with emamectin benzoates in the forests of Pinus massoniana, the community diversity and community composition of soil arthropods and flying insects (Hymenoptera) were studied at different stages of trunk injections.
Results:
The dominant taxonomic groups of soil arthropods were Collembola (30.80%), Insecta (26.42%), and Arachnida (23.84%). The taxonomic groups of flying insects (Hymenoptera) were Ichneumonidae (48.94%), Formicidae (14.10%), and Braconidae (8.44%). Trunk injection with emamectin benzoate has no significant effect on the diversity indices of total soil arthropods and flying insects (Hymenoptera). However, it has a significant effect on the diversity indices of detritivores for soil arthropods. It changed the community composition of soil arthropods but did not impact the community composition of flying insects (Hymenoptera). Redundancy analysis (RDA) between arthropod community structure and environmental variables shows total potassium, residual of green leaf, and residual of litter leaf have a significant impact on the community structure of soil arthropods, and total phosphorus, total nitrogen, water content, organic matter, and total potassium have a significant impact on the community structure of flying insects (Hymenoptera).
Conclusion:
Trunk injection with emamectin benzoate is safe for the ecological environment. The study can provide a reference for the prevention and control of pine wood nematode disease, which is of great significance to forest management and pest control in the world. This article is protected by copyright. All rights reserved.
... Most of the species collected in our study are frequently observed in agricultural (Axelsen and Kristensen, 2000;Frampton et al., 2001;Fratello et al., 1985;Ponge et al., 2003;Querner and Bruckner, 2010;Rebecchi et al., 2000;Sousa et al., 2004). ...
The genetic diversity of cultivated crops has decreased continuously since the beginning of the 20th century, because of the gradual replacement of genetically heterogeneous traditional varieties by new genetically homogenous varieties, grown in monospecific stands. The resulting agro-ecosystems are now considered as unsustainable. Increasing within-field genetic crop diversity by using a mixture of varieties could increase the sustainability of these agro-ecosystems. This could also potentially increase non-crop biodiversity. In the present study we used an experimental approach to (1) test whether the number of wheat varieties (genetic diversity), the number of functional groups (functional diversity), the composition of functional groups and wheat traits influence 1) species richness and abundance of Collembola, and (2) species and trait assemblages of Collembola. A total of 104 plots were seeded with either monocultures or mixtures of 2, 4 and 8 wheat varieties. Soil cores were collected in each plot to extract Collembola and measure soil features. Wheat variety number and functional wheat diversity did not impact abundance and species richness of Collembola. The sensitivity of wheat to septoria leaf blotch was positively related to abundance and species richness of Collembola, while specific root length was favorable to collembolan species richness. Wheat traits related to sensitivity to fungal diseases, (more especially septoria leaf blotch) and characteristics of aerial parts and roots impacted collembolan species and trait assemblages, but these effects were weak. Soil features, especially the proportion of coarse silt, were also influential. Our study did not show a favorable impact of wheat genetic diversity on soil Collembola, which might result from their low abundance. Nevertheless, it suggests correlations between some variety traits and the species richness and abundance of Collembola.
... Previous studies had shown that daytime and nighttime warming could differently change the soil processes and performance of soil nematode communities Yan et al., 2017). Microarthropods had different habitat preference in daytime and nighttime and the density and niches of Collembola and mites were changed with the sampling time during the day due to the surface temperature and predator-prey relationship (Frampton et al., 2001;Onzo et al., 2003;Parecis Silva et al., 2016). However, studies on the response of microarthropods to climate warming and nitrogen addition have mainly been concentrated on total density and species richness of soil microarthropods across longer periods of time (Briones et al., 2009;Day et al., 2009;Kardol et al., 2011;Bokhorst et al., 2012;Eisenhauer et . ...
Both climate warming and nitrogen addition have the potential to affect soil fauna. The effect of these changes on the diel variation of soil microarthropods motility remains unknown. In northeastern China, in temperate grasslands with limited moisture and nutrients, epigeic microarthropods were captured by pitfall traps and activity-density and species richness of epigeic Collembola and Oribatida were calculated after four years of simulated environmental change by warming and/or nitrogen addition both in daytime and nighttime. Warming with or without nitrogen addition reduced the total activity-density of epigeic Collembola. However, this effect was pronounced only in daytime, but not nighttime. Epigeic Oribatida was not impacted by warming treatment. Nitrogen addition had no effect on epigeic Oribatida and Collembola. Our results indicate that warming has a pronounced, adverse effect on epigeic Collembola in water-limited temperate grassland and that the effect was microarthropod taxon-specific. We conclude that warming could limit the activity-density of epigeic micro-arthropods' species that are not resistant to water deficiency and these alterations would not be alleviated by concurrent nitrogen deposition.
... For spiders living on the ground, most of their diet is arthropods running around on the surface of the soil, largely represented by springtails (Collembola) with small body size (Nyffeler and Benz, 1988). In an open environment, such as grassland, they demonstrate mainly daily activity (Frampton et al., 2001;Krumpalova and Tuf, 2013). Other potential preys of ground spiders are aphids, which, according to the research of Ximenez-Embun et al. (2014), carried out in fields of alfalfa, are available for the spiders throughout the growing season with a peak of their activity during the afternoon. ...
The paper concerns the diel and seasonal activity of ground dwelling spiders on a sandy grassland in the Bug River Valley in East-Central Poland. The spiders were captured using pitfall traps in 2009 and 2010 from May to July. The material was collected one day a week, day and night. Traps were checked every 3 h, eight times a day. It was found that for spiders with larger bodies, from the families Lycosidae and Philodromidae, the peak of their activity was in the afternoon, and smaller spiders belonging to the families Linyphiidae and Tetragnathidae showed the greatest activity in the morning. Species Pardosa palustris and Xerolycosa miniata were dominant spiders of the studied grassland. The time of their highest diel activity was different by several hours. It was observed that P. palustris individuals were more numerous in that habitat in early June and X. miniata spiders from mid-June. Spiders of the dominant family Lycosidae were in the highest numbers in the second half of May and in early June, while most of the spiders of other families were captured before or after the period of prevailing presence of dominant spiders.
... In previous studies that have used PRC analysis, an experimental "control" treatment level was used as the reference treatment level d = 0 (Van den Brink & Ter Braak 1999). Here, however, and in common with Frampton et al. (2001), an obvious "control" treatment does not exist among sampling times, and the least disturbed (most natural) site is viewed as the control. Although a reference level must be specified in the PRC analysis, the choice of reference does not limit the visual and quantitative treatment contrasts that can be made using a PRC diagram (Ter Braak & Similaeur 1998). ...
... & Tillage effects have been demonstrated in several studies (e.g., Cortet et al. 2002b;Krogh et al. 2007;Lagomarsino et al. 2009); & Treatment with biocides (e.g., Frampton et al. 2001;Rebecchi et al. 2000;Cortet et al. 2002a); & Fertilisers (e.g., Cole et al. 2005;Van der Wal et al. 2009); & Soil erosion (e.g., Baxter et al. 2013) & Soil compaction (e.g., Cluzeau et al. 1992;Heisler and Kaiser 1995) Nutrient cycling is severely impacted by intensive agriculture. Several studies have shown the decline of soil organic matter since the post-war period (e.g., Bellamy et al. 2005) largely attributed to intensive cultivation, with concomitant declines in soil biota. ...
Global demand for food is increasing in terms of the quantity, quality and reliability of supplies. Currently, over 90 % of our food is grown on (or in) a virtually irreplaceable, non-renewable natural resource - the soil. This paper examines the latest research on selected soil degradation processes (soil erosion by water, compaction, loss of organic matter, loss of soil biodiversity and soil contamination) and specifically how they impact on food production. Every year, an estimated 12 million hectares of agricultural land are lost to soil degradation, adding to the billions of hectares that are already degraded. It is estimated that soil degradation leads to a potential loss of 20 million tonnes of grain per annum, but this is likely to be an underestimate, because the evidence base is limited in identifying direct impacts of soil degradation on food production. Some soil management practices have been used to mask the effects of soil degradation on food production (e.g., additions of chemical fertilisers), but comprehensive soil conservation practices are required to respond to the multiple problems of soil degradation if the world is to be able to feed more than 9 billion people by 2050.
... In Group E, two species were more abundant in the forest soil, which suggests that they either prefer resources found in forest soil or are favoured by higher soil moisture (or other physicochemical properties linked to forest soil) as we showed that under pasture microclimate, soil moisture was higher in the forest than in the pasture soil. We only found two species classified as agricultural species that were actually more abundant in pasture soil and under pasture microclimate as supported by previous observations in agricultural habitats (Fratello et al., 1985;Dittmer and Schrader, 2000;Frampton et al., 2001). These two "pasture species" are thus likely to be primarily influenced by microclimate, resources, and soil physicochemical properties rather than by interspecific competition. ...
... In previous studies that have used PRC analysis, an experimental 'control' treatment level was used as the reference treatment level d = 0 (Van den Brink & Ter Braak 1999). Here, however, and in common with Frampton et al. (2001), an obvious 'control' treatment does not exist among sampling times, and the least disturbed (most natural) site is viewed as the control. Although a reference level must be specified in the PRC analysis, the choice of reference does not limit the visual and quantitative treatment contrasts that can be made using a PRC diagram (Ter Braak & Similaeur 1998). ...
A new approach to assess environmental integrity based on PRC analysis was proposed, tested, validated and developed. Environmental health assessment and community studies usually result in complex biological data sets. In order to find ecologically relevant patterns and tendencies from such sets of data it is necessary to reduce all the information to a summarised and simplified form, which might be more easily interpreted by ecologists, politicians, end-users and the population in general. However, several multivariate ordination methods currently used (e.g. redundancy analysis, principal component analysis, or multi-dimensional scaling) produce complex diagrams for the non-ecologist, which do not allow changes in biological communities over time to be easily understood. Here, we propose a recently developed method, principal response curves (PRC) analysis, to overcome these issues. This method has advantages over traditional ordination techniques, or any biotic index, in that it provides a powerful statistical analysis of temporal data series along spatial gradients. The PRC technique can make use of non-disturbed or unpolluted areas as reference sites with which other areas are compared, making it possible to assess changes in species composition between different areas over time. Moreover, individual species responses to stress agents can be inferred from the PRC curves. As well as providing insights into the behaviour of natural ecosystems - in particular, how ecosystem integrity changes over time - this new approach can potentially provide a practical tool for monitoring and implementing environmental policy instruments.
... When increased temperatures cause drier conditions, it may have an adverse effect on Collembola dispersal if this causes them to retreat from wind exposed surfaces to more humid microhabitats. However, studies outside Svalbard have also shown that catch densities from suction sampling of Collembola has a positive effect with temperature (Frampton et al. 2001). Although our results show with significance that temperature has a negative relationship with Collembola aerial dispersal, the truth may be too complex for such a general statement and may rely on a context involving species and how rising temperatures occur with other weather conditions, particularly relative humidity. ...
... Species traits observed under more favorable climate conditions (moderately high temperature and moisture and low altitude), are the same as those present in epigeic levels because such conditions are favorable to epigeic life and because species adapted to drought can live above-ground in open habitats (see above; Siepel, 1996). This is supported by the positive correlation of the activity of epigeic Collembola with temperature in agricultural soils (Frampton et al., 2001). At last, the post-antennal organ seems more complex (larger numbers of vesicles, in relation to the number of dendritic branches of neural systems; Altner and Thies, 1976) in most species of mull humus and edaphic levels than in moder humus and hemiedaphic levels. ...
... Moreover, principal response curves (PRC) analysis was performed using Canoco for Windows 4.5 (Ter Braak and Šmilauer 2002) commonly used to test the overall response of a biological community to environmental stress, by determining treatment effects relative to an untreated control plot(Van den Brink and Ter Braak 1999). An exhaustive description of the method could be found in the literature (e.g.Frampton et al. 2000Frampton et al. , 2001Silva et al. 2010;Van den Brink and Ter Braak 1999). ...
A field study was conducted during 2005 and 2006 in Terra Quente, northeastern Portugal, to evaluate the efficacy of the spinosad-based insecticide Spintor Cebo® (Dow Agrosciences Ibérica, S.A.) against the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), as well as the impact of the treatments on non-target arthropods. Results suggest that this insecticide could be as effective as dimethoate and since it was reported as having more benign toxicological and ecological profiles, it seems to be a good alternative to control the pest in Continental Mediterranean climates such as Terra Quente. However, its use should be evaluated carefully, mainly in conditions that increase the arthropod biological control agents’ propensity for feeding on it (e.g. absence of pollen, nectar and honeydews) to identify unintended impacts on conservation biological control of olive pests as a result of its application.
... However, the limited available data and hardly comparable methods applied by different authors make it impossible to judge if responses of postembryonic instars are similar. In addition, mobile instars can actively choose preferable temperature (Babenko 1993) or make vertical migrations (Frampton et al. 2001) which impede data interpretation and comparison among studies. At present, it might only be stated that deep litter/topsoil dwellers (like N. silvestris) could show quite pronounced responses to fluctuating temperature regimes. ...
Population responses of a forest floor saprotrophic mite, Nothrus silvestris (Oribatei), were studied in litter microcosms for 14 weeks under three temperature regimes. The regimes reflected a range of diurnal fluctuations (T10–20 and T5–25 - daily fluctuations from 10 to 20 °C and 5 to 25 °C, respectively) around a mean of 15 °C (constant regime, T15). The T5–25 regime was unfavourable, leading to the highest mortality and the lowest reproduction rates in the mite parental population. Moderate fluctuations (T10–20 regime) caused the lowest mortality and the highest offspring production and therefore, the highest population growth in N. silvestris. Population responses were intermediate under the T15 regime. Thus, a trade-off between reproduction and adult mite survival that is regulated by temperature regime seems to exist in N. silvestris. Similar trends of population responses to temperature regime were observed in another litter mite, Schwiebea sp. (Acaroidea), which was also collected from the microcosms.
... The relationships between fruit-body abundance and landuse practices at ground level were evaluated using the multivariate technique principal response curve (PRC) analysis (Van den Brink and Ter Braak 1999), a novel method for time-dependent multivariate responses of biological communities to stress. This method was developed to analyse data from mesocosm experiments in aquatic ecotoxicology (Van den Brink and Ter Braak 1999), and has rarely been applied in terrestrial ecological studies (Frampton et al. 2000a(Frampton et al. , 2001. This method is particularly suitable when the focus is not on the temporal changes of biological communities within treatments (the montado areas, in this case), but on the changes observed over time in the treated communities (the Cu, Ca, and M areas in this case) in comparison with the community in the control (the C area). ...
We assessed the impacts of current management practices used to control shrub strata in Portuguese oak woodlands dominated by Quercus suber L. (montado) on fruiting diversity and abundance of ectomycorrhizal-forming fungi (ECMF) and saprobic fungi. Fruit bodies were collected over four fruiting seasons in 16 plots (20 m × 20 m) selected in a montado landscape with extensive silvopastoral exploitation. A total of 9484 fruit bodies were found in 171 taxa (74 ECMF, 96 saprobic, and 1 parasitic). Our results show that shrub density control by permanent grazing or by cutting practices followed by soil tillage leads to lower fruiting production and greater changes in taxa composition, particularly for ECMF fruit bodies, than cutting practices without soil tillage. Principal response curve analysis showed that ECMF reacted more sensitively to these practices, in particular Laccaria laccata, Hebeloma cistophilum, Russula cyanoxantha, Cortinarius trivialis, and Lactarius volemus. We also observed that shrub cutting without soil tillage allowed ECMF fruiting to recover to predisturbance levels after 3 years. Our data imply that fruit bodies were useful indicators for assessing the severity of the effects of different land-use practices applied in montado areas on soil fungal populations.
... In previous studies that have used PRC analysis, an experimental ''control'' treatment level was used as the reference treatment (Van den Brink and Ter Braak, 1999). Here, however, and in common with Frampton et al. (2001) and Pardal et al. (2004), an obvious ''control'' treatment does not exist among sampling times, and the least disturbed (most natural) site is viewed as the control. Although a reference level must be specified in the PRC analysis, the choice of reference does not limit the visual and quantitative treatment contrasts that can be made using a PRC diagram (Ter Braak and Similaeur, 1998). ...
Marine and coastal environments are among the most ecologically and socio-economically important habitats on Earth. However, climate change associated with a variety of anthropogenic stressors (e.g. eutrophication) may interact to produce combined impacts on biodiversity and ecosystem functioning, which in turn will have profound implications for marine ecosystems and the economic and social systems that depend upon them. Over period 1980e2000, the environment of the Mondego estuary, Portugal, has deteriorated through eutrophication, manifested in the re-placement of seagrasses by opportunistic macroalgae, degradation of water quality and increased turbidity, and the system has also experienced extreme flood events. A restoration plan was implemented in 1998 which aimed to reverse the eutrophication effects, especially to restore the original natural seagrass (Zostera noltii) community. This paper explores the interactions between extreme weather events (e.g. intense floods) and anthropogenic stressors (e.g. eutrophication) on the dynamics of the macrobenthic assemblages and the socio-economic implications that follow. We found that during the previous decade, the intensification of extreme flooding events had significant effects on the structure and functioning of macrobenthic communities, specifically a de-cline in total biomass, a decline in species richness and a decline in suspension feeders. However, the earlier eutrophication process also strongly modified the macrobenthic community, seen as a decline in species richness, increase in detritivores and a decline in herbivores together with a significant increase in small deposit-feeding polychaetes. After the implementation of the management plan, macrobenthic assemblages seemed to be recovering from eutrophication, but it is argued here that those earlier impacts reduced system stability and the resilience of the macrobenthic assemblages, so that its ability to cope with other stressors was compromised. Thus, heavy flooding in the Mondego region during the recovery process had more severe effects on these assem-blages than expected, effectively re-setting the recovery clock, with significant socio-economic impacts (e.g. high mortality of fish in fish farms, and a large decline of economically important species, such as the bivalves Scrobicularia plana and Cerastoderma edule). The frequency and magnitude of these extreme events is predicted to increase in future years [IPCC WGI, 2001. Climate change 2001: the scientific basis, contri-bution of working group I to the third assessment report of the Intergovernmental Panel on Climate Change (IPCC). In: Houghton, J.Eds.), Cambridge University Press, UK, 944 p.] and there is a risk that impacted ecosystems will never recover fully, with far-reaching consequences for human well being.
... Pitfalls may give biased abundance estimates, and there is the possibility that our methods may have missed some species at some sites. However, our methods certainly minimized these potential biases because pitfall trapping is a widespread census method for Collembola and Isopoda in the field (e.g., Joosse, 1965;Neumann and Tolhurst, 1991;Collett, 1998;Bolger et al., 2000;Frampton et al., 2001). ...
Co-occurrence analyses show that non-random community structure is disrupted by fire in two groups of soil arthropods (Isopoda Oniscidea and Collembola) a b s t r a c t In this paper, we tested the hypothesis that natural catastrophes may destroy non-random community structure in natural assemblages of organisms. As a study system, we selected fire as the catastrophic event, and two groups of soil arthropods (Collembola and Isopoda Oniscidea) as target organisms. By co-occurrence analyses and Monte Carlo simulations of niche overlap analysis (C-score, with fixed-equi-probable model; RA2 and RA3 algorithms) we evaluated whether the community structure of these two groups were random/non-random at three unburnt sites and at three neighbour burnt sites that were devastated by a large-scale fire in summer 2000. Both taxa experienced a remarkable reduction in the number of species sampled in burnt versus unburnt sites, but the difference among sites was not statistically significant for Oniscidea. We determined that community structure was clearly non-random at the unburnt sites for both Collembola (according to RA3 algorithm) and Isopoda Oniscidea (according to co-occurrence analysis) and that, as predicted by theory, the catastrophic event did deeply alter the community structure by removing the non-random organization of the species interactions. We also observed a shift from segregation to aggregation/randomness in soil arthropods communities affected by fire, a pattern that was similar to that observed in natural communities of organisms perturbed by the introduction of alien species, thus indicating that this pattern may be generalizable when alteration of communities may occur.
... The method has been developed for analyses of ecotoxicological studies. It was first applied to the results of ecotoxicological experiments evaluating the effects of pesticides on freshwater ecosystems (Van den Brink and Ter Braak, 1999) but rapidly terrestrial ecosystems (Smit et al., 2002) and the analysis of ecological field experiments (Frampton et al., 2001) followed. PRC has only been applied to experimental data with the exception of a monitoring study by Leonard et al. (2000). ...
Key variables in ecosystems tend to operate on widely different time-scales. These time-scales become relevant when a disturbance rocks the ecosystem. Here we try to explain the fast dynamics of plankton and nutrients in the water column of floodplain lakes after disturbances (inundations). We take advantage of natural experiments, that is occasional massive overflow of floodplain lakes with river water. We sampled 10 lakes in two floodplains along the Dutch river Waal monthly for 3 years, capturing the impact of three inundation events. The inundations reset the plankton as well as chemical composition of most lakes to largely the same state. While biologically inert macro-ion data reflected a large and long lasting impact of the river water, dynamics of nutrients, phytoplankton and zooplankton communities between lakes diverged in a few weeks to regimes characteristic for the different lakes. While one spring inundation synchronized plankton dynamics to let the subsequent clear water phase occur at the same moment in different lakes, winter inundations did not have the same effect and apparently dynamics quickly diverged. Our results showed that effects of inundations and other processes that affect the state of the ecosystem should be studied considering the level of the slow components such as the sediment nutrient pool, fish stock and macrophyte communities. Plankton communities and lake water nutrient status give a practically instantaneous reflection of the condition of these slow components. Copyright © 2008 John Wiley & Sons, Ltd.
... Abundance, however, was below the values reported by the some authors (Petersen, 2000; Frampton and Van den Brink, 2002) who did not find any significant decrease in Collembola populations in agricultural fields when compared to forest sites. Possible causes could be related to the type of soil and soil quality (low carbon and nitrogen contents, high pH), diel activity patterns and time of sampling (Frampton et al., 2001 ), but especially to intensive management , particularly the frequent disturbance due to machinery use (alfalfa is mown several times during the year). This last factor is known to cause strong reductions in Collembola abundance (Heisler and Kaisser, 1995), and in this case only two species (F. ...
Collembola communities were sampled along a gradient of soil-use intensification in a typical Mediterranen landscape dominated by cork-oak. This gradient ranged from a land-use unit (LUU1) dominated by closed oak forest with minimum intervention to an unit entirely composed of a monoculture crop submitted to frequent anthropogenic disturbances (LUU6), passing through LUUs with managed woodland (LLU2) or dominated by open cork-oak areas and pastures (LUU3 and LUU5). The Collembola community in the overall area was dominated by a few abundant species, mainly Isotomidae, present in almost all units. Abundance, diversity and species richness decreased along the gradient, with the agricultural site presenting an impoverished community. Diversity descriptors were positively and significantly correlated with habitat diversity, measured on the basis of the proportion of the different soil-use types present at each land-use unit. Multivariate analysis revealed changes in Collembola community composition between the LUUs, with LUU6 detaching from the rest. LUU1 and LUU2, despite the less diverse community of the latter, formed a separate group from the remaining two units (LUU3 and LUU5). Species composition in all these units was mainly determined by soil-use types present at each LUU (open cork-oak land and pastures vs. closed cork-oak areas), the proportion of the different soil-use types and the different management practices adopted for each soil use. Overall analysis revealed that Collembola reacted to changes in the landscape structure, with community composition giving a more robust response than diversity indices.
... Smit et al. 2002) and the analysis of ecological field experiments (eg. Frampton et al. 2001) followed rapidly. The Principal Response Curves method was developed to overcome very cluttered biplots when the information of many sampling dates and many treatments is displayed in one diagram and time is not expressed as a single direction in the biplot (see Kersting and Van den Brink 1997 as an example). ...
This paper describes the usefulness of the group of multivariate techniques belonging to ordination for the analysis of ecotoxi cological data sets. It is argued that although ecotoxicologists often gather multivariate data sets, they usually do not evaluate them w ith techniques that can handle multivariate data. Ordination techniques enable the researcher to extract an underlying structure out of a data set (eg. differences in composition of macro-invertebrate community between sites) and, if measured, relate this structure to explanator y variables (eg. concentrations of toxicants at the same sites). Five example data sets are presented to illustrate the underlying theory a nd the possibilities of ordination techniques. Two methods are presented, one based on weighted summation (eg. Principal Component Analysis, PCA) an d one on weighted averaging (eg. Correspondence Analysis, CA). These techniques differ in the shape of the modelled response (lin ear versus unimodal) as the type of data they model (absolute versus relative). Results of these two methods are illustrated using a data set comprising levels of different PCB congeners measured in the blood of Adélie penguins in three periods. After this the constrai ned forms of PCA and CA are discussed, ie. constrained means that they are able to optimally display the differences in species compositi on (here levels of PCB congeners) due to explanatory variables (here period). Further examples illustrate the use of covariables, contin uous and nominal explanatory variables, supplementary explanatory variables and forward selection of explanatory variables. Finally, two examples of Principal Response Curves (PRC) analyses are given. PRC is a technique that is especially developed to analyse time-series i n which a control or reference is present. The PRC results are discussed for a designed experiment and a monitoring data set. The paper ends with a discussion focussing on the comparison between ordination techniques and other multivariate techniques used in the field of e cotoxicology. we try to demonstrate that multivariate techniques can be valuable in the analysis of a variety of ecotoxicological data. In this paper we will restrict ourselves to ordination techniques that operate on the original data set for its analysis and thus allow a direct interpretation in terms of the original variables, in most cases species (Ter Braak 1994 1995). These techniques are more direct than techniques that operate on (dis)similarity indices (eg. similarity analysis, clustering and multidimensional scaling). The techniques used in this paper and those based on (dis)similarity indices will be compared in the discussion section. Ordination techniques are capable of summarising very complex responses because they are not restricted to a single dimension (as for instance (dis)similarity analysis). When combined with Monte Carlo permutation testing not only is a graphical summary of the structure present in the data set obtained, but also the statistical significance of hypothesised differences (Ter Braak and smilauer 2002). This paper will present the analysis of five example data sets to illustrate the value of multivariate methods for the analysis of ecotoxicological data. We go beyond the traditional example in which a sample by species matrix is compared with a sample by environmental/explanatory variables matrix. In our examples, toxicity values, contaminant concentrations and physico-chemical parameters play the part of the species; and time, geographical position, chemical treatment and molecule characteristics play the part of explanatory variables. c
... Sweep nets have been widely used many arthropods studies (e.g. Scharff and Griswold 1996;Dippenaar-Schoeman et al. 1999a;Russell-Smith 1999;Frampton et al. 2001;Oyediran and Heinrichs 2001). ...
Spiders were sampled at Mpala Research Centre, Laikipia, Kenya by pitfall-trapping and sweep-netting from May 2001 to July 2002, at a Kenyan Long-term Exclosure Experiment. The aim was to establish species composition, checklist and examine spider responses to disturbances caused by cattle, megaherbivores (giraffe and elephants) and mesoherbivores (other ungulates) by looking at three levels of resolution, namely the overall community, guilds and individual species. This is the first controlled replicated experimental study on the effects on invertebrates (spiders) by different land uses (access by large herbivores). A total of 10,487 individuals from 132 species belonging to 30 families were recorded. The family Salticidae had the highest number of species (24), followed by Gnaphosidae (20), Araneidae and Lycosidae (15 each), Theridiidae and Thomisidae (8 each) and Zodariidae (4). Most of the other families had fewer than 4 species. Throughout the study period, species not previously sampled emerged after rainfall peaks. Exclosure treatments affected plant cover, spider diversity and total species mainly through the effects of cattle, whose presence significantly reduced relative vegetation cover. An increase in vegetation cover significantly increased the diversity, total species and species evenness of the overall spider community (total samples data set). Megaherbivores and mesoherbivores had no effects on overall spider diversity. Relative vegetation cover explained approximately 20-30 % of variation in community diversity, species richness and species evenness. At the guild level of resolution, the exclosure treatments had no significant effects on diversity, species richness and species evenness of web builders, plant wanderers and ground wanderers. Plant wanderers were significantly and positively correlated with relative vegetation cover, which explained 17% of variation in their diversity. Six individual species responded strongly and in contrasting ways to the same environmental variables, indicating that this level was more sensitive to environmental changes than guilds or the overall spider community. Spider diversity, relative vegetation cover and rainfall varied at a temporal scale of months and not at a spatial scale of hundreds of metres. Only species diversity and species richness from sweep-netting samples and total species from pitfall-trapping varied significantly at a spatial scale of hundreds of metres. Ordination analysis revealed that sweep-netting samples were a better indicator of grazing impacts than pitfalltrapping or combined samples and grouped to reflect cattle grazing, non-cattle grazing and to a small extent the control treatments. Other ordination analyses showed that only samples from sweep-netting and not from pitfall-trapping, were spatially partitioned at a scale of hundreds of metres. This study concludes that the spider fauna of black cotton soil habitats is rich and useful for environmental monitoring and that monitoring of several individual species as indicator of grazing impacts in savanna could be useful and relatively easy.
... Other factors that might affect prey choice include vertical stratification of different Collembola species within the soil (Faber & Joosse 1993) affecting encounter rates with spiders (although the Collembola targeted in our study are all considered to be primarily surface-active species). Similarly, different Collembola species have different diel activity patterns and responses to temperature (Frampton et al. 2001), which will interact in complex ways with the hunting strategies and activity patterns of different species of spider, again affecting encounter rates. For whatever reason, the spiders showed strong preference for I. anglicana, and cultural techniques that might enhance densities of this species could help to increase spider numbers and hence control of pests such as aphids. ...
Collembola comprise a major source of alternative prey to linyphiid spiders in arable fields, helping to sustain and retain these predators as aphid control agents within the crop. Polymerase chain reaction primers were developed for the amplification, from spider gut samples, of DNA from three of the most abundant species of Collembola in wheat crops in Europe, namely Isotoma anglicana, Lepidocyrtus cyaneus and Entomobrya multifasciata. The primers amplified fragments of the mitochondrial cytochrome oxidase subunit I (COI) gene and were designed following alignment of comparable sequences for a range of predator and prey species. Each of the primer pairs proved to be species-specific to a Collembola species, amplifying DNA fragments from 211 to 276 base pairs in length. Following consumption of a single collembolan, prey DNA was detectable in 100% of spiders after 24 h of digestion. We report the first use of DNA-based techniques to detect predation by arthropods on natural populations of prey in the field. All three species of Collembola were consumed by the spiders. By comparing the ratios of the Collembola species in the field with the numbers of spiders that gave positive results for each of those species, it was possible to demonstrate that the spiders were exercising prey choice. Overall, a single target species of Collembola was eaten by 48% of spiders while a further 16% of spiders contained DNA from two different species of Collembola. Preference was particularly evident for I. anglicana, the species most frequently found in spider guts yet the least numerous of the three target species in the field.
Heavily modified water bodies (HMWB) have been seriously affected by human activities and natural processes promoting their imbalance, and impacting their functioning and biodiversity. This study explores a new approach of monitoring and assessing water quality in Mediterranean reservoirs using phytoplankton communities across a disturbance gradient, according to water framework directive. Phytoplankton and environmental data were sampled in 34 reservoirs over 8 years. Two types of reservoirs were analyzed: Type1 “run-of-river reservoirs” (located in the main rivers, with a low residence time); and Type2 “true reservoirs” (located in tributaries, with high residence time). The transition from deeper and colder reservoirs (reference sites) to shallow and warmer (impaired sites) was clear in Type2, correlated to organic pollution and mineral gradients. Impaired sites from both types showed a higher richness of tolerant taxa. Principal response curve (PRC) provided a concise summary of phytoplankton temporal dynamics and assessed ecosystem health for Mediterranean HMWBs. PRC will provide a powerful tool for environmental quality assessment and be incorporated into monitoring and assessment programs. This approach can help policymakers to manage natural capital to achieve multiple objectives, mainly increasing ecosystem services, and improve readability and interpretation of spatial patterns in temporal changes.
Generalist invertebrate predators are sensitive to weather conditions, but the relationship between their trophic interactions and weather is poorly understood. This study investigates how weather affects the identity and frequency of spider trophic interactions over time, alongside prey community structure, web characteristics and prey choice. Spiders (Linyphiidae and Lycosidae) and their prey were collected from barley fields in Wales, UK, from April to September 2017-2018. The gut contents of 300 spiders were screened using DNA metabarcoding, analysed via multivariate models and compared against prey availability using null models. When linyphiids were collected from webs, the height and area of webs were recorded and compared against weather conditions. Trophic interactions changed over time and with weather conditions, primarily related to concomitant changes in prey communities. Spiders did, however, appear to mitigate the effects of structural changes in prey communities through changing prey preferences according to prevailing weather conditions, possibly facilitated by adaptive web construction. Using these findings, we demonstrate that prey choice data collected under different weather conditions can be used to refine inter-annual predictions of spider trophic interactions, although prey abundance was secondary to diversity in driving the diet of these spiders. By improving our understanding of the interaction between trophic interactions and weather, we can better predict how ecological networks are likely to change over time in response to variation in weather conditions and, more urgently, global climate change.
In this study, the abundance and biodiversity of the soil macrofauna under two
different plants coverages (Rosaceae shrubs and conifers) were investigated
using pitfall trap in Choqasabz Forest Park (Ilam province). This research was
carried out from April to September 2015 with two treatments (different plants
coverages) and five replications. Every 20 days, trapped specimens were
collected in pitfall traps and then counted and identified. During this study, a
total of 4,613 specimens were collected belonging to eight orders and 13
families of insects, and a single family of spiders. Results showed that the
families Formicidae and Carabidae and orders Collembola and Diptera were the
most abundant arthropods in pitfall trapps. Between Rosaceae and conifer
plants, there was a significant difference in the number of insects belongs to
Collembola (t(138)=2.97, P=0.004), Carabidae (t(138)=2.93, P=0.004), and
Noctuidae (t(138)=2.91, P=0.004), while there was not a significant difference
in the number of arthropods belongs to Formicidae (t (138)=0.83, P=0.406),
Chrysopidae (t (138)=0.103, P=0.918), Diptera (t (138)=1.15, P=0.253),
Orthoptera (t (138)=1.543, P=0.125), Heteroptera (t (138)=1.11, P=0.267),
insect larva (t (138)=0.816, P=0.416) and spiders (t (138)=0.420, P=0.675). The
most number of Collebmbola individuals were collected only in spring months
and after that their density reduced considerably. Collembola and Noctuidae
had significantly more density under Rosaceae than conifers while Carabidae
had more densities under conifers. Arthropods have a valueble role in soil
fertilization, nutrient cycling, plant production, decomposing matters in nature
and regulation of other animal population. The results of this study could be
useful in conservation and sustainable management of biodiversity in
Choqasabz Forest Park.
Agroforestry can improve predator recruitment by increasing the diversity of microhabitats and modifying the microclimate. Four treatment plots were defined with three tree-shading levels in a 20 years old agroforestry system combining organic vegetable crops with hybrid walnut trees. Temperature and canopy openness were recorded in each treatment in July and September 2015 and arthropods were sampled using pitfall traps at two dates (2 weeks in July and 2 weeks in September). The daily activity pattern of the main taxa was then estimated using dry pitfall traps for 7 days in July and 8 days in September. Agroforestry significantly limited the daily temperature extremes in the day and night (± 1.5 °C). We observed a significant effect of treatment on species distribution. In July, the main xerophilic species, Pseudoophonus rufipes (Coleoptera, Carabidae), was less abundant in the two most shaded plots (− 25%). Pardosa hortensis (Arachnida, Lycosidae) showed significant differences in activity-density and diurnal activity between treatments. This spider was more active between 10:00 and 14:00 in the two most shaded treatments especially in tomatoes (more than 20% of the daily activity) compared to the control (13%). The activity-density of this species was also higher in the two shaded treatments than in the control (> 20%). Our results highlight that agroforestry, by buffering climate extremes, is likely to modify predatory arthropod activity and possibly the associated services such as biocontrol.
1. Activity patterns of arthropods lead to consistent changes in community composition in many ecosystems, but this daily turnover in community membership is poorly characterised. This study used passive collection methods of ground and air active arthropods, feeding guild assignment, and body size measurements to characterise changes in a terrestrial arthropod community between consecutive 4‐h time intervals.
2. We found that arthropod communities are highly structured in time, with the time of sample collection significantly affecting family richness, relative abundance, abundance of feeding guilds, community dissimilarity, community turnover rates, and average body sizes within taxonomic orders.
3. Community dissimilarity is periodic on two timescales, 12 and 24 h. Morning and evening communities were similar to each other and supported a unique assemblage that occurred during the transition from highly dissimilar night and day arthropod communities.
4. The results offered support for previous findings that night‐active arthropods are generally larger than day‐active ones, with the pattern holding for some but not all orders.
5. These findings demonstrate that species‐specific daily activity patterns influence community composition in a predictable manner, with characteristic repeating time communities within a single habitat.
Field studies represent a powerful tool in the environmental risk assessment process. The
results may be usefully applied to risk assessment problems to provide added realism and
reduced uncertainty. For this to be the case, however, proper study design and appropriate
statistical analysis is required. Multivariate analyses, where appropriate, should be
accompanied by univariate analyses, visual inspection of the data and ecological
interpretation. This report provides discussion around many key issues of relevance to
ecotoxicological community effect field studies.
The effect of starvation on the behavioural response of three common hemiedaphic collembolan species Hypogastrura assimilis (H. assimilis), Isotoma notabilis (I. notabilis) and Proisotoma minuta (P. minuta) to light was examined. Adults of all the three species were shown to respond negatively to light, as approximately 40% of the H. assimilis, 20% of the P. minuta and 30% of the I. notabilis were recorded in the light area of the arena. However, when adults of H. assimilis were starved, they became increasingly attracted to light with increasing length of the starvation period and after 5 d of starvation, 83% were recorded in the light area. Starvation was not observed to change the behaviour of the other two species. Following these experiments, the effect of starvation on the response to gravity was tested for H. assimilis by placing individuals on a 15° slope. At day 0 of the starvation period, half of the specimens were recorded to move down the slope whilst the other half remained in the middle compartment; none were observed to move upwards. After 1 d of starvation, the proportion of collembolans moving downwards had reduced to 17% and remained low for the following 4 d of starvation. The proportion of collembolans that moved upwards increased significantly during the starvation period from 0% on day 0 to 28% on day 5 of the starvation period. © 2003 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
Data on the species composition, structure, and seasonal changes in the dynamic density of surfaceactive Collembola communities in meadows and forests of Moscow Province are provided. A total of 27 epigeic species were recorded from May to October in four biotopes (18–24 in each biotope) using pitfall traps. All of the communities studied consist of 1–2 dominant species, several subdominants, and 11–19 rare species, with the prevalence of Entomobryomorpha and Symphypleona. The springtail communities in the studied forest and meadow biotopes are very similar in species composition but differ in the relative abundance of individual species. The total dynamic density of epigeic species was shown to vary during the season, being significantly dependent on the type of biotope and the time of survey. The maximum density was recorded at the beginning of the active season (May–June); the minimum density was observed in August.
A gradient of agricultural intensification (from permanent meadows to permanent crops, with rotation crops and meadows as intermediary steps) was studied in the course of the RMQS-Biodiv program, covering a regular grid of 109 sites spread over the whole area of French Brittany. Soil biota (earthworms, other macrofauna, microarthropods, nematodes, microorganisms) were sampled according to a standardized procedure, together with visual assessment of a Humus Index. We hypothesized that soil animal and microbial communities were increasingly disturbed along this gradient, resulting in decreasing species richness and decreasing abundance of most sensitive species groups. We also hypothesized that the application of organic matter could compensate for the negative effects of agricultural intensity by increasing the abundance of fauna relying directly on soil organic matter for their food requirements, i.e. saprophagous invertebrates. We show that studied animal and microbial groups, with the exception of epigeic springtails, are negatively affected by the intensity of agriculture, meadows and crops in rotation exhibiting features similar to their permanent counterparts. The latter result was interpreted as a rapid adaptation of soil biotic communities to periodic changes in land use provided the agricultural landscape remains stable. The application of pig and chicken slurry, of current practice in the study region, alone or in complement to mineral fertilization, proves to be favorable to saprophagous macrofauna and bacterivorous nematodes. A composite biotic index is proposed to synthesize our results, based on a selection of animals groups which responded the most to agricultural intensification or organic matter application: anecic earthworms, endogeic earthworms, macrofauna other than earthworms (macroarthropods and mollusks), saprophagous macrofauna other than earthworms (macroarthropods and mollusks), epigeic springtails, phytoparasitic nematodes, bacterivorous nematodes and microbial biomass. This composite index allowed scoring land uses and agricultural practices on the base of simple morphological traits of soil animals without identification at species level.
To compare the effects of a drought disturbance on species of Oribatida and Collembola, and subsequent recovery of their populations after the drought, we examined a Norway spruce, Picea abies, stand in south-western Sweden, where 6 years of experimentally induced summer droughts had resulted in major changes in the soil faunal communities. We followed the population densities during a 4-year period and sought correlations between the species’ drought responses and their ecological characteristics. Data on depth preference, habitat choice and reproductive mode were collected from the literature. Surface-living species, which tended to have narrow habitat width, were less negatively affected by the drought. However, among species showing negative population responses to drought, species with large habitat widths tended to recover faster after the drought. Furthermore, parthenogenesis was more common among the oribatid species that showed a population recovery than among those that did not. Overall, collembolan species recovered faster than oribatids, and among the species that did not recover, Oribatida were over-represented. No general differences in characteristics between oribatids and collembolans were observed that could explain their different responses. Possibly, traits other than those examined were more important, such as differences in dispersal rates between the two groups.
Springtails are an integral and beneficial part of the soil community. As part of an extensive study of the effect of rootworm Bt corn (Cry3Bb1) on nontarget invertebrates, we evaluated both the abundance and diversity of surface-active (epedaphic) and subsurface (euedaphic) springtails at Ames, IA, and Monmouth, IL, in 2-yr field trials during 2000-2002. Springtails were collected from pitfall traps and soil cores in plots planted with rootworm Bt corn and its non-Bt isoline. Few differences were observed in the abundance of individual species in Bt and isoline corn. Nor did the estimated species richness or the Shannon or Simpson diversity indices differ significantly between Bt and isoline corn at either location during 2000-2002, indicating no effect of Bt corn on springtail diversity. In soil insecticide-treated plots, however, springtails were consistently more abundant than in check plots, perhaps because of adverse insecticide effects on springtail predators. Soil insecticide also reduced both Shannon and Simpson diversity in the Iowa euedaphic and Illinois epedaphic populations. Such consistent insecticide effects on both abundance and diversity of springtails provide a positive control by which to assess the power of the experimental design to detect a comparable impact of Bt corn on springtails. They also show that insecticide use more strongly impacts springtails and their predators than does the practice of growing transgenic crops to control the same pests.
This study was done in San Salvador and El Bondho, Mezquital valley, Hidalgo State, Mexico, with the aim of comparing the Collembola community from two plots with the same edaphic classification: San Salvador is irrigated with waste water (residual water) from Mexico City, and El Bondho, is watered from a well (sweet water). A total of 5967 Collembola from 31 species were obtained of which 19 are new records for Hidalgo State; 4833 specimens were from San Salvador and 1134 from El Bondho. Their species richness was 29 and 19, respectively. Dominant species both in abundance and frequency were Proisotoma minuta, Cryptopygus thermophilus, Xenylla grisea and Hypogastrura essa at San Salvador. Diversity and evenness were higher there than in El Bondho; in addition the species richness was lower than at San Salvador; mainly due to the dominant species. Similarity coefficient shows a disturbance in the composition of the Collembola communities, with only 70% of similarity among both plots. The irrigation type affects the density of some species like X. grisea, Folsomides parvulus, Cryptopygus ca. benhami, Pseudosinella octopunctata and C. thermophilus and composition in both plots while Lepidocyrtus violaceus, Pseudosinella violenta and Sphaeridia serrata are affected by irrigation kind and sampling date.Soil properties, such pH, EC, OM and exchangeable contents of cations (Mg2+, Na+) appear to affect the composition and abundance of the Collembola communities.
To examine the resilience of soil animal communities to large-scale disturbances. we studied the recovery of total abundance, diversity and community composition of forest soil mesofauna after a 6-year climatic disturbance. This was done in a pre-established experiment in a Norway spruce Picea abies stand in southern Sweden in which long-term summer droughts had been experimentally imposed and had caused large changes in soil fauna communities. We included both predators (mesostigmatid mites) and fungivores/detritivores (oribatid mites, collembolans) in the study because of the likelihood that they would differ in recovery ability due to differences in their feeding habits, dispersal ability and reproductive strategies. Total abundances of Collembola, Oribatida and Mesostigmata were similar in recovery and control plots after three years, but species richness, the Shannon-Wiener diversity index, and community composition recovered more slowly, particularly among the Oribatida. To only use total abundance of higher taxonomic groups was thus not sufficient when measuring community recovery. There was a tendency for more mobile groups to recover faster than the slow-moving oribatids, indicating the importance of dispersal ability for the resilience of soil communities.
A laboratory mesocosm experiment was performed to study the effects of copper-enriched sewage sludge application on a mesofauna community. For 12weeks, characteristics and changes in this defined and artificial mesofauna community structure were monitored as well as the dynamics of leaf litter decomposition. The mesofauna community comprised six species of Collembola (Folsomia fimetaria, Isotomurus prasinus, Lepidocyrtus cyaneus, Mesaphorura macrochaeta, Parisotoma notabilis, Protaphorura armata), two species of acari Oribatida (Achipteria coleoptrata, Adoristes sp.), one species of acari Gamasida (Hypoaspis aculeifer) and one species of enchytraeid (Enchytraeus crypticus). Three treatments included the addition of 22g dry weight (DW) sludge spiked with 0, 200 and 1,000mg Cu kg−1 DW sludge in each mesocosm, and one treatment had 66g DW sludge spiked with 1,000mg Cu kg−1 DW sludge added in each mesocosm. Copper, complexed with sludge due to a favourable pH, had no effect on community and litter parameters when added to low amount of sludge. In contrast, tripling the sludge dose in addition to a high dose of Cu changed in time the sludge and leaf chemical composition as well as mesofauna community structure. Responses of the mesofauna to this treatment differed between species. The abundance of species such as I. prasinus, L. cyaneus, M. macrochaeta and P. notabilis decreased, whereas the abundance of H. aculeifer increased and became dominant.
Effects of sewage sludge on litter mesofauna communities (Collembola and Acari) and cork oak (Quercus suber L.) leaf litter decomposition have been studied during 18 mo using litterbags in an in situ experimental forest firebreak in southeastern France. The sludge (2.74 t DM ha(-1) yr(-1)) was applied to fertilize and maintain a pasture created on the firebreak. Litterbag colonization had similar dynamics on both the control and fertilized plots and followed a typical Mediterranean pattern showing a greater abundance in spring and autumn and a lower abundance in summer. After 9 mo of litter colonization, Collembola and Acari, but mainly Oribatida, were more abundant on the sludge-fertilized plot. Leaf litter decomposition showed a similar pattern on both plots, but it was faster on the control plot. Furthermore, leaves from the fertilized plot were characterized by greater nitrogen content. Both chemical composition of leaves and sludges and the decomposition state of leaves have significantly affected the mesofauna community composition from each plot.
In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)–pH–alkalinity–conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
1. A 24 h time-sorting pitfall trap was used to collect Carabidae in a field in north-east England in 1974, 1976 and 1977.2. Harpalus rufipes comprised 62% of the 5288 adult Carabidae caught. It was nocturnal, with an activity peak after midnight. The male activity pattern lagged behind that of females by about 1 h. The activity peak shifted to earlier in the night during September.3. Activity curves are given for eighteen other common species. Large species were all nocturnal, but a third of the smaller species were active in the day. The numbers caught of twenty-eight less common species are tabulated and show the same trend. Overall, nearly 60% of all species caught were nocturnal and 20% diurnal; the remainder did not show a distinct pattern of day or night activity.4. A total of eighty-two larvae of H.rufipes, Nebria brevicollis and Notiophilus biguttatus were caught, and showed similar activity patterns to those of the respective adult beetles.
Experiments in microcosms and mesocosms, which can be carried out in an advanced tier of risk assessment, usually result in large data sets on the dynamics of biological communities of treated and control cosms. Multivariate techniques are an accepted tool to evaluate the community treatment effects resulting from these complex experiments. In this paper two methods of multivariate analysis are discussed on their merits: 1) the canonical ordination technique Principal Response Curves (PRC) and 2) the similarity indices of Bray-Curtis and Stander. For this, the data sets of a microcosm experiment were used to simultaneously study the impact of nutrient loading and insecticide application. Both similarity indices display, in a single graph, the total effect size against time and do not allow a direct interpretation down to the taxon level. In the PRC method, the principal components of the treatment effects are plotted against time. Since the species of the example data sets, react in qualitatively different ways to the treatments, more than one PRC is needed for a proper description of the treatment effects. The first PRC of one of the data sets describes the effects due to the chlorpyrifos addition, the second one the effects as a result of the nutrient loading. The resulting principal response curves jointly summarize the essential features of the response curves of the individual taxa. This paper goes beyond the first PRC to visualize the effects of chemicals at the community level. In both multivariate analysis methods the statistical significance of the effects can be assessed by Monte Carlo permutation testing.
Samples (679) from various forest sites in the atlantic temperate region (lowlands in the northern half of France) have been studied. Their Collembolan species composition 145 species, with only 43 rare species) was analysed by Benzecri's correspondence analysis, a multivariate method. Five groups of species, each associated with a given habitat, were determined: above the ground surface a distinction is evident between light species (open sites), hygrophilic species (moist forest sites) and corticolous species (dry forest sites); edaphic species may be divided into acidophilic species (mor, moder and acid mull humus) and neutroacidocline species (earthworm mull). A depth gradient may be traced from edaphic to atmobiotic species in both forest and open sites. As a conclusion, it is apparent that vegetation in itself does not directly influence Collembola but may effect them indirectly through humus formation.
It has been widely assumed that Collembola respond to light, but until now there has been very little experimental proof of this. Field observations allowed to distinguish soil-dwelling species that would escape from light from surface-dwelling species that would be attracted to light. However, the supposed effect of light could be due to other factors such as temperature or dryness. We demonstrated that individuals of the collembolan species Heteromurus nitidus (Entomobryidae), when placed in a light gradient (temperature and moisture being homogeneous), clustered in the darker area. This effect occurred rapidly and changes in the distribution of animals persisted after illumination ceased. This shows light to act as a strong repellent for this soil-dwelling collembolan species.
p>Carbendazim (a selective fungicide) and the broad-spectrum compounds propiconazole, pyrazophos and triadimenol were screened in the laboratory to assess their toxicity to Sminthurinus aureus and all caused significant increases in mortality, pyrazophos being the most toxic. White sand and plaster of Paris were unsuitable as substrates for Collembola in toxicological experiments. Suction (D-vac) sampling in winter barley in 1985 showed that pyrazophos applied to replicated plots of area c. 2.7 ha significantly reduced populations of five out of 11 species of surface-dwelling Collembola ( Sminthurus viridis, Sminthurinus elegans, S. aureus, Jeannenotia stachi and Isotoma viridis ). Reductions in populations were large when compared with the effects of the broad-spectrum insecticide dimethoate. Suction and pitfall trap sampling in winter wheat in 1986 showed that populations of seven out of 13 surface-dwelling Collembola species ( S. viridis, S. elegans, Deuterosminthurus spp., J. stachi, Pseudosinella alba, Lepidocyrtus cyaneus and I. viridis ) were significantly reduced by applications of carbendazim, propiconazole and triadimenol to replicated 10m x 10m barriered and unbarriered plots. Nearly all the significant effects were in unbarriered plots and few ere detected by pitfall-trapping. Temporal patterns in populations of Collembola in wheat were investigated in summer 1987. All species exhibited a diurnal peak in catches on several dates, in contrast to the results of some other studies. Plant-climbing species were identified by sweep net sampling. The efficiencies of different methods for sampling surface-dwelling Collembola were compared and the number of samples needed for accurate sampling determined. The relevance of a correction for spatial variability in pre-treatment insect counts is discussed. The limitations of this and other recent pesticide studies are considered and recommendations for improvements are proposed.</p
A time-sorting pitfall trap was used to collect Carabidae, Staphylinidae and Collembola in a heavily grazed pasture in Belgium, Melle, E Flanders. Activity curves are given for all numerous species; data on less common species are tabulated. Overall, data are discussed on 43 carabid species, 36 staphylinid species and 7 collembolan species. Information on beetle larvae is added.-Authors
In the N Chihuahuan Desert, migration occurs in some taxa (Speleorchestes sp. (Nanorchestidae) and Spinibdella cronini (Bdellidae)). Other taxa (Cunaxa spp. (Cunaxidae), Eupodes (?) sp. (Eupodidae), Isotominae and Neanurinae (Collembola), Liposcelis sp. (Psocoptera)) enter a cryptobiotic state and remain in the litter during the day. -from Authors
In this paper a novel multivariate method is proposed for the analysis of community response data from designed experiments repeatedly sampled in time. The long-term effects of the insecticide chlorpyrifos on the invertebrate community and the dissolved oxygen (DO)-pH-alkalinity-conductivity syndrome, in outdoor experimental ditches, are used as example data. The new method, which we have named the principal response curve method (PRC), is based on redundancy analysis (RDA), adjusted for overall changes in community response over time, as observed in control test systems. This allows the method to focus on the time-dependent treatment effects. The principal component is plotted against time, yielding a principal response curve of the community for each treatment. The PRC method distills the complexity of time-dependent, community-level effects of pollutants into a graphic form that can be appreciated more readily than the results of other currently available multivariate techniques. The PRC method also enables a quantitative interpretation of effects towards the species level.
Contiguous winter wheat fields of similar cropping history and soil type were used in a study of the responses of Collembola to summer sprays of cypermethrin and pirimicarb in southern England. Chlorpyrifos was included in the study as a toxic standard. Epigeic arthropods were captured by suction sampling and crop-inhabiting species obtained by dissecting wheat ears. Eight genera of Collembola responded significantly to the insecticide treatments. Collembolan abundance decreased after chlorpyrifos was applied but increased after use of cypermethrin. Negative effects of cypermethrin and pirimicarb on Collembola were not detected in this study. Effects of chlorpyrifos varied spatially as a result of faunal heterogeneity among the fields, despite apparent homogeneity of the site. Some species known to be susceptible to chlorpyrifos were absent from one or more of the fields. The implications of these findings for the interpretation of non-target pesticide effects and the potential use of Collembola as bioindicators in field studies with pesticides are discussed. (C) 1999 Society of Chemical Industry.
Replication of experimental treatments is necessary for the unambiguous interpretation of pesticide effects on wildlife using statistical hypothesis testing but is incompatible with the large temporal and spatial scales required for a fully realistic field study. In this paper I consider the pros and cons of some large-scale experimental approaches used during the last two decades in England to investigate long-term effects of pesticide use on arthropods and other farmland wildlife. I present a potential solution to the trade-off between scale and replication in long-term studies which may be particularly appropriate for patchily-distributed species. Advantages of the recently-developed multivariate analysis method Principal Response Curves (PRC) for interpreting long-term effects of pesticides on arthropods at the community level are discussed.
We examined the extent to which depletion of local carabid populations and disturbance of trap sites can influence estimates of overall catch, seasonal occurrence, and community structure of carabid beetles that are obtained using pitfall traps. A 3x3 factorial experiment was used, wherein trap stations were placed at three distances from one another (10, 25 or 50 m), and were subjected to three different trapping methods (permanent, disturbed, or revolving) over 8 weeks in 1993. Overall, fewer carabids were captured in traps at the 10 metre spacing (indicating depletion occurred) and in permanent traps (indicating a disturbance effect), but reponses to treatments varied among the four most abundant species. Permanent traps and those at the 10 metre spacing were less sensitive to changes in activity over time, and both types of treatments generated patterns within trapping periods as well as over the course of the entire experiment. The most similar species assemblages and the fewest rare species were found in traps at the 10 metre spacing; disturbed traps had higher species richness but lower evenness than permanent traps. These results suggest that disturbance and depletion can affect pitfall catches of carabid beetles in forest environments. This information should aid in the of design pitfall studies with minimal unknown bias.
(1) In 1973 vacuum and sweep net samples were taken from spring barley and sweep samples from winter wheat at regular intervals throughout a 24-h cycle. In 1974 sweep net samples were taken from spring barley and winter wheat and the ground zone fauna was sampled with a pooter. (2) In both 1973 and 1974 the gut contents of arthropod predators sampled were examined for aphid remains. In 1974 the precipitin test was also used to detect aphid feeding. (3) In 1973 large differences were found between arthropod taxa present in vacuum and sweep net samples taken at different times of the 24-h cycle. The largest differences were in the numbers of Thysanoptera and Coleoptera. More Thysanoptera were found during the day and more Coleoptera at night. (4) More polyphagous predators were found in vacuum (x3) and sweep net samples (x20) at night in 1973. A similar pattern was evident in 1974. (5) In both 1973 and 1974 many of the polyphagous predators, including Staphylinidae, Carabidae, Dermaptera and Araneae, fed on aphids. (6) More polyphagous predators fed on aphids at night. For example, 17% of the predators from vacuum samples taken at 15.00 hours contained aphids, compared with 67% at 03.00 hours.
1. The floor of a wood is shown to yield higher pitfall captures than either an open scrub or a ley, and this is considered to be due to the presence of a distinct litter layer. 2. Distribution of locomotor activity, as measured by pitfalls, is more uniform throughout the twenty-four hour day-night cycle in the wood than in the scrub. This difference is not simply the result of the damping of climatic fluctuations in the wood, but is again related to the litter which provides extra food and extra retreats during periods of inactivity. 3. It is concluded that these results support the hypothesis that more complex communities have a more symmetrical disposition of activity than simpler communities.
The prime object of this book is to put into the hands of research workers, and especially of biologists, the means of applying statistical tests accurately to numerical data accumulated in their own laboratories or available in the literature.
The book is organized into 10 chapters: general introduction; review of the literatire on springtails; evolution, systematics and biogeography; ecomorphology and anatomy; taxonomic methods and the species concept in Collembola; interactions between Collembola and the abiotic environment; interactions between Collembola and the biotic environment; reproduction, development and life histories; ecology and conservation; and ecotoxicology. There are three appendices: World genera of Collembola; regional checklists of Collembola; and laboratory/field studies on the effects of chemicals on Collembola.
A RECENT letter in NATURE1 directed attention to instances of swarming of certain species of Collembola. It was stated that ``In most ... cases ... (if not all) the factor producing this phenomenon would seem to be the relative abundance of the food supply''. In another instance it was suggested that ``migration may account for swarming''.
Contiguous winter wheat fields of similar cropping history and soil type were used in a study of the responses of Collembola to summer sprays of cypermethrin and pirimicarb in southern England. Chlorpyrifos was included in the study as a toxic standard. Epigeic arthropods were captured by suction sampling and crop-inhabiting species obtained by dissecting wheat ears. Eight genera of Collembola responded significantly to the insecticide treatments. Collembolan abundance decreased after chlorpyrifos was applied but increased after use of cypermethrin. Negative effects of cypermethrin and pirimicarb on Collembola were not detected in this study. Effects of chlorpyrifos varied spatially as a result of faunal heterogeneity among the fields, despite apparent homogeneity of the site. Some species known to be susceptible to chlorpyrifos were absent from one or more of the fields. The implications of these findings for the interpretation of non-target pesticide effects and the potential use of Collembola as bioindicators in field studies with pesticides are discussed.© 1999 Society of Chemical Industry
(1) The arthropod faunas of herbicide-treated and untreated headland plots of a spring wheat crop were compared in a replicated within-field experiment in Hampshire, England. (2) Unsprayed headland plots had more weed species, higher weed densities, greater weed biomass and a higher percentage weed cover. (3) Unsprayed headland plots supported significantly higher densities of non-target arthropods, especially the non-pest species which are important in the diet of insect-eating gamebird chicks. These plots also contained higher densities of predatory arthropod groups, especially the polyphagous species and their alternative prey. (4) Within plywood enclosures placed in treated and untreated headland plots, no significant between-treatment differences were found in the total pitfall trap catch of the two most numerous carabid beetle species, Pterostichus melanarius (Illiger) and Agonum dorsale (Pontoppidan). However, a significantly greater proportion of female A. dorsale were caught in the enclosures in treated plots than in untreated plots. (5) Dissection revealed that significantly more gut sections of gravid and non-gravid female and male P. melanarius and gravid female and male A. dorsale from untreated plots contained solid arthropod food remains. Both carabids had also taken significantly more meals and preyed upon a wider variety of arthropod food in untreated plots. As a consequence fewer cereal aphids were consumed by beetles in unsprayed plots. (6) Higher numbers of eggs per female were found for both species of carabid beetle collected from untreated plots. (7) The consequences of the changes in the pesticide use on the edges of cereal fields to pest-predator relationships are discussed.
The formation and biological significance of aggregations of 6 species of surface dwelling Collembola of a coniferous forest soil were studied. The species are: Tomocerus minor (Lubbock), Lepidocyrtus cyaneus Tullberg, Orchesella cincta (Linné), Entomobrya nivalis (Linné), Isotomurus palustris (Müller) and Isotoma viridis Bourlet. All species showed a marked aggregation, but to a different degree and in different places, since the degree of aggregation of total Collembola appeared to be less than that of the individual species. The different degree of aggregation could not only in field studies, but also in laboratory experiments be related to the specific humidity preferences of the species. The stenohygric species Lepidocyrtus cyaneus, Isotoma viridis and Tomocerus minor appeared to have a high degree of aggregation, the euryhygric species Orchesella cincta and Entomobrya nivalis a lower one. The observations contribute to the view that aggregation is the result of the coming together of individuals by undirected movements in sites with optimum humidity conditions, the specific movements being stimulated by drought. The biological significance of aggregation is described as a protectional function (survival, moulting) and as a meeting system where reproductive behaviour is not yet developed.
The significance of variations in soil moisture for the distribution and abundance of the four collembolan species Tomocerus minor, Orchesella cincta. Lepidocyrtus lignorum and Entomnbrya nivalis has been studied in a pine forest. During a relatively dry summer, the distribution and abundance of these species were examined on two sites with an initially different soil water content and depth of the titter/humus layer. The distribution of the species investigated could be described with the negative binomial distribution. During the sampling period. Lloyd's “index of patchiness”, x̄/x̄ for T. minor and E. nivalis was subject to changes. For T. minor this was probably related to soil water content.
The densities of T. minor and O. cincta were higher in the wet site than in the drier site. At the beginning and at the end of the sampling period the drought tolerant E. nivalis reached equal densities in both sites. The density fluctuations of the four species appeared to be totally different during the sampling period: the drought sensitive species T. minor decreased strongly, L. lignorum remained constant and the drought tolerant species O. cincta and E. nivalis increased strongly. These latter two species were able to survive the dry periods and to attain high densities by reproduction. The results agree with laboratory data on distribution and survival in relation to humidity.
1. Information is lacking on how possible future changes in the seasonal occurrence and intensity of precipitation in Europe will affect the arthropod community of arable farmland.
2. We used a novel experimental approach to investigate the responses of farmland arthropods to spring precipitation in a spring-sown legume. Replicated plots were subjected to spring drought (plots shielded from rainfall), actual rainfall (reference) and spring irrigation. Shielding plots extended an existing drought to 58 days.
3. The response of epigeic arthropods was investigated using principal components analysis (PCA) and principal response curves (PRC). Temporal changes in treatment effects at the community level were more clearly displayed by PRC than by PCA, while PRC improved the interpretation of individual species' responses. PRC analysis has potential for wider application in ecological experiments and monitoring.
4. Short-term manipulation of precipitation in May affected the arthropod community for at least 97 days, despite exceptionally high rainfall in June. The effects of drought on the abundance of herbivores, mycophages, omnivores and predators were negative, while those of irrigation were positive. There were no differences in the responses of beneficial and pest taxa.
5. In addition to their intrinsic importance, these findings illustrate that spring weather might affect the availability of arthropod prey for insectivorous wildlife. Food availability has been implicated in the population declines of several insectivorous farmland birds.
6. The difficulty of manipulating rainfall in a temperate climate precludes realistic field studies of how farmland arthropods respond to precipitation. We suggest that automated rain shielding of experimental plots provides a technique for wider application in drought studies.
More than 6500 species of Collembola are known from throughout the world and these are only a small part of the still undescribed species. There are many checklists and catalogues of Collembola for smaller territories and entire continents. Biogeographical analyses have been made for some genera and smaller territories. The most serious problems for a global biogeographical analysis is the lack of enough records from immense territories of all continents. Local biodiversity of Collembola can be very high, reaching over 100 species in small mountain ranges. Sampling methods do not impede documenting biodiversity on a global scale. Collembola have well differentiated ecomorphological life-forms and feeding guilds which enable the functional role that Collembola play in ecosystems to be recognised in some degree. Collembola play an important role in plant litter decomposition processes and in forming soil microstructure. They are hosts of many parasitic Protozoa, Nematoda, Trematoda and pathogenic bacteria and in turn are attacked by different predators. They utilise as food Protozoa, Nematoda, Rotatoria, Enchytraeidae, invertebrate carrion, bacteria, fungi, algae, plant litter, live plant tissues, and some plant pathogens. Soil acidification, nitrogen supply, global climate change and intensive farming have greatly impacted collembolan diversity.
Temperature is limiting for the snow surface activity ofIsotoma hiemalis: values below a threshold of –2.5 to –3C are avoided. Changing barometric pressure leads to increased surface activity, thus being responsible for mass appearances. These experiments provide the first evidence for sensitivity to and reaction to barometric pressure changes in insects.
The influence of several mechanical field disturbances, when using pitfall-traps for activity determinations, is analysed. The disturbances result in higher catches of surface-dwelling Collembola; the animals being stimulated to higher locomotory activity.
The disturbance by walking in the field results in a multiple of the control catch. This effect lasts for about 1 hour.
The digging-in effect lasts for about two days but more or less different for the various species. The cause is sought in the CO2 production in the soil, which is considerable after soil disturbances. The reaction of Collembola to rather high CO2 concentrations in the air results in an increase of the locomotory activity.
Another interpretation, namely attraction to CO2 sources, could not be demonstrated.
The springtails Tomocerus minor, Orchesella cincta and Isotoma viridis survive only in air with a saturation deficit near zero. Their survival time is inversely related to saturation deficit and not simply to the relative humidity. The different species show different reactions to the same saturation deficit values, which agree with the humidity preferences of the species in their natural habitats.
Drought stimulates Collembola to start locomotory activity which may lead them to aggregate in optimal humidity conditions. Thus this reaction may play a part in increasing the survival rate of these animals.
DIE BEZIEHUNG ZWISCHEN SÄTTIGUNGSDEFIZIT UND ÜBERLEBENSDAUER SOWIE ZWISCHEN S.D. UND LOKOMOTORISCHER AKTIVITÄT BEI EPEDAPHISCHEN COLLEMBOLEN
Die Bezichung zwischen Sättigungsdefizit (S.D.) und Überlebenszeit und zwischen S.D. und lokomotorischer Aktivität wurde an drei epedaphischen Collembolen-Arten untersucht. Die Überlebensdauer verhält sich umgekehrt proportional zum S.D., und steht in keinem direkten Verhältnis zur relativen Luftfeuchte. Die verschiedenen Arten weisen unterschiedliche Reaktionen zu den gleichen S.D.-Werten auf. Diese Reaktionen stimmen mit den Feuchte-Präferenzen der drei Arten in ihren natürlichen Habitats überein. Hohe S.D.-Werte führen zu lokomotorischer Aktivität, mittels welcher dic Tiere optimale Feuchtigkeitsverhältnisse erreichen können.
Diese Ergebnisse weisen auf einen ökologischen Überlebensmechanismus hin.
Pitfall-traps are used to study the phenology and activity phenomena of four surface dwelling Collembola e. g. Entomobrya nivalis (Linn), Lepidocyrtus cyaneus
Tullberg, Orchesella cincta (Linn) and Tomocerus minor (Lubbock).It is concluded that Entomobrya is active during the day, whereas Orchesella and Tomocerus are active during the night. As to Lepidocyrtus no definite conclusion can be drawn.A digging-in effect is demonstrated for Tomocerus minor. A negative effect of the roofs appears during the day for Entomobrya nivalis and Lepidocyrtus cyaneus.Weather conditions exert an influence upon these surface dwelling Collembola.Die Fallenfangmethode wurde angewandt zum Studium der Phnologie und der Aktivitt von vier Collembolen-Arten der Bodenoberflche, nmlich Entomobrya nivalis (Linn), Lepidocyrtus cyaneus
Tullberg, Orchesella cincta (Linn) und Tomocerus minor (Lubbock).
Entomobrya erwies sich als tagaktive Art, Orchesella und Tomocerus sind nachtaktive Tiere. Fr Lepidocyrtus waren die Resultate nicht eindeutig.Eine Reaktion auf das Eingraben der Fallen wurde festgestellt fr Tomocerus minor.Fallendcher haben einen negativen Effekt auf den Fang von Entomobrya nivalis und Lepidocyrtus cyaneus whrend des Tages.Die Aktivitt dieser Collembolen der Oberflche wird durch Witterungsverhltnisse beeinflut.
Diurnal patterns of microarthropod abundance in surface leaf litter were related to its moisture content. Leaf litter moisture was nearly 7% by weight at 0800h but fell to less than 1% by mid-day. Oribatid and tydeid mites moved into litter in the early morning and back into the soil before mid-day. There were no significant differences in numbers of nematodes in litter or soil and 78–98% of the nematodes were anhydrobiotic (coiled) in soil and litter at all times sampled.Following simulated rainfall there were fewer microarthropods in litter at mid-day in the absence of marked decreases in soil and litter moisture content. During drying, there were gradual reductions in numbers and species diversity of litter microarthropods. Nematode numbers did not change as litter dried. Anhydrobiotic nematodes in the soil increased from 14% on day 1 to 85% on day 4. Between 24 and 36 h after simulated rainfall, the proportion of anhydrobiotic litter nematodes increased from 35 to 80%,.Within 1 h after simulated rainfall, there were marked increases in numbers and diversity of microarthropods in surface litter. No collembolans were extracted from dry litter controls but the wet litter was dominated by isotomid, sminthurid and onychiurid collembolans. There were increases in numbers and diversity of oribatid, tydeid and gamasid mites in the wet surface litter within l h after wetting compared to controls.
Community characteristics of Collembola assemblages in conventional, integrated and organic fields of winter wheat were compared among three randomly chosen areas in England using analysis of similarities, cluster analysis, multi-dimensional scaling and several measures of diversity and evenness. Indicator values were used to identify indicator species. Significant differences were found in the abundance of most species and in community structure among the three geographical regions but few differences between the farming regimes were significant. Despite a lack of significant differences among regimes, Entomobrya multifasciata and Isotomurus spp. were consistently, although not significantly more common in conventional than organic fields whereas the opposite was true for Isotoma viridis and Isotoma notabilis. Farming regime significantly affected the abundance of Sminthurinus elegans and Sminthurus viridis but the effect differed between geographical regions. Community composition and species dominance were influenced by farming regime, but no species were indicative of the different farming systems, as most occurred ubiquitously in all fields. Organically and conventionally farmed fields were found not to differ significantly from each other in community composition, but both differed from integrated fields. These findings are compared with the results from other recent European studies of the effects of farming systems on arthropods and their wider ecological implications are discussed.
We hypothesized that changes in the pattern of spring precipitation would alter the species composition of a temperate soil-surface collembolan community. Experimental manipulation of precipitation during a drought in southern England was used to test this hypothesis in spring 1997. Replicated plots in a field of spring peas received spring drought (plots shielded from rainfall), reference (actual) rainfall and spring irrigation during the first 2 weeks of May. Shielding plots extended the existing drought to 58 days. Thereafter all plots received natural precipitation only, which in June considerably exceeded the long-term average for the site. Redundancy Analysis (RDA) and the recently-developed method of Principal Response Curves analysis (PRC) were used to summarise and test statistically changes in community composition under the three precipitation treatments, using counts of soil-surface species obtained by suction sampling. Irrigation decreased counts of Bourletiella hortensis, but had a positive impact on all other species studied, whilst the effect of spring drought was negative. Effects of spring precipitation persisted for the 97-day duration of the study despite the unusually wet summer. The possibility that changes in patterns of rainfall in northern Europe would promote some species as crop pests is proposed, but not supported by our findings. We use the collembolan data to illustrate some advantages of PRC analysis over RDA and other ordination techniques for analysing community responses to experimental treatments.
Thesis (doctoral)--Basel, 1942.
A reanalysis of data published earlier indicates that the springtail, Folsomia candida, kept in continuous darkness, lengthens its intermolt interval (stadia) with age. At an environmental temperature of 21 degrees or 26 degrees C, the early stadia show an about-half-weekly or circasemiseptan interval and later stadia an about-weekly or circaseptan intermolt interval. At 15 degrees C, early stadia are about circaseptan, lengthening to nearly circadiseptan with aging. Our own studies of Folsomia candida at 23 degrees C show that the incidence of molting in 24 springtails observed at 3-hr intervals for 17 days is characterized by a prominent circadian rhythmicity and an infradian periodicity with a period of about 3 days. Both components are statistically highly significant (P = 0.001) when assessed concomitantly by least-squares rhythmometry.