Dinotefuran, a third-generation neonicotinoid insecticide, is widely used in agriculture production due to its excellent insecticidal efficacy. Considering its persistence and high toxicity in soil, it is essential to evaluate its low-dose toxic effects on non-target soil organisms such as the springtail (Folsomia candida). The results revealed that the 7-day half lethal concentration (7d-LC50) of dinotefuran contact toxicity to springtails was 0.029 mu g cm(-2). Its chronic toxicity in 4 soil types was ranked as: red soil (0.021 mg kg(-1)) > fluvo-aquic soil (0.040 mg kg(-1)) > artificial soil (0.049 mg kg(-1)) > black soil (0.085 mg kg(-1)). Soil organic matter (SOC), pH, and total nitrogen (TN) were identified as critical factors affecting dinotefuran toxicity. Biochemical assay results showed that environmental concentrations (0.2-1.6 mg kg(-1)) of dinotefuran induced oxidative stress and oxidative damage in springtails. Oxidative stress-related enzymes (including superoxide dismutase (SOD) and catalase (CAT)) and detoxification enzymes were subjected to initial activation at low dinotefuran concentrations, inhibition and re-activation at high concentration. Target enzyme acetylcholinesterase (AChE), malondialdehyde (MDA) content, and total protein content were inhibited with prolonged exposure time and increasing concentrations of dinotefuran. Molecular docking analysis showed that dinotefuran bound to the active sites of related enzymes, thus disrupting their structure and functions, eventually resulting in damages to physiological functions of springtails. In summary, this study deciphers the dinotefuran toxicological mechanism on soil springtails at environmental concentrations. Our findings lay theoretical basis for further assessing its pollution risk and managing its application.

The agricultural industry prioritizes minimizing crop yield losses caused by pests, making it essential to develop effective, safe and sustainable pesticide formulations. Hydrogels are promising carriers for pesticide delivery, due to their high surface area, large pore volume, and pore size. In this study, we synthesized Cassia fistula (CA-g-AA) and its derivative carboxymethylated Cassia fistula-grafted polysodium acrylate hydrogel (CMCA-g-AA) using free radical polymerization, with N, N'-methylene bisacrylamide (MBA) as a crosslinker, for the ex-situ encapsulation of dinotefuran. Characterization was performed using FTIR, 13C CPMAS-NMR, SEM, TGA, rheology, and XRD. The maximum swelling capacity of hydrogels was investigated in distilled water. CA-g-AA and CMCA-g-AA hydrogels exhibited a dinotefuran loading percentage of 37 and 39% and released dinotefuran for 26 and 29 h, respectively. The dinotefuran release kinetics was analyzed by using the Korsmeyer-Peppas and Higuchi models. Under drought like conditions, CMCA-g-AA-treated soil sustained plant growth for 7 days, compared to CA-g-AA (5 days) and untreated soil (3 days). The novel hydrogel CMCA-g-AA enhanced soil water absorption and retention along with highlighting its potential for extended pesticide release. Thus, the developed CMCA-g-AA hydrogel is an efficient strategy for sustainable agriculture.

DOI: 10.18474/JES23-104 Abstract Systena frontalis (F.) is an insect pest of nursery production systems in the Midwest, Southeast, and Northeast regions of the United States. Adults feed on plant leaves and can reduce salability of container-grown nursery plants. Limited management options are available to protect plants from S. frontalis adult feeding damage. Insecticide spray applications to plant leaves are labor-intensive and not cost-efficient. Systemic insecticide applications to the growing medium may protect plants from S. frontalis adult feeding. In 2023, we conducted two laboratory and two greenhouse experiments to assess the residual activity of the systemic insecticides dinotefuran, thiamethoxam, and acephate against field-collected populations of S. frontalis adults. In the laboratory experiments, growing medium containing Itea virginica L. 'Little Henry' plants were treated with these three systemic insecticides. Twenty-five and 45 d after treatments were applied, leaves were collected and placed into petri dishes with a single S. frontalis adult. In the greenhouse experiments, Itea plants were placed into plastic observation cages. Eight S. frontalis adults were released into each cage with a single Itea plant. In the laboratory experiments 25 and 45 d after application of dinotefuran and thiamethoxam, the S. frontalis adults in the dishes with treated leaves had 66-90% mortality after 72 h. In the greenhouse experiments, dinotefuran and thiamethoxam protected Itea plants from S. frontalis adult feeding 45 d after application; 2.4 and 2.8 mm2 of leaf area were fed upon by S. frontalis adults. These results indicate that systemic insecticides can reduce feeding damage by S. frontalis adults on container-grown nursery plants.