Inhibition mechanism of Rhizoctonia solani by pectin-coated iron metal-organic framework nanoparticles and evidence of an induced defense response in rice.

Nanocrop protectants have attracted much attention as sustainable platforms for controlling pests and diseases and improving crop nutrition. Here, we reported the fungicidal activity and disease inhibition potential of pectin-coated metal-iron organic framework nanoparticles (Fe-MOF-PT NPs) against rice stripe blight (RSB). An in vitro bacterial inhibition assay showed that Fe-MOF-PT NPs (80 mg/L) significantly inhibited mycelial growth and nucleus formation. The Fe-MOF-PT NPs adsorbed to the surface of mycelia and induced toxicity by disrupting cell membranes, mitochondria, and DNA. The results of a nontargeted metabolomics analysis showed that the metabolites of amino acids and their metabolites, heterocyclic compounds, fatty acids, and nucleotides and their metabolites were significantly downregulated after treatment with 80 mg/L NPs. The difference in metabolite abundance between the CK and Fe-MOF-PT NPs (80 mg/L) treatment groups was mainly related to nucleotide metabolism, pyrimidine metabolism, purine metabolism, fatty acid metabolism, and amino acid metabolism. The results of the greenhouse experiment showed that Fe-MOF-PT NPs improved rice resistance to R. solani by inhibiting mycelial invasion, enhancing antioxidant enzyme activities, activating the jasmonic acid signaling pathway, and enhancing photosynthesis. These findings indicate the great potential of Fe-MOF-PT NPs as a new RSB disease management strategy and provide new insights into plant fungal disease management.

Pectin-Coated Iron-Based Metal-Organic Framework Nanoparticles for Enhanced Foliar Adhesion and Targeted Delivery of Fungicides.

Conventional agrochemicals are underutilized due to their large particle sizes, poor foliar retention rates, and difficult translocation in plants, and the development of functional nanodelivery carriers with high adhesion to the plant body surface and efficient uptake and translocation in plants remains challenging. In this study, a nanodelivery system based on a pectin-encapsulated iron-based MOF (TF@Fe-MOF-PT NPs) was constructed to enhance the utilization of thifluzamide (TF) in rice plants by taking advantage of the pectin affinity for plant cell walls. The prepared TF@Fe-MOF-PT NPs exhibited an average particle size of 126.55 nm, a loading capacity of 27.41%, and excellent dual-stimulus responses to reactive oxygen species and pectinase. Foliar washing experiments showed that the TF@Fe-MOF-PT NPs were efficiently adhered to the surfaces of rice leaves and stems. Confocal laser scanning microscopy showed that fluorescently labeled TF@Fe-MOF-PT NPs were bidirectionally delivered through vascular bundles in rice plants. The in vitro bactericidal activity of the TF@Fe-MOF-PT NPs showed better inhibitory activity than that of a TF suspension (TF SC), with an EC50 of 0.021 mg/L. A greenhouse test showed that the TF@Fe-MOF-PT NPs were more effective than TF SC at 7 and 14 d, with control effects of 85.88 and 78.59%, respectively. It also reduced the inhibition of seed stem length and root length by TF SC and promoted seedling growth. These results demonstrated that TF@Fe-MOF-PT NPs can be used as a pesticide nanodelivery system for efficient delivery and intelligent release in plants and applied for sustainable control of pests and diseases.

Effect of Brucea javanica Oil on the Toxicity of ß-Cypermethrin Emulsifiable Concentrate Formulation.

Enhancing the performance of traditional pesticide formulations by improving their leaf surface wetting capabilities is a crucial approach for maximizing the pesticide efficiency. This study develops an emulsifiable concentrate (EC) of 4.5% ß-cypermethrin containing Brucea javanica oil (BJO). The incorporation of BJO aims to improve the leaf-wetting properties of the EC formulation and enhance its insecticidal effectiveness. The droplet size and emulsion characteristics of ß-CYP EC emulsion with varying concentrations of the emulsifier were evaluated, and changes after incorporating BJO were assessed to develop the optimal formulation. A comprehensive comparison was conducted among commercial 4.5% ß-cypermethrin EC (ß-CYP EC-1), 4.5% ß-cypermethrin EC with BJO (ß-CYP EC-2), and 4.5% ß-cypermethrin EC without BJO (ß-CYP EC-3). This comparison encompassed various factors including storage stability, insecticidal activity, cytotoxicity, and wetting performance on cabbage leaves. The results indicated that the ideal emulsifier concentration was 15% emulsifier 0201B. ß-CYP EC-2 demonstrated superior wetting properties on cabbage leaves (the wetting performance of ß-CYP EC-2 emulsion on cabbage leaves is 2.60 times that of the ß-CYP EC-1 emulsion), heightened insecticidal activity against the third larvae of Plutella xylostella [diamondback moth (DBM)] [the insecticidal activity of the ß-CYP EC-2 emulsion against the third larvae of DBM is 1.93 times that of the ß-CYP EC-1 emulsion (12 h)], and more obvious inhibitory effects on the proliferation of DBM embryo cells than the other tested formulations. These findings have significant implications for advancing pest control strategies and promoting sustainable and effective agricultural practices.

Enhanced Insecticidal Activity of Chlorfenapyr against Spodoptera frugiperda by Reshaping the Intestinal Microbial Community and Interfering with the Metabolism of Iron-Based Metal-Organic Frameworks.

Spodoptera frugiperda (S. frugiperda) is an invasive pest that threatens global crop production and food security and poses a serious threat to maize production worldwide. Metal-organic framework (MOF) nanocarriers have great potential for agricultural pest control applications. The present study successfully prepared the chemical cross-linking of iron-based metal-organic framework nanoparticles (MIL-101(Fe)-NH2 NPs) with sodium lignosulfonate (SL) as a pH/laccase double stimuli-responsive pesticide release system. The average particle size of the prepared chlorfenapyr (CF)-loaded nanoparticles (CF@MIL-101-SL NPs) was 161.54 nm, and the loading efficiency was 44.52%. Bioactivity assays showed that CF@MIL-101-SL NPs increased the toxicity of CF to S. frugiperda and caused the rupture of the peritrophic membrane and enlargement of the midgut. Data from 16S rRNA gene sequencing showed that CF@MIL-101-SL treatment reduced the resistance of S. frugiperda to pesticides and pathogens and affected nutrient and energy availability by remodeling the intestinal microbiota of S. frugiperda. The dysregulated microbial community interacted with the broken peritrophic membrane, which exacerbated damage to the host. Nontargeted metabolomic results showed that ABC transporters may be a potential mechanism for the enhanced toxicity of CF@MIL-101-SL to S. frugiperda. In summary, the present study provides effective strategies for toxicological studies of nanopesticides against insects.

Effects of sublethal azadirachtin on the immune response and midgut microbiome of Apis cerana cerana (Hymenoptera: Apidae).

As a wildly used plant-derived insecticide, azadirachtin (AZA) is commonly reported as harmless to a range of beneficial insects. However, with the research on the effect of AZA against pollinators in recent years, various negative physiological effects on other Apidae species have been demonstrated. Thus to explore the safety of azadirachtin to Apis cerana cerana, the different physiological effects of sublethal concentration of azadirachtin on worker bees A.c.cerana has been studied. With the exposure of 5 mg·L-1 and 10 mg·L-1 azadirachtin for 5 d, the relative expression of Apidaecin, Abaecin and Lysosome genes in workers has decreased significantly at 1, 2,3 and 5 d, and the mRNA levels of Defensin 2 and Hymenoptaecin were also significantly inhibited by 10 mg·L-1 azadirachtin at each check point. Besides, the activity of midgut antioxidant enzymes Superoxide Dismutase (SOD) and Catalase (CAT) which are the first line of defence in antioxidant systems was not affected by AZA, the activity of Peroxidase (POD) showed a fluctuating pattern at 24 h and 48 h, while the activity of polyphenol oxidase (PPO) has significantly inhibited by AZA. However, through 16sRNA analysis it was observed that 5 mg·L-1 AZA did not affect the midgut microbiome colony composition and relative abundance, as well as its main function. Therefore, to a certain extent, azadirachtin is safe for workers, but we should pay more attention to the sublethal effect of AZA that also detrimental to the healthy development of the honeybee colony.