| Pesticides play an important role in preventing and controlling plant diseases and pests,protecting crop productivity,and promoting sustainable and stable growth of agricultural production.However,traditional pesticides suffer from defects such as massive use of organic solvents,dust drift,poor dispersibility and stability,low effective utilization rate and biological activity,which make pesticide usage increase dramatically and eventually lead to a series of ecological and environmental problems,seriously restricting food,ecological safety,and sustainable agricultural development.Therefore,there is an urgent need to develop green pesticide with slow-release technology to improve the utilization and safety of pesticides.Recently,the application of nanotechnology in the field of pesticides has become a research hotspot,especially the use of nanomaterials,because of their small size effect,interface effect,targeted intelligent delivery,controlled release and environmental response,and other mesoscopic properties of the original pesticide formulations by processing dosage form and physical property improvement,constructing a nano-pesticide delivery system,can greatly improve the water solubility,dispersibility and wettability of pesticides,effectively improve the efficacy and safety of pesticide used,thereby reducing the amount of pesticide,agricultural residues and environmental pollution.Controlledrelease pesticide delivery systems via exogenous stimulus-responsive have attracted extensive attention,as they can reduce the direct contact between pesticides and environmental media.Due to the abundance of oxidants or reducing reductants present in living organisms(e.g.,plants)or environmental media(e.g.,soil and air),redoxresponsive carriers can be used to construct smart controlled-release pesticide delivery systems to protect agricultural crops.In this study,mesoporous silica nanoparticles(MSNs)with high stability,large specific surface area,easy surface modification and good biocompatibility were used as nanocarriers,the plant endogenous reductant glutathione(GSH)as the stimulating factor,and acetamiprid(Ace)as the active ingredient of pesticide,a redox-responsive nano-acetamiprid pesticide named NanoAce was designed and developed for pest control,and its environmental safety was analyzed in combination with soil microbiology and plant metabolomics.The specific research contents and results are as follows:(1)MSNs(～17 nm)were prepared by soft-template method.The nanoacetamiprid pesticide(Nano-Ace)with redox-responsive release characteristics was synthesized and prepared using MSNs as nanocarriers by modifying sulfhydryl functional groups and decanethiol "gatekeeper" capping on the surface to loading the neonicotinoid pesticide acetamiprid in the mesoporous pores of the carriers.The NanoAce(～20 nm)was synthesized and prepared with redox-responsive release characteristics.Due to the large specific surface area(413.4±22.2 m2/g)and pore volume(2.31±0.32 cm3/g),the nanocarriers showed a good loading effect on acetamiprid(18.05 μg/mg).Meanwhile,Nano-Ace also has good wettability,adhesion,pH stability,temperature stability,light stability,long-term storage stability,biosafety,and redox-responsive release characteristics.(2)Nano-Ace could release Ace in response to the accumulation of endogenous GSH in plants mainly caused by aphid stress.Not only does it provide efficient control of adult aphids but also inhibit their reproduction,alleviate the stress on V.faba plants,and reduce the pesticide residues of V.faba leaves.Particularly,Nano-Ace(1.5 mg Nano-Ace/plant,5 days of aphid infestation)treatment resulted in the population reduction rate and control effect of adult aphids were 98.7%and 98.4%,respectively,the juvenile population reduction rate reached 99.3%,and the leaf final Ace residue(0.32±0.004 mg/kg)was lower than the MRL(0.4 mg/kg)of international Codex Alimentarius Commission(CAC).However,the residue of equivalent commercial Ace was 24.87-fold higher than that of the Nano-Ace.Metabolic analysis of V.faba leaves showed that Nano-Ace mainly promoted the synthesis of flavonoid substances(e.g.,kaempferol,quercetin,aflatoxin,rutin)to activate plant defense responses and enhance the stress resistance of leaves.(3)Nano-Ace could release Ace in response to the increase of endogenous GSH mainly caused by plutella xylostella L.stress,and control against the masticatory pest to a certain extent,alleviate the stress on B.chinensis and reduce the Ace residue of leaves.The foliar spraying of 50 mg/L Nano-Ace to B.chinensis,resulted in the population reduction rate and control effect of P.xylostella were 85%and 78.6%at 72 h,respectively.The Ace residue(0.29±0.04 mg/kg)of B.chinensis leaves was lower than the MRL(1.0 mg/kg)regulated by China standard(GB 2763-2021),while the equivalent amount of commercial Ace residue was 27.62 times higher than that of Nano-Ace treatment.Metabolic analysis of B.chinensis leaves showed that Nano-Ace mainly promoted energy metabolism through up-regulation of TCA cycle intermediate(cis-aconitine),carbon cycle related sucrose and nitrogen cycle related metabolites(amino acids,purine metabolites,etc.),as well as biotin(dethiobiotin),B vitamins(folate),phytohormones(IAA)to promote leaf physiological metabolism,improve the resistance of B.chinensis and maintain healthy growth.Indoor toxicological experiments showed that the LC50 of Ace and Nano-Ace against P.xylostella was 46.76 mg/L and 70.94 mg/L,respectively.Nano-Ace could disrupt antioxidant protective enzymes and detoxification enzymes of P.xylostella and cause the death.(4)The soil application of high concentrations of Nano-Ace did not affect the normal growth of V.faba under short-term(2 weeks),medium-term(4 weeks),and long-term exposure(6 weeks).At the metabolic level,Nano-Ace improved the abiotic stress capacity of V.faba by promoting flavonoid metabolism(short-term).Regulating the nitrogen cycle(e.g.,amino acid and purine metabolism)and carbon cycle(sugar metabolism)to promote TCA cycle and detoxification capacity of V.faba(mid-term).Additionally,Nano-Ace enhance the plant resistance by increasing the content of TCA cycle intermediates and up-regulating amino acids,riboflavin,purine metabolites,and phytohormones(long-term).Soil microbial results revealed that the Nano-Ace did not affect microbial α-diversity and β-diversity in the short-term exposure period.The αdiversity increased after medium-and long-term exposure.At the phylum level,NanoAce did not significantly affect microbial community composition in response to both short-and long-term exposures.After medium-term exposure,Nano-Ace significantly increased the beneficial microorganisms Proteobacteria and Acidobacteria by 9.8%and 45.7%,respectively.In contrast,the Ace group significantly reduced Gemmatimonadetes and Acidobacteria by 35.9%and 29.5%,respectively,after longterm exposure.At the genus level,Nano-Ace still recruited beneficial microorganisms under short-and medium-term exposure.For short-term exposure,the Streptomyces and Pseudomonas were significantly increased by 420.7%and 33.8%,respectively,while Ace caused their inhibition by 4.7%and 33.8%,respectively.After medium-term exposure,Ace decreased the pesticide-degrading bacterium Flavobacterium by 51.9%,while Nano-Ace increased by 23.3%.After long-term exposure,Ace down-regulated the Sphingomonas by 26.8%and significantly increased the bacterial pathogen Acidophilus by 1257.6%,while Nano-Ace decreased Acidophilus by 44.5%.Nano-Ace showed a tendency of low promotion and high inhibition on soil enzyme activities(e.g.,soil cellulase,invertase,alkaline phosphatase,urease,arylsulfatase)involved in soil C,N,S and P cycles and peroxidase,while the inhibition was overall weaker than Ace.In summary,the application of Nano-Ace has a good control effect on crop aphids and P.xylostella,and its slow release could contribute to mitigate phytotoxicity and does not negatively affect plant health and soil microbial communities,which can promote green,safe,efficient,and low-toxic environmentally-friendly nanopesticide to control pest in sustainable agriculture. |
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