RESUMO

BACKGROUND: The application of synthetic insecticides is the main strategy used to reduce the damage caused by the diamondback moth Plutella xylostella in commercial Brassica crops. However, incorrect insecticide use can cause biological and ecological disturbances in agroecosystems. Cycloneda sanguinea is a generalist voracious predator and is distributed widely in cultivated and noncultivated ecosystems. This study investigated the efficiency of four insecticides for the control of P. xylostella and the lethal and sublethal effects of these insecticides on C. sanguinea. RESULTS: Spinosad (92% mortality) and chlorfenapyr (76% mortality) were highly toxic to P. xylostela. However, chlorantraniliprole (10% mortality) and methomyl (no mortality) were ineffective against this pest. Chlorantraniliprole was the only insecticide that was highly toxic to C. sanguinea by contact (90% mortality), however, it was nontoxic following the ingestion of chlorantraniliprole-contaminated aphids. Interestingly, ingestion of prey contaminated with methomyl and chlorfenapyr was highly toxic (100% mortality) to C. sanguinea. Spinosad was nontoxic to C. sanguinea via exposure to contaminated surfaces and following ingestion of contaminated prey. However, direct contact of the insects with both methomyl and spinosad significantly affected C. sanguinea flight activity (vertical flight and free-fall flight), whereas chlorfenapyr impacted vertical flight only. CONCLUSION: These findings showed that chlorantraniliprole was not only ineffective for the control of P. xylostela, but was also highly toxic to C. sanguinea. The results indicated that spinosad was efficient against P. xylostela and was of low toxicity to C. sanguinea; however, the deleterious effects of this insecticide on flight behavior could result in reduced predatory efficiency. © 2022 Society of Chemical Industry.

Assuntos

RESUMO

In recent years, the official authorities in Chile have reported transgressions in the maximum residue levels of pesticides in fresh vegetables. There is no official information about traceability, pesticide levels, and potential health risks. The aim of this study was to analyse pesticide residues and their corresponding dietary risk assessments in tomatoes from supermarkets in the Metropolitan Region. Pesticides were extracted using the Quick, Easy, Cheap, Effective, Rugged and Safe, QuEChERS method, and their concentrations were determined by using chromatography with HPLC-FL/UV and GC-MS/ECD/NPD, following the Analytical Quality Control and Method Validation Procedures for Pesticides Residues Analysis in Food and Feed, SANTE guide and ISO 17025:2017 standard. In addition, a dietary risk assessment was carried out by comparing Chilean data to international references. The results reported that 9% of the samples had pesticide residue levels above the maximum residue levels permitted in Chile. All the scenarios evaluated revealed the highest estimated daily intake and hazard quotients for methamidophos and chlorpyrifos. Both the active substances used were acetylcholinesterase inhibitors and were neurotoxic under chronic risk assessment. The results showed the highest chronic hazard index in the Chilean scenario for all age groups and genders. The evidence obtained revealed that methamidophos, methomyl, and chlorpyrifos should be restricted for their use in Chilean agriculture.

RESUMO

Over the last years, the detection of pesticide residues in the official food surveillance programs of Chile has been increased, mainly in fresh vegetables such as tomatoes and lettuces. The Metropolitana Region of Chile presents the highest detections in the country. The lack of evaluations of toxicological risks in human health have increased uncertainty of the potential effects of pesticides exposures in the Chilean population. This research aims to determinate health risks assessment of pesticide residues associated to tomatoes and lettuces produced in Metropolitana Region. The findings of this study reveal that tomatoes and lettuces cultivated in the MR show more than 50% of samples with one or multiple pesticides residues. From the total samples, 16% were over the Chilean Maximum Residue Levels (MRLs). The main pesticides detected in tomatoes and lettuces were methamidophos, methomyl, difenoconazole, cyprodinil and boscalid. The results obtained using the official data of the Ministry of Health of Chile (MINSAL) compared to the World Health Organization (WHO), describe relevant risks through the Estimated Daily Intakes (EDI), Hazard Quotients (HQ) and Hazard Index (HI) for the Chilean population due to high concentrations of methamidophos, methomyl and cyprodinil. More restrictions for the use of methamidophos, methomyl, difenoconazole, cyprodinil and boscalid and effective control programs should be implemented in order to mitigate the impacts on the Chilean population.

Assuntos

RESUMO

Granular activated carbon (GAC) fixed bed adsorption technology was applied to remove carbamates carbaryl, methomyl and carbofuran from public water supply. In order to minimize the effect of clogging and to evaluate adsorbent saturation for carbamates, the microfiltration (MF) was previously used to adsorb and the backwash procedure of the GAC bed was carried out. The determination and quantification of the carbamates were performed by analytical technique in high performance liquid chromatography with post-column derivatization and fluorescence detector. The MF of the water previously adsorbed in the GAC fixed bed allowed the greater removal of 100% of the carbamates pesticides with an initial concentration of 25 µg L-1 during the first 48 h of operation. The saturation of the GAC fixed bed occurred in 240 h, due to the partial removal of the natural organic matter by the MF, consequently the competition for adsorptive sites of the GAC was smaller. The backwashing procedure contributed to the partial recovery of the performance of the hydraulic filtration and allowed to identify the saturation of the adsorption column, since the sealing phenomenon preceded the saturation. Finally, the use of public water supply was considered a relevant and positive aspect, since it allowed the identification of the performance of this technology in the removal of carbamates pesticides considering the presence of substances inherent to the public water supply.

Assuntos

RESUMO

The application of a fixed bed adsorption column of granular activated carbon (FBAC-GAC), in the removal of carbaryl, methomyl and carbofuran at a concentration of 25 µg L-1 for each carbamate, from the public water supply was investigated. For the determination of the presence of pesticides in the water supply, the analytical technique of high-performance liquid chromatography with post-column derivatization was used. Under conditions of constant diffusivity, the FBAC-GAC was saturated after 196 h of operation on a pilot scale. The exhaust rate of the granular activated carbon (GAC) in the FBAC-GAC until the point of saturation was 0.02 kg GAC m-3 of treated water. By comparing a rapid small-scale column test and FBAC-GAC, it was confirmed that the predominant intraparticle diffusivity in the adsorption column was constant diffusivity. Based on the results obtained on a pilot scale, it was possible to estimate the values to be applied in the FBAC-GAC (full scale) to remove the pesticides, which are particle size with an average diameter of 1.5 mm GAC; relationship between the internal diameter of the column and the average diameter of GAC ≥50 in order to avoid preferential flow near the adsorption column wall; surface application rate 240 m3 m-2 d-1 and an empty bed contact time of 3 min. ABBREVIATIONS: BV: bed volume; CD: constant diffusivity; EBCT: empty bed contact time; FBAC-GAC: fixed bed adsorption column of granular activated carbon; GAC: granular activated carbon; MPV: maximum permitted values; NOM: natural organic matter; PD: proportional diffusivity; pHPCZ: pH of the zero charge point; SAR: surface application rate; RSSCT: rapid small-scale column test; WTCS: water treated conventional system.

Assuntos

RESUMO

The polished silver solid amalgam electrode (p-AgSAE) combined with square wave voltammetry (SWV) was used in the development of an analytical procedure to Methomyl determination in natural water samples. The experimental and voltammetric parameters were optimized and the use of cationic surfactant cetyltrimethyl ammonium bromide promoted a considerable change in the kinetic and mechanism of the Methomyl reaction. Was observed the presence one-single reduction peak, related to a totally irreversible two-electrons transfer, followed by chemical reaction involving two protons. Analytical parameters (linearity range, analytical curve equations, correlation coefficient, detection and quantification limits, recovery efficiency, and relative standard deviation for intraday and interday experiments) were evaluated indicating that the proposed voltammetric procedure is suitable for determination of Methomyl. The application of the proposed procedure in natural water analysis indicated high robustness with only simple filtration, without pre-concentration steps, good stability and suitable sensitivity to determination of Methomyl in natural water samples.

RESUMO

The use of microorganisms in the degradation and detoxification of many toxic xenobiotics, especially pesticides, is an efficient tool for the decontamination of polluted sites in the environment. A novel bacterial strain (M1) was isolated from several water samples contaminated with methomyl which is capable of degrading methomyl pesticide (1000 ppm) in the presence of 0.05 percent glucose. These water samples were collected from different irrigation sites in Egypt where methomyl is heavily applied. The partial sequence of 16SrRNA gene of the isolate showed the highest similarity to Stenotrophomonas maltophilia. Restriction fragment patterns of isolated plasmid DNA showed that this strain harbours two different plasmids PMa (8Kb) and PMb (5Kb). PMb succeeded to be transferred to Escherichia coli DH5á strain. This transformed strain (M2) acquired the ability to grow in the presence of methomyl (1000 ppm) and 0.05 percent glucose. So it was deduced that the gene responsible for the degradation process was encoded by this plasmid. The ability of the two strains M1 and M2 to degrade methomyl was detected by using solid phased extraction coupled to capillary liquid chromatography-electrospray ionization-mass spectrometry (SPE-LC-ESI-MS).

Assuntos

RESUMO

Spot Blotch is a plant disease which causes yield losses in oat and other cereals. Selection for resistant genotypes using Helminthosporium sativum toxic filtrates is an efficient technique, which reduces the pathogen variability and the influence of the environment over the genotype expression. The filtrates extraction is time consuming and a difficult process, and the possibility of using a synthetic product to simulate its action of inhibiting the cell electron transport chain would be useful. The Methomyl insecticide is an efficient product to simulate the effects of the fungus that causes spot blotch in corn. The objective of this study was to check its efficiency in oat. Oat roots and callus growth were evaluated in the insecticide presence. Growth values that were less inhibited by the insecticide were used to correlate with spot blotch resistance. The results indicate that Methomyl reduces the growth of oat root and calli and may be used to differentiate genotypes more and less resistant to Spot Blotch. Therefore, UFRGS 14, which was the most affected genotype in the presence of the fungus toxic filtrates, had also the most reduced root and calli growth in the presence of Methomyl.

A helmintosporiose é uma moléstia que afeta a cultura da aveia, reduzindo seu rendimento e qualidade de grão. A seleção de genótipos resistentes com utilização de filtrados tóxicos do fungo Helminthosporium sativum é eficaz, pois delimita a variabilidade do patógeno e reduz a interferência do ambiente na expressão do genótipo. Contudo, a obtenção dos filtrados tóxicos deste fungo é um processo lento e delicado. Dessa forma, a possibilidade do uso de substâncias sintéticas que simulem seu efeito, inibindo o transporte de elétrons da cadeia respiratória, é de grande interesse. O inseticida Methomyl é eficaz para simular o efeito da toxina do fungo que causa a helmintosporiose em milho, tendo o presente trabalho visado testar sua eficiência na cultura da aveia. Para isso, foi avaliado o crescimento de calos e raízes de aveia expostas ao Methomyl, quando crescimentos maiores indicaram maior resistência ao produto, e possível resistência à moléstia. Os resultados indicam que o Methomyl afeta o crescimento de raízes e calos de aveia e pode ser utilizado para separar os grupos de genótipos com e sem resistência à helmintosporiose. Assim, UFRGS 14, com maior sensibilidade aos filtrados tóxicos de H. sativum em outros estudos, também apresentou crescimento mais afetado pelo Methomyl em todos os experimentos aqui conduzidos.

RESUMO

Spot Blotch is a plant disease which causes yield losses in oat and other cereals. Selection for resistant genotypes using Helminthosporium sativum toxic filtrates is an efficient technique, which reduces the pathogen variability and the influence of the environment over the genotype expression. The filtrates extraction is time consuming and a difficult process, and the possibility of using a synthetic product to simulate its action of inhibiting the cell electron transport chain would be useful. The Methomyl insecticide is an efficient product to simulate the effects of the fungus that causes spot blotch in corn. The objective of this study was to check its efficiency in oat. Oat roots and callus growth were evaluated in the insecticide presence. Growth values that were less inhibited by the insecticide were used to correlate with spot blotch resistance. The results indicate that Methomyl reduces the growth of oat root and calli and may be used to differentiate genotypes more and less resistant to Spot Blotch. Therefore, UFRGS 14, which was the most affected genotype in the presence of the fungus toxic filtrates, had also the most reduced root and calli growth in the presence of Methomyl.

A helmintosporiose é uma moléstia que afeta a cultura da aveia, reduzindo seu rendimento e qualidade de grão. A seleção de genótipos resistentes com utilização de filtrados tóxicos do fungo Helminthosporium sativum é eficaz, pois delimita a variabilidade do patógeno e reduz a interferência do ambiente na expressão do genótipo. Contudo, a obtenção dos filtrados tóxicos deste fungo é um processo lento e delicado. Dessa forma, a possibilidade do uso de substâncias sintéticas que simulem seu efeito, inibindo o transporte de elétrons da cadeia respiratória, é de grande interesse. O inseticida Methomyl é eficaz para simular o efeito da toxina do fungo que causa a helmintosporiose em milho, tendo o presente trabalho visado testar sua eficiência na cultura da aveia. Para isso, foi avaliado o crescimento de calos e raízes de aveia expostas ao Methomyl, quando crescimentos maiores indicaram maior resistência ao produto, e possível resistência à moléstia. Os resultados indicam que o Methomyl afeta o crescimento de raízes e calos de aveia e pode ser utilizado para separar os grupos de genótipos com e sem resistência à helmintosporiose. Assim, UFRGS 14, com maior sensibilidade aos filtrados tóxicos de H. sativum em outros estudos, também apresentou crescimento mais afetado pelo Methomyl em todos os experimentos aqui conduzidos.