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Abundance, biomass and community composition of soil saprophagous macrofauna in conventional and organic sugarcane fields
Abstract
Tropical island saprophagous invertebrates have received little attention despite their important role in sustaining soil fertility. Soil biodiversity in the agroecosystems of the Lesser Antilles is subject to various anthropic and environmental perturbations; therefore, it is crucial to promote agricultural practices that help preserve it. Here, we investigate the effect of conversion to organic farming in sugarcane production on soil saprophagous invertebrates in a Martinique plantation (Lesser Antilles). The abundance, biomass and diversity of communities were measured in three fields undergoing organic conversion and in two control fields under conventional production. Invertebrates were sampled both by pitfall trapping and Tullgren extraction. The results indicated that abundance was significantly higher in fields undergoing conversion (342 ± 78 ind.m⁻²) compared to fields under conventional farming (146 ± 34 ind.m⁻²). The response of the whole community's biomass to organic conversion was not significant, reflecting a contrasting response of each invertebrate taxa: isopod biomass was the most impacted, earthworm biomass was moderately impacted and diplopod biomass was not significantly affected. A total of 25 morphospecies for all taxa were distinguished in this study. However, the diversity did not differ and community composition remained similar under both farming practices. The response of invertebrate abundance and biomass could be either due to the direct toxicity of herbicides intensively used in conventional sugarcane cultivation or to the indirect effects of herbicides modifying micro-habitat parameters (weed biomass, amount of mulch and litter humidity). In conclusion, the study shows that organic farming has a beneficial effect on soil saprophagous invertebrates even after a short period of conversion (between one and two years), which is promising for restoring soil biological processes in the context of agroecological transition.
... A study demonstrated that herbicide application reduced the abundance and community diversities of soil invertebrates in a sugarcane plantation. The author argued that the reduction resulted from either the direct effect of the herbicide or the indirect effects of herbicides in modifying micro-habitat parameters such as weed biomass, amount of mulch, and litter humidity (Coulis 2021). Chemical disturbances due to the intensive use of fertilizer, pesticides, and herbicides may exercise important control on the soil fauna (Cassani et al. 2021) in other ecosystems such as plantain crops (Loranger-Merciris et al. 2022) and conventional land use (Sünnemann et al. 2021). ...
... There is no doubt that long-term application of herbicides results in various effects including weed resistance to certain herbicides, crop phytotoxicity, residual effects in the soil, and harmful effect on non-target species such as soil invertebrates and humans. The effect of various herbicides on non-target species has widely been reported in various cropping systems, such as in sugar cane plantations (Coulis 2021), banana plantations (Loranger-Merciris et al. 2022), and coffee-based agroforestry (Asfaw and Zewudie 2021). However, there is limited information of the effect of herbicide mixtures to control weeds in smallholder rubber farms. ...
... However, the treatments did not change the category of their existence which is low in 3111 diversity. Our finding is in accordance with the work of others who reported that agrichemical application affected soil fauna communities (Niemeyer et al. 2018;Asfaw and Zewudie 2021;Coulis 2021). Abiotic and biotic factors, including feed availability and natural enemies (predators), affected the variation of diversity and distribution of soil macrofauna. ...
Chaniago I, Yulistriani, Umami IM, Bukhari ZZ. 2023. Soil macrofauna diversity and weed dynamics in response to different methods of weed control in smallholder rubber farming. Biodiversitas 24: 3106-3113. Weeds interference in rubber farmland may reduce latex yield. Farmers apply herbicides to control weeds. However, the herbicide not only controls weed but also affects the presence of soil macrofauna. A study has been conducted to determine the effect of different method of weed control on soil macrofauna and weeds at smallholder rubber farming at Pulau Punjung, Dharmasraya District, West Sumatra, Indonesia. The experiment was conducted in a completely randomized block design with 6 treatments and 4 pseudo-replications. Treatment was mechanical control, without weed control, and 4 doses of herbicide glyphosate+metsulfuron-methyl (1.5 L ha-1 + 15 g ha-1, 2 L ha-1 + 15 g ha-1, 2.5 L ha-1 + 15 g ha-1, 3 L ha-1 + 15 g ha-1) with 400 L ha-1 of volume. Pitfall traps were used to collect the soil macrofauna. Data were analysis with ANOVA for weed and soil macrofauna in response to different methods of weed control. Results demonstrated that the application of glyphosate+metsulfuron-methyl herbicide significantly suppressed weeds higher than that of other methods of weed control (p<0.05). Para grass (Brachiaria mutica (Forssk.) Stapf) was the most dominant weed but has been affected most by 3 L ha-1 + 15 g ha-1 herbicide mixture. Soil macrofauna of the order Hemiptera was affected most by the application of herbicide with a total reduction of 71.58% of number of individuals at 12 weeks after application of herbicide. In general, different weed control methods resulted in varied numbers of orders and individuals of the soil macrofauna.
... Most studies nevertheless investigated the effect of fertilization type on macroinvertebrate communities without balancing the input of each major nutrient (notably of N, P and K), thereby questioning if the observed effects were due to fertilization type or unbalance between nutrients added. In addition, numerous studies focused on comparing the effect on macroinvertebrates of a set of agricultural practices (conventional vs. organic), which typically included different fertilization types but also different tillage and pesticide application practices (Coulis, 2021). The specific effect of a partial substitution of synthetic fertilizers by different organic fertilizers within a given agroecosystem has been little studied and in particular in the context of sugarcane agroecosystems. ...
... Mulching the soil surface most likely favored the development of the macroinvertebrates in the study, providing them with both a habitat and a food resource (Abreu et al., 2014;Coulis, 2021;Pasqualin et al., 2012;Portilho et al., 2011). Isopoda, the main saprophagous organisms in the trial, are the animals that benefited most from this practice, and in particular from the incorporation of litter into the soil in 2021. ...
Macroinvertebrates play a central role in processes supporting soil fertility. In the framework of the ecological intensification of agriculture, the choice of management practices should be guided by their ability to support these beneficial organisms supplying ecosystem services. This study aims at investigating the specific effect of partial substitution of synthetic fertilizers by locally produced organic fertilizers at a similar level of major nutrient inputs on macroinvertebrate abundance and diversity in sugarcane agroecosystems, on a Nitisol. Invertebrates visible to the naked eye were sampled in 2013, 2016, 2019 and 2023 using the standardized TSBF method on a long-term experimental field trial in Réunion island. The individuals were identified and soil samples were analyzed for physico-chemical properties. Despite the low response of macroinvertebrates to the fertilizer type, total macroinvertebrate abundance increased over time, especially isopods and earthworms. The input of organic carbon via the return of litter to the soil surface and the root turnover after each harvest enables soil macroinvertebrates to be more abundant even after replanting tillage. Mulching and root turnover are therefore important levers to consider for promoting macroinvertebrates in sugarcane agroecosystems.
... These studies, conducted between 2018 and 2021 have made possible their identification for the very first time in this particular context of organic certified and agroecological fields. As an example, it seems that organic conversion had an effect on the composition of saprophagous macrofauna fields in Martinique island (Coulis, 2021) where thousands of hectares of conventional sugarcane were grown for more than 30 years. Therefore, we wanted to know the type of arthropod fauna living and developing in the specific context of organic sugarcane. ...
... It is admitted that arthropods diversity and abundance are low under conventional sugarcane agriculture, but studies are scarce and even mineral or organic fertilization does have significant effects on diversity and amounts on invertebrate populations (Chi et al., 2020). Moreover Coulis (2021) found no significant difference between organic (in conversion) and conventional fields regarding the diversity of soil macrofauna. However, these studies were limited to the saprophagous macrofauna and didn't consider the arthropod biodiversity of the aerial parts of sugarcane as we did in this present study. ...
... In addition, soil macroinvertebrates are assumed to play a major role in ecosystem dynamics as they are involved in the decomposition of organic matter through fragmentation of litter, and can also influence microbial activity by provision of high-quality substrates and dispersal of microbial propagules (Coulis, 2021;Lavelle and Spain, 2002;Zahorec et al., 2022). Recent studies on community functional diversity based on species traits offer new insights into the mechanisms of soil fauna responses to environmental change (Chikorowondo et al., 2018;Pan et al., 2022;Schirmel et al., 2016). ...
... Thus, only species with functional traits that match the specific environment can pass these filters (Poff, 1997). Vegetation and soil properties have been demonstrated to be the key factors shaping soil invertebrate communities and determining their functional composition (Coulis, 2021;Wu et al., 2015). Yin et al. (2020) showed that changes in hydrothermal conditions decreased the total biomass of soil fauna via reduced mean body size. ...
Soils contain a remarkable diversity of organisms that are important regulators of ecosystem functions. However, the knowledge of how the environment shapes biodiversity patterns below ground remains limited in alpine areas of the Tibetan Plateau. Here, we conducted a microhabitat scale study (400 m2 plot) integrating data on soil and plant community characteristics to explore the driving forces of functional diversity of soil microbial and macroinvertebrate communities under disturbance by plateau zokor (Eospalax baileyi), a subterranean rodent inhabiting the Tibetan Plateau. The results show that plateau zokor disturbance led to a decline in the belowground biomass of grasses, whereupon the total belowground plant biomass and soil organic carbon decreased significantly. The functional diversity of soil microbial and macroinvertebrate communities was significantly increased under plateau zokor disturbance. Redundancy analysis indicated that soil moisture, temperature and compaction, in combination with plant species richness and belowground biomass of forb were the most important factors in driving soil microbial and macroinvertebrate functional diversity. Piecewise structural equation modeling (SEM) revealed that plateau zokor mound disturbance had positive effects on the functional diversity of soil microbial and macroinvertebrate communities by regulating soil physical properties (moisture, temperature, and compaction) and plant species richness within the habitat. Further, zokor disturbance affected the functional diversity of soil microbial and macroinvertebrate communities indirectly via regulating soil organic carbon. Our study provides evidence that the functional diversity of microbes is more driven by environmental changes than those of macroinvertebrates.
... This finding was not unexpected because many of the known beetle species are coprophagous and saprophagous, meaning they depend on decaying organic matter for nourishment (Aldebron et al., 2020;Culliney, 2013). Therefore, their population here was probably negatively affected by the low organic matter within the conventional land use compared to the integrated land use which had a positive influence through rich organic matter resulting from dung deposited by the integrated livestock and residue retention practices (Bai et al., 2018;Coulis, 2021;Nependa et al., 2021). ...
Agricultural intensification is one of the major drivers of biodiversity decline and the losses of its functions in the soil. For soil health and sustainability planning, it is important to understand the effects associated with agricultural management on soil function and biodiversity. This study explored soil fauna, physicochemical properties, soil quality and multifunctionality and how they are affected by agroecosystem management in four different land uses i.e., conventional agriculture, livestock-integrated agriculture, conservation agriculture and natural grassland. The conventional land use favoured some nutrients, however soil of both the integrated and conservation land uses had physical and chemical properties indicative of good soil quality e.g. low compaction, low C:N ratio and stable aggregates. Soil fauna abundance was more responsive to land use and the soil environment compared to species diversity which did not show significant responses as expected. Tillage is known to negatively influence soil fauna, soil functions and physicochemical properties through intense soil structure disruption. Here, its detrimental effect is reflected by the lowest record of soil fauna, poor soil physicochemical quality and low multifunctionality observed within the conventional landuses managed under deep tillage, compared to other land uses which are under zero tillage. Overall, the study shows that the implementation of sustainable soil management practices which improves the physical and chemical status will not only be beneficial for productivity but also for the promotion of important soil fauna, better soil quality and ecosystem multifunctionality.
... Our analysis on trophic groups showed that predator, herbivore and decomposer abundances decreased significantly, and drastically, with herbicide applications. These results are consistent with other studies, suggesting that predator (such as spiders, carabids and beetles), herbivore and decomposer abundances are higher in organic farming fields due to a large amount of weeds and a consistent soil cover when herbicides are not used (Coulis, 2021;Dassou & Tixier, 2016). Indeed, herbivores are directly affected by the suppression of weeds, leading to a decrease in their abundance and thus a decline in predator abundance. ...
... Among soil biological properties, soil fauna has been identified as an important indicator of soil conservation management (Coulis, 2021;Li et al., 2021), and soil macrofauna (organisms visible with the naked eye) (Lavelle et al., 1994). These organisms are prominent in key soil processes, such as nutrient cycling (Lal, 1988;Quadros and Zimmer, 2018); soil organic matter humification and mineralization (Frouz, 2018;Frouz et al., 2020); water infiltration rate due to the formation of channels and galleries (Lamoureux and O'Kane, 2012); changes in soil pH and N content (Sheehan et al., 2006;Frouz et al., 2020), and soil porosity (van Vliet et al., 1993;Bottinelli et al., 2010;Melo et al., 2019). ...
Soil macrofauna is an important indicator of soil quality, as it is sensitive to changes in the environment as a result of soil management, which includes soil chemical and physical properties and the diversity of cultivated species. This study aimed to evaluate the composition and structure of soil macrofauna under a no-tillage system in different crop sequences, with and without crop rotation, over two growing seasons: a rainy summer and a dry winter. The crop sequences were soybean/corn rotation in the summer and corn in the winter; soybean/corn rotation in the summer and sunn hemp in the winter; soybean monoculture in the summer and sunn hemp in the winter; and corn monoculture in the summer and corn monoculture in the winter growing season. The nutrient content of the crop residues left on the soil surface, soil chemical and physical properties, and soil macrofauna were determined. Functional plant groups (grasses or legumes) individually influenced the composition of soil macrofauna more significantly than the effect of crop sequence, with or without rotation, and growing season. Grasses favored an increased density of groups such as Oligochaeta, Isoptera, and Formicidae. In contrast, legumes contributed to the variation in the total density of individuals and Diplura and Coleoptera groups. Furthermore, the influence of functional plant groups (grasses or legumes) on the composition and density of soil macrofauna were related to soil chemical (P and N content) and physical properties (particulate organic carbon and soil moisture), which determined the composition of soil macrofauna groups.
Keywords
rotation; organic matter; bottom-up effects; soil chemistry; ecosystem engineers
... Soil biology was monitored by studying earthworms, which are a good indicator of the biological activity of soil and have proven to be sensitive to the conversion to organic farming (Coulis, 2021;El Jaouhari et al., 2022). The spade test was therefore used, which consisted in excavating a 30×30 cm monolith then carrying out manual sorting of clods. ...
... Moreover, the high biomass input instantly provided by mowing might have led to the similar pattern of increased activity shortly after management. Also, it might have contributed to attract and maintain the macro-and meso-fauna of decomposers, which use bigger plant particles as resource, opposed to the chemical treatment, which delivers smaller sequential inputs of litter along with toxic substances for these saprophytes (Coulis 2021). In the absence of exogenous molecules, the non-chemical management may have sustained microbial activity for longer periods (Darras et al. 2019). ...
Tropical forest restoration is needed to mitigate the negative consequences of anthropogenic disturbances and climate change. One of the main limitations for the establishment of tropical forests is the competition with invasive species decreasing the survival and growth of native trees. Invasion management should affect soil microorganisms, which play essential roles in nutrient cycling, plant nutrition and on ecosystem functioning. Although chemical and non-chemical methods are applied worldwide to herbaceous invasion management, their impacts on soil microbial biomass, respiration and litter decomposition have yet to be measured over longer timeframes (> 3 months) after application. Using a three-year-old tropical forest restoration managed through chemical (herbicide pulverization) or non-chemical (mowing) treatments, and a secondary native forest patch nearby used as reference, we measured (1) soil microbial biomass and (2) basal soil respiration over six months, and on (3) litter decomposition over one year, after one management. We used mixed models to test whether management affected the response variables and found that chemical management resulted in lower microbial biomass and respiration after five months. Similarly, after one year, litter decomposition rate under chemical management was lower than that in the non-chemical and in the control. Chemical management effects on soil activity and litter decomposition should be considered when choosing suitable methods and its frequency to manage invasion, targeting the success of native trees and general ecosystem functioning.
... Although, at first sight, the effect of the farming system on fungivorous beetles can be difficult to ascertain, because they can be unaffected by pesticide use in orchards [84], we found that they benefited from organic farming; we observed similar results for saprophages and, more markedly, for mixed-feeding coleopterans, which is in line with previous studies [73,85]. Surprisingly, xylophagous coleopterans were strongly affected by both the farming system and the hillside aspect, showing a preference for conventional orchards from the shady hillside. ...
The conversion of traditional land-use systems into more intensive agriculture forms plays a main role in biodiversity loss. Within this framework, organic management has received widespread attention since it is assumed to enhance multiple taxa, including different groups of insects and plants. However, its contribution to the promotion of organism diversity is still controversial. We developed a study in traditional cherry orchards from the Jerte Valley (western Spain) to examine how coleopteran and plant assemblages are driven by farming system (organic vs. conventional), topographic features, and seasonality. The coleopteran community was examined on the basis of its taxonomic and trophic guild response. Organic orchards supported a higher number of beetle families and a greater plant species richness. Additionally, beetle and plant communities were highly correlated; conventional orchards were more homogeneous in terms of both plant and beetle composition, while organic orchards were more heterogeneous, their composition being also shaped by the hillside aspect. From a more functional approach, the different coleopteran trophic guilds exhibited varying responses to the factors analyzed. The benefits of organic farming were notable even when working in traditional systems: highly valuable habitats for overall biodiversity. Therefore, we highlight the potential of organic orchards for conservation purposes.
... Decomposition of organic residues is controlled by many factors (e.g., fractional composition of organic matter, temperature, soil moisture, soil organisms' activity), but their quantity (C-rich) and quality (N-rich) along with soil organisms' community are considered key-factors in subtropical agricultural systems [10]. The consensus is that Cand N-rich residues are generally found to stimulate habitat provision and decomposition, respectively [11,12]. Other studies have provided evidence of C-rich residues negatively influencing decomposition rates [13,14]. ...
The use of mulching, compost, and their interaction on organic residue (OR) decomposition rate (k), time of residue decay, primming effect, and soil organisms' community composition was tested in a 16-year P. pyrifolia field experiment conducted from January 2020 to June 2021. A 2 × 2 factorial design was used with compost and mulching as the two factors within four blocks. OR decomposition was characterized by using litter bags with different mesh, and soil organisms were identified at family level. The half-decay rate (hd), total-decay rate (td), and remaining residue mass (Rm) varied among the organic residue management and mesh-type. The highest values of k and primming effect were found in litter bags with 15 mm 2 size containing compost in the plots that received compost. For soil organisms' abundance and richness, the highest values were found on plot that received both mulching and compost. The observed results suggested that the OR management determined organic matter decomposition, soil organisms' abundance and richness in an Acrisols of the Southern Brazil. Soil organisms were the main factors contributing to the data variance (e.g., Acaridae, Blattidae, Chrysopidae, Halictophagidae, and Forficulidae).
The French West Indies are part of the biodiversity “hot spot” of the Caribbean islands. The landscape of these islands has constantly evolved and been shaped by the agricultural context. Today the agricultural landscape is dominated by banana plantations, sugar cane fields, pastures and market gardens, which can harbour an important biodiversity of earthworms (Annelida, Clitellata). Several studies were interested in earthworms in natural environments of Guadeloupe and the agronomic role of earthworms in agricultural environments was also studied until the 1990s; but no synthesis exists to date. The objective of this work is to establish a complete list of earthworm species in agricultural environments in the French West Indies based on a synthesis of the literature and new collects. The results of the literature synthesis show the presence of 10 species already mentioned in agricultural environments. Our recent collections allowed us to identify seven species new for the French West Indies: Dichogaster (Dt.) annae (Horst, 1893), Dichogaster (Dt.) saliens (Beddard, 1893), Drawida barwelli (Beddard, 1886), Polypheretima taprobanae (Beddard, 1892) Onychochaeta windlei (Beddard, 1890), Periscolex brachycystis (Cognetti de Martiis, 1905) and Periscolex nevoi Csuzdi & Pavlíček, 2009. These new data also extend the distribution of several species to islands where no records previously existed in the literature. However, knowledge is unequally distributed among the islands, depending mainly on the sampling effort. The agricultural environments of Martinique are the best known, the rarefaction curve is close to saturation at 16 species reflecting a substantial sampling effort. On the other hand, we can expect the discovery of additional species in the cultivated environments of Guadeloupe because the rarefaction curve is far from the saturation point with only nine species. For the 15 species for which individuals from recent collections were available, the analysis of a mitochondrial gene fragment of cytochrome c oxidase I (COI) was performed. This was done in order to constitute a reference library of DNA barcodes whose morphological identification is verified to facilitate future work on the taxonomy of earthworms in this area. All these data are integrated in a detailed determination key allowing to identify 21 species, i.e., the 17 whose presence is confirmed as well as four additional species whose presence is highly probable but not yet attested in the cultivated areas of the French West Indies.
In this chapter, the soil ecosystem is introduced as a multiphase system that (i) acts as habitat for a wide diversity of soil organisms and (ii) varies at both spatial and temporal scale. The soil formation varies according to a combination of geological factors and biological process (e.g., here included the influence of mankind) that result in an almost infinite variation in soil-forming factors. Basically, five forming factors are defined as the most important factors. These forming factors are parent material, climate, topography, time, and the activity of soil organisms (e.g., plant roots, insects, microorganisms, human influence, etc.). Considering the wide range of soil properties, i.e., physical, chemical, and biochemical variables, in this chapter we focused only on describing the most important and significant properties to soil organisms, such as soil organic carbon, soil pH, soil aggregation, and moisture. Finally, when considering the tremendous variety of soil types, the need for soil ecologist to recognize this variation must be considered to avoid stresses. Especially, if the student is considering both spatial and temporal variation into soil ecosystem. In view of this, it is important that soil ecologist must consider both soil biota and soil ecosystem characterization.
Forests provide a critical habitat for different species and in turn support different ecosystem services for Earth’s functioning. With climate change, a risk to the food system, with its function of capturing and storing carbon, the importance of forest biological diversity (gene pool) becomes more pivotal. However, the biological diversity at different levels of the inhabiting species determines their ability to respond to possible climate change.The species’ genetic diversity critically affects its relation to other species through different structural and functional components in the associated soil ecosystem. As a consequence of the association of the genes, important processes such as energy flow, biogeochemical cycles, and signaling secondary metabolites are altered. Understanding such associations is a prerequisite, as it can impact diverse ecosystem services/productivity of forests such as food and fiber. Apropos, the present chapter highlights different components of the forest ecosystem, their interplay, and their impact on soil structure and function, thus affecting different ecosystem productivity.KeywordsForest ecosystemGenetic diversitySoil structureSoil functionSoil ecosystem
Cet article présente les premières listes de nématodes parasites des plantes (Tylenchida et Dorylaimida) des départements français d’Amérique: Guadeloupe, Martinique et Guyane. Ces listes ont étéétablies suite aux nombreuses enquêtes faunistiques en nématologie conduites dans ces départements depuis les premiers résultats d’analyses nématologiques de Scotto La Massèse en 1968. L’inventaire général comporte 171 entrées taxinomiques, réparties en 42 genres et 18 nouvelles espèces. Ainsi, à la Guadeloupe, 82 espèces ont été inventoriées dont 3 espèces nouvelles; à la Martinique, 87 espèces ont été inventoriées dont 7 espèces nouvelles; et en Guyane, 97 espèces ont été inventoriées dont 8 espèces nouvelles. Quelques-unes de ces espèces sont sur les listes A1 et A2 de l’OEPP (Aphelenchoides besseyi A2/122, Radopholus similis A2/126, Xiphinema americanum sensu lato A1/150 et Xiphinema rivesi A2/262). L’intérêt de telles études en nématologie est discuté ainsi que les dispositions réglementaires quant à la présence d’espèces économiquement importantes ou réglementées, au regard de l’accroissement des échanges inter-îles ou intercontinentaux et des risques phytosanitaires encourus, que ce soit dans les départements français d’outre-mer (DOM) ou les pays et territoires d’outre-mer (PTOM).
The efficiency of agricultural subsidy programmes for preserving biodiversity and improving the environment has been questioned in recent years. Organic farming operates without pesticides, herbicides and inorganic fertilizers, and usually with a more diverse crop rotation. It has been suggested that this system enhances biodiversity in agricultural landscapes. We analysed the effects of organic farming on species richness and abundance using meta‐analysis of literature published before December 2002.
Organic farming usually increases species richness, having on average 30% higher species richness than conventional farming systems. However, the results were variable among studies, and 16% of them actually showed a negative effect of organic farming on species richness. We therefore divided the data into different organism groups and according to the spatial scale of the study.
Birds, insects and plants usually showed an increased species richness in organic farming systems. However, the number of studies was low in most organism groups (range 2–19) and there was significant heterogeneity between studies. The effect of organic farming was largest in studies performed at the plot scale. In studies at the farm scale, when organic and conventional farms were matched according to landscape structure, the effect was significant but highly heterogeneous.
On average, organisms were 50% more abundant in organic farming systems, but the results were highly variable between studies and organism groups. Birds, predatory insects, soil organisms and plants responded positively to organic farming, while non‐predatory insects and pests did not. The positive effects of organic farming on abundance were prominent at the plot and field scales, but not for farms in matched landscapes.
Synthesis and applications. Our results show that organic farming often has positive effects on species richness and abundance, but that its effects are likely to differ between organism groups and landscapes. We suggest that positive effects of organic farming on species richness can be expected in intensively managed agricultural landscapes, but not in small‐scale landscapes comprising many other biotopes as well as agricultural fields. Measures to preserve and enhance biodiversity should be more landscape‐ and farm‐specific than is presently the case.
We have examined the indirect effect of the herbicide glyphosate on the spider Lepthyphantes tenuis in field margins. Glyphosate was applied to a randomised block design field experiment comprising 360, 720 and 1440 g glyphosate AE ha ⁻¹ treatments and an unsprayed control. Spiders were sampled in each month from June to October 1998. Spider abundance was significantly lower in all the treatments than in the unsprayed control. Abundance was also significantly lower in the 720 and 1440 g treatments than in the 360 g treatment. No significant difference could be detected between the 720 and 1440 g treatments. Poisson regression models showed that patterns of decline in L tenuis were related to increasing dead vegetation and decreasing vegetation height. Glyphosate applications only had a within‐season indirect habitat effect on L tenuis as field margins sprayed 16 months after an application of 360 g glyphosate ha ⁻¹ showed no detrimental effect.
© 2001 Society of Chemical Industry
The dynamics of earthworm populations were investigated in continuously-cropped, conventional disk-tilled corn agroecosystems which had received annual long-term (6 years) amendments of either manure or inorganic fertilizer. Earthworm populations were
sampled at approximately monthly intervals during the autumn of 1994 and spring and autumn of 1995 and 1996. The dominant earthworm species were Lumbricus terrestris L. and Aporrectodea tuberculata (Eisen), which comprised 50–60% and 8–13%, respectively, of the total annual earthworm biomass. Lumbricus rubellus (Hoffmeister) and Aporrectodea trapezoides (Dugés) were much less abundant and contributed a small fraction of total earthworm biomass. Earthworm numbers and biomass were significantly greater in manure-amended plots compared to inorganic fertilizer-treated plots during the majority of the study period. Seasonal fluctuations in earthworm numbers and biomass were attributed to changes in soil temperature and moisture, and cultivation. Unfavorable climatic conditions in the summer and autumn of 1995 caused earthworm abundance and biomass to decline significantly. Mature L. terrestris, L. rubellus and A. tuberculata were most abundant in May and June of 1995 and 1996, and cocoon production was greatest in June and July 1995 and June 1996. Recruitment of juveniles of Lumbricus spp. and Aporrectodea spp. into earthworm communities occurred primarily in the autumn. Long-term amendments of manure or inorganic fertilizer did not change the species composition of earthworm communities in these agroecosystems. The earthworm populations in both manure and inorganic fertilizer plots have declined significantly after 5 years of continuously-cropped corn.
This paper synthesises information on the food requirements of soil macroinvertebrates and some of their effects on soil organic
matter dynamics. Some clues to techniques that would optimise their activities through organic matter management are suggested.
Soil macroinvertebrates can consume almost any kind of organic residues in mutualistic association with soil microflora. Significant
amounts estimated at several T per ha of predominantly easily assimilable C are used yearly in natural ecosystems as energy
to sustain these activities. Sources of C used are highly variable depending on the feeding regime. The largest part of the
energy assimilated (e.g., 50% by the tropical earthworm Millsonia anomala) is actually spent in burrowing and soil transport and mixing. Bioturbation often affects several thousand tons of soil per
hectare per year and several tenth of m3 of voids are created in soil. A great diversity of biogenic structures accumulate and their nature and persistance over time
largely controls hydraulic soil properties. The OM integrated into the compact biogenic structures (termite mounds, earthworm
globular casts) is often protected from further decomposition. Most management practices have negative effects on the diversity
and abundance of macroinvertebrate communities. Structures inherited from faunal activities may persist for some weeks to
years and the relationship between their disappearance and soil degradation is rarely acknowledged. When SOM supply is maintained
but diversity is not, the accumulation in excess of structures of one single category may have destructive effects on soil.
It is therefore essential to design practices that provide the adequate organic sources to sustain the activity and diversity
of invertebrates. Special attention should also be paid to the spatial array of plots and rotations in time.
The side effects of 5 insecticides, 8 fungicides and 6 herbicides on 24 species of beneficial organisms were tested by members of the Working Group «Pesticides and Beneficial Organisms» of the International Organization for Biological Control (IOBC), West Palaearctic Regional Section (WPRS). The tests were conducted by 24 members in 11 countries according to internationally approved guidelines.
The insecticide buprofezin (Applaud), the fungicides triforine (Saprol), procymidone (Sumisclex), anilazine (Dyrene), triadimenol (Bayfidan), hexaconazole (Anvil), tridemorph (Calixin) and the herbicides tralkoxydim (Grasp), bentazone (Basagran) were harmless to nearly all the beneficial organisms. Diflubenzuron (Dimilin) affected spiders and the larvae of predatory insects. The remaining 10 preparations were more toxic and should therefore be further tested in semi-field and field experiment on relevant organisms.
The pantropical, geophagous earthworm species Pontoscolex corethrurus (Müller) is common in lowland soils supporting sugarcanc in notheastern Queensland. In comparison with situations where harvest residues are burned, its populations are substantially increased under cultural treatments in which harvest residues are retained as a surface mulch or are mechanically incorporated into the topsoil. The δ 13C values of stem and leaf materials, soil organic matter and the earthworm whole-body tissues and casts were determined. It is unlikely that P. corethrurus assimilates much of its tissue C from the more complex fractions of soil organic matter or directly from decomposing residues, at least until a late stage of breakdown. No differences in δ513C values were apparent in samples of this species from the different cultural treatments. From field observations of an intimate association between P. corethrurus and the sugarcane roots, we suggest that this species may derive much of its tissue C from rhizospherc sources.
Habitat destruction and fragmentation of remaining habitat are major threats to global biodiversity. In this paper, we drew upon data from grassland butterflies, legume-feeding herbivores and their parasitoids, and the interactions between rape pollen beetles and their paraitoids in the agricultural landscapes of Germany to explore the following issues: (1) the relative importance of small habitat fragments for the conservation of biodiversity (in contrast to the prevailing arguments in favor of large fragments); (2) the disruption of interspecific interactions in fragmented habitats and (3) the relative importance of the spatial arrangement of habitat fragments in landscapes of different complexity. The percentage of polyphagous butterfly species and their abundance were higher in small than in large calcareous grassland fragments, showing the relative importance of the landscape surrounding habitat fragments for less specialized species. A landscape perspective is also needed to explain why several small fragments supported more butterfly species (even when only endangered species were considered) than the same area composed of only one or two fragments. Analyses of insects on legumes showed trophic-level differences, in that species numbers of parasitoids, but not of herbivores, benefited from habitat subdivision in landscapes. As percentage of parasitism (i.e., the strength of ecological interactions) increased with fragment area, both the "several small" and "single large" strategies appeared to have merit. An intermediate-fragmentation strategy of habitat conservation in human-dominated landscapes may combine the advantages. Small habitat fragments should be scattered enough to cover a range of geographical area wide enough to maximize beta diversity and the spreading of but with large habitat fragments close enough to enable dispersal among fragments, to reduce the extinction probability of area-sensitive species, and to stabilize predator-prey interactions. Parasitism of rape pollen beetles exhibited a distinct edge effect: it was higher near the crop field edge, i.e., near the parasitoids' overwintering sites (such as grassy strips). However, this was only true in landscape, dominated by annual crops in landscapes with a high percentage of permanent noncrop area (>20%), such edge effects disappeared, presumably because of the high overall density or these parasitoids. These data indicate that spatial configuration is important to mitigate extinction risks when habitat availability in a landscape is low, whereas no effect will be observed when overall area of habitat is high.
Effects of chlorpyrifos, carbofuran, mancozeb and their formulated products on survival, growth and reproduction of the tropical earthworm Perionyx excavatus were investigated in standard artificial soil. The toxicity of the three chemicals decreased in the order carbofuran>chlorpyrifos>mancozeb. In general, formulations were more toxic than the active ingredients, but differences in LC50 and ECx values were significant only in two cases and not more than a factor of 2.0. This could mainly be due to masking of the effects of additives in the soil. Comparison with available survival data revealed that P. excavatus is more sensitive than the standard test species Eisenia andrei or E. fetida. The use of tropical species in the risk assessment of pesticides in tropical regions should therefore be encouraged.
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In a study of a 15-year-old pasture in Martinique (French West Indies), abundance and organization of microarthropod communities were correlated with the spatial distribution of the earthworm Polypheretima elongata (Megascolecidae). In patches of high earthworm density (133 individuals m-2), microarthropod density was significantly higher (80 000 individuals m-2) than in patches with few earthworms (31 worms m-2 and 49 000 microarthropods m-2). The diversity of microarthropod communities followed a similar pattern, the Shannon index for Collembola communities being, respectively, 3.12 and 1.82 in and outside earthworm patches. These results suggest that mesofauna abundance and diversity might be at least partly determined by the activity of larger invertebrates, as a result of the dramatic effects that the latter group exerts upon soil structure, pore distribution and food resources.
"The sustainability of soil fertility in agricultural systems of the humid tropics has recently become a major issue as a consequence of continued land degradation and the critical need to provide more food. For socioeconomic, pedological, and ecological reasons, the development of sustainable high-input agriculture has proven to be slow and difficult and much effort needs to be directed towards the improvement of productivity in low-input agriculture."
The importance of secondary tropical forests regarding the maintenance of soil fauna abundance and diversity is poorly known. The aims of this study were (1) to describe soil fauna abundance and diversity and (2) to assess the determinants of soil fauna abundance and diversity in two stands of a tropical semi-evergreen secondary forest. Soil macrofauna and microarthropod abundance and soil macrofauna diversity were described at two sites developed on different soils and with different site histories: (1) a natural secondary stand (natural forest) under two dominant tree species, Pisonia subcordata and Bursera simaruba, and (2) a planted secondary forest (planted forest) under three tree species, B. simaruba, Swietenia macrophylla, and Tabebuia heterophylla. The effects of both soil and main tree species' litter quality were assessed to explain soil fauna abundance and diversity. The abundance of soil macrofauna was significantly higher in the soil under the planted forest, and soil fauna communities were contrasted between the two sites. In the planted forest, a soil-dwelling macrofauna community developed (mainly consisting of the anecic earthworm Polypheretima elongata). In the natural forest, soil macrofauna and microarthropod communities were located at the soil surface. The effect of plant litter quality varied according to each dominant tree species and was superimposed to soil effect. The lowest macrofauna abundance was associated with B. simaruba in the natural forest. T. heterophylla supported a much greater macrofauna community than the two other tree species studied at the same soil, and it appears likely that this is due to the palatability of its leaves compared with the other trees (low lignin, tannins, soluble phenols).
The influence of human activities on soil arthropods of vertisols was assessed in several plots characterized by different land uses in the south-eastern part of Martinique (French West Indies). Abundance acid diversity of soil invertebrate groups and collembolan species were measured in a 40-year-old secondary forest, a 15-year-old fallow, a 4-year-old fellow, a 4-year-old pasture, a 15-year-old pasture and a 20-year-old market-garden. Agricultural practices modified abundance and species distribution of soil arthropods, compared to forest. Arthropod richness (number of taxa present) decreased from forest to market-garden, according to a gradient of intensification of agricultural use (pesticides, tillage, weed control). In the old pasture, the arthropod diversity was lower in spite of a high carbon content. Species richness of Collembola decreased together with plant diversity and water availability.
A small earthworm material from Guadeloupe Islands (French West-Indies) was studied. Altogether 14 earth¬worm species were collected, 12 of which are common tropical peregrine. On the other hand, two seem to be endemic in the islands. One of these native species, Eutrigaster (Graffia) musciphila (James, 1996) is reported for the first time after the original description, the other, Periscolex nevoi sp. nov. is proved to be new to science.
Effects of genetically modified herbicide-tolerant (GMHT) and conventional crop management on invertebrate trophic groups (herbivores, detritivores, pollinators, predators and parasitoids) were compared in beet, maize and spring oilseed rape sites throughout the UK. These trophic groups were influenced by season, crop species and GMHT management. Many groups increased twofold to fivefold in abundance between early and late summer, and differed up to 10-fold between crop species. GMHT management superimposed relatively small (less than twofold), but consistent, shifts in plant and insect abundance, the extent and direction of these effects being dependent on the relative efficacies of comparable conventional herbicide regimes. In general, the biomass of weeds was reduced under GMHT management in beet and spring oilseed rape and increased in maize compared with conventional treatments. This change in resource availability had knock-on effects on higher trophic levels except in spring oilseed rape where herbivore resource was greatest. Herbivores, pollinators and natural enemies changed in abundance in the same directions as their resources, and detritivores increased in abundance under GMHT management across all crops. The result of the later herbicide application in GMHT treatments was a shift in resource from the herbivore food web to the detritivore food web. The Farm Scale Evaluations have demonstrated over 3 years and throughout the UK that herbivores, detritivores and many of their predators and parasitoids in arable systems are sensitive to the changes in weed communities that result from the introduction of new herbicide regimes.
Accurate estimation of soil macroinvertebrate fresh biomass is crucial to link macroinvertebrate community to ecosystem functions, but remains a challenging task under field conditions. Here, we present allometric equations to estimate the fresh biomass of three diplopods (Rhinocricidae), one earthworm (Glossoscolescidae) and one earwig species (Anisolabididae) that are abundant in soil communities and potentially important for the provision of soil ecological functions in tropical agroecosystems. Body length, body width, and body volume, were measured using a novel method of image analysis, and then used to estimate the fresh biomass. Our results show that length-biomass allometric relationships provide reliable estimation of fresh biomass for diplopods (r² = 0.98) and earwigs (r² = 0.97). However, the biomass of earthworms was not as accurately predicted by body length (r² = 0.82). The use of body volume, estimated with body length and width, allowed to increase the predictive power for earthworms. Furthermore, a general allometric equation based on body volume, including all taxa considered in this study, was found to predict 96% of the observed body weight variability, suggesting that this equation could be generalizable to a large range of soil macroinvertebrates. Therefore, we conclude that using body volume could provide a better accuracy in estimating soil macroinvertebrate biomass. Although the estimation of body volume on each individual requires an additional measure, the use of image analysis software renders this step feasible for a large number of individuals. By improving the feasibility of trait measurements, this method may facilitate field surveys and foster trait-based studies on soil macroinvertebrates.
A survey of the earthworms of Guadeloupe was undertaken to improve knowledge of the diversity of native and introduced earthworms of the island and to evaluate native species for use in vermicomposting. Twenty-eight species were found, 8 introduced, 4 uncertain, and 16 presumed native. The introduced species are Pontoscolex corethrurus, Pontoscolex spiralis, Amynthas rodericensis, Perionyx excavatus, Polypheretima elongata, Dichogaster affinis, Eudrilus eugeniae, and Drawida sp. Juveniles of the genera Righiodrilus, Glossodrilus and Periscolex were found, but one cannot say if they are introduced or not without a confirmed identification. Omodeoscolex divergens was collected in several locations, with variation in color, size and male sexual function suggestive of long residence on the island, but we are counting this as of uncertain status and tentatively placing all in the same species. Late juveniles of a large endogeic species of a heretofore unknown genus of the Rhinodrilidae were found only in the most remote location sampled and are presumed to be native. Seven previously reported native Dichogaster were found. Eight non-recorded species of Dichogaster were found, five represented by single specimens or juveniles, for which we give only a brief precis. The three described here are Dichogaster spolstoni n. sp., Dichogaster caraibensis n. sp.,.and Dichogaster etaspiqui n. sp. These are compared to and differentiated from previously known Dichogaster species of the world and of Guadeloupe.
Herbicide runoff from cropping fields has been identified as a threat to the Great Barrier Reef ecosystem. A field investigation was carried out to monitor the changes in runoff water quality resulting from four different sugarcane cropping systems that included different herbicides and contrasting tillage and trash management practices. These include (i) Conventional – Tillage (beds and inter-rows) with residual herbicides used; (ii) Improved – only the beds were tilled (zonal) with reduced residual herbicides used; (iii) Aspirational – minimum tillage (one pass of a single tine ripper before planting) with trash mulch, no residual herbicides and a legume intercrop after cane establishment; and (iv) New Farming System (NFS) – minimum tillage as in Aspirational practice with a grain legume rotation and a combination of residual and knockdown herbicides.
Conventional agriculture strongly alters soil quality due to industrial practices that often have negative effects on soil life. Alternative systems such as conservation agriculture and organic farming could restore better conditions for soil organisms. Improving soil life should in turn improve soil quality and farming sustainability. Here, we have compared for the first time the long-term effects of conservation agriculture, organic farming, and conventional agriculture on major soil organisms such as microbes, nematofauna, and macrofauna. We have also analyzed functional groups. Soils were sampled at the 14-year-old experimental site of La Cage, near Versailles, France. The microbial community was analyzed using molecular biology techniques. Nematofauna and macrofauna were analyzed and classified into functional groups. Our results show that both conservation and organic systems increased the abundance and biomass of all soil organisms, except predaceous nematodes. For example, macrofauna increased from 100 to 2,500 %, nematodes from 100 to 700 %, and microorganisms from 30 to 70 %. Conservation agriculture showed a higher overall improvement than organic farming. Conservation agriculture increased the number of many organisms such as bacteria, fungi, anecic earthworms, and phytophagous and rhizophagous arthropods. Organic farming improved mainly the bacterial pathway of the soil food web and endogeic and anecic earthworms. Overall, our study shows that long-term, no-tillage, and cover crops are better for soil biota than periodic legume green manures, pesticides, and mineral fertilizers.
Most cultivated soils in temperate regions support earthworms. Population densities vary widely and the species present differ in relation to climatic conditions, soil type and cropping. Cultivation by mechanical disturbance completely changes the environment in which earthwormslive, destroying the habitat and changing the soil temperature and moisture and the availability of food. All these factors influence the size of earthworm populations, their species diversity, dominance and vertical distribution (Fig. 10. I).
Conventional agriculture strongly alters soil quality due to industrial practices that often have negative effects on soil life. Alternative systems such as conservation agriculture and organic farming could restore better conditions for soil organisms. Improving soil life should in turn improve soil quality and farming sustainability. Here, we have compared for the first time the long-term effects of conservation agriculture, organic farming, and conventional agriculture on major soil organisms such as microbes, nematofauna, and macrofauna. We have also analyzed functional groups. Soils were sampled at the 14-year-old experimental site of La Cage, near Versailles, France. The microbial community was analyzed using molecular biology techniques. Nematofauna and macrofauna were analyzed and classified into functional groups. Our results show that both conservation and organic systems increased the abundance and biomass of all soil organisms, except predaceous nematodes. For example, macrofauna increased from 100 to 2,500 %, nematodes from 100 to 700 %, and microorganisms from 30 to 70 %. Conservation agriculture showed a higher overall improvement than organic farming. Conservation agriculture increased the number of many organisms such as bacteria, fungi, anecic earthworms, and phytophagous and rhizophagous arthropods. Organic farming improved mainly the bacterial pathway of the soil food web and endogeic and anecic earthworms. Overall, our study shows that long-term, no-tillage, and cover crops are better for soil biota than periodic legume green manures, pesticides, and mineral fertilizers.
Diplopods play an important role in the dynamics of terrestrial ecosystems, actively participating in the decomposition of organic matter and soil aeration. They have gained increased attention from ecotoxicology research because they are continuously exposed to soil contaminants and biological effects of chemical stressors can be measurable at various levels of biological organization. This paper is the first review on the use of diplopods as soil bioindicators and compiles the effects of the different toxic chemical agents on these animals. Special emphasis is given on the interpretation of the effects of heavy metals and complex mixtures in target organs of diplopods.
Five herbicides, atrazine, dalapon, monuron, TCA, and 2,4-D, were applied once to grassland to evaluate their effects for at least two summers after application on the numbers of wireworms, Agriotes spp., springtails (Collembola suborder Arthropleona), mites (Acarina), earthworms (Lumbricidae), and millipedes (Diplopoda) in the soil. In plots treated with atrazine, wireworms, earthworms, and springtails declined in numbers. Dalapon increased the numbers of millipedes, springtails, and mites. Monuron reduced the numbers of wireworms, millipedes, earthworms, springtails, and mites. TCA increased the numbers of millipedes, springtails, and mites and decreased the number of earthworms. Treatment with 2,4-D did not affect the numbers of wireworms, springtails, or mites. The data suggest that faunal fluctuations were chiefly caused indirectly by the herbicides altering the floristic composition of the grassland.The results show that certain herbicides may diminish or increase the numbers of both beneficial and ...
Earthworms provide key soil functions that favour many positive ecosystem services. These services are important for agroecosystem sustainability but can be degraded
by intensive cultural practices such as use of pesticides. Many literature reports have investigated the effect of pesticides on earthworms. Here, we review those reports
to assess the relevance of the indicators of earthworm response to pesticides, to assess their sensitivity to pesticides,
and to highlight the remaining knowledge gaps. We focus on European earthworm species and products authorised in Europe, excluding natural compounds and metals. We consider different organisation levels: the infra-individual level (gene expression and physiology),
the individual and population levels (life-history traits, population density and behaviour) and the community level : community biomass and density. Our analysis showsthat earthworms are impacted by pesticides at all organisation
levels. For example, pesticides disrupt enzymatic activities, increase individual mortality, decrease fecundity
and growth, change individual behaviour such as feeding rate and decrease the overall community biomass and density. Insecticides and fungicides are the most toxic pesticides
impacting survival and reproduction, respectively.
Losses of about 40% in cane yields due to natural stands of weeds were found in experiments conducted in sugarcane var. Co 527 in the year of planting at Guneid Sugarcane Research Station, Sudan. Weed competition lowered millable stalks per metre row by 32%, stalk height by 24%, stalk thickness by 15% and number of nodes per stalk by 14%. Tillering was the growth phase most affected by weed competition.
Cane yields were increased as number of hand weedings increased, but four weedings were not markedly better than three. The average yield (67·04 t ha ⁻¹ ) obtained from four weedings was not significantly ( P = 0·05) better than that of three weedings carried out at 3, 6 and 9 weeks after cane planting.
Juice analysis components were also affected by weeds and a 15% reduction in sucrose recovery was recorded. Reductions in the other components were only 4–7%.
Atrazine and diuron (3·3 kg ha ⁻¹ ), metribuzin (2·4 kg ha ⁻¹ ) and metribuzin (1·3 kg ha ⁻¹ ) in tank mixture with diuron (1·5 kg ha ⁻¹ ) gave excellent residual weed control of the dominant weed species, Ipomoea cordofana Choisy., Brachiaria eruciformis (Sm.) Griseb., Corchorus fascicularis Lam., Ocimum basilicum L. and Dinebra retroflexa (Vahl) Panz., for most of the first growing season. Excellent control of weeds achieved by the herbicide treatments resulted in comparable yields to frequently‐weeded cane. These herbicides were not phytotoxic to sugarcane var. Co 527.
Four herbicides, atrazine, simazine, paraquat, and glyphosate were tested for their acute and chronic toxicity as well as repellent effects on five common carabid beetles (Amara sp., Agonum sp., Pterostichus sp., Anisodactylus sp., and Harpalus sp.) in laboratory and greenhouse experiments. These carabid species are potential biocontrol agents and interference with their biology through herbicide applications, either directly or indirectly, could lead to soil pest outbreaks. Short-term field studies also were conducted to verify laboratory and greenhouse results. The four herbicides did not have significant acute or chronic effects on male or female carabid longevity or food consumption during one year after exposure to initial field-rate applications. Only simazine and atrazine had a repellent effect on carabids, which lasted approximately three days in greenhouse studies. Behavioral studies indicate that once carabids, especially smaller ones (< 10 mm in length), establish burrows and foraging territories, they tend to remain in these areas and migrate out of them only slowly. There was no toxic or repellent effect of any herbicide in the field. Carabids, instead, apparently responded to the destruction of plant material which provided a less favorable habitat for the larger (> 10 mm length) carabids. Glyphosate and paraquat had the greatest effect on carabids by the second week in field studies, with significantly fewer large carabids found in these two treatments than in the control. Large carabids did not return to paraquat- and glyphosate-treated field areas until approximately 28 days after application; consequently, lower rates of predation of early-season lepidopteran pests by these carabid species may occur in no-tillage corn fields that utilize herbicides for weed control.
Herbicide combinations of paraquat, glyphosate, alachlor, linuron, fluazifopbutyl, aciflurofen, and bentazon were investigated for their impact on soil arthropod population dynamics and surface wheat straw decomposition (weight loss) within a North Carolina coastal plain agroecosystem. Herbicides were applied twice (preemergence and mid-bloom) at recommended field rates to soybeans no-till planted into wheat residue. Separate measurements were made for surface crop residue and soil-dwelling (0–3 cm depth) arthropods. Decomposition of herbicide (glyphosate) and nonherbicide-treated wheat straw residue was compared using mesh bag techniques. Decay rate constants were estimated for glyphosate and nonherbicide-treated wheat straw residue by fitting a two-component model to the data. Comparison of soil microarthropod numbers from herbicide and nonherbicide treatments showed no consistent trend, suggesting that abiotic factors such as soil temperature and moisture were probably more significant than herbicide effects in regulating soil microarthropod number and activity. Herbicides had no effect on soil macroarthropod number or activity until late in the season when macroarthropods were most abundant under weedy, no-tillage conditions. Moist soil and litter, low soil temperature, floral diversity, and high weed-seed availability probably enhanced macroarthropod numbers in nonherbicide treatments. Decomposition (ash-free weight loss) of nonherbicided, surface crop residues was more rapid than herbicide (glyphosate) treated, indicating that herbicide effects occur at the decomposer as well as producer level of agroecosystems.
The aim of this study was to use the diplopod Rhinocricus padbergi as test organism to verify the possible toxic effects of the herbicide trifluralin in a representative of the edaphic fauna. Histological and histochemical techniques were applied in the midgut of the animals after exposure to different concentrations of trifluralin for 7 and 90 days (acute and subchronic exposure, respectively). The individuals from the control group did not present alterations to any of the exposures. In the acute exposure, the group exposed to a quarter and half of the field dose presented an accumulation of cytoplasmic granules in the hepatic cells; the field dose group presented an increase in the rate of epithelial renewal and the group exposed to double the field concentration presented an increase in the release of secretory vesicles. The subchronic response was obtained with the field dose and double field dose because the animals from a quarter and half groups did not survive until the end of the experiment. In both groups, the animals presented disruption of the epithelium and higher occurrence of hemocytes among the hepatic cells. The group exposed to double the field dose presented sites of cytoplasmic vacuolization, dilatation of the intercellular space, increase in the epithelial renewal, and release of secretory vesicles. The results alert for a careful use of this herbicide, since it promoted alterations in the midgut cells of the test organism used. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.
The effects of land management including undisturbed native forest, native grassland, sugarcane (Saccharum spp.) (preharvest burnt or green cane harvested), exotic forest (gum, Eucalyptus grandis; pine, Pinus elliottii; wattle, Acacia mearnsii), orchard crops (orange, Citrus sinensis; banana, Musa accumunata; avocado, Persea americana) and grazed kikuyu grass (Pennisetum clandestinum) on the size and composition of earthworm communities and on related soil properties (organic C, soluble C, microbial biomass C) were investigated. The study locality was in the tropical, northern part of KwaZulu-Natal. Earthworm numbers followed the order: . Earthworm numbers and biomass were closely positively correlated with soluble C, microbial biomass C and also pH. A total of 11 species of earthworms were collected. Over 80% of individuals collected were accidentally introduced exotic species which originated from India, South America and West Africa. Most land use types supported five to seven species but sugarcane and wattle supported only two or three species. Juveniles dominated the community under all land uses except kikuyu pasture and avocado. Epigeic species dominated under native forest and native grassland, avocado and gum. For the other types of land use, endogeics predominated. The most numerous species present was Pontoscolex corethrurus which was present under all land uses. The most common epigeic species was Amynthus rodericensis which made up a substantial portion of the community under native and gum forests and banana. The third most numerous species was A. minimus which is a polyhumic, endogeic species and was particularly numerous under kikuyu pasture. Dichogaster saliens was an important component of the community under some land uses. It was concluded that land use has major effects on the size, composition and diversity of earthworm communities in the region.
The intensification and expansion of modern agriculture is amongst the greatest current threats to worldwide biodiversity. Over the last quarter of the 20th century, dramatic declines in both range and abundance of many species associated with farmland have been reported in Europe, leading to growing concern over the sustainability of current intensive farming practices. Purportedly ‘sustainable’ farming systems such as organic farming are now seen by many as a potential solution to this continued loss of biodiversity and receive substantial support in the form of subsidy payments through EU and national government legislation.
We tested a trait-based approach to link a soil disturbance to changes in invertebrate communities. Soils and macro-invertebrates were sampled in sandy soils contaminated by long-term wastewater irrigation, adding notably organic matter and trace metals (TM). We hypothesized that functional traits of invertebrates depict ways of exposure and that exposure routes relate to specific TM pools. Geophages and soft-body invertebrates were chosen to inform on exposure by ingestion or contact, respectively. Trait-based indices depicted more accurately effects of pollution than community density and diversity did. Exposure by ingestion had more deleterious effects than by contact. Both types of exposed invertebrates were influenced by TM, but geophages mainly responded to changes in soil organic matter contents. The trait-based approach requires to be applied in various conditions to uncorrelate specific TM impacts from those of other environmental factors.
Laboratory tests were conducted to compare the effects of various concentrations of glyphosate and 2,4-D on earthworms (Eisenia foetida) cultured in Argissol during 56 days of incubation. The effects on earthworm growth, survival, and reproduction rates were verified for different exposure times. Earthworms kept in glyphosate-treated soil were classified as alive in all evaluations, but showed gradual and significant reduction in mean weight (50%) at all test concentrations. For 2,4-D, 100% mortality was observed in soil treated with 500 and 1,000 mg/kg. At 14 days, 30%-40% mortality levels were observed in all other concentrations. No cocoons or juveniles were found in soil treated with either herbicide. Glyphosate and 2,4-D demonstrated severe effects on the development and reproduction of Eisenia foetida in laboratory tests in the range of test concentrations.
Earthworm ecology in cultivated soils
- Edwards
Alternatives de séquestration du carbone et spatialisation des stocks actuels et simulés (c. r. du programme GESSOL)
- E Blanchart
- M Bernoux
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Antilles (Martinique, Guadeloupe). Alternatives de séquestration du carbone et
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Montpellier, France.