Pesticide Combinations Research Articles

Individual and Combined Effects of Pesticides with Active Ingredients of Mancozeb and Methomyl on the DNA Damage of Daphnia magna (Straus, 1820; Cladocera, Daphniidae)

Mancozeb and methomyl are active ingredients commonly contained in pesticides applied in shallot farming. Surface runoff can carry pesticide residues that enter water bodies and affect non-target organisms, such as Daphnia magna. This study evaluated the genotoxicity effects of individual and combined mancozeb and methomyl on the DNA damage of D. magna. Organisms at 24 h old and 48 h old were exposed to individual and combined concentrations of mancozeb and methomyl for 24 h to obtain the LC50-24 h values. These values were used to evaluate DNA damage by calculating the tail intensity (TI) (%), tail moment (TM), and tail factor (TF). Results showed that based on the LC50-24 h values, methomyl has the highest toxicity level, followed by the mancozeb:methomyl combination, and then mancozeb. The combination index of mancozeb:methomyl for both D. magna ages (24 h and 48 h) indicated that the two pesticides antagonistically interact (CI>1). However, based on TI%, TM, and TF values, the level of damage was almost the same between the individual and combined pesticide concentrations, and the DNA damage was more massive with increased pesticide concentration. The DNA damage of 24 h old and 48 h old D. magna did not significantly differ. Increased DNA damage in D. magna indicated that this parameter was sensitive to the presence of pesticides. In application, DNA damage can be used as a biomarker for biomonitoring pesticide pollution in the aquatic ecosystem.

Synergistic test of atrazine 72% and mesotrion 8% herbicide against broadleaf weeds and grass weeds in corn (Zea mays L.) cultivation

Weed control employing single pesticide continually in the long-term causes weeds to become resistant. The usage of combined pesticides helps limit the occurrence of weed resistance. Herbicide formulations containing two or more active ingredients will exhibit interactions between constituents which could be synergistic, additive or antagonistic. The purpose of this study was to determine the effectiveness and synergism test of the mixture with the active ingredients atrazine 72%+mesotrion 8% against several types of weeds in sweet corn plantations. The experiment was carried out during 2022 at the Agricultural Training and Development Research Center, Padjadjaran University, Bandung, Indonesia. The treatment consisted of three types of herbicides with six dose levels, there was mixture of atrazine 72%+mesotrion 8%, herbicide atrazine 72% and herbicide mesotrion 8% with four replications. Target weeds included Ageratum conyzoides, Borreria alata, Synedrella nodiflora, Richardia brassiliensis, Eleusine indica, Digitaria ciliaris and Paspalum conjugatum. Data analysis used the percentage of weed damage to determine the effectiveness of each herbicide and linear regression analysis using the Multiplicative Survival Model (MSM) method to determine the LD50 of each herbicide. The results showed that the mixed herbicides atrazine 72%+mesotrion 8% suppressed the growth of the target weeds and had a treatment LD50 of 0.32 l/ha and an expected LD50 of 0.36 l/ha with a co-toxicity value of 1.125 ( greater than 1), so the mixed herbicides were synergistic.

Efficiency of using tank mixtures of fungicides for the control of phytopathogens in potato agrocenoses

Goal. To evaluate the level of effectiveness of phytopathogen control elements in agrocenoses of potatoes for different combinations of pesticides with biologically active substances, methods of application and the reaction of Aria potatoes to them.
 Methods. Field — for monitoring the main diseases of potatoes in field experiments, recording the harvest, determining the effectiveness of combinations of fungicides with plant growth regulators and microfertilizers; laboratory — for recording damage to tubers by diseases. Research was conducted in accordance with generally accepted methods.
 Results. In 2019—2021, the Laboratory of Plant Immunity and Protection of the Institute of Potato Breeding of the National Academy of Sciences conducted research on the improvement of elements of phytopathogen control technology in potato agrocenoses under various schemes of using tank mixtures of fungicides, growth regulating substances (RRS) and microfertilizers. The research used the Aria variety selected by the institute. The lowest level of development of Alternaria was in the version where tuber treatment was carried out (fungicide impregnant + microfertilizer + PPR) and two plant treatments (Kurzat R + microfertilizer + PPR). The development of the disease was 14.7% for the spread of 66.6%, and the technical efficiency of the protection elements was 68.8%. To effectively control the development of common scab, rhizoctoniosis and fusarium dry rot, it is advisable to treat tubers with a tank mixture of impurity-fungicide + PPR + microfertilizer and to treat plants with a mixture of Kurzat P + PPR + microfertilizer, which significantly reduces the level of tuber disease control and limits their spread compared to and chemical standards. The yield of potatoes in the variants was higher than in the control (25.4 t/ha) — 29.8—36.8 t/ha. The level of the preserved harvest compared to the control was in the range of 4.4—11.4 t/ha or 17.3—44.9%. The highest level of yield (36.8 t/ha) was in the variant: treatment of tubers — impregnation-fungicide + micro-fertilizer + PPR and two plant treatments — Cuproxate + micro-fertilizer + PPR. This indicator is 11.4 t/ha (44.9%) higher than the control and 4.7 t/ha (14.6%) higher than the standard.
 Conclusions. The use of tank mixtures of fungicides with a growth regulator and microfertilizer significantly reduces the level of potato diseases and increases the yield. It was established that the use of a mixture of impurity-fungicide + PPR + microfertilizer for treating potato tubers and Kurzat P + microfertilizer + PPR for treating plants significantly reduces the level of common scab, rhizoctoniosis and fusarium dry rot and limits their spread, compared to control and chemical standards.

Dynamics of a Double-Impulsive Control Model of Integrated Pest Management Using Perturbation Methods and Floquet Theory

We formulate an integrated pest management model to control natural pests of the crop through the periodic application of biopesticide and chemical pesticides. In a theoretical analysis of the system pest eradication, a periodic solution is found and established. All the system variables are proved to be bounded. Our main goal is then to ensure that pesticides are optimized, in terms of pesticide concentration and pesticide application frequency, and that the optimum combination of pesticides is found to provide the most benefit to the crop. By using Floquet theory and the small amplitude perturbation method, we prove that the pest eradication periodic solution is locally and globally stable. The acquired results establish a threshold time limit for the impulsive release of various controls as well as some valid theoretical conclusions for effective pest management. Furthermore, after a numerical comparison, we conclude that integrated pest management is more effective than single biological or chemical controls. Finally, we illustrate the analytical results through numerical simulations.

Impacts of co-exposure to zearalenone and trifloxystrobin on the enzymatic activity and gene expression in zebrafish

Although humans and animals are usually exposed to combinations of toxic substances, little is known about the interactive toxicity of mycotoxins and farm chemicals. Therefore, we can not precisely evaluate the health risks of combined exposure. In the present work, using different approaches, we examined the toxic impacts of zearalenone and trifloxystrobin on zebrafish (Danio rerio). Our findings showed that the lethal toxicity of zearalenone to embryonic fish with a 10-day LC50 of 0.59 mg L−1 was lower than trifloxystrobin (0.037 mg L−1). Besides, the mixture of zearalenone and trifloxystrobin triggered acute synergetic toxicity to embryonic fish. Moreover, the contents of CAT, CYP450, and VTG were distinctly altered in most single and combined exposures. Transcriptional levels of 23 genes involved in the oxidative response, apoptosis, immune, and endocrine systems were determined. Our results implied that eight genes (cas9, apaf-1, bcl-2, il-8, trb, vtg1, erβ1, and tg) displayed greater changes when exposed to the mixture of zearalenone and trifloxystrobin compared with the corresponding individual chemicals. Our findings indicated that performing the risk assessment based on the combined impact rather than the individual dosage response of these chemicals was more accurate. Nevertheless, further investigations are still necessary to reveal the modes of action of mycotoxin and pesticide combinations and alleviate their effects on human health.

Mixture effects of thiamethoxam and seven pesticides with different modes of action on honey bees (Aplis mellifera)

Even though honey bees in the field are routinely exposed to a complex mixture of many different agrochemicals, few studies have surveyed toxic effects of pesticide mixtures on bees. To elucidate the interactive actions of pesticides on crop pollinators, we determined the individual and joint toxicities of thiamethoxam (THI) and other seven pesticides [dimethoate (DIM), methomyl (MET), zeta-cypermethrin (ZCY), cyfluthrin (CYF), permethrin (PER), esfenvalerate (ESF) and tetraconazole (TET)] to honey bees (Aplis mellifera) with feeding toxicity test. Results from the 7-days toxicity test implied that THI elicited the highest toxicity with a LC50 data of 0.25 (0.20–0.29) μg mL−1, followed by MET and DIM with LC50 data of 4.19 (3.58–4.88) and 5.30 (4.65–6.03) μg mL−1, respectively. By comparison, pyrethroids and TET possessed relatively low toxicities with their LC50 data from the range of 33.78 (29.12–38.39) to 1125 (922.4–1,442) μg mL−1. Among 98 evaluated THI-containing binary to octonary mixtures, 29.59% of combinations exhibited synergistic effects. In contrast, 18.37% of combinations exhibited antagonistic effects on A. mellifera. Moreover, 54.8% pesticide combinations incorporating THI and TET displayed synergistic toxicities to the insects. Our findings emphasized that the coexistence of several pesticides might induce enhanced toxicity to honey bees. Overall, our results afforded worthful toxicological information on the combined actions of neonicotinoids and current-use pesticides on honey bees, which could accelerate farther comprehend on the possible detriments of other pesticide mixtures in agro-environment.

Are fungicides a driver of European foulbrood disease in honey bee colonies pollinating blueberries?

IntroductionBlueberry producers in Canada depend heavily on pollination services provided by honey bees (Apis mellifera L.). Anecdotal reports indicate an increased incidence of European foulbrood (EFB), a bacterial disease caused by Melissococcus plutonius, is compromising pollination services and colony health. Fungicidal products are commonly used in blueberry production to prevent fungal diseases such as anthracnose and botrytis fruit rot. Pesticide exposure has been implicated in honey bee immunosuppression; however, the effects of commercial fungicidal products, commonly used during blueberry pollination, on honey bee larval susceptibility to EFB have not been investigated.MethodsUsing an in vitro infection model of EFB, we infected first instar honey bee larvae with M. plutonius 2019 BC1, a strain isolated from an EFB outbreak in British Columbia, Canada, and chronically exposed larvae to environmentally relevant concentrations of fungicide products over 6 days. Survival was monitored until pupation or eclosion.ResultsWe found that larvae chronically exposed to one, two, or three fungicidal products [Supra® Captan 80WDG (Captan), low concentration of Kenja™ 400SC (Kenja), Luna® Tranquility (Luna), and/or Switch® 62.5 WG (Switch)], did not significantly reduce survival from EFB relative to infected controls. When larvae were exposed to four fungicide products concurrently, we observed a significant 24.2% decrease in survival from M. plutonius infection (p = 0.0038). Similarly, higher concentrations of Kenja significantly reduced larval survival by 24.7–33.0% from EFB (p < 0.0001).DiscussionThese in vitro results suggest that fungicides may contribute to larval susceptibility and response to M. plutonius infections. Further testing of other pesticide combinations is warranted as well as continued surveillance of pesticide residues in blueberry-pollinating colonies.

Mixture toxicities of tetrachlorantraniliprole and tebuconazole to honey bees (Apis mellifera L.) and the potential mechanism

The extensive use of pesticides has negative effects on the health of insect pollinators. Although pollinators in the field are seldom exposed to individual pesticides, few reports have assessed the toxic impacts of pesticide combinations on them. In this work, we purposed to reveal the combined impacts of tetrachlorantraniliprole (TET) and tebuconazole (TEB) on honey bees (Apis mellifera L.). Our data exhibited that TET had greater toxicity to A. mellifera (96-h LC50 value of 298.2 mg a.i. L-1) than TEB (96-h LC50 value of 1,841 mg a.i. L-1). The mixture of TET and TEB displayed acute synergistic toxicity to the pollinators. Meanwhile, the activities of CarE, CYP450, trypsin, and sucrase, as well as the expressions of five genes (ppo, abaecin, cat, CYP4G11, and CYP6AS14) associated with immune response, oxidative stress, and detoxification metabolism, were conspicuously altered when exposed to the mixture relative to the individual exposures. These results provided an overall comprehension of honey bees upon the challenge of sublethal toxicity between neonicotinoid insecticides and triazole fungicides and could be used to assess the intricate toxic mechanisms in honey bees when exposed to pesticide mixtures. Additionally, these results might guide pesticide regulation strategies to enhance the honey bee populations.

Organophosphate Pesticides and Pyrethroids in Farmland of the Pearl River Delta, China: Regional Residue, Distributions and Risks.

A regional-scale survey was conducted to assess the occurrence, distribution, and risk of two extensively used pesticides (organophosphate pesticides and pyrethroids) in agricultural soils from the Pearl River Delta (PRD), South China. All target organophosphate pesticides (OPPs) and pyrethroids (PYs) were detected in the soil samples and both with a detection rate of 100%. The residues of the sum of six OPPs and the sum of four PYs were in the range of LOD-991 ng/g and 8.76-2810 ng/g, respectively. Dimethoate was the dominant OPPs, and fenpropathrin was the predominant PYs in the soils of the PRD region. With intensive agricultural activities, higher residues of OPPs and PYs in soils were detected closer to the seaside, among which Zhuhai city and Huizhou city suffered more serious combined pesticide pollution. The vertical compositional profiles showed that dimethoate could be detected through each soil layer in the PRD region's nine cities. The human exposure estimation of OPPs showed insignificant risks to the local population. In contrast, cypermethrin and fenpropathrin showed a potential ecological risk of 2.5% and 3.75% of the sampling sites, respectively. These results can facilitate those commonly used pesticide controls and promote sustainable soil management.

Acute pesticide poisoning in the central part of Iran: A 4-year cross-sectional study.

Intoxication with pesticides is a well-known public health problem. We aimed to describe the demographic and toxico-clinical characteristics and outcomes of patients with pesticide poisoning. This retrospective cross-sectional study was performed in Khorshid Hospital affiliated with Isfahan University of Medical Sciences, Isfahan, Iran. All patients with pesticide poisoning (insecticides, herbicides, fungicides, rodenticides, and acaricides) were evaluated. The patients' demographic, toxicological, clinical, and laboratory findings from March 2016 until March 2021 were collected and analyzed. During the study period, 25,659 patients with acute poisoning were admitted, of which, 1567 (6.1% of the total poisoning) with pesticide poisoning were included. The mean ± SD age of the patients was 31.34 ± 13.7 years and 55.3% were men (male/female ratio = 1.23). In approximately 75% of the patients, poisoning occurred by suicidal attempts, while in 14.3% (n = 224), it was accidental. Insecticides caused about 51.30% of the poisonings. However, rodenticides were most commonly used in completed suicide attempts (79.9%). The frequency of previously attempted suicide, and self-harming was different among the patients with respect to the type of pesticide poisoning (p < 0.05). Previous suicidal attempts (35.3%) and self-harming (17.3%) were reported more in patients poisoned with the combination of pesticides. Half of the patients were employed. Nausea and vomiting (56.7%, n = 889) were the most common clinical manifestations; 8.3% (n = 130) of the patients died, 64 of whom had rodenticide poisoning. The prevalence of pesticide poisoning was relatively low; most were insecticide poisoning. Poisoning occurred most through attempted suicide. Rodenticides and herbicides had higher mortality rates than other pesticides. Patients with previously attempted suicide and self-harming behavior may use a combination of pesticides.

Study of the Methylation of Bovine GSTP1 Gene under the Influence of Pesticide Mospilan 20SP Alone and in Combination with Pesticide Orius 25EW.

DNA methylation, one of the most studied epigenetic mechanisms, when present in the promoter region of genes, causes inhibition of gene expression, and conversely, hypomethylation of these regions enables gene expression. DNA methylation is susceptible to nutritional and environmental influences, and undesirable alterations in methylation patterns manifested in changes in the expression of relevant genes can lead to pathological consequences. In the present work, we studied the methylation status of the bovine GSTP1 gene under the influence of pesticide Mospilan 20SP alone and in combination with pesticide Orius 25EW in in vitro proliferating bovine lymphocytes. We employed methylation-specific PCR, and when studying the effect of pesticide combinations, we also used its real-time version followed by a melting procedure. Our results showed that Mospilan 20SP alone at 5, 25, 50, and 100 µg.ml-1 and 5, 10, 25, and 50 µg.ml-1 for the last 4 and 24 hours of culture with in vitro proliferating bovine lymphocytes, respectively, did not induce methylation of the bovine GSTP1 gene. The same results were revealed when studying the effect of the combination of the pesticides added to the lymphocyte cultures for the last 24 hours of cultivation in the following amounts: 1.25, 2.5, 5, 10, and 25 µg.ml-1 of Mospilan 20SP and 1.5, 3, 6, 15, and 30 µg.ml-1 of Orius 25EW. We have also revealed that the less laborious real-time MSP followed by a melting procedure may replace MSP for studying the methylation status of the GSTP1 gene.

Combined Effect of Pesticides Containing Active Ingredients of Chlorpyrifos and Mancozeb on the DNA Damage of Chlorella Sorokiniana Shihira and Krauss

The intensive use of pesticides in agricultural areas can leave residues of pesticide mixtures on the soil surface. Surface run-off can carry pesticide residues, enter water bodies, and then may affect non-target organisms. Chlorpyrifos and mancozeb are active ingredients commonly contained in pesticides applied in shallot farming. This study aims to evaluate the combined effect of pesticides containing active ingredients of chlorpyrifos and mancozeb on the growth and DNA damage of the microalgae Chlorella sorokiniana. The test organism was exposed to the combined concentration of chlorpyrifos:mancozeb, i.e., 0:0, 20%:20%, 20%:80%, 80%:20%, and 80%:80% of the individual EC50 of each pesticide with sampling time at hours 0, 6, 24, and 48. Microalgae growth was estimated by cell counting method, and DNA damage was analyzed by alkaline comet assay method with parameters, i.e., Tail Intensity (TI%), Head Intensity (HI%), Tail Moment (TM), Olive Tail Moment (OTM), and Tail Factor (TF). The results showed that the combined pesticides inhibited the growth of C. sorokiniana, with the highest growth inhibition being at a combined concentration of 80%:80%. The TM and OTM values of C. sorokiniana increased with the increase of combined concentrations at an exposure period of up to 24 hours. In conclusion, the combined exposure could induce growth inhibition and DNA damage of Chlorella sorokiniana, mainly in the first 24 hours. The TM and OTM can be used as sensitive biomarkers for biomonitoring pesticide pollution.

Comparative toxicological and hygienic assessment and combined action of modern fungicides based on azoxystrobin, pydiflumetofen, propiconazole

Annotation. The creation of combined pesticide formulations for the purpose of more effective protection of agricultural crops is a significant factor in the importance of assessing their synergistic effects. Substances that produce a similar pesticidal effect, in combination with each other, can enhance the toxic effect and, therefore, show dose additivity. The aim is toxicological and hygienic evaluation and determination of the type of combined action of pydiflumetofen, azoxystrobin and propiconazole – the active substances of the mixed formulations “Miravis Ace 275 SE” and “Miravis Neo 300 SE” according to toxicity indicators. Analytical review of scientific publications was carried out using data from EFSA, FAO, ECHA, PPDB, Internet sites. According to the literature, a comparative toxicological-hygienic evaluation of fungicidal preparations and their active substances was carried out. The general mechanism of fungicidal action was evaluated according to the classification developed by the Fungicide Resistance Action Committee (FRAC). The hazard class according to the toxic metric parameters of the substances under study was determined in accordance with the Hygienic classification of pesticides according to the degree of hazard (DSanPiN 8.8.1.002-98). The nature and type of combined action was carried out according to the Finney method with evaluation according to the criteria of acute toxicity. Systematization of data, their structuring for the purpose of further toxicological assessment of substances at the level of their inactive and threshold doses was carried out in the table editor Microsoft Excel 2019 (Microsoft Office 2019, Microsoft). As a result of the conducted research, the most toxic mixed fungicide “Miravis Neo 300 SE” based on three active substances was determined (the average lethal dose (LD50) is 550 mg/kg). It has been established that in cases of combinations of active substances to obtain a lethal effect, a dose of substances that does not exceed 100% in total is required, which indicates the strengthening (potentiation) of toxicity. It was pointed out that the share of propiconazole in the potentiation of the toxic effect in both mixed preparations is the highest compared to other active substances and is 0.87 for “Miravis Neo 300 SE” and 0.88 for “Miravis Ace 275 SE”. It was observed that the adverse effects of simultaneous exposure to several pesticides may change during the transition from acute to chronic exposure. Therefore, it is important to continue the research of the active substances of pesticides with the determination of limiting criteria for harmfulness, taking into account the remote effects of exposure. Thus, the toxicological and hygienic assessment made it possible to establish that the combined fungicides “Miravis Neo 300 SE” and “Miravis Ace 275 SE” are more toxic in the mode of single oral exposure in comparison with the single-component fungicide “Miravis 200 SC”. Increased toxicity (potentiation) can be considered as a consequence of the simultaneous exposure of several active substances. The active substance propiconazole poses the main danger of adverse effects on the body at the level of lethal doses. The obtained values of the potentiation coefficients will be taken into account in further studies of the risk assessment of complex and combined effects of pesticides on workers and their potential danger when entering the human body with food products.

Atmospheric degradation of two pesticides mixed with volatile organic compounds emitted by citrus trees. Ozone and secondary organic aerosol production

Once pesticides are released into the environment, their active ingredient and other formulation compounds, such as coadjuvants or solvents, may undergo biological and chemical degradation, and form a range of products that could be even more hazardous than their precursors. These degradation products may also interact with the natural biogenic compounds emitted by treated crops, which leads to secondary air pollutants, such as ozone (O3) or fine particulate matter, which directly affect human health and climate warming. This research provides evidence for the atmospheric process influencing the atmospheric and environmental fate of pesticides, active substance chloropicrin and commercially formulated chlorpyriphos, which interact with biogenic volatile organic compounds (α-pinene and a mixture of monoterpenes) simulating mixtures of terpenes emitted by orange trees at the large outdoor European PHOto-REactor (EUPHORE). Significant SOA formations were observed during the photolysis and/or ozonolysis of both pesticides in the presence of biogenic volatile organic compounds. For the photolysis of chloropicrin in the presence of α-pinene, the aerosol and O3 formation yields ranged from 6 to 16% and 167–338%, respectively, depending on the initial conditions. For the photolysis of commercial chlorpyrifos in the presence of a mixture of terpenes, the formed aerosol yield was 24%, higher than those obtained by the photolysis of the terpenes in the absence of pesticides. Both pesticides in combination with terpenes increased O3 formation. O3 reacted with those terpenes, which increased particulate matter formation and may pose atmospheric issues on local and global scales.

Enhanced removal of trace pesticides and alleviation of membrane fouling using hydrophobic-modified inorganic-organic hybrid flocculants in the flocculation-sedimentation-ultrafiltration process for surface water treatment

Pesticide concentrations in surface water occasionally exceed regulated values due to seasonal events (rainy season in high intensity agricultural areas) or intermittent discharges (leakage, spillage, or other emergency events). The need to remove pesticide compounds in these situations poses a challenge for drinking water treatment plants (DWTPs). In this work, the performance of dosing hydrophobic-modified inorganic-organic hybrid flocculants (HOC-M; lower acute toxicity than corresponding metal salt coagulants; acceptable economic costs when M=Al or Fe; prepared in large-scale quantities), for the removal of four different pesticides (each initial concentration: 0.25 μg/L) from Yangtze River water, and in mitigating membrane fouling, by an integrated flocculation-sedimentation-ultrafiltration (FSUF) process, was evaluated over a period of 40 days; the FSUF is well-established in many DWTPs. The mechanisms underlying the treatment were unveiled by employing a combination of instrumental characterizations, chemical computations, material flow analyses, and statistical analyses. Efficient pesticide removal (80.3%∼94.3%) and membrane fouling reduction (26.6%∼37.3% and 28.3%∼57.6% for reversible and irreversible membrane resistance, respectively) in the FSUF process were achieved by dosing HOC-M, whereas conventional inorganic coagulants were substantially inferior for pesticide removal (< 50%) and displayed more severe fouling development. Hydrophobic association between the pesticides and the hydrophobic organic chain of HOC-M played a predominant role in the improvement in pesticide removal; coexisting particulate/colloid inorganic minerals and natural organic matter with HOC-M adsorbed on the surface, acting as floc building materials, provided sites for the indirect combination of pesticides into flocs. The observed fouling alleviation from dosing HOC-M was ascribed to both the pre-removal of fouling-causing materials in the flocculation-sedimentation prior to UF, and a stable hydrophilization modification effect of residual HOC-M in the UF unit. The latter effect resulted from a hydrophobic association between the PVDF substrate of the membranes and the hydrophobic organic chains of the HOC-M, causing the hydrophilic ends of the HOC-M to be exposed away from the membrane surface, thereby inhibiting foulant accumulation. This work has not only demonstrated the superior performance of dosing HOC-M in the FSUF process for trace pesticide removal in DWTPs, but also clarified the underlying mechanisms.

Sociality is a key driver of foraging ranges in bees

Bees are important pollinators of wild and agricultural plants1,2,3,4,5 and there is increasing evidence that many bee populations decline due to a combination of habitat loss, climate change, pesticides, and other anthropogenic effects.6,7,8,9,10,11 One trait that shapes both their role in plant reproduction12,13 and their exposure to anthropogenic stressors is the distance at which bees forage. It has been suggested that bee sociality14 and diet15 affect bee foraging ranges, but how these traits and their potential interactions drive foraging ranges remains unclear. We analyzed flight distance data from 90 bee species and developed an agent-based model to test how social, dietary, and environmental factors affect foraging ranges. We confirm that bee sociality is positively associated with foraging range, with average-sized social bees foraging up to 3 times farther from the nest than size-matched solitary bees. A comparative analysis of social bees and computer simulations shows that foraging distances increase with colony size, supporting the hypothesis that greater foraging distances are an emergent property of increasing colony sizes in a food-limited environment. Flower constancy and communication, two traits often found in social bees, synergistically increase foraging distances further in many simulated environments. Diet breadth (oligolectic versus polylectic diet), on the other hand, does not appear to affect foraging ranges in solitary bees. Our findings suggest that multiple traits linked to bee sociality explain why social bees have greater foraging ranges. This has implications for predicting pollination services and for developing effective conservation strategies for bees and isolated plant populations.15,16,17,18,19.

Biochemical responses, feeding and survival in the solitary bee Osmia bicornis following exposure to an insecticide and a fungicide alone and in combination

In agricultural ecosystems, bees are exposed to combinations of pesticides that may have been applied at different times. For example, bees visiting a flowering crop may be chronically exposed to low concentrations of systemic insecticides applied before bloom and then to a pulse of fungicide, considered safe for bees, applied during bloom. In this study, we simulate this scenario under laboratory conditions with females of the solitary bee, Osmia bicornis L. We studied the effects of chronic exposure to the neonicotinoid insecticide, Confidor® (imidacloprid) at a realistic concentration, and of a pulse (1 day) exposure of the fungicide Folicur® SE (tebuconazole) at field application rate. Syrup consumption, survival, and four biomarkers: acetylcholinesterase (AChE), carboxylesterase (CaE), glutathione S-transferase (GST), and alkaline phosphatase (ALP) were evaluated at two different time points. An integrated biological response (IBRv2) index was elaborated with the biomarker results. The fungicide pulse had no impact on survival but temporarily reduced syrup consumption and increased the IBRv2 index, indicating potential molecular alterations. The neonicotinoid significantly reduced syrup consumption, survival, and the neurological activity of the enzymes. The co-exposure neonicotinoid-fungicide did not increase toxicity at the tested concentrations. AChE proved to be an efficient biomarker for the detection of early effects for both the insecticide and the fungicide. Our results highlight the importance of assessing individual and sub-individual endpoints to better understand pesticide effects on bees.

Effect of flight velocity on droplet deposition and drift of combined pesticides sprayed using an unmanned aerial vehicle sprayer in a peach orchard

Extensive research has been conducted on plant protection unmanned aerial vehicle (UAV) chemical application technology in recent years owing to its importance as a means of pest and disease control. UAV spraying in orchards faces the drawback of drift risk and can be hazardous to non-targeted crops, humans, and the environment. A detailed and systematic analysis must be performed to determine the uniformity and drift risk of plant UAV sprays. In this study, a peach orchard is sprayed with a plant-protection UAV at three different flight velocities and we evaluate the combined pesticide deposition performance of the canopy, ground loss, downwind ground drift, and airborne drift. Additionally, the droplet size and coverage rate in the canopy are calculated by using water-sensitive paper. The results demonstrate that there is significant difference in the droplet size at flight velocities of 1–3 m/s. The droplet size in the lower canopy is slightly smaller than those in the middle and upper parts. Increasing the flight velocity helps the pesticide droplets to spread and penetrate the canopy. However, it also causes a non-uniform pesticide deposition, reduced effective coverage ratio and effective density ratio. Among the three pesticides used in the experiment, imidacloprid exhibits the best deposition efficiency. The deposition amount and normalized deposition amount in the canopy were the highest at a flight velocity of 2 m/s, accompanied by a lower ground loss under the canopy. The highest near-field ground drift is observed at a velocity of 1 m/s, and the far-field airborne drift is highest at 3 m/s. Lastly, this study provides a reference for the commercial application of plant-protection UAVs.

Distribution of pesticide residues in agricultural topsoil of the Huangshui catchment, Qinghai Tibet Plateau.

This study presents monitoring data on the spatial distribution and occurrence of pesticide residues of cultivated soil in the Huangshui catchment in the northeastern part of the Qinghai Tibet Plateau. We also provide factors that influence the distribution of pesticides, such as the properties of pesticides and soil and crop types. A total of 110 soil samples were collected in early April 2021, and 49 pesticides were analyzed. Only 3.6% of the samples contained no pesticide residues (concentrations < limit of quantitation or not detected [ND]), and the total pesticide concentration ranged from ND to 0.925mg/kg. Most commonly, two to five pesticides were found in the soil samples (> 70.9%), and up to 10 pesticide residues were present in some samples. A total of 85 different pesticide combinations were observed in all the soil samples. Chlorpyrifos and difenoconazole were the dominant compounds. The levels of pesticide residues were mainly driven by their half-life values. Bulk density, along with soil water content and pH, also affected the retention of pesticides in the soil. The crop type played no role in the distribution of pesticides.

Investigating the effect of solids retention time on pesticides removal in an activated sludge process

The levels of pesticides reaching the biological wastewater treatment plants have been increasing. Operational conditions leading to the most efficient removal of pesticides in these plants should be evaluated first before attempting tertiary-level treatment options. This study investigated the influence of solids retention times (SRTs) on the removal of three pesticides (carbendazim, imidacloprid, and aclonifen) in the activated sludge process. Laboratory-scale reactors receiving these pesticides (0–400 μg/L) were operated at five different SRTs (3, 8, 10, 20, and 30 d). When the pesticides were present individually, all of the reactors were capable of removing carbendazim up to 25 μg/L, imidacloprid, and aclonifen up to 10 μg/L, by almost 100%, regardless of SRT. When the pesticides were present in combination, higher pesticide removals were generally attained, although there was no clear correlation between SRT and removal efficiency. Aclonifen being the least soluble one was removed more efficiently, either individually or in a mixture, when the SRT was set to 3 or 30 d. The COD removal efficiency was not impaired at all until 50, 10, and 10 μg/L of individual carbendazim, imidacloprid, and aclonifen levels, respectively, at all SRTs. When the pesticides were present in combination, each 50 μg/L, there were no adverse effects on COD removal, provided that SRT is 30 d. The competitive inhibition of COD removal was evident. The obtained results demonstrated that the activated sludge process receiving pesticides in combination could be operated with better pesticide and COD removal performances if SRT is closely controlled.