Search Results (53)

Glutathione S-transferases (GSTs) are phase II detoxification enzymes that display several enzymatic activities, including transferase, peroxidase, reductase, and isomerase functions, as well as non-enzymatic roles (e.g., serving as binding proteins). Their complex functionality lies in the biotransformation of xenobiotics (e.g., pesticides, drugs) and certain endogenous compounds, primarily metabolites produced by phase I detoxification enzymes. Several plant-derived compounds have been shown to modulate the activity and expression levels of these enzymes. Phytochemical activators of GSTs are potentially beneficial for detoxification in cases of exposure to various toxic compounds, whereas inhibitors of GSTs could have positive effects as adjuvant treatments for cancers that express high levels of GSTs associated with drug resistance. Full article

In mountainous citrus orchards, the application of conventional ground sprayers for the control of citrus red mite (Panonychus citri) is often constrained by complex terrain and low operational efficiency. The Unmanned Aerial Spraying System (UASS), due to its low-altitude, low-volume, and high-maneuverability characteristics, has emerged as a promising alternative for pest management in such challenging environments. To evaluate the spray performance and field efficacy of different UASS types in controlling P. citri, five representative UASS models (JX25, DP, T1000, E-A2021, and T20), four mainstream pesticide formulations, and four novel tank-mix adjuvants were systematically assessed in a field experiment conducted in a typical hilly citrus orchard. The results showed that T20 delivered the best overall spray deposition, with upper canopy coverage reaching 10.63%, a deposition of 3.01 μg/cm², and the highest pesticide utilization (43.2%). E-A2021, equipped with a centrifugal nozzle, produced the finest droplets and highest droplet density (120.3–151.4 deposits/cm²), but its deposition and coverage were lowest due to drift. Nonetheless, it exhibited superior penetration (dIPR 72.3%, dDPR 73.5%), facilitating internal canopy coverage. T1000, operating at higher flight parameters, had the weakest deposition. Formulation type had a limited impact, with microemulsions (MEs) outperforming emulsifiable concentrates (ECs) and suspension concentrates (SCs). All adjuvants improved spray metrics, especially Yimanchu and Silwet, which enhanced pesticide utilization to 46.8% and 46.4% for E-A2021 and DP, respectively. Adjuvant use increased utilization by 4.6–11.9%, but also raised ground losses by 1.5–4.2%, except for Yimanchu, which reduced ground loss by 2.3%. In terms of control effect, the rapid efficacy (1–7 days after application, DAA) of UASS spraying was slightly lower than that of ground sprayers—electric spray gun (ESG), while its residual efficacy (14–25 DAA) was slightly higher. The addition of adjuvants improved both rapid and residual efficacy, making it comparable to or even better than ESG. E-A2021 with 5% abamectin·etoxazole ME (5A·E) and Yimanchu achieved 97.4% efficacy at 25 DAA. Among UASSs, T20 showed the rapid control, while E-A2021 outperformed JX25 and T1000 due to finer droplets effectively targeting P. citri. In residual control (14–25 DAA), JX25 with 45% bifenazate·etoxazole SC (45B·E) was most effective, followed by T20. 5A·E and 45B·E showed better residual efficacy than abamectin-based formulations, which declined more rapidly. Adjuvants significantly extended control duration, with Yimanchu performing best. This study demonstrates that with optimized spraying parameters, nozzle types, and adjuvants, UASSs can match or surpass ground spraying in P. citri control in hilly citrus orchards, providing valuable guidance for precision pesticide application in complex terrain. Full article

Papilio polytes is a cosmopolitan Lepidoptera species of controversial use and management. It remained unclear how its epidermal ultrastructure changes during development and how this affects its wetting properties in relation to water and pesticide adjuvants. In this study, the epidermis of P. polytes was systematically examined at the important feeding stage (from 3rd to 5th instar). Its ultrastructure was quantitatively observed by scanning electron microscopy. Its wetting properties towards the three main types of adjuvants and water were evaluated by contact angle. The chemical functional group differences between different instars and different adjuvant treatments were analyzed by mid-infrared spectroscopy. The correlation between the ultrastructural deformation and variations in wetting properties was verified by simulation tests. It was found that the complication of the epidermal structure was the leading factor for the significant increase in hydrophobicity during development. Cationic adjuvants had the best infiltrating effect on complex epidermal structures and organosilicon adjuvants had the best infiltrating effect on simple epidermal structures. The results provide data for biomimetic design for different wetting properties and suggest the feasibility and advantages of selecting pesticide adjuvants based on developmental changes in the structural characteristics of the insect epidermis. Full article

Soil organic matter (SOM) is a key component of soil that determines the possibility of sustainable development of the environment by influencing, among other things, the binding and migration of elements in the soil. The properties of SOM are largely dependent on the properties of humic acids (HAs). New information about changes in their structure, determining their characteristics, can be obtained on the basis of their optical properties. The aim of this study was to assess the influence of the selected herbicides on the optical properties of HAs indicating changes in their structure. HAs were extracted from the mollic horizon of different phaeozems. The effect of HA interaction with two herbicides was assessed using UV–Vis spectroscopy and fluorescence. The investigation indicated clear differences in the structure of the HA molecules investigated as a result of interaction with the herbicides used. Each herbicide showed a different effect, likely due to the adjuvants used, which enhanced or weakened the process of HA–herbicide–HA complex formation. The results obtained show that the different additives used in the commercial products strongly influence the ability of HA to bind pesticides. Full article

The spatial transportation of pesticide spray droplets and their deposition and retention on plant leaf surfaces are critical factors contributing to pesticide loss. Adding adjuvants to pesticide solutions to improve their wettability and deposition behavior can enhance the targeted deposition efficiency of pesticides sprayed by unmanned aerial vehicle (UAV) sprayers. In this study, Maifei (MF), a prevalent vegetable oil adjuvant, was selected to analyze its effects on the physicochemical properties of water and 10% difenoconazole water-dispersible granules (D) and the wetting performance of droplets on litchi leaves. The changes in the drift and deposition of the spray solutions with or without MF were tested using a UAV sprayer, DJI T40. The results indicated that the addition of MF to water or D significantly decreased the surface tension (by 58.33% and 23.10%, respectively), wetting time (by 97.81% and 90.95%, respectively), and contact angle (by 40.95% to 70.75% for the adaxial and abaxial surfaces of litchi leaves), achieving the best effects at a 1% MF addition. Moreover, during the drift test, the addition of 1% MF to the solutions significantly reduced the cumulative drift rate (CDR) (by 48.10%). Finally, owing to the weakened spray drift risk and improved wettability of the droplets on litchi leaves with a 1% MF addition, the droplet deposition and penetration in the litchi canopy significantly improved, demonstrating an increased droplet density of 38.17% for the middle layers of the litchi and 15.75% for the lower layers, corresponding to increased coverage by 59.49% and 12.78%, respectively. Hence, MF can improve the interfacial properties of the spray solution on litchi leaves, reduce the drift risk, and promote deposition, thereby facilitating the efficient transfer and deposition of pesticide droplets from UAV sprayers. Full article

Asian citrus psyllid (ACP), Diaphorina citri (Hemiptera: Liviidae), is one of the most devastating pests in citrus orchards due to its role in transmitting Huanglongbing (HLB). Currently, chemical control remains the most effective strategy for ACP management. Mineral oils are commonly used as insecticides or adjuvants in integrated pest management (IPM) practices. To extend the product life of synthetic pesticides, we evaluated the toxicity of chlorpyrifos (CPF), thiamethoxam (THX), or pyriproxyfen (PPF) mixed with mineral oil Lvying (LY) against ACP nymphs under different weather conditions. Individual application of CPF, THX, and PPF effectively controlled against ACP nymphs under no rain conditions, with mortality rates varying from 20 to 100% during 1–5 d after treatment. The addition of LY at 1.0% or 0.5% rates to CPF, THX, and PPF significantly enhanced their control efficacy, achieving sustained mortality rates from 60 to 100% during the same period. Light rain had less impact on the control efficacy of these insecticide mixtures compared to individual insecticides. However, cumulative rainfall above 20 mm significantly reduced the control efficacy of individual insecticides and their mixtures. The addition of LY decreased both surface tension and contact angle of THX solution on citrus leaves, thereby enhancing the solution’s wetting and increasing THX deposition. Moreover, the rainfastness of THX was improved after adding LY, leading to a greater retention on the leaves. LY at a rate of 1.0% exhibited excellent efficacy against ACP nymphs, and observations using scanning electron microscopy (SEM) showed that LY altered ACP mouthpart morphology and blocked spiracles, likely contributing to its insecticidal effects. This study revealed that mineral oils can serve as both insecticides to combine with synthetic pesticides for enhancing toxicity against ACP and as adjuvants to facilitate the deposition and rainfastness of synthetic pesticides on leaves, which could be recommended for sustainable ACP management in citrus orchards. Full article

Adjuvants alter the physical–chemical properties of pesticide formulations, influencing either the droplet size or drift phenomenon. Selecting the appropriate adjuvant and understanding its characteristics can contribute to the efficiency of Plant Protection Product (PPP) application. This reduces drift losses and promotes better deposition on the crop. The objective of this study was to evaluate the effects of four commercial adjuvants based on mineral oil (Agefix and Assist), vegetable oil (Aureo), and polymer (BREAK-THRU) on the physical–chemical properties (surface tension, contact angle, volumetric mass, electrical conductivity, and pH), droplet size, and drift, using pure water as the control treatment (no adjuvant). Surface tension and contact angle were measured with a DSA30 droplet shape analyzer, while droplet size measurements were determined through a laser diffraction particle analyzer (Malvern Spraytec), using a single flat fan spray nozzle (AXI 110 03) operating at 0.3 MPa. Drift reduction potential was evaluated inside a wind tunnel with an air speed of 2 m s⁻¹. All adjuvants reduced surface tension and contact angle compared to water. volumetric median diameter (VMD) increased for Aureo, Assist, and Agefix, generating coarse, medium, and medium droplets, respectively, while BREAK-THRU formed fine droplets, similar to those generated by water. Aureo had the greatest reduction in Relative Span Factor ($RSF$), with a reduction of 30.3%. Overall, Aureo, Assist, and Agefix adjuvants significantly reduced the percentage of droplets <100 µm and increased those >500 µm. Drift reduction potential was achieved for all adjuvants, with Aureo showing the highest reduction of 59.35%. The study confirms that selecting the appropriate adjuvant can improve PPP application and promote environmental sustainability in agricultural practices. Full article

Induced resistance (IR) based on elicitors application aims to strengthen plant defenses, rather than directly targeting pathogens. These compounds are less toxic than conventional pesticides and are useful in reducing their use. Strategies based on COS–OGA, Swinglea glutinosa, and low copper doses were tested in this three-year (2021–2023) field investigation against grapevine downy (DM) and powdery (PM) mildew. Their effectiveness was compared to copper, sulfur, untreated, and water-sprayed plants in a naturally infected vineyard. Combined treatments provided higher levels of protection. COS–OGA at 2 L ha⁻¹ combined with low copper doses and an adjuvant protected canopy and production from both DM and PM at the same level as copper and farm application (based on copper and sulfur). In favorable seasons, 2023 for DM and 2022 for PM, this strategy reduced the DM McKinney Index compared to untreated plants by 74% and 39% on leaves and bunches, respectively. Reductions observed for PM were 85% on leaves and 46% on bunches. S. glutinosa showed reductions only in one assessment against PM on bunches. This work validates IR-based DM and PM management strategies under field conditions and paves the way toward concrete reduction in copper and sulfur use in vineyards. Full article

Off-target drift from aerial pesticide applications in croplands can be a major source of pesticide exposure to pollinators. Pesticide adjuvants (PAs) are added to pesticides but can be as toxic as pesticides’ active ingredients. Ongoing experiments have identified sodium alginate (SA) as a drift-reducing PA less toxic to honeybees. Hence, SA and fenugreek polymer (FP) have been tested as drift-reducing PAs for aerial applications using the Remotely Piloted Aerial Application System (RPAAS). Two spray experiments were carried out in the field: (i) water only (W) and (ii) water and adjuvant (WA). Droplet spectrum and on-target coverage were collected using a VisiSize P15 image analyzer and kromekote cards, respectively. The drift reduction potentials (DRPs) of the adjuvants were analyzed based on droplet size (diameters of 10%, 50%, and 90% volume) and the proportion of driftable volume with droplets < 200 µm. Compared to the W only, the W-A treatment produced larger droplets, suggesting the presence of DRP. There were 14.5%, 8.3% to 14.4%, and 2.3% to 7.7% driftable fines in the W, WA (SA), and WA (FP) treatments, respectively. The FP treatment improved the on-target coverage (3.0% to 3.1%) compared to water (2.7%). Our results indicate that SA and FP have the potential to mitigate off-target drift and protect pollinator health. Full article

Pesticide use in crops is a severe problem in some countries. Each country has its legislation for use, but they differ in the degree of tolerance for these broadly toxic products. Several synthetic pesticides can cause air, soil, and water pollution, contaminating the human food chain and other living beings. In addition, some of them can accumulate in the environment for an indeterminate amount of time. The agriculture sector must guarantee healthy food with sustainable production using environmentally friendly methods. In this context, biological biopesticides from microbes and plants are a growing green solution for this segment. Several pests attack crops worldwide, including weeds, insects, nematodes, and microorganisms such as fungi, bacteria, and viruses, causing diseases and economic losses. The use of bioproducts from microorganisms, such as microbial biopesticides (MBPs) or microorganisms alone, is a practice and is growing due to the intense research in the world. Mainly, bacteria, fungi, and baculoviruses have been used as sources of biomolecules and secondary metabolites for biopesticide use. Different methods, such as direct soil application, spraying techniques with microorganisms, endotherapy, and seed treatment, are used. Adjuvants like surfactants, protective agents, and carriers improve the system in different formulations. In addition, microorganisms are a tool for the bioremediation of pesticides in the environment. This review summarizes these topics, focusing on the biopesticides of microbial origin. Full article

In the last decade, unmanned aerial vehicles (UAVs) for plant protection have rapidly developed worldwide as a new method for pesticide application, especially in China and other Asian countries. To improve the deposition quality in UAV applications, adding appropriate types of spray adjuvants into pesticide solutions is one of the most effective ways to facilitate droplet deposition and control efficacy. At present, research on spray adjuvants for UAVs are mainly based on droplet drift and laboratory tests. Few studies have been conducted on the physicochemical properties of spray adjuvants and the effects of droplet deposition characteristics. To explore the properties of four different kinds of spray adjuvants (Mai Fei, Bei Datong, G-2801, and Agrospred 910) and the deposition characteristics of spray adjuvants on litchi leaves, an automatic surface tension meter, a contact angle measuring device, an ultraviolet visible spectrophotometer, and a DJI AGRAS T30 plant protection UAV was used to measure the surface tension, contact angle, and droplet deposition characteristics on litchi under UAV spraying operations. The results showed that the addition of spray adjuvants could significantly reduce the surface tension of the solution. The surface tension value of the solution after adding the spray additives was reduced by 53.1–68.9% compared with the control solution. Among them, the Agrospred 910 spray adjuvant had the best effect on reducing the surface tension of the solution. The contact angle of the control solution on the litchi leaves varied from 80.15° to 72.76°. With the increase in time, the contact angle of the spray adjuvant solution gradually decreased, the Agrospred 910 spray adjuvant had the best effect, and the contact angle decreased from 40.44° to 20.23° after the droplets fell on the litchi leaves for 60 s. The adjuvant solutions increased the droplet size, but the uniformity of the droplet size decreased. The Dv0.5 of different spray solutions ranged from 97.3 to 117.8 μm, which belonged to the fine or very fine droplets, and the Dv0.5 of adjuvants solutions were significantly greater than that of the control solution. The RSs of adjuvant solutions were very similar and ranged from 0.92 to 0.96, all of which were significantly greater than the result of the control solution (0.57). Compared with the deposition of the control solution, the Mai Fei, Bei Datong, and G-2801 solutions clearly increased spray deposition, with total depositions of 0.776, 0.705, and 0.721 μL/cm², which are all greater than the total deposition of the control solution of 0.645 μL/cm². The addition of tank-mixed adjuvants could effectively increase the uniformity of the spray deposition, and all the average CVs of adjuvant solutions were lower than 96.86%. On the whole, Mai Fei performed best in increasing the spray deposition and promoting penetration, followed by Bei Datong and G-2801. Meanwhile, the test can also provide a reference for improving the utilization rate of UAV pesticide applications. Full article

In recent years, the number of available chemical pesticides has been dramatically reduced, urging the need for the discovery of alternatives to chemical pesticide products such as, among others, natural zeolites (zeolitic rocks). We determined the mineralogical and chemical composition of a specific and continuous layer of zeolitic rock sample (ZeotP) from Petrota, Evros, Greece, and evaluated its oviposition-deterrent effect on the olive fruit fly Bactrocera oleae Gmelin (Diptera: Terphritidae). The tested natural zeolite contained 70 wt. % clinoptilolite, 18 wt. % amorphous material, 7 wt. % feldspars, 4 wt. % cristobalite, and 1 wt. % quartz. We tested the oviposition-deterrent effect of ZeotP mixed or not with an emulsifier adjuvant, NU-FILM-P^®, in water and applied it to the surface of olive fruits. The ZeotP oviposition-deterrent effect on the olive fly was very high under a series of tested temperatures (17 °C, 20 °C, 25 °C, and 30 °C) and RHs (23%, 33%, 55%, 75%, and 94%). In addition, the ZeotP residual deterrent effect after equable water spraying was high, like the respective effect of the pyrethroid insecticide Decis^® (deltamethrin). Our results may contribute to the effective control of the olive fruit fly using an alternative to chemical pesticides: natural zeolite (zeolitic rocks) products. Full article

The tarnished plant bug, Lygus lineolaris, and the red-banded stink bug, Piezodorus guildinii, pose significant economic threats to cotton and soybean crops in the mid-southern USA. However, the efficacy of insecticide spraying is comparatively low, and adjuvants play a crucial role in optimizing insecticide performance. This study evaluated the impact of two adjuvants, sodium alginate (SA) and polyacrylamide (PAM), on enhancing the efficacy of bifenthrin and imidacloprid via laboratory spray bioassays. Both SA and PAM demonstrated insignificant variation in LC₅₀ values with formulated bifenthrin and imidacloprid. However, SA and PAM exhibited synergistic effects with two technical-grade insecticides. High concentrations of PAM increased the efficacy of bifenthrin by 1.50- and 1.70-fold for L. lineolaris and P. guildinii, respectively. Conversely, no enhancement effect was observed for the SA–technical-grade bifenthrin combination against either insect pests. Additionally, both SA and PAM enhanced the effectiveness of imidacloprid in P. guildinii by up to 2.68- and 2.73-fold, respectively. While a high concentration of PAM had a 1.45-fold synergistic effect on technical-grade imidacloprid, no enhancement effect was observed for the SA/imidacloprid combination in L. lineolaris. This study explored the synergistic impact of SA and PAM on the efficacy of technical-grade and formulated bifenthrin and imidacloprid, providing valuable insights into optimizing pest control strategies in agriculture. Full article

This study investigated the efficacy of three spray adjuvants (Coerce, Wetcit, and Silwet408) in enhancing dinotefuran permeation in rice leaves. Different concentrations of these adjuvants were tested using an external standard method. The rice leaf surface was analyzed by using the van Oss–Chaudhury–Good method to establish a link between surface free energy (SFE) and dinotefuran permeation. All of the adjuvants effectively increased dinotefuran permeation in rice leaves, with the highest permeation of 8.496 mg/kg achieved using Wetcit at 1000 mg/L. The SFE of the rice leaf surface was determined to be 29.28 mJ/m². A notable correlation was observed between the energy difference (the SFE of the pesticide liquid versus the SFE of the rice leaf surface) and permeation. Various fitting methods, including linear, exponential, logarithmic, polynomial, and power methods, were applied. Polynomial fitting demonstrated the highest coefficient of determination (R² > 0.9000). The relationship between the permeation (y) and energy difference (Δγ) conformed to the polynomial equation y = aΔγ² + bΔγ + c, where a, b, and c are constants. This model provides a predictive tool for the optimal dosage of spray adjuvants according to target plant characteristics, enhancing the understanding of the interaction between pests and pesticides. Full article

Population growth and the need for increased agricultural productivity pose a global problem. Therefore, the development of green compounds to ensure agricultural sustainability is an urgent necessity. Surfactant compounds hold significant commercial importance due to their diverse industrial uses. However, the synthetic origin of these agents limits their commercial application due to their toxicity. As a result, extensive research has focused on the production of microbial-originated green surfactants, known as biosurfactants, over the past fifteen years. These biomolecules not only offer a green alternative for agriculture but also exhibit reduced toxicity and excellent stability under specific environmental conditions. Biosurfactants can lower surface tension more effectively than synthetic surfactants. With properties such as detergency and foam formation, biosurfactants are suitable for various agricultural applications, particularly in pesticide and agrochemical formulations. They can function as biopesticides to manage pests, pathogens, phytopathogenic fungi, and weeds due to their antimicrobial activity. Moreover, plants can benefit from biosurfactant molecules and microorganisms as nutrients. They can also aid efficiently in the distribution of micronutrients and metals in the soil. They also stimulate plant immunity and are utilized for soil hydrophilization to ensure proper moisture levels and uniform fertilizer distribution. This review aims to provide valuable insights into the role and properties of biosurfactants as agricultural adjuvants, fostering the development of sustainable formulations to replace the chemical surfactants used in pesticides. For this purpose, the general aspects of global agricultural activity are initially described, followed by a discussion of pesticides, including herbicides, fungicides, and insecticide products. Next, the properties of chemical surfactants are discussed and the use of green surfactants, with emphasis on microbial biosurfactants, is demonstrated. The application of biosurfactants in the agricultural industry and trends are addressed and prospects for the application of these agents are discussed. Full article