Pest Management Science最新文献

Background: The hemibiotrophic fungus Zymoseptoria tritici causing Septoria tritici blotch (STB), is a devastating foliar pathogen of wheat worldwide. A common group of fungicides used to control STB are the demethylation inhibitors (DMIs). DMI fungicides restrict fungal growth by inhibiting the sterol 14-α-demethylase, a protein encoded by CYP51 gene and essential for maintaining fungal cell permeability. However, the adaptation of Z. tritici populations in response to intensive and prolonged DMI usage has resulted in a gradual shift towards reduced sensitivity to this group of fungicides. In this study, 311 isolates were collected pre-treatment from nine wheat-growing regions in Europe in 2019. These isolates were analysed by high-throughput amplicon-based sequencing of nine housekeeping genes and the CYP51 gene.

Results: Analyses based on housekeeping genes and the CYP51 gene revealed a lack of population structure in Z. tritici samples irrespective of geographical origin. Minimum spanning network (MSN) analysis showed clustering of multilocus genotypes (MLGs) based on CYP51 haplotypes, indicating an effect of selection due to DMI fungicide use. The majority of the haplotypes identified in this study have been reported previously. The diversity and frequencies of mutations varied across regions.

Conclusion: Using a high-throughput amplicon-sequencing approach, we found several mutations in the CYP51 gene combined in different haplotypes that are likely to cause fungicide resistance. These mutations occurred irrespective of genetic background or geographical origin. Overall, these results contribute to the development of effective and sustainable risk monitoring for DMI fungicide resistance. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plant-parasitic nematodes are among the most destructive plant pathogens, resulting in a global annual economic loss of about 358 billion dollars. Using synthetic nematicides to control plant-parasitic nematodes has resulted in broad-spectrum toxicity to the environment. Plant-derived secondary metabolites have recently emerged as viable options that provide effective, greener, and renewable routes for managing plant-parasitic nematodes in various cropping systems. However, limited comprehensive information on plant-derived secondary metabolites sources, chemical structures, and nematicidal activities is available. This study aims to compile and analyze data on plant-based secondary metabolites with nematicidal properties collected over the last two decades. In this review, we identified 262 plant-based metabolites with nematicidal activities that were isolated from 35 plant families and 65 plant species. Alkaloids, terpenoids, saponins, flavonoids, coumarins, thiophenes, and annonaceous acetogenins were among the most studied compounds. In addition to the structure-activity relation for specific metabolites with nematicidal potency, various techniques for their extraction and isolation from plant material are discussed. Our findings demonstrate the potential of plants as a feedstock for sourcing nematicidal compounds and discovering new chemistries that could potentially be used for developing the next generation of nematicides. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Nesodiprion zhejiangensis, a multivoltine sawfly, is widely distributed in south China and has caused serious damage to forests. Historically, N. zhejiangensis management has relied heavily on synthetic chemicals. To reduce the reliance on chemical control, we previously isolated a nucleopolyhedrovirus, NezhNPV, from deceased N. zhejiangensis larvae. A subsequent pathogenicity assay confirmed its high virulence in a laboratory setting.

Results: In order to comprehensively examine the hypothesis that NezhNPV is an effective new biocontrol agent for N. zhejiangensis, we carried out a field test in Beijing, China, and characterized NezhNPV morphologically by electron microscopy and genetically by genome sequencing. Our field trials showed that NezhNPV was effective in controlling N. zhejiangensis in a naturally infested Himalayan blue pine forest. The occlusion bodies of NezhNPV consist of irregular polyhedra that occlude rod-shaped enveloped virions with a single nucleocapsid per virion. The NezhNPV genome is 80 637 bp in length, and contains 90 open reading frames, including 38 core, eight lepidopteran baculovirus, 34 hymenopteran baculovirus and 10 unique baculovirus genes, representing the smallest known genome among baculoviruses. The combined results based on phylogenetic analyses, Kimura-2-parameter distances and biological characteristics indicate that NezhNPV is a novel gammabaculovirus and candidate for species status with the provisional name Gammabaculovirus nezhejiangensis. NezhNPV is highly collinear with other gammabaculoviruses and contains nonsyntenic regions with an inversion and rearrangement between orf3 and orf35.

Conclusion: The combined results from our field trials, coupled with morphological and genomic characterization clearly demonstrate the bioactivity of NezhNPV. This gammabaculovirus may be included in pest management practices against N. zhejiangensis as a novel biocontrol agent. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Cucumber Fusarium wilt (CFW), triggered by Fusarium oxysporum f. sp. cucumerinum, leads to substantial yield reductions in global cucumber (Cucumis sativus L.) production. Common management strategies for CFW include soil fumigation, grafting, and crop rotation. However, these methods have limitations regarding safety and efficacy stability, necessitating the development of new, cost-effective, and eco-friendly control strategies. Our prior research demonstrated that L-arabinose, an inexpensive and safe sugar commonly used in food and beverages, effectively suppressed bacterial wilt in tomatoes. This study explores the potential of L-arabinose in managing CFW and investigates its mechanism of action.

Results: Soil applications of L-arabinose, ranging from 0.00001 to 0.01%, effectively suppressed CFW. The most significant suppressive effect was observed at 0.01%, reducing the disease severity index by 67.5% compared to the control treatment. Microscopic examination of transverse root sections showed that pathogen hyphae colonized the epidermis but seldom penetrated the cortical layer of roots in L-arabinose-treated seedlings. In contrast, the entire root tissue of control seedlings was colonized by the pathogen. Quantitative real-time PCR revealed a significant increase in the expression of defense-related genes dependent on salicylic acid, jasmonic acid, and ethylene in L-arabinose-treated plants compared to control plants, 6 and 10 days post pathogen inoculation.

Conclusion: This study demonstrated that soil application of L-arabinose can effectively suppress CFW by priming root tissues for multiple defense signaling pathways. Therefore, L-arabinose holds potential as a new fungicide for managing CFW. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Ceratocystis fimbriata is a fungal pathogen that infects sweet potato roots, producing enormous economic losses. Cyclic polyhydroxy compound quinic acid is a common metabolite synthesized in plant tissues, including sweet potato tubers, showing weak antifungal properties. Although several O-acylated quinic acid derivatives have been synthesized and found in nature and their antifungal properties have been explored, derivatives based on modification of the carboxylic acid have never been evaluated.

Results: In this study, amide derivatives were synthesized via linkage of amines with the carboxylic acid moiety of quinic acid. Derivatives with high dipolar moments and a low number of rotatable bonds showed greater antifungal activities toward C. fimbriata in vitro than quinic and chlorogenic acids. Derivative 5b, which was synthesized by coupling p-aminobenzoic acid (pABA) with quinic acid, had the greatest antifungal activity. 5b showed iron(II)-chelating properties and reduced ergosterol content in C. fimbriata cells, causing irregularities in the fungal cell wall and inhibiting conidia agglutination. Application of 3 mm 5b reduced black rot symptoms in sweet potatoes by 70.1%.

Conclusions: Collectively, derivatization of the carboxylic acid from quinic acid was demonstrated to be a suitable strategy to improve the antifungal properties of this compound. This study reveals a new efficient strategy for management of the sweet potato pathogen C. fimbriata. © 2024 Society of Chemical Industry.

Background: Biofilm plays a crucial role in Pseudomonas syringae pv. tomato (Pst) infection. We identified (1R,4S)-(-)-fenchone (FCH) as the most potent antibiofilm agent against Pst among 39 essential oil compounds. Subsequently, we synthesized a series of FCH oxime ester and acylhydrazine derivatives to explore more potent derivatives.

Results: II3 was screened out as the most potent derivative, exhibiting a minimal biofilm inhibitory concentration of 60 μg mL^-1 and a lowest concentration with maximal biofilm inhibition (LCMBI) of 200 μg mL^-1, lower than those of FCH (80 and 500 μg mL^-1, respectively). II3 and FCH showed minimum inhibitory concentration values >1000 μg mL^-1 and similar maximal biofilm inhibition extents of 48.7% and 49.5% at their respective LCMBIs, respectively. Meanwhile, neither of them influenced cell viability or the activity of metabolic enzymes at their respective LCMBIs. II3 at its LCMBI significantly reduced biofilm thickness, extracellular polysaccharide content, and pectinase and cellulase production indices. In vivo assay results indicated that II3 could preventatively reduce the bacterial contents in tomato leaves at its LCMBI, and when combined with kasugamycin (KSG) (10 μg mL^-1), II3 achieved the same level of bacterial reduction as the sole application of KSG (70 μg mL^-1), thereby reducing the required dosage of KSG. Mechanistic studies demonstrated that II3 can down-regulate biofilm-related genes and inhibit PsyR/PsyI quorum sensing system, which differs from the bactericidal mechanisms.

Conclusion: These results underscore the potential of II3 as an antibiofilm agent for the control of Pst or FCH as a promising natural candidate for future in-depth optimization. © 2024 Society of Chemical Industry.

Background: Huanglongbing (HLB) is the primary and most destructive disease affecting citrus, caused by a pathogen transmitted by an insect vector, Diaphorina citri. There are no curative methods for the disease, and rapid and accurate methods are needed for early detection in the field, even before symptoms appear. These will facilitate the faster removal of infected trees, preventing the spread of the bacteria through commercial citrus orchards.

Results: It was possible to determine ranges of hyperspectral bands that demonstrated significant differences in relative reflectance between treatments consisting of healthy and infected plants from the first days of evaluation, when plants infected with 'Candidatus Liberibacter asiaticus' (CLas) were still in the asymptomatic stage of the disease. From the Week 2 of evaluation [58 days after infection (DAI) of plants] until the last week, spectral differences were detected in the red edge region (660-750 nm). From the Week 6 onwards (86 DAI), spectral differences between healthy and symptomatic plants were observed in bands close to the visible region (520-680 nm).

Conclusion: Spectral differences were detected in the leaves of C. sinensis infected by CLas before the appearance of symptoms, making it feasible to use the hyperspectral sensor to monitor the disease. Our results indicate the need for future studies to validate the use of hyperspectral sensors for managing and detecting HLB in commercial citrus orchards, contributing to the integrated management of the disease. © 2024 Society of Chemical Industry.

Background: An increasing human population, the emergence of resistances against pesticides and their potential impact on the environment call for the development of new eco-friendly pest control strategies. RNA interference (RNAi)-based pesticides have emerged as a new option with the first products entering the market. Essentially, double-stranded RNAs targeting essential genes of pests are either expressed in the plants or sprayed on their surface. Upon feeding, pests mount an RNAi response and die. However, it has remained unclear whether RNAi-based insecticides should target the same pathways as classic pesticides or whether the different mode-of-action would favor other processes. Moreover, there is no consensus on the best genes to be targeted.

Results: We performed a genome-wide screen in the red flour beetle to identify 905 RNAi target genes. Based on a validation screen and clustering, we identified the 192 most effective target genes in that species. The transfer to oral application in other beetle pests revealed a list of 34 superior target genes, which are an excellent starting point for application in other pests. Gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses of our genome-wide dataset revealed that genes with high efficacy belonged mainly to basic cellular processes such as gene expression and protein homeostasis - processes not targeted by classic insecticides.

Conclusion: Our work revealed the best target genes and target processes for RNAi-based pest control and we propose a procedure to transfer our short list of superior target genes to other pests. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: The Asian corn borer (ACB), Ostrinia furnacalis (Guenée), is a major pest restricting maize production in Asia. The Chinese government has approved the commercial planting of Bt-Cry1Ab maize (event DBN9936), but its control potential against the ACB in southern regions remains unclear. This study evaluated the sensitivity of ACB to Cry1Ab protein expressed in Bt-Cry1Ab maize and determined the control efficacy of Bt-Cry1Ab maize against the ACB in Sichuan Province, a major maize-producing region in southern China, based on pilot planting in the field, and larval feeding bioassays in the field and laboratory.

Result: The Cry1Ab protein contents in different tissues of Bt-Cry1Ab maize ranged from 31.20-88.27 μg g^-1. The range of median lethal concentrations (LC₅₀) and median growth inhibitory concentration (GIC₅₀) values of Cry1Ab protein expressed in Bt-Cry1Ab maize against ACB larvae were 0.036-0.109 μg mL^-1 and 0.002-0.018 μg mL^-1, respectively. The first and fourth instar ACB larvae were unable survive feeding on different tissues of Bt-Cry1Ab maize plants. Field experiments conducted from 2023 to 2024 indicated that the number of ACB larvae per 100 plants, plant damage rate, leaf damage rate, male ear damage rate, female ear damage rate, and stalk damage rate in the Bt-Cry1Ab maize fields were reduced by 95.36% ± 2.17%, 83.98% ± 1.73%, 89.45% ± 1.50%, 100.00% ± 0.00%, 69.79% ± 4.88% and 100.00% ± 0.00%, respectively, compared to conventional maize fields.

Conclusion: The ACB population in Sichuan Province, China is sensitive to Cry1Ab expressed in Bt-Cry1Ab maize (event DBN993). Planting Bt-Cry1Ab maize efficiently reduces the population of ACB larvae and the percentage of damaged maize plants, and has great application potential in the integrated pest management of the ACB in Sichuan Province, China. © 2024 Society of Chemical Industry.

Background: The agricultural sector faces a challenge in balancing increasing food demand while minimizing environmental impacts. Crop protection products are crucial for achieving high crop yields and ensuring food security. However, life cycle assessment (LCA), the standard framework for evaluating environmental impact, is time-consuming and costly, especially during early product development. To address this, a novel tool correlating process mass intensity (PMI) with greenhouse gas (GHG) emissions has been developed as a streamlined alternative.

Results: A strong linear correlation (R² = 0.95) was identified between PMI and product GHG emissions, enabling rapid carbon footprint estimation using simplified PMI data. The model was validated using 13 small molecule active ingredients (AIs), showing a mean absolute error (MAE) of 55 g CO₂/kg AI and a root mean square error (RMSE) of 64 kg CO₂/kg AI. Residual analysis demonstrated random distribution, suggesting reliable predictions.

Conclusion: The PMI-based tool provides rapid, accurate estimates of product carbon footprint (PCF), supporting early-stage decision-making in research and development for agrochemical processes. Its simplicity makes it applicable across various chemical sectors and valuable for sustainability efforts. © 2024 Society of Chemical Industry.