Emamectin benzoate nanogel suspension constructed from poly(vinyl alcohol)-valine derivatives and lignosulfonate enhanced insecticidal efficacy

To reduce the negative impact of nanopesticide carriers of on the environment, a greener nanodelivery system is necessary. Nanogels are nontoxic and degradable carriers, however, the potential of nanogels for delivering pesticides has not been proven. In this study, poly(vinyl alcohol)-valine, an ecofriendly polymer, was synthesized and used to fabricate emamectin benzoate nanogel suspension (EB NS). The nanoformulation showed favorable stability at low temperature, high temperature or one year storage, and in water with different hardnesses. The retention of the EB NS solution on leaves was higher than that of an EB emulsifiable concentrate (EC) by approximately 9% at a concentration of 10 mg L^-1. The half-life of EB nanogels under Ultra Violet irradiation was prolonged by 3.3-fold. Moreover, the bioactivity of the EB NS against Plutella xylostella was higher than that of the EB EC. These advantages resulted in a relatively long duration of pest control. The response of nanogels to laccase, a digestive enzyme in the digestive tract of lepidopteran pests, enables pesticide release on demand. Nanogels have the advantages of being ecofriendly carriers, exhibiting higher utilization, and prolonged pest control periods, and they have a brilliant future in pesticide delivery.

Lignin-Modified Electronegative Epoxy Resin Nanocarriers Effectively Deliver Pesticides against Plant Root-Knot Nematodes (Meloidogyne incognita)

It is highly desirable to fabricate a pesticide delivery system with excellent permeability to reduce the damage caused by root-knot nematodes in the soil. In this work, a novel electronegative pesticide nanocarrier was established by bonding anionic lignosulfonate with epoxy resin nanocarriers, which were loaded with abamectin (Aba). The results demonstrated that nanoparticles were negatively charged (-38.4 mV) spheres with an average size of 150 nm, and the encapsulation efficiency of nanocarriers for Aba was 93.4%. Polymer nanocarriers could prevent premature release of Aba and protect active ingredients from microbiological degradation. The adsorption strength of the soil to Aba loaded in nanocarriers was reduced by 6 to 10 times, so nanonematicides have remarkable soil mobility. Meanwhile, nanoparticles could easily penetrate the roots and nematodes. The application test confirmed that the control effect of this nanopesticide was 26-40% higher than that of the other agrochemicals. In consideration of its superior bioactivity and utilization rate, this pesticide delivery system has promising potential to control root-knot nematodes and improve the pesticide's utilization efficiency.

Assessment of ethylene glycol diacetate as an alternative carrier for use in agrochemical emulsifiable concentrate formulation

The conventional emulsifiable concentrate (EC) formulation contains a large amount of aromatic solvents, which causes adverse effects to both the environment and human health due to the toxicity of the solvents. Here, we developed a 2.5% lambda-cyhalothrin EC formulation with ethylene glycol diacetate (EGDA) as the solvent, and the developed formulation serves as an environmental-friendly alternative to overcome the adverse effects of aromatic solvents. The physicochemical characterizations, wettability properties, phytotoxicity and bioassays of the EGDA-EC formulation were systematically investigated and compared with that of the EC formulation with xylene as the solvent. The results showed that both EC formulations had excellent emulsion properties and storage stabilities. Additionally, the EGDA-EC formulation possessed a higher flash point (96 °C), indicating safer production, storage and transport. The retentions of the EGDA-EC sample on leaves were 1.22-1.46-fold higher than that of the xylene-EC sample, and the EGDA-EC also exhibited lower surface tensions and contact angles, which would benefit decreasing drift-off and improving utilization. Furthermore, the bioassays demonstrated that the EGDA-EC formulation had lower acute toxicity to aquatic organisms and higher control efficacy to target insects compared with the xylene-EC formulation. Therefore, EGDA is a promising carrier for oil-soluble agrochemicals to improve their application performance and reduce their adverse effects.

Porous epoxy phenolic novolac resin polymer microcapsules: Tunable release and bioactivity controlled by epoxy value

Microcapsules (MCs) prepared with diverse wall material structures may exhibit different properties. In this study, MCs were fabricated with three kinds of epoxy phenolic novolac resins (EPNs), which possessed unique epoxy values as wall-forming materials by interfacial polymerization. The effects of the EPN types on the surface morphology, particle size distribution, encapsulation efficiency, thermal stability as well as release behavior and bioactivity of the MCs were investigated. In all three samples, the MCs had nearly spherical shapes with fine monodispersities and sizes in the range of 7-30 μm. Scanning electron microscopy (SEM) images showed that some small pores (ranging from 50 nm to 400 nm) appeared on the microcapsule surfaces and that the porosity decreased with an increasing of epoxy value. The X-ray diffractometer (XRD) analysis indicated that the cured EPN shells had larger degrees of crosslinking with higher epoxy values, leading to better thermal stabilities. Moreover, the release rate of the core material (pendimethalin) decreased with an increasing of epoxy value and thus resulted in a lower herbicidal control efficacy. The results of our research will enhance the potential application of EPNs as smart wall-forming materials to prepare porous MCs for controlled release.