Effects of biocontrol bacteria and earthworms on Aphanomyces euteiches root-rot and growth of peas (Pisum sativum) studied in a pot experiment

The role of below-ground interactions between microbial biocontrol agents and soil fauna for combatting soil-borne plant diseases have not been studied sufficiently. This study tested the hypothesis that the beneficial bacterium Bacillus velezensis UCMB5113 and the anecic earthworm Lumbricus terrestris positively influence health and growth of peas (Pisum sativum L.) infested with the pathogen Aphanomyces euteiches causing root-rot disease. A greenhouse fully factorial experiment studied the effects of A. euteches, B. velezensis and L. terrestris on the emergence, growth and health of pea plants. The factors B. velezensis and L. terrestris resulted in taller plants (p = .003 and p = .030). B. velezensis treatment resulted in a higher biomass of shoots and roots (p <= .001 and p = .005). The effects increased with the presence of both factors (p = .036). Earthworms reduced the disease symptoms significantly (p = .032). The decreased disease symptoms caused by the earthworms might be due to the consumption of A. euteiches (direct effect) as well as soil disturbance (indirect effect). Interactions between the microorganisms added and the earthworms were shown. B. velezensis and L. terrestris can be useful for enhancement of plant growth and for biological control of root-rot in peas

Land-use intensification and agroforestry in the Kenyan highland: impacts on soil microbial community composition and functional capacity

This study investigates microbial communities in soil from sites under different land use in Kenya. We sampled natural forest, forest plantations, agricultural fields of agroforestry farms,agricultural fields with traditional farming and eroded soil on the slopes of Mount Elgon,Kenya. We hypothesised that microbial decomposition capacity, biomass and diversity 1)decreases with intensified cultivation; and 2)can be restored by soil and land management in agroforestry. Functional capacity of soil microbial communities was estimated by degradation of 31 substrates on Biolog EcoPlates™. Microbial community composition and biomass were characterised by phospholipid fatty acid (PLFA)and microbial C and N analyses. All 31 substrates were metabolised in all studied soil types, i.e. functional diversity did not differ. However,both the substrate utilisation rates and the microbial biomass decreased with intensification of land use, and the biomass was positively correlated with organic matter content. Multivariate analysis of PLFA and Biolog EcoPlate™ data showed clear differences 25 between land uses, also indicated by different relative abundance of PLFA markers for certain microorganism groups. In conclusion, our results show that vegetation and land use control the substrate utilisation capacity and microbial community composition and that functional capacity of depleted soils can be restored by active soil management, e.g. forest plantation. However, although 20 to 30 years of agroforestry farming practises did result in improved soil microbiological and chemical conditions of agricultural soil as compared to traditional agricultural fields, the change was not statistically significant

Commercial Fungicide Toxic Effects on Terrestrial Non-Target Species Might Be Underestimated When Based Solely on Active Ingredient Toxicity and Standard Earthworm Tests

The ecosystem services provided by earthworms are lost when land management reduces their populations, hence, the importance of thorough assessments of management effects on this group. The present study aimed to: (1) review the possible influence of other ingredients within the formulations of two commercial fungicides; (2) assess the sublethal effects of these commercial fungicides on Eisenia fetida; and (3) assess the acute lethal effects of one commercial fungicide on both Glossoscolex none and E. fetida. Examining all components of the studied commercial formulations revealed that alongside the toxic active ingredients are other ingredients that are equally as or more toxic than the former and may even be in higher concentrations. The inhibition concentration of 10% of E. fetida's progeny (IC10) was estimated at 133 mg kg(-1) for PROSARO (R) and 1544 mg kg(-1) for SWING PLUS (R). Both fungicides showed an effect of hormesis on the progeny. In this first toxicity study with G. nione, it was found that this species is more sensitive to PROSARO (R) than E. fetida, with preliminary 14 day-lethal concentrations of 285 mg kg(-1) for the former and >1000 mg kg(-1) for the latter

Control biológico de enfermedades y plagas promovido por lombrices

A pesar de vaivenes en la historia al respecto de cómo se ha interpretado la acción de las lombrices sobre el suelo y las plantas, actualmente se acepta como un hecho que estos anélidos tienen un efecto positivo indirecto sobre la productividad y sanidad vegetal, al mejorar las propiedades del suelo que sustenta la vida de las plantas. Lo que resulta más novedoso, quizás, es la acción directa que se ha descubierto que pueden tener las lombrices al suprimir ciertas plagas y enfermedades; o influyendo directamente sobre el sistema de defensa de las plantas. Estas líneas de investigación tienen varias décadas de desarrollo a nivel mundial, pero son muy poco conocidas en el mundo hispano-parlante, con escasa literatura en el tema escrita en español. La presente revisión pretende reunir los casos que han demostrado un efecto positivo significativo de las lombrices sobre la sanidad vegetal, indagar en los mecanismos por los cuales éstas pueden participar del control biológico de parástitos, fitófagos o fitopatógenos, y discutir las perspectivas de aplicación del control biológico mediante el uso de lombrices como parte de una agricultura sustentable y agroecológica

Carbon routes from decomposing plant residues and living roots into soil food webs assessed with C-13 labelling

This field experiment investigated how C from fresh organic amendments and from a growing leek crop was allocated into different soil microbial and faunal groups in an arable field. A C-13-enriched red clover green manure was incorporated in one treatment, while the growing leek crop was pulse labelled with (CO2)-C-13 in another. Incorporation of C-13 into microbial fatty acids, micro- and macroarthropods, enchytraeids and earthworms was determined on several occasions during the growing season in order to determine whether different groups or species of microorganisms and fauna were specialised on either the decomposing green manure material or root-derived C. Compound-specific stable isotope ratio analysis showed fatty acid markers of actinomycetes and Gram-positive bacteria to be more strongly linked to C originating from the decomposing green manure material, whereas the marker for arbuscular mycorrhizal fungi was more linked to C from the growing leek crop. In contrast, several markers for Gram-negative bacteria were the most C-13-enriched and had incorporated more C-13 than the other phospholipid fatty acids in both treatments, indicating a general dominance irrespective of C source. Most soil fauna seemed to derive their C directly or indirectly from the decomposing plant material, while C from the growing crop appeared to be of secondary importance in this agroecosystem. (C) 2008 Elsevier Ltd. All rights reserved

Response of soil mite abundance and diversity to a monospecific timber Tectona grandis plantation in Ivory Coast

This study aims to assess the impact of monospecific Tectona grandis forest plantation on the soil mite abundance and diversity. To achieve these objectives, two sites situated in Ivory Coast were investigated. The first, a primary forest was characterized by a very weak human activities whereas the second, a teak plantation was characterized by a high disturbance performed during the planting. After extracting, sorted and description, 116 mite species were described in the two sites. Mite densities were lower in teak plantation and also higher in the litter and decreased to the depth in both sites. Species richness recorded in teak plantation (52 species) was significantly lower compared to primary forest (98 species). The same trend was observed for Oribatida but not for Gamasida. The lower Oribatida (5 vs. 17) and higher Oribatida (24 vs. 41) were recorded respectively in teak plantation and primary forest. Mite Shannon index and evenness were significantly different between sites. High Jaccard index values and the appearance of exclusive species in both habitats showed that the sites are very distinct. Total number of species recorded corresponded to 58%–63% of the total number of species estimated by ACE and Chao 1&2 estimators, indicating that the sampling effort was not sufficient. Mite abundance and diversity varied depending on the characteristics of habitats. Chemical element (Corg, Ctot, Ntot, and SOM) values were lower in teak plantation (disturbed habitat) and significantly different to primary forest in the topsoil. Apart from litter height, soil depth, pH and C/N ratio, others variables were strongly correlated to mite abundance and diversity [Current Zoology 59 (5): 633–643, 2013]

Response of soil mite abundance and diversity to a monospecific timber Tectona grandis plantation inIvory Coast

his study aims to assess the impact of monospecific Tectona grandis forest plantation on the soil mite abundance and diversity. To achieve these objectives, two sites situated in Ivory Coast were investigated. The first, a primary forest was characterized by a very weak human activities whereas the second, a teak plantation was characterized by a high disturbance performed during the planting. After extracting, sorted and description, 116 mite species were described in the two sites. Mite densities were lower in teak plantation and also higher in the litter and decreased to the depth in both sites. Species richness re- corded in teak plantation (52 species) was significantly lower compared to primary forest (98 species). The same trend was ob- served for Oribatida but not for Gamasida. The lower Oribatida (5 vs. 17) and higher Oribatida (24 vs. 41) were recorded respec- tively in teak plantation and primary forest. Mite Shannon index and evenness were significantly different between sites. High Jaccard index values and the appearance of exclusive species in both habitats showed that the sites are very distinct. Total number of species recorded corresponded to 58%–63% of the total number of species estimated by ACE and Chao 1&2 estimators, indi- cating that the sampling effort was not sufficient. Mite abundance and diversity varied depending on the characteristics of habi- tats. Chemical element (Corg, Ctot, Ntot, and SOM) values were lower in teak plantation (disturbed habitat) and significantly dif- ferent to primary forest in the topsoil. Apart from litter height, soil depth, pH and C/N ratio, others variables were strongly corre- lated to mite abundance and diversit