Since the invasion of the fall armyworm moth (
Spodoptera frugiperda
) in China in January 2019, damage to maize crops has gradually intensified, and chemical control has become the main control ...measure. This study aimed to examine methods of effective pest control while monitoring the environmental impact of pesticide use. The effectiveness of
S. frugiperda
pest control by foliar spraying and root irrigation of maize plants with acephate was determined, and the absorption, distribution, and dissipation of acephate and methamidophos by maize were studied. Field trials showed that acephate treatment at 6000 g a.i. ha
−1
was the most effective for controlling
S. frugiperda
. Acephate and methamidophos were absorbed from the roots, transported upward, and concentrated in the leaves, particularly new leaves. The terminal residues of acephate and methamidophos in maize grains were below detectable levels at 60 days after treatment. The results demonstrate that acephate treatment via root irrigation can more effectively control the infestation of
S. frugiperda
in maize than acephate treatment via foliar spraying. The translocation and distribution of acephate and methamidophos by root irrigation were more uniform, and the holding efficiency was higher than those in foliar spraying, suggesting an extended period of control efficacy. This pest control method could be utilized to reduce pesticide residues while safely and efficiently controlling
S. frugiperda
infestation.
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.
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•Azadirachtin has down-regulated Apidaecin, Lysosome, Abaecin and Vitellogenin genes.•Azadirachtin has no effect on the activities of superoxide dismutase and catalase.•Azadirachtin did not affect the composition and function of midgut microbes.•Azadirachtin significantly inhibite the activity of polyphenol oxidase
The fungus gnat is a major pest of chive in China. Its control has been relied heavily on the application of clothianidin. Due to the intensive application, its control efficacy become reduced. The ...present study was intended to evaluate co-drenching of clothianidin with hexaflumuron on absorption and dissipation of clothianidin in chive plants and soils and determine the effect of such application on control efficacies. Chive production fields in Guangdong and Hubei Provinces were drenched with clothianidin alone and a mixture of clothianidin and hexaflumuron at low application rates. Concentrations of clothianidin in chive plants and soils were analyzed by HPLC. Results showed that co-application had higher control efficacies against the fungus gnat than clothianidin alone. The co-application enhanced clothianidin absorption and dissipation and extended the half-lives of clothianidin in chive. It was likely that hexaflumuron protected chive roots from larva damage, and healthy roots absorbed more clothianidin, resulting in the extension of the half-lives. Additionally, the terminal residues of clothianidin in chive after 14 days of application were lower than the maximum residue limit in chive set by the Codex Alimentarius Commission. This study for the first time documented that co-application of clothianidin and hexaflumuron improved chive plants in absorption and dissipation of clothianidin and enhanced fungus gnat control efficacies.
In this study, pH-responsive LC@O-CMCS/PU nanoparticles were prepared by encapsulating λ-cyhalothrin (LC) with O-carboxymethyl chitosan (O-CMCS) to form LC/O-CMCS and then covering it with ...polyurethane (PU). Characterization and performance test results demonstrate that LC@O-CMCS/PU had good alkaline release properties and pesticide loading performance. Compared to commercial formulations containing large amounts of emulsifiers (e.g., emulsifiable concentrate, EC), LC@O-CMCS/PU showed better leaf-surface adhesion. On the dried pesticide-applied surfaces, the acute contact toxicity of LC@O-CMCS/PU to Harmonia axyridis (H. axyridis) was nearly 20 times lower than that of LC EC. Due to the slow-releasing property of LC@O-CMCS/PU, only 16.38 % of LC was released at 48 h in dew and effectively reduced the toxicity of dew. On the pesticide-applied leaves with dew, exposure to the LC (EC) caused 86.66 % mortality of H. axyridis larvae significantly higher than the LC@O-CMCS/PU, which was only 16.66 % lethality. Additionally, quantitative analysis demonstrated 11.33 mg/kg of λ-cyhalothrin in the dew on LC@O-CMCS/PU lower than LC (EC) with 4.54 mg/kg. In summary, LC@O-CMCS/PU effectively improves the safety of λ-cyhalothrin to H. axyridis and has great potential to be used in pest control combining natural enemies and chemical pesticides.
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Enhancing pesticide selectivity is one of the important strategies to improve pesticide utilization and protect non-target organisms. Herein, a pH-controlled release carrier was prepared to enhance ...insecticidal activity and reduce toxicity to bees by polysaccharide materials O-carboxymethyl chitosan (O-CMCS) and crosslinker‑sodium tripolyphosphate (TPP). Chlorfenapyr (CF) was encapsulated through crosslinking and self-assembled to form a stable nanopesticide (CF@O-CMCS) with a loading ratio of 5.27 %. CF@O-CMCS had excellent pH release dependency. In 36 h, only 26.39 % of the CF in the CF@O-CMCS was released at pH 5.0, whereas 95.28 % was released at pH 10.0. Treated for 48 h with 2.5 mg.ai/L, CF@O-CMCS was 73.33 % more effective at controlling Spodoptera frugiperda larvae than CF SC (Suspension), which was only 40.00 % effective. The lethal concentration 50 % (LC50) of 11.41 mg/L in CF@O-CMCS was four times lower than that of 2.71 mg/L in CF SC at 96 h, making it safer for worker bees. Additionally, CF@O-CMCS treated the gut of worker bees had considerably lower contents of chlorfenapyr and tralopyril (1.13 and 0.59 mg/kg) than CF SC (3.22 and 1.91 mg/kg) group. In consideration of its eco-friendly, enhanced bioactivity, and low toxicity to worker bees, CF@O-CMCS will have a broad application prospect in sustainable agriculture.
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•Eco-friendly CF@O-CMCS with sensitive pH-responsive release.•CF@O-CMCS has good insecticidal activity and UV light stability.•Compared to the commercial suspension, CF@O-CMCS significantly reduced toxicity to honey bees.•Lower pesticide levels were detected in acidic gut of bees after CF@O-CMCS treatment.
The frequent application of pesticides has caused adverse effects on humans and the environment. Stimuli-responsive nanoparticles can enhance the control efficacy of pesticides to pest insects or ...fungus and reduce impacts on non-target organisms. In the present work, 4-(hydroxymethyl) phenylboronic acid pinacol ester (PBAP) groups were conjugated onto β-cyclodextrin (β-CD) to form a H2O2-eliminating material (Ox-bCD), and then the nanoparticiles (PYR@OxbCD) loaded pyraclostrobin (PYR) were successfully fabricated by a nanoprecipitation. The prepared PYR@OxbCD had excellent reactive oxygen species (ROS) release dependency, and significantly enhanced fungicidal activity against Rhizoctonia solani in vitro. PYR@OxbCD could accurately release PYR at infected rice plants, providing a better control efficacy than PYR suspension concentrate (SC). The contact angle of PYR@OxbCD on leaves was reduced, and the spreading and antiphotolysis properties were increased, which may lead to an increase of deposition and a lower dissipation rate. Furthermore, the released PYR from PYR@OxbCD enhanced the activity of peroxidase (POD) and catalase (CAT), and up-regulated the expression of defense genes including PAL, PR10, CHI, CAT, GluPOD and AsPOD. PYR@OxbCD exhibited a much weaker effect on microbial abundance in rice cropping systems. The study provides an idea for smart delivery of fungicides to prevent plant pathogens and offers a more comprehensive view about the resistance of R. solani-infected rice triggered by PYR@OxbCD in levels of phenotype, enzymatic activity, gene expression, and microbiome.
Lignin, renowned for its renewable, biocompatible, and environmentally benign characteristics, holds immense potential as a sustainable feedstock for agrochemical formulations. In this study, raw ...dealkaline lignin (DAL) underwent a purification process involving two sequential solvent extractions. Subsequently, an enzyme-responsive nanodelivery system (Pyr@DAL-NPs), was fabricated through the solvent self-assembly method, with pyraclostrobin (Pyr) loaded into lignin nanoparticles. The Pyr@DAL-NPs shown an average particle size of 250.4 nm, demonstrating a remarkable loading capacity of up to 54.70 % and an encapsulation efficiency of 86.15 %. Notably, in the presence of cellulase and pectinase at a concentration of 2 mg/mL, the release of Pyr from the Pyr@DAL-NPs reached 92.66 % within 120 h. Furthermore, the photostability of Pyr@DAL-NPs was significantly improved, revealing a 2.92-fold enhancement compared to the commercially available fungicide suspension (Pyr SC). Bioassay results exhibited that the Pyr@DAL-NPs revealed superior fungicidal activity against Botrytis cinerea over Pyr SC, with an EC50 value of 0.951 mg/L. Additionally, biosafety assessments indicated that the Pyr@DAL-NPs effectively declined the acute toxicity of Pyr towards zebrafish and posed no negative effects on the healthy growth of strawberry plants. In conclusion, this study presents a viable and promising strategy for developing environmentally friendly controlled-release systems for pesticides, offering the unique properties of lignin.
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•Different DAL fractions were obtained by solvent extraction.•DAL-NPs with different particle sizes were synthesized.•An enzyme responsive nanodelivery system (Pyr@DAL-NPs) was constructed.•Pyr@DAL-NPs possessed potent fungicidal activity.•Pyr@DAL-NPs exhibited excellent release properties, photostability and biosafety.
Rotenone is a botanical pesticide and has long been used for control of insect pests and also as a natural piscicide for management of fish populations in many countries. Field application for pest ...control, however, often encounters the movement of rotenone into surface water due to spray drift or surface runoff after rainfall, which could potentially result in water pollution and unexpected death of fishes. To minimize its effect on freshwater and the problem of fish dying, one solution was to encapsulate rotenone in specific microspheres, limiting its release and reducing its toxicity since rotenone can be quickly degraded under sunlight. In this study, pH-responsive alginate-based microspheres were synthesized to encapsulating rotenone, which were designated as rotenone beads. The rotenone beads, along with alginate beads (devoid of rotenone) were characterized and evaluated for their responses to pH and effects on zebrafish. Results showed that the microspheres had high loading efficiency (4.41%, w/w) for rotenone, and rotenone beads well responded to solution pH levels. The cumulative release rates of rotenone from the beads were 27.91%, 42.72%, and 90.24% at pH 5.5, 7.0, and 9.0, respectively. Under acidic conditions, the rotenone release rate was lower due to hydrogen bonding. On the contrary, rotenone became more quickly released at the high pH due to intermolecular repulsion. The toxicity of rotenone beads to zebrafish and fish embryos at a pH of 5.5 was reduced by 2- and 4-fold than chemical rotenone. Since pH levels in most freshwater lakes, ponds, and streams vary from 6 to 8, rotenone release from the beads in such freshwater could be limited. Thus, the synthesized rotenone beads could be relatively safely used for pest control with limited effects on freshwater fishers.
•Botanical pesticide rotenone was encapsulated in alginate-based microspheres.•Rotenone beads were pH sensitive and released rotenone in a controlled fashion.•Rotenone beads were less toxic zebrafish and fish embryos than chemical rotenone.•Rotenone beads could be safely used for pest control with little effects on fish.
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