Water-soluble food dye of Allura Red as a tracer to determine the spray deposition of pesticide on target crops

Tank-Mix Adjuvants Enhance Pesticide Efficacy by Improving Physicochemical Properties and Spraying Characteristics for Application to Cotton with Unmanned Aerial Vehicles

Tank-mix adjuvants have been used to reduce spray drift and facilitate the efficacy of pesticides applied with unmanned aerial vehicles (UAVs). However, the effects of specific adjuvants on pesticide characteristics and the mechanism of action remain unclear. Herein, we analyzed the effects of three different types of tank-mix adjuvants (plant oil; mineral oil; and mixture of alcohol and ester) on the surface tension (ST), contact angle, wetting, permeation, evaporation, spray performance, and aphid-control effects of two types of pesticides. The mineral oil adjuvant Weichi (WCH) was highly effective in reducing the pesticide solution ST, improving the wetting and penetration ability, increasing droplet size, and promoting droplet deposition. The mixed alcohol and ester adjuvant Quanrun (QR) showed excellent wetting and antievaporation properties and promoted droplet deposition. A plant oil adjuvant (Beidatong) moderately improved wetting and penetration ability and reduced droplet drift. Field tests showed that the control efficiencies (CEs) of two pesticides were increased after the addition of adjuvants, even with 20% reductions in pesticide application. When the UAV was operated at 1.5 m, the CEs of two pesticides were increased from 65.39 and 66.63% to 73.11-76.52% and 77.91-88.31%, respectively. When operated at 2.5 m, the CEs were increased from 51.24 and 68.60% to 65.06-75.70% and 77.57-92.59%, respectively. Especially, the CEs of pesticides with WCH and QR increased obviously. Importantly, neither WCH nor QR inhibited hatching of the critical insect natural enemy ladybird beetle at concentrations used in the field. This study provides a framework for assessment of tank-mix adjuvants in aerial sprays and directly demonstrates the value of specific adjuvants in improving pesticide bioavailability and minimizing associated environmental pollution.

Optimizing UAV spray parameters to improve precise control of tobacco pests at different growth stages

BACKGROUND

Unmanned aerial vehicles (UAVs) for pesticide application show promising potential in tobacco pest management. However, the impact of flight parameters on spray efficacy requires further investigation. Three field experiments were conducted from the rosette to the maturation stage of tobacco to systematically assess spray efficacy under varying flight heights, speeds, and application volumes. Using a multi-index weight analysis method, optimal operational parameter combinations for different tobacco growth stages were evaluated and compared with backpack electric sprayers.

RESULTS

For the rosette stage, the recommended parameter is a flight speed of 5 m s-1, a flight height of 2 m, and a liquid application volume of 30 L hm-2; during the vigorous growth stage, the suggested parameter includes a flight speed of 3 m s-1, a flight height of 2 m, and a liquid application volume of 22.5 L hm-2. In the maturing stage, optimal parameter consists of a flight speed of 3 m s-1, a flight height of 3.5 m, and a liquid application volume of 30 L hm-2. Furthermore, UAV spraying achieves higher droplet deposition on both sides of tobacco leaves compared to traditional electric backpack sprayers.

CONCLUSIONS

Adjusting UAV spraying parameters for different tobacco growth stages is crucial. These results can provide the methods for the precise control technology of tobacco pests at different growth stages. © 2024 Society of Chemical Industry.

Minimizing Occupational Exposure to Pesticide and Increasing Control Efficacy of Pests by Unmanned Aerial Vehicle Application on Cowpea

Pesticide operators are often exposed to high levels of contaminants, leading to potential adverse health impacts on these agricultural workers. In tropical regions, pesticide applicators are more vulnerable to dermal exposure than their counterparts in temperate regions. Thus, it is highly desirable to develop new spraying methods to minimize the pesticide exposure level without sacrificing the pest control efficiency. Due to their flexibility, high efficiency, and lower labor intensity, unmanned aerial vehicles (UAVs) have attracted considerable attention in precision pest management. However, the pesticide operator exposure assessment during the spraying application with UAVs, especially the comparison with conventional ground sprayers, has not been well investigated. In this work, the control effect against thrips on cowpea and operator exposure determination by aerial and ground spraying in Hainan Province were carried out and compared. When biopesticide spinetoram with the same dosage was applied, the field control efficacy against cowpea thrips sprayed by UAVs was higher than that of knapsack electric sprayers. Moreover, UAV spraying could greatly reduce water consumption and working time. For UAV spraying, when the amounts of water applied per hectare were 22.5, 30, and 37.5 L, the control effects on thrips on the first day were about 69.79%, 80.15%, and 80.58%, respectively. When Allura Red as a pesticide surrogate was applied under similar spraying scenarios with the field control against thrips on cowpea, the average total unit exposure of the knapsack operator (1952.02 mg/kg) was greatly higher than that of the UAV operator (134.51 mg/kg). The present research indicates that plant protection UAV is the direction of development of modern intensive sustainable agriculture.

Assessing Pesticide Residue and Spray Deposition in Greenhouse Eggplant Canopies to Improve Residue Analysis

Pesticide residue analysis is critically important for ensuring food safety and regulating international trade. In a greenhouse setting, we assessed pesticide residue and exposure patterns using liquid chromatography-mass spectrometry and Allura Red tracer analysis. Our results show significant effects of eggplant canopy position and spray concentration on deposition parameters. Specifically, spray coverage, spray density, deposition, and residue were generally greater for leaves in the higher canopy. Deposition and residue, unlike spray coverage and spray density, linearly correlated with spray concentration. Pesticide residues on leaves linearly correlated with depositions on artificial targets, and a correction factor was constructed to estimate residues from tracer depositions. This comparative analysis suggests that tracer analysis using Allura Red in combination with artificial targets is a time- and cost-saving alternative to conventional residue analysis for assessing spray parameters under high-volume spraying scenarios. A better understanding of pesticide residue and spray patterns will not only enhance the safety of our food supply chain but also improve pest control efficacy within the sustainable integrated pest management framework.

Biocidal activity of polylactic acid-based nano-formulated abamectin on Acyrthosiphon pisum (Hemiptera: Aphididae) and the aphid predator Adalia bipunctata (Coleoptera: Coccinellidae)

Abamectin is a common biocide used to control agricultural insect pests. However, the water insolubility of abamectin may result in extra organic solvent introduced in the environment. To solve this issue, it is desirable to develop nanoformulations to encapsulate abamectin with environment-friendly polymers. In this study, two polylactic acid based abamectin nanoformulations were prepared. The average particle sizes, measured by dynamic light scattering and transmission electron microscope, were 240 nm and 150 nm, respectively. The insecticidal activity of these nano-formulated abamectin was examined in the laboratory on the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae). The acute toxicity of nano-formulated abamectin on non-target aphid predator Adalia bipunctata (Coleoptera: Coccinellidae) was also evaluated by topical, residual and oral exposure. The two nano-formulated abamectin had comparable insecticidal effect with commercial abamectin formulation against the pea aphid. Taking median lethal concentration (LC50) as the toxicological endpoint, nanoformulations had higher contact toxicity and lower oral toxicity to first-instar larvae of the predator A. bipunctata. These results are expected to contribute to the application of solvent-free nano-formulated pesticides that comply with the integrated pest management (IPM) strategies.