Search

BACKGROUND: Septoria tritici blotch (STB), caused by the fungus Zymoseptoria tritici, is a foliar disease affecting wheat crops against which conventional control methods are not totally effective. During inter‐epidemic periods the fungus survives in wheat residues left on the ground. In this study, we tested the potential of the collembolan Heteromurus nitidus – a springtail species present in field soils and known to interact with different fungal species – as a potential bioregulation agent of Z. tritici on wheat residues through a choice and consumption experiment. RESULTS: Springtails preferred inoculated fresh residues but did not have a preference between inoculated and uninoculated old residues. Springtails grazed on Z. tritici fruiting bodies and reduced pycnidiospore numbers by ten‐fold compared to control inoculated fresh residues. Attraction toward fresh inoculated residues and pycnidiospore reduction support the hypothesis that Z. tritici is a food source for springtails. Heteromurus nitidus showed no preference between inoculated and uninoculated 18‐month‐old residues, probably because they no longer produced ascospores. CONCLUSION: Attraction towards fresh residues and spore reduction support our hypothesis that H. nitidus may contribute to the bioregulation of Z. tritici. Perspectives for field application would be determined by the ability of H. nitidus and Z. tritici to interact at key epidemiological stages. The impact of H. nitidus on the quantity of pathogen primary inoculum over time should be estimated using residues of intermediate age. This would help to identify the optimal period for enhancing the effectiveness of springtails as consumers of Z. tritici. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Copyright of Functional Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Soil invertebrates are members of terrestrial ecosystems, contributing to the processing of organic matter, resulting in carbon and nutrient cycling that is essential for continuous productivity. By linking species delineations, morphological traits and measured or inferred functional roles, we demonstrate a method for functional identification of soil faunal assemblages based on molecular information. Here we align the genetic inter‐relatedness and functional trait expression in nematodes and springtails. Nematodes were assigned feeding guild, plant parasitic feeding type and coloniser‐persister (c‐p) value, with springtail sequences assigned to soil vertical stratification level, soil moisture preference and a selection of morphological traits. We found that both nematode and springtail feeding preferences show significant phylogenetic clustering. In contrast, greater dispersal was found amongst nematode coloniser‐persister (c‐p) values and springtail soil vertical stratification level and moisture preferences. Minimum patristic (p) distances between species supported the clustering amongst nematode feeding guilds, with plant feeders being separated from all other guilds by at least p = 0.99. Distances between endoparasitic, ectoparasitic and sedentary plant parasitic nematodes were also distinct with minimal distances of p = 0.35–0.72 between parasitic types. Springtail stratification level and soil moisture preferences showed greater dispersion across phylogenies, with negligible between‐group minimum patristic distances. However, nematode c‐p values and springtail moisture preference alignments indicate some genetic conservation at the genus level. These results indicate how ecosystems can direct trait conservation beyond that of environmental stimuli. Being able to assign functional traits to novel sequences will allow individual species' likely contribution to ecosystem functioning to be inferred without the need for exact taxonomic identification. More broadly, such information can advance our understanding of the evolution of soil faunal traits and the contribution of diverse soil assemblages to functional soil systems, particularly those with a high proportion of undescribed species. [ABSTRACT FROM AUTHOR]

Trophic niche differentiation may explain coexistence and shape functional roles of species. In complex natural food webs, however, trophic niche parameters depicted by single and isolated methods may simplify the multidimensional nature of consumer trophic niches, which includes feeding processes such as food choice, ingestion, digestion, assimilation and retention.Here we explore the correlation and complementarity of trophic niche parameters tackled by four complementary methodological approaches, that is, visual gut content, digestive enzyme, fatty acid and stable isotope analyses—each assessing one or few feeding processes, and demonstrate the power of method combination.Focusing on soil ecosystems, where many omnivore species with cryptic feeding habits coexist, we chose Collembola as an example. We compiled 15 key trophic niche parameters for 125 species from 40 studies. We assessed correlations among trophic niche parameters and described variation of these parameters in different Collembola species, families and across life‐forms, which represent microhabitat specialisation.Correlation between trophic niche parameters was weak in 45 out of 64 pairwise comparisons, pointing at complementarity of the four methods. Jointly, the results indicated that fungal‐ and plant‐feeding Collembola assimilate storage, rather than structural polysaccharides, and suggested bacterial feeding as a potential alternative feeding strategy. Gut content and fatty acid analyses suggested alignment between ingestion and assimilation/retention processes in fungal‐ and plant‐feeding Collembola. From the 15 trophic niche parameters, six were related to Collembola family identity, suggesting that not all trophic niche dimensions are phylogenetically structured. Only three parameters were related to the life‐forms, suggesting that species use various feeding strategies when living in the same microenvironments.Consumers can meet their nutritional needs by varying their food choices, ingestion and digestion strategies, with the connection among different feeding processes being dependent on the consumed resource and consumer adaptations. Multiple methods reveal different dimensions, together drawing a comprehensive picture of the trophic niche. Future studies applying the multidimensional trophic niche approach will allow us to trace trophic complexity and reveal niche partitioning of omnivorous species and their functional roles, especially in cryptic environments such as soils, caves, deep ocean or benthic ecosystems. [ABSTRACT FROM AUTHOR]

Soil fauna play a fundamental role on key ecosystem functions like organic matter decomposition, although how local assemblages are responding to climate change and whether these changes may have consequences to ecosystem functioning is less clear. Previous studies have revealed that a continued environmental stress may result in poorer communities by filtering out the most sensitive species. However, these experiments have rarely been applied to climate change factors combining multiyear and multisite standardized field treatments across climatically contrasting regions, which has limited drawing general conclusions. Moreover, other facets of biodiversity, such as functional and phylogenetic diversity, potentially more closely linked to ecosystem functioning, have been largely neglected. Here, we report that the abundance, species richness, phylogenetic diversity, and functional richness of springtails (Subclass Collembola), a major group of fungivores and detritivores, decreased within 4 years of experimental drought across six European shrublands. The loss of phylogenetic and functional richness was higher than expected by the loss of species richness, leading to communities of phylogenetically similar species sharing evolutionary conserved traits. Additionally, despite the great climatic differences among study sites, we found that taxonomic, phylogenetic, and functional richness of springtail communities alone were able to explain up to 30% of the variation in annual decomposition rates. Altogether, our results suggest that the forecasted reductions in precipitation associated with climate change may erode springtail communities and likely other drought‐sensitive soil invertebrates, thereby retarding litter decomposition and nutrient cycling in ecosystems. [ABSTRACT FROM AUTHOR]

The present knowledge on chemical communication in springtails (Collembola), one of the two most abundant invertebrate groups living in soil and environments in tight contact with soil (e.g. plant litter, moss), is reviewed here. Chemical communication in an environment where light is absent or dimmed becomes a prominent driver of trophic and non-trophic interactions between soil organisms at a time when better knowledge on the biological determinants of soil communities is required. Like insects and many other arthropods, collembolan individuals of the same population intercommunicate by pheromones, which allow them signalling a risk or clustering in places favourable for feeding, mating, moulting and ovipositing. Olfaction is also used to select preferred food and mates. Researches so far conducted allowed discerning common trends in the role and chemical composition of odour blends used by Collembola. However, much more needs to be done before reaching straightforward conclusions about chemical communication issues at evolutionary and community levels, making this domain even more rewarding. [ABSTRACT FROM AUTHOR]

Trait-based approaches have the potential to reveal general and predictive relationships between organisms and ecosystem functioning. However, the mechanisms underlying the functional structure of communities are still unclear. Within terrestrial ecosystems, several studies have shown that many ecological processes are controlled by the interacting above- and below-ground compartments. However, few studies have used traits to reveal the functional relationships between plants and soil fauna. Mostly, research combining plants and soil fauna solely used the traits of one assemblage in predictive studies., Above-ground (plants) and below-ground (Collembola) compartments were sampled over a flooding gradient in northern France along the Seine River. First, we measured the effect of flooding on functional and taxonomic assembly within both communities. We then considered the linkages between plant and Collembolan species richness, community traits and assessed whether traits of both compartments converged at high flooding intensity (abiotic filtering) and diverged when this constraint is released (biotic filtering)., Species richness of both taxa followed the same bell-shaped pattern along the gradient, while a similar significant pattern of functional richness was only observed for plants. Further analyses revealed a progressive shift from trait convergence to divergence for plants, but not for Collembola, as constraints intensity decreased. Instead, our results highlighted that Collembola traits were mainly linked to the variations in plant traits. This leads, within Collembola assemblages, to convergence of a subset of perception and habitat-related traits for which the relationship with plant traits was assessed., Synthesis. Using a trait-based approach, our study highlighted that functional relationships occur between above- and below-ground compartments. We underlined that functional composition of plant communities plays a key role in structuring Collembola assemblages in addition to the role of abiotic variables. Our study clearly shows that functional diversity provides a new approach to link the above- and below-ground compartments and might, therefore, be further considered when studying ecological processes at the interface between both compartments. [ABSTRACT FROM AUTHOR]

Soil invertebrates are known to be much involved in soil behaviour and therefore in the provision of ecosystem services. Functional trait-based approaches are methodologies which can be used to understand soil invertebrates’ responses to their environment. They (i) improve the predictions and (ii) are less dependent on space and time. The way traits have been used recently has led to misunderstandings in the integration and interpretation of data. Trait semantics are especially concerned. The aim of this paper is to propose a thesaurus for soil invertebrate trait-based approaches. T-SITA, an Internet platform, is the first initiative to deal with the semantics of traits and ecological preferences for soil invertebrates. It reflects the agreement of a scientific expert community to fix semantic properties (e.g. definition) of approximately 100 traits and ecological preferences. In addition, T-SITA has been successfully linked with a fully operational database of soil invertebrate traits. Such a link enhances data integration and improves the scientific integrity of data. [ABSTRACT FROM AUTHOR]

Scarcity of organic matter and nutrients in the topsoil is a typical feature of lowland primary tropical rain forests. However, clumped defecation by vertebrate herbivore troops and further dung beetle processing may contribute to locally improve soil biological activity and plant growth. We studied the impact of clumped defecation by the red howler monkey ( Alouatta seniculus), a frugivorous primate, on the vertical distribution of topsoil (0-6 cm) main nutrients and microstructures in a tropical rain forest (French Guiana). Three latrines, where monkey troops regularly defecate, were sampled, together with adjoining controls for carbon, nitrogen, phosphorus and microscopic components. The vertical distribution of C and N was affected by clumped defecation: nutrients were mostly restricted to the top 2 cm in control areas while latrines exhibited homogeneously distributed C and N, resulting in higher C and N content below 2 cm. No marked effect of defecation was registered on Olsen P. A small although significant increase in pH (0.1-0.3 pH units) and a marked increase in soil respiration (×1.5-2.5) were registered in latrines. Soil microstructures were studied by the small-volume method. Variation according to depth, site and clumped defecation was analysed by Redundancy Analysis. The three latrines were characterized by an increase in root-penetrated mineral-organic assemblages, mainly composed of recent and old earthworm faeces. The local stimulation of plant roots, microbial and earthworm activity was prominent, together with an increase in soil fertility. Consequences for the regeneration of tropical rain forests in the Amazonian basin were discussed, in the light of existing knowledge. [ABSTRACT FROM AUTHOR]

Invasive plants are recognised as a major threat to biodiversity. Although they are well-established in natural areas, the supposed negative impacts of invasive plants upon communities and ecosystems have so far been poorly investigated in urban areas, where invasions are a main issue for ecologists and for urban planners and managers. We propose to assess the effects of an invasive species along an invasion gradient in a typical urban habitat. We focused on the Japanese knotweed ( Reynoutria japonica Houtt.), a widespread invasive species in Europe and North America. We considered eight urban wastelands invaded by this species in the heart of the Greater Paris Area, France. On each site, we ran four transects from the centre of the Japanese knotweed patch towards the uninvaded peripheral vegetation. We recorded the flora using the line intercept method, and several soil parameters (thickness of A horizon, abundance of earthworm casts, topsoil Munsell value, pH) every metre along each transect. The A horizon was thicker and the topsoil darker under R. japonica canopy. Thus, this invasive plant species seemed to influence soil organic matter pool. However, our results also steadily showed that R. japonica locally excluded and/or severely reduced the cover of many plant species through competition. Our study clarified the local effects of R. japonica: an influence on the soil organic matter, and a severe negative impact on wasteland plant communities. We suggest implications in both conservation and restoration ecology. [ABSTRACT FROM AUTHOR]

The collembolan species Heteromurus nitidus, exclusively located in soils at pH>5, can be cultured in acidic humus. As this species is attracted to the excreta of earthworms from calcic mull, its distribution is supposed to be determined only indirectly by soil pH through the distribution of earthworms. Higher densities and biomasses of Lumbricidae were observed in a calcic mull (pH 7.8) than in an acidic mull (pH 4.8) and a moder humus (pH 4.2). Choice experiments were performed to compare the attraction of H. nitidus to the mucus-urine mix of five earthworm species from the calcic mull and the acidic mull. H. nitidus was attracted to the excreta of the five species, whatever their ecological category and the humus form from which they originated. The collembolan Heteromurus major, which was indifferent to soil pH, was not attracted to earthworm excreta, which emphasizes the significance of this phenomenon for the distribution of H. nitidus over a pH range. The attraction of H. nitidus to earthworm excreta tended to be weaker and more variable when earthworms originated from acidic mull compared to calcic mull, particularly in the case of Lumbricus terrestris. Increased earthworm density reinforced by better mucus quality and quantity could determine the distribution of H. nitidus according to soil acidity. The only urine compound capable of attracting H. nitidus was NH3 at a low concentration (0.03 g l–1). The NH3 content of the mucus-urine mix which attracted H. nitidus was 0.037 g l–1, and was therefore responsible, at least partly, for the attraction. [ABSTRACT FROM AUTHOR]

The mature petiole of celery is an organ with versatile sink/source capacities where sucrose and mannitol are unloaded from and reloaded into the phloem cells. Plasma-membrane vesicles were purified by twophase partitioning either from phloem strands isolated from mature petioles of celery ( Apium graveolens L.) or from mature petioles devoid of vascular bundles. Both types of vesicle were comparable in purity (more than 86% of plasma-membrane origin), size (135 nm diameter) and orientation (72% right-side-out). Plasma-membrane vesicles from phloem tissues had a higher vanadate-sensitive ATPase activity than plasma-membrane vesicles from petioles. Plasma-membrane vesicles from phloem tissues accumulated mannitol and sucrose in response to an artificial proton-motive force, in agreement with the existence of proton/substrate carriers. Plasma-membrane vesicles from petioles devoid of vascular bundles accumulated only mannitol following application of an artificial proton-motive force. The data suggest the volvement of apoplasmic transport events. The pathway for sucrose uptake in storage parenchyma cells is discussed in the light of the available physiological data. [ABSTRACT FROM AUTHOR]

The author regrets at the beginning of the sub-section "Sex pheromones" (page 428 of the published version) within the section "The use of pheromones, allomones and kairomones by Collembola" [ABSTRACT FROM AUTHOR]