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Open AccessArticle

Neonicotinoid Sunflower Seed Treatment, While Not Detected in Pollen and Nectar, Still Impacts Wild Bees and Crop Yield

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Agrochemicals 2023, 2(2), 279-295; https://doi.org/10.3390/agrochemicals2020018 - 06 Jun 2023

Viewed by 152

Abstract

Neonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated [...] Read more.

Neonicotinoid seed treatments are commonly used in agricultural production even though their benefit to crop yield and their impact on pollinators, particularly wild bees, remains unclear. Using an on-farm matched pair design in which half of each field was sown with thiamethoxam treated seed and half without, we assessed honey bee and wild bee exposure to pesticides in sunflower fields by analyzing pesticide residues in field soil, sunflower pollen and nectar, pollen-foraging and nectar-foraging honey bees, and a sunflower specialist wild bee (Melissodes agilis). We also quantified the effects of thiamethoxam-treated seed on wild bee biodiversity and crop yield. M. agilis abundance was significantly lower with thiamethoxam treatment and overall wild bee abundance trending lower but was not significantly different. Furthermore, crop yield was significantly lower in plots with thiamethoxam treatment, even though thiamethoxam was only detected at low concentrations in one soil sample (and its primary metabolite, clothianidin, was never detected). Conversely, wild bee richness was significantly higher and diversity was marginally higher with thiamethoxam treatment. Nectar volumes harvested from the nectar-foraging honey bees were also significantly higher with thiamethoxam treatment. Several pesticides that were not used in the sunflower fields were detected in our samples, some of which are known to be deleterious to bee health, highlighting the importance of the landscape scale in the assessment of pesticide exposure for bees. Overall, our results suggest that thiamethoxam seed treatments may negatively impact wild bee pollination services in sunflower. Importantly, this study highlights the advantages of the inclusion of other metrics, such as biodiversity or behavior, in pesticide risk analysis, as pesticide residue analysis, as an independent metric, may erroneously miss the impacts of field realistic pesticide exposure on bees. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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Open AccessArticle

Influence of Chemical Control on the Floristic Composition of Weeds in the Initial and Pre-Harvest Development Stages of the Sunflower Crop

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Elielton Germano dos Santos

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Miriam Hiroko Inoue

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Ana Carolina Dias Guimarães

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Jennifer Stefany Queiroz Bastos

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Ricardo Alcántara-de la Cruz

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Kassio Ferreira Mendes

Agrochemicals 2023, 2(2), 193-202; https://doi.org/10.3390/agrochemicals2020014 - 15 May 2023

Viewed by 386

Abstract

The presence of weeds in the sunflower crop is one of the main factors linked to the low increase in productivity of this crop, and to determine the most appropriate management of weeds, it is essential to carry out a diagnosis through the [...] Read more.

The presence of weeds in the sunflower crop is one of the main factors linked to the low increase in productivity of this crop, and to determine the most appropriate management of weeds, it is essential to carry out a diagnosis through the phytosociological survey. The objective of this study was to assess the influence of chemical control on the phytosociological community of weeds in three areas cultivated with sunflower in the Parecis region (Brazil). The areas were treated with 2,4-D + glyphosate for desiccation; S-metolachlor was used for pre-emergence control in the three areas; meanwhile, sulfentrazone and flumioxazin were applied only in one area; and, finally, clethodim was applied for post-emergence weed management. Sampling was carried out at two different times, in the initial and pre-harvest stages (at 35 and 100 days after the emergence of the crop, respectively), using a quadrate, in which weeds were identified and quantified to determine the frequency, relative frequency, density, relative density, abundance, relative abundance, importance index, and similarity index between areas and times. Seventeen weed species were found in the sunflower crop (70.6% dicot and 29.4% monocotyledonous) in the two seasons, grouped into nine botanical families, with Poaceae being the most diverse family. The dicots Tridax procumbens and Acanthospermum hispidium were present in low frequency only in the initial stages of development of the sunflower crop. The weeds with the highest importance index values in the initial and pre-harvest stages were Euphorbia hirta (104 and 91%) and Bidens pilosa (45 and 66%, respectively), both belonging to the dicots group. These two species were present in the two evaluated periods and in the three experimental areas, demonstrating that there was a similarity index between them with values above 93%. These results of the phytosociological study may contribute to determining more efficient management strategies for weed chemical control in the sunflower crop. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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Open AccessArticle

Fungicide Scent Pollution Disrupts Floral Search-and-Selection in the Bumblebee Bombus impatiens

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Nour Yousry

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Paige Henderson

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Jordanna Sprayberry

Agrochemicals 2023, 2(2), 181-192; https://doi.org/10.3390/agrochemicals2020013 - 18 Apr 2023

Viewed by 691

Abstract

Bumblebees are valuable generalist pollinators. However, micro- and macro-stressors on bumblebees negatively impact both foraging efficiency and pollination efficacy. Given that colonies have a resource threshold for successful reproduction, factors that decrease foraging efficiency could negatively impact conservation efforts. Recently, agrochemical odor pollution [...] Read more.

Bumblebees are valuable generalist pollinators. However, micro- and macro-stressors on bumblebees negatively impact both foraging efficiency and pollination efficacy. Given that colonies have a resource threshold for successful reproduction, factors that decrease foraging efficiency could negatively impact conservation efforts. Recently, agrochemical odor pollution has been shown to hinder floral odor learning and recognition in Bombus impatiens via an associative odor learning assay (FMPER). These results may have implications for the field foraging behavior of bumblebees. Building on this prior work, our study aimed to determine if negative effects of fungicides on associative odor learning and recognition scale up to negative impacts on actively foraging bumblebees. These experiments investigated whether the presence of a background fungicide odor (Reliant^® Systemic Fungicide) impacts the location of a learned floral resource (lily of the valley-scented blue flowers) in a wind tunnel. Experiments were run with and without early access to visual cues to determine if fungicide odor pollution is more impactful on bees that are engaged in olfactory versus visual navigation. Fungicide odor pollution reduced landing frequency in both paradigms. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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Open AccessArticle

Multiple Pesticide Resistance in Rust-Red Flour Beetle (Tribolium castaneum, Herbst 1797) from Northern Nigeria Is Probably Driven by Metabolic Mechanisms

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Agrochemicals 2023, 2(2), 170-180; https://doi.org/10.3390/agrochemicals2020012 - 06 Apr 2023

Viewed by 791

Abstract

There is a severe lack of information about molecular mechanisms of pesticide resistance in the rust-red flour beetle, a major pest destroying grains and flour across Nigeria, hindering evidence-based control. Here, we identified to the species level three populations of the red flour [...] Read more.

There is a severe lack of information about molecular mechanisms of pesticide resistance in the rust-red flour beetle, a major pest destroying grains and flour across Nigeria, hindering evidence-based control. Here, we identified to the species level three populations of the red flour beetle from Kano, Nigeria, as Tribolium castaneum (Herbst 1797) and investigated the mechanism driving their insecticide resistance. The IRAC susceptibility bioassays established cypermethrin resistance, with LC₅₀s of 4.35–5.46 mg/mL in the three populations, NNFM, R/Zaki and Yankaba. DDT and malathion resistance were observed in NNFM, with LC₅₀s of 15.32 mg/mL and 3.71 mg/mL, respectively. High susceptibility was observed towards dichlorvos in all three populations with LC₅₀s of 0.17–0.35 mg/mL. The synergist bioassay with piperonylbutoxide significantly restored cypermethrin susceptibility, with mortality increasing almost threefold, from 24.8% obtained with 1.5 mg/mL of cypermethrin to 63.3% in the synergised group (p = 0.013), suggesting a preeminent role of P450s. The two major knockdown resistance (kdr) mutations, T929I and L1014F, in the IIS4 and IIS6 fragments of the voltage-gated sodium channel were not detected in both cypermethrin-alive and cypermethrin-dead beetles, suggesting a lesser role of target-site insensitivity mechanisms. These findings highlight the need to explore alternative control tools for this pest and/or utilise synergists, such as piperonyl butoxide, as additional chemistries in pesticide formulations to improve their efficacy. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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Open AccessArticle

EU Chemical Plant Protection Products in 2023: Current State and Perspectives

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Patrice A. Marchand

Agrochemicals 2023, 2(1), 106-117; https://doi.org/10.3390/agrochemicals2010008 - 08 Feb 2023

Cited by 1 | Viewed by 2181

Abstract

Agrochemicals are synthetic or hemi-synthetic crop protection substances which are supervised by the EU Regulation EC 1107/2009, which give rise to plant protection products (PPP) with market authorizations. Most of these active substances of chemical origin were transferred from the previous Annex I [...] Read more.

Agrochemicals are synthetic or hemi-synthetic crop protection substances which are supervised by the EU Regulation EC 1107/2009, which give rise to plant protection products (PPP) with market authorizations. Most of these active substances of chemical origin were transferred from the previous Annex I of Directive 91/414/EEC to Part A of Regulation EU 540/2011, with newly approved active substances mainly being listed in Part B or E, while renewed substances were moved from Part A to Part B or E. In this study, approved agrochemicals from the early part of 2023 are organized into categories, families, functions, usages, treated crop categories, regulatory characteristics, and maximum residue limits (MRLs). Perspectives regarding their evolution are also described together with pending approvals. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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Open AccessArticle

Oxyfluorfen and Linuron: Residual Effect of Pre-Emergence Herbicides in Three Tropical Soils

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Dilma F. de Paula

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Guilherme A. de P. Ferreira

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Tiago Guimarães

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Maura G. da S. Brochado

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Leandro Hahn

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Kassio F. Mendes

Agrochemicals 2023, 2(1), 18-33; https://doi.org/10.3390/agrochemicals2010003 - 09 Jan 2023

Viewed by 1296

Abstract

Knowledge about the residual effect of herbicides is important in order to increase agronomic efficacy and reduce environmental problems. Therefore, the objective of this study was to evaluate the residual effect of oxyfluorfen and linuron in three soils. Pots of 0.35 dm³ [...] Read more.

Knowledge about the residual effect of herbicides is important in order to increase agronomic efficacy and reduce environmental problems. Therefore, the objective of this study was to evaluate the residual effect of oxyfluorfen and linuron in three soils. Pots of 0.35 dm³ were filled with three Brazilian soils: Ultisol, Oxisol, and Inceptisol. Then, the herbicides were applied at different times at 0, 15, 30, 45, 60, 90, 120, 150, 180, and 200 days and the bioindicator species of linuron and oxyfluorfen were sown. Then, the injury was evaluated at 7, 14, and 21 days after emergence (DAE) to find the half-life of the herbicide residue level (RL₅₀) and the dose of herbicide that provides a 50% reduction in dry matter (GR₅₀). In the soil with oxyfluorfen application, the RL₅₀ at 21 DAE was 59, 57, and 51 days and GR₅₀ was 49, 47, and 31 days for Ultisol, Oxisol, and Inceptisol, respectively. Soils with linuron application had RL₅₀ of 75, 92, and 149 days and GR₅₀ of 52, 48, and 120 days for Ultisol, Oxisol, and Inceptisol, respectively. The higher organic matter and clay content of Ultisol compared to Oxisol and Inceptisol resulted in a lower residual effect of linuron. There was little difference between soil type and the residual effect of oxyfluorfen, which may be related to the physicochemical characteristics of the molecule. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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Review

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Open AccessReview

Development of Quality Requirements of Chemical Analytical Measurements

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Henriett Szemanné-Dobrik

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Adrienn Vásárhelyi

Agrochemicals 2022, 1(1), 29-40; https://doi.org/10.3390/agrochemicals1010005 - 16 Dec 2022

Viewed by 1026

Abstract

The development of quality requirements for the analyses of chemical contaminants is reviewed from the formation of the first association of analytical chemists in 1884. Without attempting to give complete coverage, it is shown that the elaboration of quality systems is commanded by [...] Read more.

The development of quality requirements for the analyses of chemical contaminants is reviewed from the formation of the first association of analytical chemists in 1884. Without attempting to give complete coverage, it is shown that the elaboration of quality systems is commanded by the needs of the industry and international trade. Progress along the line of the initial inter-laboratory comparison, methods validated with collaborative tests, and development of internationally harmonized guidelines and protocols to perform complex studies aiming to improve the accuracy and reliability of the results facilitate international trade, and protect consumer health, as well as the environment. The international cooperation for limiting the replication of various (e.g., analytical, toxicological) tests is promoted by multilateral agreements that are also supported by legal obligations. Notwithstanding, the rapid development of requirements and guidance documents provides only the frame for obtaining accurate, defendable results. The production of such results is the duty of the laboratory management, analysts, and study personnel who play the decisive role and bear full responsibility for the samples analyzed. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

Open AccessFeature PaperReview

Using Nitrogen for the Control of Stored Product Insects: One Single Application for Multiple Purposes

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Christos G. Athanassiou

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Maria K. Sakka

Agrochemicals 2022, 1(1), 22-28; https://doi.org/10.3390/agrochemicals1010004 - 11 Oct 2022

Cited by 2 | Viewed by 1093

Abstract

Nitrogen treatment can be used as an alternative method to chemical control. Most of the research on nitrogen treatment mainly investigated the optimum concentration of oxygen level as well as duration as a means of insect control. Other parameters such as temperature and [...] Read more.

Nitrogen treatment can be used as an alternative method to chemical control. Most of the research on nitrogen treatment mainly investigated the optimum concentration of oxygen level as well as duration as a means of insect control. Other parameters such as temperature and different insect species have been extensively studied and recent research focus on the modelling of nitrogen concentration and the efficacy on commodity. In this paper, we briefly review the major parameters (temperature, oxygen level, relative humidity, exposure time) using nitrogen treatment against stored product insects. Exposure to different oxygen levels or different exposure times can remarkably change pest control mortality. Moreover, different insect species and life stages have differing susceptibility to nitrogen treatment. Finally, these studies are reviewed in this paper to illustrate that nitrogen treatment can be used as a part of an IPM strategy. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

Other

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Open AccessConcept Paper

Evaluation of Monitoring Data in Foods

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Agrochemicals 2023, 2(1), 69-95; https://doi.org/10.3390/agrochemicals2010006 - 18 Jan 2023

Cited by 1 | Viewed by 1393

Abstract

Pesticide residue monitoring data reflect the actual residues in foods as traded and are suitable for estimating consumers’ exposure, evaluating compliance with maximum residue limits, MRLs, and refining future risk-based sampling programmes. The long-term exposure (daily intake) is calculated from the national or [...] Read more.

Pesticide residue monitoring data reflect the actual residues in foods as traded and are suitable for estimating consumers’ exposure, evaluating compliance with maximum residue limits, MRLs, and refining future risk-based sampling programmes. The long-term exposure (daily intake) is calculated from the national or regional food consumption data and average residues in the edible portions of food. The non-detected residues may be counted as LOQ, 0.5 LOQ, or 0. The short-term intake is calculated from the large portion consumption of individual foods multiplied by the highest residue concentration found in them and the relevant variability factor. Dietary exposure to a pesticide residue may be characterised by the hazard quotient (HQ) and the hazard index (HI). Cumulative exposure should only be assessed for those compounds having the common mechanism of toxicity (cumulative assessment group, CAG). The number of residue data required for these assessments should be calculated with distribution-free statistics at the targeted confidence level. The proper evaluation of the numerous results can only be completed if they are electronically recorded and can be retrieved in specific formats. Our objectives are to present methods for consumer risk assessment, testing compliance with MRLs, and ranking commodities for risk-based sampling and to give examples of electronic processing of residue data. Full article

(This article belongs to the Special Issue Feature Papers to Celebrate the Inaugural Issue of Agrochemicals)

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