Search Results (9)

Root-knot (Meloidogyne spp.) and false root-knot (Nacobbus aberrans) nematodes limit greenhouse tomato productivity. The effectiveness of integrating pre-plant biofumigation with post-plant chemical, biological, and botanical inputs was assessed under commercial conditions. A split-plot trial (2019) contrasted biofumigated and non-biofumigated whole plots (50 t ha⁻¹ of sorghum residues plus poultry and sheep manures) and 13 subplot treatments (fluopyram, Purpureocillium lilacinum, Pochonia chlamydosporia, Trichoderma viride, Tagetes erecta, and plant oil formulations). Nematodes were sampled 0, 60, and 120 days after transplanting, and the area under the nematode population curve (AUNPC), area under the root-damage curve (AURDC), and yield were analyzed. Biofumigation reduced pre-transplant N. aberrans populations by 86% and lowered the AUNPC by 39% relative to the non-biofumigated treatment; the whole-plot yields did not differ. Meloidogyne incognita remained at a very low density throughout. Among the subplot treatments, fluopyram decreased the AURDC by ≈22% and more than doubled the yield (63 vs. 26 t ha⁻¹; +142%), while the AUNPC of N. aberrans was unchanged. Biological and botanical packages reduced damage indices in some cases but did not increase the yield. No whole-plot × subplot interaction was detected for the yield. The results indicate that sorghum-based biofumigation, complemented by a low-risk nematicide at transplanting, can be embedded in integrated nematode-management programs for greenhouse tomato. Full article

The primary strategy for managing Nacobbus aberrans has traditionally relied on synthetic chemicals. However, increasing regulatory pressure on unsafe products has led to a growing research focus on nematicides. Despite this, chemical nematicides remain more effective than other control methods. Consequently, there is a pressing need to develop novel nematicides that are both effective and environmentally safer. This study aimed to evaluate the nematocidal efficacy of various synthetic molecules against the second-stage juveniles of N. aberrans, the false root-knot nematode. A total of fifty-eight synthetic derivatives were obtained and tested in vitro at a concentration of 500 µg/mL. The results identified the AGAz family as the most promising, with AGAz-3 (LC₅₀: 52.7 µg/mL) and AGAz-4 (LC₅₀: 103.22 µg/mL) surpassing the efficacy of chitosan. Our findings emphasize the strong potential of AGAz-3 and AGAz-4 as nematocidal agents, particularly for in situ applications in agricultural settings. Additionally, AGAz-3 demonstrates potential not only as a nematocidal agent but also as an incentive for related research exploring its analogs as effective ovicidal compounds and investigating its efficacy against other phytonematodes. Furthermore, compounds from the N-Sulfonyl-hydrazone and N-acyl-hydrazone series showed efficacy (>50%), warranting additional experiments to assess their effectiveness across the most important pest phytonematodes. Full article

Pleurotus ostreatus, an edible mushroom widely consumed worldwide, generates a by-product known as spent mushroom substrate (SMS). This material has demonstrated biological activity against agricultural crop pathogens. In this study, we evaluated the nematocidal effectiveness of hydroalcoholic extracts (T5, T2, AT5, and AT2) derived from SMS of P. ostreatus against (J₂) of the phytonematode Nacobbus aberrans and assessed their potential toxicity towards the non-target nematode Panagrellus redivivus. Among these extracts, AT5 exhibited the highest efficacy against N. aberrans and was the least toxic against P. redivivus. Liquid–liquid partitioning yielded the AQU fraction, which showed significant nematocidal activity against J₂ (75.69% ± 8.99 mortality), comparable to chitosan. The GC-MS analysis revealed the presence of several compounds, including palmitic acid, linoleic acid, and 2,4-Di-tert-butylphenol. These findings are consistent with studies confirming the antagonistic effectiveness of these compounds against phytonematodes. Additionally, all extracts exhibited toxicity against P. redivivus, with T2 being the most toxic. Our findings demonstrate that while the AT5 extract displays antagonistic effectiveness against both N. aberrans and P. redivivus, it was the least toxic among the extracts tested. Thus, SMS of P. ostreatus holds potential as a source of nematocidal compounds, which could offer significant benefits for agricultural pest control. Full article

In the present study, the nematicidal and acaricidal activity of three Enterobacter endophytic strains isolated from Mimosa pudica nodules was evaluated. The percentages of mortality of Enterobacter NOD4 against Panagrellus redivivus was 81.2%, and against Nacobbus aberrans 70.1%, Enterobacter NOD8 72.4% and 62.5%, and Enterobacter NOD10 64.8% and 58.7%, respectively. While against the Tyrophagus putrescentiae mite, the mortality percentages were 68.2% due to Enterobacter NOD4, 64.3% due to Enterobacter NOD8 and 77.8% due to Enterobacter NOD10. On the other hand, the ability of the three Enterobacter strains to produce indole acetic acid and phosphate solubilization, characteristics related to plant growth-promoting bacteria, was detected. Bioinformatic analysis of the genomes showed the presence of genes related to IAA production, phosphate solubilization, and nitrogen fixation. Phylogenetic analyzes of the recA gene, phylogenomics, and average nucleotide identity (ANI) allowed us to identify the strain Enterobacter NOD8 related to E. mori and Enterobacter NOD10 as E. asburiae, while Enterobacter NOD4 was identified as a possible new species of this species. The plant growth-promoting, acaricidal and nematicidal activity of the three Enterobacter strains makes them a potential agent to include in biocontrol alternatives and as growth-promoting bacteria in crops of agricultural interest. Full article

Chemotherapy has advanced modern agriculture with costly side effects such as the extinction of beneficial species, resistant pest resurgence, environmental pollution, tainted food consumption, and health implications. Attention is now focused on biopesticides as a solution to the abovementioned disadvantages. Additionally, there is a growing need to understand the range and relative effectiveness of biopesticides in controlling pests and promoting sustainable agriculture. The latter is the major driver of the Sustainable Development Goals (SDGs). In comparison to synthetic pesticides, biopesticides offer nearly similar protection against the most notorious pests, except Albugo candida (oomycetes), Ustilago maydis (fungi), Phytomonas spp. (protozoa), Nacobbus aberrans (nematode), and Cyperus rotundus (weed). This study shows that viruses are more vulnerable to essential oils, nematodes and weeds to natural enemies, herbivorous insects to biochemical insecticides, and plant pathogens to plant-incorporated protectants and microbial pesticides. This work also demonstrates that it is preferable to use plant-derived biopesticides in a field concurrently. Incorporating these findings into large-scale farming via the integrated pest management method would improve the outcome of sustainable agriculture (SA), which connects 11 of the 17 SDGs. Despite their proven efficacy and sustainable attributes, biopesticides have some deficiencies, such as slow action and a short shelf life span, which can be improved by omics, RNA interference, and nano-based technologies. This field of technologies provides relevant prospects for improving existing biopesticides and discovering and developing new bio-controlling agents (BCA). Full article

Plant-parasitic nematodes (PPNs) are among the most notorious and underrated threats to food security and plant health worldwide, compromising crop yields and causing billions of dollars of losses annually. Chemical control strategies rely heavily on synthetic chemical nematicides to reduce PPN population densities, but their use is being progressively restricted due to environmental and human health concerns, so alternative control methods are urgently needed. Here, we review the potential of bacterial and fungal agents to suppress the most important PPNs, namely Aphelenchoides besseyi, Bursaphelenchus xylophilus, Ditylenchus dipsaci, Globodera spp., Heterodera spp., Meloidogyne spp., Nacobbus aberrans, Pratylenchus spp., Radopholus similis, Rotylenchulus reniformis, and Xiphinema index. Full article

Phytophthora capsici is an important pathogen worldwide because its spread affects pepper production globally. The “Criollo de Morelos” pepper 334 (CM-334) is resistant to P. capsici strains, regardless of the aggressiveness of the strain or the environmental conditions. However, when the nematode Nacobbus aberrans infects peppers, they lose this resistance by a process defined as “Resistance-breaking”. Breakdown of resistance results from a transcriptomic reconfiguration of the pepper that induces some defense genes, such as WRKY-a, POX, and EAS. The interest in identifying and describing the resistance process to P. capsici, and the breakdown that occurs by N. aberrans, has allowed us to establish a model in which we can analyze the modulation process in both scenarios and identify this transcriptomic modulation. The objective of the present work is to carry out a transcriptomic analysis that demonstrates the modulation of resistance and resistance-breaking processes. It would allow us to identify relevant genes in the early (12 h) and late (24 h) stages in these processes of the CM-334 pepper. Our findings demonstrate that modulation of resistance and resistance-breaking are independent processes that depend on the presence of both pathogens (P. capsici and N. aberrans) and that their timing modulation is dynamic. Full article

The genus Serratia is widely distributed in soil, water, plants, animals, invertebrates, and humans. Some species of this genus have antifungal, antibacterial, and nematicidal activity. In this work, the nematicidal activity of the endophytic strain of Serratia sp. in chili, Capsicum annuum L., is reported, where at a bacterial concentration of 4 × 10⁹ cel/mL, the penetration of nematodes into the roots significantly decreased by 91 and 55% at 7 and 21 days after inoculation. This bacterial concentration also significantly decreased the number of galls, eggs, egg masses and reproduction factor produced by Nacobbus aberrans in Chili plants, with respect to the control where this bacterial strain was not applied. In the analysis of the genome of the strain, based on average nucleotide identity (ANI), the isolate could be affiliated to the species Serratia ureilytica. The size of the genome is 5.4 Mb, with a 59.3% content of GC. Genes related to the synthesis of chitinases, siderophores, proteases C, serralisins, hemolysin, and serrawettin W2 that have been reported for biocontrol of nematodes were identified in the genome. It is the first report of Serratia ureilytica with nematicidal activity. Based on these results of nematicidal activity, this strain can be evaluated in the field as an alternative in the biocontrol of Nacobbus aberrans in chili cultivation. Full article

Nacobbus aberrans ranks among the “top ten” plant-parasitic nematodes of phytosanitary importance. It causes significant losses in commercial interest crops in America and is a potential risk in the European Union. The nematicidal and phytotoxic activities of seven plant extracts against N. aberrans and Solanum lycopersicum were evaluated in vitro, respectively. The chemical nature of three nematicidal extracts (EC_50,48h ≤ 113 µg mL⁻¹) was studied through NMR analysis. Plant extracts showed nematicidal activity on second-stage juveniles (J2): (≥87%) at 1000 µg mL⁻¹ after 72 h, and their EC₅₀ values were 71.4–468.1 and 31.5–299.8 µg mL⁻¹ after 24 and 48 h, respectively. Extracts with the best nematicidal potential (EC_50,48h < 113 µg mL⁻¹) were those from Adenophyllum aurantium, Alloispermum integrifolium, and Tournefortia densiflora, which inhibited L. esculentum seed growth by 100% at 20 µg mL⁻¹. Stigmasterol (1), β-sitosterol (2), and α-terthienyl (3) were identified from A. aurantium, while 1, 2, lutein (4), centaurin (5), patuletin-7-β-O-glucoside (6), pendulin (7), and penduletin (8) were identified from A. integrifolium. From T. densiflora extract, allantoin (9), 9-O-angeloyl-retronecine (10), and its N-oxide (11) were identified. The present research is the first to report the effect of T. densiflora, A. integrifolium, and A. aurantium against N. aberrans and chemically characterized nematicidal extracts that may provide alternative sources of botanical nematicides. Full article