Agrochemicals, Volume 2, Issue 4 (December 2023) – 8 articles

Trichome is a hair-like structure involved in mechanical and chemical defenses of plants against herbivorous insects. Nicotiana benthamiana, a wild tobacco plant, has well-developed glandular trichomes that secrete sugar esters with potent repellent and insecticidal properties. However, there is a lack of information about the effectiveness of trichome extract in the control of plant-sapping insects. The objective of this study was to investigate the effects of N. benthamiana trichome exudates on Bemisia tabaci MED (Gennadius) (Hemiptera: Aleyrodidae), a highly destructive insect pest that poses significant threats to both vegetable and ornamental plants globally. First, we determined the host preference and mortality of B. tabaci adults using the choice test and feeding assay towards tomato and N. benthamiana plants. B. tabaci preferred tomato over N. benthamiana plants. Second, we extracted N. benthamiana trichome exudates by washing the leaves with either water or ethanol and evaluated their oral toxicities against B. tabaci adults using a parafilm feeding chamber containing 20% sucrose solution. Oral ingestion of both extracts significantly increased mortality in a concentration-dependent manner. Oral ingestion of ethanol-washed 10% trichome extract caused >60% mortality in B. tabaci adults after 36 h. Third, trichome exudates were concentrated by drying to obtain a powder form, which was more potent in killing whiteflies than the liquid form. Oral ingestion of 1% trichome powder was completely lethal to B. tabaci within 36 h. N. benthamiana trichome exudates are highly toxic to B. tabaci through oral ingestion, suggesting that N. benthamiana can be used as a potential natural pesticide for whitefly management. Full article

Recently, the search for sustainable and environmentally friendly agrochemicals from natural origin is steadily growing. Propolis, a resinous substance collected by honeybees, well known for its diverse biological activities, has attracted the attention of scientists and farmers with its agrochemical potential in the last years. This review article aims to delve into the fascinating world of propolis and its utilization in agriculture. Here, we provide a brief overview of propolis: its chemical composition and the bioactive substances responsible for its biological properties. The effectiveness of propolis in controlling common pests and diseases that affect crops, suppressing postharvest illnesses of fruits and vegetables, stimulating plant defenses and increasing stress resistance, is reviewed. Discussion of the challenges and future perspectives related to the integration of propolis in agriculture is also one of our objectives, including chemical variability, standardization and regulatory considerations. We also focused on the latest research trends and technological advances that promise to unlock the full potential of propolis as a sustainable agricultural tool. Full article

Membrane fractionation with track-etched membranes was used to size-profile the microelement composition of water-extractable soil colloids (WESCs). The aim of the study is the element composition of narrow WESC fractions of typical chernozems in the range of 0.01–10 µm. Micro-/ultrafiltration through a cascade of track-etched polycarbonate membrane filters with pore sizes of 5, 2, 1, 0.8, 0.4, 0.2, 0.1, 0.05, 0.03, and 0.01 µm at room temperature was used. ICP–AES using direct spraying of obtained fractions without decomposition was used; Al, Ba, Cd, Cr, Cu, Fe, Mn, Si, Sr, Ti, Zn, Ca, K, Mg, Na, P, and S were found. Narrow WESC fractions differ significantly. For macro- and microelements, maximum amounts of Si, Al, Fe, and Ti and their maximum percentages are observed in fractions with sizes above 1 µm, while Ca, Mg, Mn, Cu, Zn, K, and S are accumulated more in fractions with sizes below 1 µm. The developed approach provides preparative isolation of a detailed set of narrow WESC fractions in the micrometer–nanometer range. This provides element soil profiles that reveal distinct differences and the individual character of each fraction as well as trends in changes in the mineral matrix and microelement composition with fraction size. Full article

In Benin, synthetic insecticides are the main pest control option used by farmers to protect and enhance their production. However, failures to control the target pests are often observed after application and may be related to agricultural practices or insecticide quality. The present work was designed to assess a rapid, simple, and reliable analytical method for detecting and quantifying the most commonly used insecticides (λ-cyhalothrin and acetamiprid) in Benin. The analytical standard technical grade separation was performed by gradient reversed-phase high-performance liquid chromatography on a C₁₈ stationary-phase column. The mobile phase consisted of a mixture of acetonitrile/water using a gradient flow. The flow rates were 1 and 1.4 mL·min⁻¹ for λ-cyhalothrin and acetamiprid, respectively. The analysis times were 15 and 20 min, with retention times of 2.35 and 7.94 min for λ-cyhalothrin and acetamiprid, respectively. Results reveal that most of the surveyed farmers were not educated (70% < Primary School Certificate) and were men (95%). Of the main insecticides applied by farmers, λ-cyhalothrin and acetamiprid were found to be the most technical-grade ones. Furthermore, the analysis of insecticides showed that the concentrations obtained in our study often differed from the ones mentioned on insecticide labels. The proposed method is useful for quantifying insecticides in various technical and commercial formulations with little interference from additives. Full article

Biocontrol agent (BCA) plant protection active substances composed from microorganisms, semiochemicals and substances from natural origins are increasing in Europe, since their entry into force of Regulation (EC) 1107/2009, in number and as a percentage of total active substances. As they are included in the scope of plant protection products (PPPs), this raises the question as to whether they are only substitute active substances, more socially acceptable, sustainable and environmentally preferable, or really another way of managing bioaggressors, pests and diseases. As we have conducted a survey of all active substances listed in all Parts of Regulation EU 540/2011 and compared chemical to BCA active substances, described their evolution and characteristics since 2011 and predicted the global perspective in the future years for both chemical, which are in decline, and BCA AS separately, these works raised the question of whether these BCA AS are a substitution, as is often the case for users, for the previous chemical AS, or whether they are fundamentally different new substances, which clearly obey a new vision of crop protection. This study therefore encompasses all active substances approved at any time in Europe since 2011 for both categories, whether still approved or not. At the end of this assessment, the following conclusion can be drawn: BCA AS are mainly fundamentally different substances from chemical AS, in all the compartments studied. A comparison between BCAs and chemical active substances allowed under (EC) 1107/2009 PPP Regulation is described together with a characterisation of BCA AS listed in EC 540/2011 PPP Regulation. Finally, the specific distinction of BCA vs. chemical active substance profile is analysed. This work allows us to conclude on the evolution of crop protection and the means that must be implemented to face current and new threats. Full article

The global demand for sustainable agricultural practices is increasing, necessitating the preference for fertilizers and organic stimulants with minimal chemical transformation. This study investigates the potential use of Mucuna (Mucuna pruriens sp.) and avocado (Persea americana Mills) seed residues in the cultivation of cherry-tomato crops (Lycopersicon esculentum Mill.) var. cerasiforme. After extracting L-dopa, the Mucuna ground residual seeds were incorporated into the soil substrate as an edaphic fertilizer. In contrast, the hydrolyzed avocado seed was mixed with water or the nutrient Long Ashton and applied as a foliar biostimulant to cherry plants grown in a greenhouse. We report the nutrients and amino acid content in hydrolysates of the avocado and Mucuna’s residue seeds and experiment with their effect in plants employing a completely blocked random design of eight treatments with four replicates. Data inspection involved analysis of variance, and mean differences were determined using Fisher’s least significant difference test. Significant differences (p < 0.05) were observed among the treatments regarding the number of flowers (70%), fruits (23%), and dry weight fruits (25%) in favor of those using these seed residues. A second experiment revealed that treatments containing both seed residues slightly increased the °Brix in fruits. This study supports with evidence that residual seeds benefit tomatoes and probably other important plants, contributing to the path to sustainable agriculture. Full article

The unintended loss of glyphosate and P from cropland may pose an environmental risk to downstream water quality and marine ecosystems. Glyphosate and P compete for exchange sites, and since glyphosate is an organophosphate, it reacts similarly to phosphates in soil. The competition for exchange sites between glyphosate and P could lead to an increased risk of loss due to leaching, leading to water quality degradation and harm to aquatic wildlife. The focus of this study was to (i) determine the sorption tendencies of P and orthophosphate in Florida Entisols and (ii) determine the sorption tendencies of glyphosate in Florida Entisols. Adsorption and desorption experiments were performed for both P and glyphosate. The data from the sorption experiments were fitted to linear, Freundlich, and Langmuir models. Orthophosphate-P (ortho-P) was best represented by the linear isotherm. Glyphosate adsorption was best represented by the linear isotherm, and desorption was best represented by both the linear and Freundlich models. Phosphorus and glyphosate sorption and desorption increased with soil depth, likely due to the higher concentrations of Fe and Al with greater depth. These results could improve P and glyphosate application rates when applied in tandem to citrus trees, increasing overall tree health and improving soil quality. Full article

Greek consumers perceive an increased risk of pesticide residues in food. This study examined Greek consumers’ perceptions of the safety of Greek plant-based food compared to those from other EU countries. One-half of Greek consumers believe Greek food is as safe as other European foods, while the other half disagree. According to a principal component analysis and a bivariate logistic regression, several factors, such as the perceived safety of plant foods, education, age, gender, traceability, perceived benefits and risks of pesticides, actual pesticide use, and authoritative information sources, influence this attitude. Authoritative knowledge in this field can reduce risk perception and improve Greek consumers’ attitudes towards food safety. The latent class analysis identified two categories of consumers. The first class receives limited information about pesticides, leading to lower perceived pesticide benefits, higher mistrust of traceability, and concerns about pesticide residues. In contrast, the second class actively searches for information from credible sources, endorses the Greek plant foods safety, acknowledges the pesticide benefits, and trusts traceability. Official information is associated with reduced risk perception. Regulators should consider the impact of sociodemographic and other intrinsic characteristics on individuals’ risk perceptions and prioritise transparency in risk communication strategies. Full article