Preparation of a Chlorantraniliprole-Thiamethoxam Ultralow-Volume Spray and Application in the Control of Spodoptera frugiperda

Insecticidal potential and risk assessment of diamide pesticides against Spodoptera frugiperda in maize crops

The effectiveness, tolerance, and safety of pesticides must be established before their scientific or rational. This study evaluates the field control efficacy of broflanilide, tetraniliprole, and chlorantraniliprole in combating Spodoptera frugiperda in maize crops, as well as the resistance of S. frugiperda to these three diamide pesticides after exposure. By assessing field control efficiency, toxicity, effects on development and reproduction, and detoxification enzyme activity of these diamide pesticides on S. frugiperda, highlights broflanilide's significant insecticidal potential. A highly sensitive and efficient method using QuEChERS/HPLCMS/MS was developed to simultaneously detect residues of these three pesticides on maize. Initial concentrations of broflanilide, tetraniliprole, and chlorantraniliprole ranged from 2.13 to 4.02 mg/kg, with their respective half-lives varying between 1.23 and 1.51 days. Following foliar application, by the time of harvest, the terminal residue concentrations of these pesticides were all under 0.01 mg/kg. Chronic dietary intake risk assessments and cumulative chronic dietary exposure for three pesticides indicated that the general population's terminal residue concentration was within acceptable limits. Not only does this research provide valuable insights into field control efficiency, insecticidal effects, resistance, residues, and risk assessment results of broflanilide, tetraniliprole, and chlorantraniliprole on maize, but additionally, it also paves the way for setting suitable Maximum Residue Limits (MRLs) values based on pre-harvest interval values, rational dosage, and application frequency.

Enhanced dosage delivery of pesticide under unmanned aerial vehicle condition for peanut plant protection: tank-mix adjuvants and formulation improvement

BACKGROUND

Suspension concentrate (SC) is one of the most widely used formulations for agricultural plant protection. With the rapid development of unmanned aerial vehicle (UAV) plant protection, the problems of spray drift, droplet rebound and poor wettability in the application of SC from UAVs have attracted wide attention. Although some tank-mix adjuvants have been used to enhance dosage delivery for UAV, their effects and mechanisms are not fully clear, and few formulations are specifically designed for UAV.

RESULTS

The type and concentration of tank-mix adjuvant affect the dosage delivery of SC. MO501 can significantly reduce DV<100μm , and inhibit droplet rebound on peanut leaves at concentrations ≥0.5%. Silwet 408 can achieve complete wetting and superspreading after adding ≥0.2% concentrations, but only ≥0.5% can inhibit rebound. XL-70 shows excellent regulation ability even at low concentration, and 0.2% concentration can simultaneously suppress impact and promote spreading. Besides, the formulation oil dispersion (OD) can significantly reduce the driftable fine fraction and inhibit rebound at dilution ratios of ≤250-fold, thus enhancing dosage delivery.

CONCLUSION

SC is prone to rebound on hydrophobic leaf surfaces and shows poor wetting and spreading properties. Appropriate types and concentrations of tank-mix adjuvants and formulation improvement are two effective strategies for improving the dosage delivery of pesticides, whereas the addition of inappropriate adjuvants may cause potential risks instead. These findings provide guidance for the rational selection of tank-mix adjuvants and potential applications of OD for UAV plant protection. © 2023 Society of Chemical Industry.

Quantifying pesticide emissions for drift deposition in comparative risk and impact assessment

Estimating emissions of chemical pesticides used in agriculture is an essential component in evaluating the potential toxicity-related impacts on humans and ecosystems in various comparative risk and impact assessment frameworks, such as life cycle assessment, environmental footprinting, absolute environmental sustainability assessment, chemical substitution, and risk prioritization. Emissions related to drift deposition-usually derived from drift experiments-can reach non-target areas, and vary as a function of crop characteristics and application technique. We derive cumulative drift deposition fractions for a wide range of experimental drift functions for use in comparative and mass-balanced approaches. We clarify that cumulative drift deposition fractions require to integrate the underlying drift functions over the relevant deposition area and to correct for the ratio of deposition area to treated field area to arrive at overall mass deposited per unit mass of applied pesticide. Our results show that for most crops, drift deposition fractions from pesticide application are below 0.03 (i.e. 3% of applied mass), except for grapes and fruit trees, where drift fractions can reach 5% when using canon or air blast sprayers. Notably, aerial applications on soybeans can result in significantly higher drift deposition fractions, ranging from 20% to 60%. Additionally, varying the nozzle position can lead to a factor of five differences in pesticide deposition, and establishing buffer zones can effectively reduce drift deposition. To address remaining limitations in deriving cumulative drift deposition fractions, we discuss possible alternative modelling approaches. Our proposed approach can be implemented in different quantitative and comparative assessment frameworks that require emission estimates of agricultural pesticides, in support of reducing chemical pollution and related impacts on human health and the environment.

Treatment of Four Stored-Grain Pests with Thiamethoxam plus Chlorantraniliprole: Enhanced Impact on Different Types of Grain Commodities and Surfaces

An insecticide containing the neonicotinoid thiamethoxam + the diamide chlorantraniliprole was evaluated against adults of Rhyzopertha dominica, Tribolium castaneum, Trogoderma granarium, and Sitophilus oryzae under laboratory bioassays both on freshly treated grain as well as on treated grain stored over 90 days for its persistence in efficacy. In laboratory bioassays, the insecticide was applied on wheat, maize, or rice at four doses, while in persistence bioassays on wheat at the same doses. Mortality and progeny were assessed in both laboratory and persistence bioassays. After 14 days of exposure, S. oryzae exhibited 100% mortality on all three commodities at the highest dose, while R. dominica showed complete mortality on wheat or rice and T. castaneum on wheat. For a period of 90 days, S. oryzae exhibited 42.69% mortality, followed by R. dominica (35.26%), T. castaneum (27.08%), and T. granarium (18.63%) at the highest dose. Progeny was successfully suppressed in all cases of complete mortality in laboratory bioassays and for S. oryzae for 90 days in persistence bioassays. Laboratory trials were also performed on plywood, concrete, ceramic tile, and steel at one dose. The highest mortality was observed on steel, followed by concrete, ceramic tile, and plywood for all insect species tested. This study demonstrates that thiamethoxam + chlorantraniliprole is effective against the tested species depending on exposure, storage period, surface, commodity, and dose.

Using tank-mix adjuvant improves the physicochemical properties and dosage delivery to reduce the use of pesticides in unmanned aerial vehicles for plant protection in wheat

BACKGROUND

Unmanned aerial vehicles (UAVs) are widely used to improve the efficiency of pesticide applications. Low-volume spraying operations require more efficient deposition of droplets on the target surface. Therefore, pesticide deposition and retention on plant surfaces is a serious challenge for modern precision agriculture. Tank-mix adjuvants have been used to improve spray dilutions performance; however, their effects on the physicochemical properties of spray dilutions, dosage delivery, and pesticide dosage are unclear.

RESULTS

Tank-mix adjuvant 8860 significantly improved the physicochemical properties of spray dilutions, inhibited spray droplets rebound, improved the wetting and spreading performance of spray dilutions on wheat leaves, and increased the effective deposition of tebuconazole on wheat leaves. Even when its dosage was reduced by one-third, the spray solution still showed excellent disease control and effective deposition of the active ingredient on wheat leaves.

CONCLUSION

The use of appropriate tank-mix adjuvants in UAV-based plant protection for wheat can significantly improve the performance of spray dilutions, increase the efficiency of pesticide dosage delivery, and improve disease control. These adjuvants can also help reduce the pesticide use while ensuring their effectiveness. © 2022 Society of Chemical Industry.

Preparation and application of a thidiazuron·diuron ultra-low-volume spray suitable for plant protection unmanned aerial vehicles

Spraying of defoliant can promote centralized defoliation of cotton and advance maturity to facilitate harvesting. Modern pesticide application equipment includes plant protection unmanned aerial vehicles (UAVs), which are used widely for spraying defoliants. However, commonly used defoliant formulations are mainly suspension concentrates and water-dispersible granules, which need to be diluted with water when used. These are not suitable for plant protection UAVs with limited load capacity, especially in arid areas such as Xinjiang, China. Therefore, we prepared a thidiazuron·diuron ultra-low-volume (ULV) spray, which can be used directly without dilution in water. We found that ULV sprays had better wettability than the commercially available suspension concentrate, could quickly wet cotton leaves and spread fully. The volatilization rate was lower. ULV sprays also showed better atomization performance and more uniform droplet distribution than the commercially available suspension concentrate. At a dosage of 4.50-9.00 L/ha, the coverage rate on cotton leaves was 0.85-4.15% and droplet deposition densities were 15.63-42.57 pcs/cm2; defoliation rate and spitting rate were also greater than those of the reference product. This study could be contributed to the development of special pesticide formulations suitable for UAVs.