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Nanoemulsion provides an effective way for the efficient, safe, and environmentally friendly use for pesticides. In this study, the influence of the type, dosage of emulsifier, and emulsifying process on the formation and stability of nanoemulsion were investigated. On this basis, the optimal nanoemulsion formula loaded with pyriproxyfen was obtained. Pyriproxyfen (5%) and polyoxyethylene castor oil ether (6%; EL-20) were dissolved in hydrocarbon solvent (5%; S-100) with deionized water replenished to 100%. Compared with oil-in-water emulsion (EW) and emulsifiable concentrate (EC), the longest drying time ensured that the nanoemulsions had a more durable control effect. The pyriproxyfen-loaded nanoemulsions had a high pupation inhibition rate and 100% eclosion inhibition rate. In addition, at 7 and 14 days, the 50% lethal concentrations (LC 50 ) of pyriproxyfen-loaded nanoemulsions to Eisenia fetida were 1450.63 and 804.19 mg/kg, respectively, indicating their low acute toxicity to earthworms and environmental friendliness. Moreover, the pyriproxyfen-loaded nanoemulsions showed a low apoptosis rate (5.29%), whose value was considerably lower than that of EW (29.51%) and EC (9.45%), indicating a low toxicity to human hepatocyte L02 cells. This research facilitated the design and fabrication of nanoemulsions for water-insoluble pesticides to enhance the insecticidal activity, lower the cytotoxicity, and reduce environmental pollution of such chemicals.

Pesticides are the primary defending strategy against major biological invaders and important for ensuring national food security. Intelligent nanopesticides with precise controlled release modes are currently an emerging area of interest in the field of green, safe, and sustainable pesticide formulation. In this study, βcypermethrin (β-CYP) was loaded into ZIF-8 by the one-pot method, which successfully prepared a pH-responsive delivery nanoparticle (β-CYP/ZIF-8) to control termites. Results demonstrated that β-CYP/ZIF-8 had a mean diameter of 188 ± 2 nm and a loading capacity of approximately 21%. In vitro release experiments showed that β-CYP/ZIF-8 releases better in acidic than in neutral conditions due to the presence of intermediate acidunstable imidazole organic compounds. The acidic microenvironment in which termites thrive can promote β-CYP release due to ZIF-8 decomposition, thus improving pesticide targeting and reducing toxic side effects. The bioactivity survey confirmed that β-CYP/ZIF-8 could control termites (Coptotermes formosanus Shiraki) for a longer duration compared to commercial wettable powder (WP) and emulsifiable concentrate (EC). Moreover, an acute toxicity test showed an over 2-and 10-fold reduction in the acute toxicity of β-CYP/ZIF-8 to earthworms and zebrafish, respectively, compared to that of commercial WP and EC. Finally, the cytotoxicity assay of β-CYP/ZIF-8 showed higher safety to human hepatocyte LO2 cells. Overall, these β-CYP/ZIF-8 nanoparticles, prepared using the one-pot method, have great application potential in sustainable pest management and protection of the ecological environment.

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BACKGROUND: Research on selenium nanoparticles (SeNPs) in chemical defense and chemotherapy of plants has developed rapidly owing to their high microbial toxicity, environmental safety, and degradability. Pine wilt disease (PWD) threatens pine forests worldwide; however, it is difficult to kill the nematodes (Bursaphelenchus xylophilus) inside the tree that cause PWD using traditional pesticide formulations. SeNPs could be the key to controlling PWD.RESULTS: In this study, approximately 50 nm SeNPs were prepared using a simple and green method, and chitosan was used to increase their biocompatibility and stability. The preparation and characterization results showed that the prepared SeNPs coated with chitosan (SeNPs@CS) were spherical and evenly dispersed. The bioassay results showed that SeNPs@CS had an LC 50 of 15.627 mg L −1 against B. xylophilus. In addition, the killing mechanism of SeNPs@CS against B. xylophilus was studied. Confocal microscopy and transmission electron microscopy demonstrated that B. xylophilus were killed by reactive oxygen species, and the penetration of nano-form materials to B. xylophilus was higher than that of non-nano-form materials. To verify the effective penetration of SeNPs in pine tissues, Cy5-labeled SeNPs@CS was observed inside pine needles and branches using frozen sections and confocal microscopy. In addition, the cytotoxicity of SeO 2 and SeNPs@CS was tested, and the results showed that the cytotoxicity of SeNPs@CS to MC3T3-E1 cells was reduced.CONCLUSION: These results show that SeNPs are expected to be used as a new strategy for the control of PWD with oxidative damage and high penetration to B. xylophilus and effective target penetration and biosafety.

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