Black truffle, Tuber melanosporum Vittad., production is increasing due to an improvement in cultivation management and to the demand for this highly appreciated fungus. However, this intensification of truffle cultivation has led to the appearance of problems related to pest incidence. Specifically, the truffle beetle, Leiodes cinnamomeus (Panzer, 1793) (Coleoptera: Leiodidae), causes significant losses in black truffle marketability. However, its biology is still poorly known, and no effective agro-ecological methods exist to mitigate its damage to the truffles. This study aimed at assessing the population dynamics of L. cinnamomeus over four seasons (2019-2023) in an orchard located in NE Spain and relating these dynamics to weather variables and damage to truffle fruit bodies. Moreover, we described the diversity of arthropods captured in the traps in search of potential natural enemies of this beetle. The maximum population peak was observed in November, except for a single season in which it occurred in December. Moreover, the sex ratio was balanced (0.54 on average), but it varied over the growing season and among years. Significant and positive relationships of the population density of truffle beetles with air temperature and relative humidity were observed. The number of beetles per trap and day was strongly linked to heat accumulation. Finally, the Carabid Percus (Pseudopercus) patruelis (L. Daufour, 1820) was identified as a natural enemy of L. cinnamomeus. These results could be used in the future for monitoring and predicting truffle beetle populations.
Large quantities of chlordecone-based insecticides were produced and used throughout the world. One of its most important uses was to control the damage caused by Cosmopolites sordidus in banana-growing regions. In the islands of Martinique and Guadeloupe, 18,000 ha of farmland are potentially contaminated. Despite the key role played by soil macrofauna in agroecosystems, there are currently no data on their contamination. The aim of this study was to explore the fate of chlordecone (CLD) and its transfer to different organisms of the soil food web. Seven species of invertebrates representing different taxonomic groups and trophic levels of the soil communities of Martinique were targeted and collected in six experimental banana fields, with a level of contamination within a range of values classically observed. Soil samples and macrofauna from the study sites were analysed for CLD and chlordecol (CLDOH) its main transformation product. The contamination of the soil fauna were related to delta 15N 15 N (trophic level), proportion of soil ingestion (diet) and types of epidermis (mucus or exoskeleton) in order to study the different mechanisms of macrofauna contamination. Presence of CLD and CLDOH could be quantified in all the soil organisms from contaminated fields. Results showed a significant relationship between the CLD contamination of detritivorous and the ash content of their faeces, suggesting that soil ingestion was the main contamination pathway. In contrast, the exoskeleton-bearing diplopod Trigoniulus coralinus and the soft-bodied earthworm Eudrilus eugeniae, both detritivores with a comparable diet, had similar contamination levels, suggesting that the type of tegument has little influence on bioaccumulation. At the scale of the entire trophic network, a significant relationship was uncovered between delta 15N 15 N values and CLD contamination of the fauna, therefore providing some in situ evidence for a bioamplification process along the soil food chain.
Plant-parasitic nematodes (PPNs) pose a critical challenge in agriculture, particularly when it comes to managing fruit orchards. To address the potential damage, our study aimed to analyze 110 soil samples from pome-fruit tree rhizospheres to identify PPNs. After transferring the samples to the lab, soil washing and nematode extraction were performed using a modified combination of the sieve and centrifugation method by Jenkins, followed by fixation and transfer to glycerin according to De Grisse's method. The results showed that of the 27 identified species, Amplimerlinius parbati, Pratylenchus estoniensis, Rotylenchus bialaebursus, and R. secondus were new records for Iran. A. parbati was distinguished by between four and five head annuli, large stylet with downward knobs, and annulated tail with hemispherical shape. P. estoniensis was identified by two annuli in the lip region, well-developed empty spermathecal, and striated tail tip. R. bialaebursus possessed a rounded lip region with four annuli, phasmids in between nine and 12 annuli anterior to the anus, and a rounded tail with between six and eight annuli. R. secondus was recognized by conoid and slightly offset labial region without/with faint annulation, stylet pointed and less than 30 mu m, rounded tail and vulva situated at 50-70%. Subsequently, the potential threat of the species to fruit orchards is discussed.
We report for the first time that larvae of the genus Bothynus Hope (Coleoptera: Melolonthidae) caused economic damage to lucerne (Medicago sativa L., Fabaceae) crops in General Acha, province of La Pampa, Argentina. In two consecutive years (2021 and 2022), this insect infested 150 ha of lucerne, causing seedling losses of 80 ha. Based on soil sampling and laboratory insect rearing, the species was identified as Bothynus striatellus (Faimaire) (Coleoptera: Melolonthidae). Information is given here on the damage recorded in this forage crop, the density of the larvae observed at the time of damage assessment and the morphological characteristics of the third instar larvae reported in this crop in Argentina.
With the widespread use of biochar, the cascading effects of biochar exposure on soil fauna urgently require deeper understanding. A meta-analysis quantified hierarchical changes in functional traits and community diversity of soil fauna under biochar exposure. Antioxidant enzymes (24.1 %) did not fully mitigate the impact of MDA (13.5 %), leading to excessive DNA damage in soil fauna (21.2 %). Concurrently, reproduction, growth, and survival rates decreased by 20.2 %, 8.5 %, and 21.2 %, respectively. Due to a 39.7 % increase in avoidance behavior of soil fauna towards biochar, species richness ultimately increased by 80.2 %. Compared to other feeding habits, biochar posed a greater threat to the survival of herbivores. Additionally, macrofauna were the most sensitive to biochar. The response of soil fauna also depended on the type, size, concentration, and duration of biochar exposure. It should be emphasized that as exposure concentration increased, the damage to soil fauna became more severe. Furthermore, the smaller the biochar sizes, the greater the damage to soil fauna. To mitigate the adverse effects on soil fauna, this study recommens applying biochar at appropriate times and selecting large sizes in low to medium concentrations. These findings confirm the threat of biochar to soil health from the perspective of soil fauna.
In production of cereals like maize ( Zea mays L.) and barley ( Hordeum vulgare L.), seeds are often treated with pesticides and/or commercial products of plant beneficial microorganisms (PBM) to reduce possible root damage from insect pests and soil borne root diseases. In a field experiment with maize and barley under conservation agriculture, we examined how such seed treatments affected the resident root and soil microbiota. The seed treatments included a pesticide mixture and different commercial products of common PBM based on the biocontrol agents (BCA) Trichoderma harzianum and Metarhizium anisopliae alone and in combination and a mix of plant growth promoting rhizobacteria (PGPR), which were compared to a negative control without seed treatment. Soil and root samples were taken at two and three sampling times during the crop cycles for barley and maize, respectively, to measure root biomass, root colonization with mycorrhizal fungi and pathogens, soil microbial communities at a general taxonomic level using biomarker fatty acids, and ecological guilds of soil nematodes. Root health was monitored with observations of the presence of insect feeding larvae and root disease symptoms, which in general showed healthy roots during the full crop cycle. Overall, most of the root and soil biota variables measured changed during the crop cycle. However, for both crops, the seed treatments had no effects on the soil and root microbiota measured, except in the case of barley root infection with Polymyxa sp., which was reduced by all treatments. In conclusion, the pesticide and PBM seed treatments evaluated in the present study for maize and barley under conservation agriculture, in general, had limited effects on the resident root and soil microbiota. However, future studies should include complementary high-resolution sequencing methods when examining non-target effects of pesticides and microbial inoculants on the root and soil microbiota.
The decomposition of returned straw is increasing facing the negative impacts by metal nanoparticles (NPs), however, which may be modulated by soil fauna and this modulation effect is unclear. Here, the interactive effects of ZnO NPs with soil fauna on wheat straw decomposition were investigated in a potted rice cropping system. The results showed that ZnO NP below middle concentrations did not significantly influence straw decomposition, and mass loss was mainly driven by microfauna and microbes. High concentrations of ZnO NPs significantly impeded decomposition, mainly by reducing the complexity of fungal communities. This negative effect was ascribed to the promotion of Zn solubilization by bacterial taxa such as unclassified Acidobacteria, Bacteroidetes and Gemmatimonadetes. ZnO NPs had a greater impact on soil microorganisms than on fauna, reduced microbial activity, promoted the released straw nutrients entering into the soil by damaging nutrient transferring microorganisms and dominated the effects on soil stoichiometry. However, soil fauna significantly increased the activities of C- and N-releasing enzymes, decreased the activity of P-releasing enzymes, regardless of ZnO NP concentration, and promoted straw C decomposition. ZnO NPs altered soil microbial community composition, but these changes were modulated by soil fauna. Nonetheless, nutrient transport by fungi such as Ascomycota and Zygomycota and grazing by fauna were the predominant modulators on straw stoichiometry. The results of this study revealed that rational control of soil fauna will be helpful for promoting straw decomposition and efficient recycling of straw nutrients by crops under ZnO NP contamination. High ZnO NP concentrations inhibit straw decomposition mainly by reducing diversity of fungal community.The negative effects of ZnO NPs are ascribed to Zn solubilization by bacterial taxa such as unclassified Acidobacteria, Bacteroidetes and Gemmatimonadetes.ZnO NPs have greater impact on soil microorganisms than on fauna, reduce microbial activity, promote the released nutrients into soil and dominate the effects on soil stoichiometry.Fungal transport (e.g., Ascomycota and Zygomycota) and fauna grazing are the predominant modulators on straw stoichiometry.
1. The relationship between biodiversity and multitrophic ecosystem functions (BEF) remains poorly studied in forests. There have been inconsistent reports regarding the significance of tree diversity effects on ecosystem functions, which may be better understood by considering critical biotic interactions of trees. 2. This study investigates the role of tree-mycorrhizal associations that may shape forest BEF relationships across multiple ecosystem functions. We used a field experiment (MyDiv) that comprises 10 deciduous tree species associated with either arbuscular mycorrhizal (AM) or ectomycorrhizal (EcM) fungi to create gradients in species richness (1, 2, 4 species) and different mycorrhizal communities (only AM-species [AM fungi associated tree species] or EcM-species [EcM fungi associated tree species], or a combination of both). We investigated the effects of tree species richness and mycorrhizal types on crucial multitrophic ecosystem functions (foliage damage, predation [using artificial caterpillars] and soil fauna feeding activity [similar to 0-10 cm]) and assessed how these effects were mediated by stand characteristics. 3. Overall, we found that tree species richness and mycorrhizal types strongly affected multitrophic ecosystem functions. Compared to monocultures, 4-species mixtures with both mycorrhizal types experienced significantly lower foliage damage. The mixtures of EcM-species supported significantly higher predation (i.e. a greater proportion of artificial caterpillars being attacked), and this effect strengthened with tree species richness. The effects of tree species richness on soil fauna feeding activity were negative across all mycorrhizal types in the lower soil layer. Moreover, we showed that tree diversity effects were mediated by above-ground tree biomass, vertical structural complexity and leaf quality, with the dominating mechanisms largely depending on the mycorrhizal types. 4. Synthesis. Tree species richness affected multitrophic ecosystem functioning by (1) directly decreasing the proportion of foliage damage in the communities with both mycorrhizal types, where AM-species benefited from mixing with EcM-species, and (2) increasing predation rates via changes in the vertical structural complexity in mixtures of EcM-species. Our results highlight the importance of considering mycorrhizal types for managing well-functioning mixed-species forests and contribute to broadening the mechanistic understanding of the context-dependent BEF relationships in forests.
Millet/cowpea intercropping is a promoted practice in Sub-Saharan agriculture. However, because cowpea is known as a host for plant-parasitic nematodes that may also infect millet, we examined whether intercropping may increase the risk of nematode-mediated millet damage, and if this risk may be controlled by organic amendments. In twelve Senegalese farmers' fields which had been either non-manured or regularly manured over the past 10 years at least, we assessed the effects of intercropping millet and cowpea on the abundance of free-living and plant-parasitic nematodes, ecological indices, and land equivalent ratios (LER). Six fields were manured, and six non-manured. Each field included four plots: millet and cowpea as pure stands, and two plots with millet intercropped with cowpea sown at two densities. Soil nematofauna was evaluated before sowing and at cowpea flowering. Soil nematofauna was dominated by plant-parasitic nematodes. Before manure application and crop sowing, regularly manured fields had higher structure indices of nematofauna than non-manured ones, and Pratylenchus was almost absent. At crop flowering, abundance of Pratylenchus increased and was drastically higher in pure cowpea (149 individuals 100 g(-1) dry soil) than in intercropping and pure millet (18 and 17 individuals 100 g(-1) dry soil, respectively), regardless of the manuring regime. Manuring had significant positive effects on various bacterivorous families, on fungivorous and plant-parasitic trophic groups, but not on Pratylenchus. Millet and cowpea yields of manured fields were the highest, regardless of cropping pattern. LER averaged 1.7 and 1.5 in manured and non-manured intercropping, respectively. Regardless of the treatments, ecological indices indicated that the soil food web was undisturbed, with moderate enrichment, and suppressive against crop pests. Intercropping millet with cowpea, even in poorly manured fields and with high cowpea density, constitutes an appropriate way to improve productivity without increasing Pratylenchus pressure in nutrient-poor soils of central Senegal.
Wetlands play a crucial role in oxygen production, air purification, and quality maintenance. Thus, conservation of wetland is essential in response to natural and anthropogenic damaging activities. Restored farmland, utilized to repair the southern buffer zone of Jiangsu Yancheng Wetland National Nature Reserve for Rare Birds, was used to investigate and analyze the diversity of migratory birds and soil fauna. In this study, five different crops, colza oil, mustard, Chinese cabbage, wheat, and barley, were planted in the restored plots, which were foraged by overwintering migratory birds, resulting in low crop yield. The soil fauna biodiversity and biomass in the wheat, Chinese cabbage, and colza oil plots during winter were relatively rich, which attracted many migratory birds to roost and feed. The variability and population of migratory birds significantly improved (18 species and 164231 migratory birds), which was owed to soil fauna and planted crops. Therefore, based on the results of our study, farmland restoration could significantly enrich the biodiversity of soil fauna and migratory birds, improve the ecological environment of wetlands, and attract more migratory birds as inhabitants.