Potential of Streptomyces avermitilis: A Review on Avermectin Production and Its Biocidal Effect.

Secondary metabolites produced by the fermentation of Streptomyces avermitilis bacterium are powerful antiparasitic agents used in animal health, agriculture and human infection treatments. Avermectin is a macrocyclic lactone with four structural components (A1, A2, B1, B2), each of them containing a major and a minor subcomponent, out of which avermectin B1a is the most effective parasitic control compound. Avermectin B1a produces two homologue avermectins (B1 and B2) that have been used in agriculture as pesticides and antiparasitic agents, since 1985. It has a great affinity with the Cl-channels of the glutamate receptor, allowing the constant flow of Cl- ions into the nerve cells, causing a phenomenon of hyperpolarization causing death by flaccid paralysis. The purpose of this work was to gather information on the production of avermectins and their biocidal effects, with special emphasis on their role in the control of pests and phytopathogenic diseases. The literature showed that S. avermitilis is an important producer of macrocyclic lactones with biocidal properties. In addition, avermectin contributes to the control of ectoparasites and endoparasites in human health care, veterinary medicine and agriculture. Importantly, avermectin is a compound that is harmless to the host (no side effects), non-target organisms and the environment.

Phytotoxicity of Extracts of Argemone mexicana and Crotalaria longirostrata on Tomato Seedling Physiology.

Phytotoxicity caused by secondary metabolites of botanical extracts is a drawback in agriculture. The objective of this study was to evaluate the phytotoxic effects of methanolic extracts of Crotalaria longirostrata and Argemone mexicana on the germination and physiological variables of tomato seedlings. The results indicated that high doses of both extracts (Clong500 and Amex500) inhibited tomato seed germination, while their mixture (Cl50 + Am50) promoted germination by 100%. At 30 days after transplanting (dat), the plant height increased by 15.4% with a high dose of C. longirostrata (Clong500) compared to the control. At 30 dat, the vigor index displayed a notable increase with Cl50 + Am50, reaching 29.5%. The root length increased with the mean dose of A. mexicana (Amex95) at 10, 20, and 30 dat (59.7%, 15.1%, and 22.4%, respectively). The chlorophyll content increased with Amex95 by 66.1% in 10 dat, 22.6% at 20 dat, and 19.6% at 30 dat. On the other hand, Amex95 had a higher nitrogen content throughout the trial. Amex95 produced the greatest increase in root dry weight by 731.5% and 209.4% at 10 and 20 dat. The foliage dry weight increased by 85.7% at 10 dat with Amex95 and up to 209.7% with Amex50 at 30 dat. The present investigation reveals the ability of the extracts to stimulate tomato growth at low and medium doses, though at high doses they exhibit allelopathic effects.

Residuos de glifosato en cereales de desayuno de origen internacional y nacional comercializados en Saltillo, Coahuila / Glyphosate residues in breakfast cereals of national and international origin marketed in Saltillo, Coahuila

Resumen Objetivo: Detectar y cuantificar residuos de glifosato en cereales de desayuno comercializados en la ciudad de Saltillo, Coahuila. Materiales y Métodos: Se analizaron tres muestras de 12 marcas de cereal distintas. Para la extracción de plaguicidas se utilizó un equipo Soxhlet y la cuantificación se realizó por medio de Cromatografía Líquida de Alta Eficiencia (HPLC), utilizando un equipo marca Agillent modelo 1100 Series acoplado a un detector UV-Vis. Resultados: Se detectó glifosato en el 100% de las muestras analizadas, se obtuvieron concentraciones de entre 170 a 2 400 mg/kg, las muestras que presentaron mayores concentraciones fueron las de marcas internacionales. Conclusiones: Se detectaron residuos de glifosato en las 24 muestras analizadas de cereales de desayuno, las cuales sobrepasaron los LMR establecidos en el CODEX ALIMENTARIUS, por lo que es importante realizar más estudios con el fin de monitorear y asegurar la inocuidad de los productos procesados que son consumidos.

Abstract Objective: To detect and quantify glyphosate residues in breakfast cereals marketed in the city of Saltillo, Coahuila. Materials and Methods: Two samples of 12 different cereal brands were analyzed. A Soxhlet apparatus was used for pesticide extraction and quantification was performed by High Performance Liquid Chromatography (HPLC) using an Agillent model 1100 Series equipment coupled to a UV- Vis detector. Results: Glyphosate was detected in 100% of the samples analyzed, with concentrations ranging from 170 to 2 400 mg/kg; the samples with the highest concentrations were those of international brands. Conclusions: All the concentrations detected in the commercial cereal samples exceeded the MRLs established in CODEX ALIMENTARIUS, so it is important to carry out more studies in order to monitor and ensure the safety of the processed products that are consumed.

Determinación de plaguicidas organofosforados a trabajadores de control de plagas del estado de Coahuila, México / Determination of organophosphate pesticides to pest control workers of the state of Coahuila, México / Determinação de pesticidas organofosforados para trabalhadores de controle de pragas no estado de Coahuila, México / Détermination des pesticides organophosphorés chez les travailleurs chargés de la lutte antiparasitaire dans lÉtat de Coahuila, Mexique

Resumen Objetivo Determinar el nivel de plaguicidas organofosforados en muestras de orina, con la finalidad de proponer el uso adecuado de medidas de seguridad para reducir riesgos laborales provocados por la constante exposición a estos productos. Materiales y métodos Se realizó una técnica colorimétrica para la determinación de cuatro plaguicidas organofosforados: metamidofos, malatión, clorpirifos y naled, en muestras de orina recolectadas en el estado de Coahuila. Se utilizó un espectrofotómetro ultravioleta visible para su análisis. Resultados Los datos obtenidos en esta investigación mostraron que los cuatro productos analizados se encontraron presentes en las muestras de orina, en un rango de concentraciones de 11.4 a 654.15 μl/ml. Conclusiones Se obtuvieron resultados positivos en las dieciséis muestras de orina, encontrándose presencia de los cuatro plaguicidas organofosforados estudiados, lo que podría indicar una falta de uso de medidas de seguridad en los trabajadores.

Abstract Object To determine the level of organophosphorus pesticides in urine samples, in order to propose the appropriate use of safety measures to reduce occupational hazards caused by constant exposure to these products. Materials and methods A colorimetric technique was used to determine four organophosphorus pesticides: methamidophos, malathion, chlorpyrifos and naled, in urine samples collected in the state of Coahuila. A visible ultraviolet spectrophotometer was used for analysis. Results The data obtained in this investigation showed that the four products analyzed were present in the urine samples, in a concentration range of 11.4 to 654.15 μl / ml. Conclusions Positive results were obtained in the sixteen urine samples, finding presence of the four organophosphorus pesticides studied, which could indicate a lack of use of safety measures in workers.

Resumo Objetivo Determinar o nível de pesticidas organofosforados nas amostras de urina, a fim de propor o uso adequado de medidas de segurança para reduzir os riscos ocupacionais causados pela exposição constante a esses produtos. Materiais e métodos Foi realizada uma técnica colorimétrica para a determinação de quatro pesticidas organofosforados: metamidofós, malatião, clorpirifós e naled, em amostras de urina coletadas no estado de Coahuila. Um espectrofotômetro ultravioleta visível foi utilizado para sua análise. Resultados Os dados obtidos nesta investigação mostraram que os quatro produtos analisados estavam presentes nas amostras de urina, na faixa de concentração de 11,4 a 654,15 μl / ml. Conclusões Resultados positivos foram obtidos nas dezesseis amostras de urina, encontrando a presença dos quatro pesticidas organofosforados estudados, o que pode indicar falta de uso de medidas de segurança nos trabalhadores.

Résumé Objectif Déterminer le niveau de pesticides organophosphorés dans des échantillons d'urine, afin de proposer l'utilisation appropriée de mesures de sécurité pour réduire les risques professionnels causés par une exposition constante à ces produits. Matériels et méthodes Une technique colorimétrique a été utilisée pour déterminer quatre pesticides organophosphorés- méthamidophos, malathion, chlorpyrifos et naled - dans des échantillons d'urine prélevés dans l'État de Coahuila. Un spectrophotomètre à ultraviolet visible a été utilisé pour l'analyse. Résultats Les données obtenues dans cette recherche ont montré que les quatre produits analysés étaient présents dans les échantillons d'urine, dans une fourchette de concentration de 11,4 à 654,15 μl/ml. Conclusions Des résultats positifs ont été obtenus dans les seize échantillons d'urine, révélant la présence des quatre pesticides organophosphorés étudiés, ce qui pourrait indiquer un manque d'utilisation de mesures de sécurité chez les travailleurs.

[Fusarium species associated with basal rot of garlic in North Central Mexico and its pathogenicity]. / Patogenicidad de especies de Fusarium asociadas a la pudrición basal del ajo en el centro norte de México.

Garlic in Mexico is one of the most profitable vegetable crops, grown in almost 5,451ha; out of which more than 83% are located in Zacatecas, Guanajuato, Sonora, Puebla, Baja California and Aguascalientes. Blossom-end rot caused by Fusarium spp is widely distributed worldwide and has been a limiting factor in onion and garlic production regions, not only in Mexico but also in other countries. The presence of Fusarium oxysporum has been reported in Guanajuato and Aguascalientes. Fusarium culmorum has been reported in onion cultivars of Morelos; and Fusarium proliferatum, Fusarium verticillioides, Fusarium solani and Fusarium acuminatum have been previously reported in Aguascalientes. The goal of this work was identifying the Fusarium species found in Zacatecas, Guanajuato and Aguascalientes, to assess their pathogenicity. Plants with disease symptoms were collected from hereinabove mentioned States. The samples resulted in the identification of: F. oxysporum, F. proliferatum, F. verticillioides, F. solani and F. acuminatum species; out of which Aguascalientes AGS1A (F. oxysporum), AGS1B (F. oxysporum) and AGSY-10 (F. acuminatum) strains showed higher severity under greenhouse conditions.

A review of techniques for detecting Huanglongbing (greening) in citrus.

Huanglongbing (HLB) is the most destructive disease of citrus worldwide. Monitoring of health and detection of diseases in trees is critical for sustainable agriculture. HLB symptoms are virtually the same wherever the disease occurs. The disease is caused by Candidatus Liberibacter spp., vectored by the psyllids Diaphorina citri Kuwayama and Trioza erytreae. Electron microscopy was the first technique used for HLB detection. Nowadays, scientists are working on the development of new techniques for a rapid HLB detection, as there is no sensor commercially accessible for real-time assessment of health conditions in trees. Currently, the most widely used mechanism for monitoring HLB is exploration, which is an expensive, labor-intensive, and time-consuming process. Molecular techniques such as polymerase chain reaction are used for the identification of HLB disease, which requires detailed sampling and processing procedures. Furthermore, investigations are ongoing in spectroscopic and imaging techniques, profiling of plant volatile organic compounds, and isothermal amplification. This study recognizes the need for developing a rapid, cost-effective, and reliable health-monitoring sensor that would facilitate advancements in HLB disease detection. This paper compares the benefits and limitations of these potential methods for HLB detection.

Patogenicidad de especies de Fusarium asociadas a la pudrición basal del ajo en el centro norte de México / Fusarium species associated with basal rot of garlic in North Central Mexico and its pathogenicity

El ajo en México es uno de los cultivos de hortalizas más rentables, más del 83% de esta superficie es aportada por los estados de Zacatecas, Guanajuato, Sonora, Puebla, Baja California y Aguascalientes. La pudrición basal ocasionada por Fusarium spp. se encuentra ampliamente distribuida a nivel mundial; esta enfermedad se ha convertido en una limitante en zonas productoras de cebolla y ajo, no solo en México, sino también en otros países, En México, se ha informado la presencia de Fusarium oxysporum en plantas en Guanajuato y en semillas de ajo en Aguascalientes. En el estado de Morelos se ha reportado la presencia de Fusarium culmorum en cultivares de cebolla. Asimismo, en Aguascalientes se tienen antecedentes de otras especies como Fusarium proliferatum, Fusarium verticillioides, Fusarium solani y Fusarium acuminatum. Para este trabajo se planteó como objetivo identificar las especies de Fusarium encontradas en los estados de Zacatecas, Guanajuato y Aguascalientes, y evaluar su patogenicidad. Se realizaron recolectas de plantas con síntomas de la enfermedad en los estados antes mencionados. De los muestreos realizados se identificaron las especies F. oxysporum, F. proliferatum, F. verticillioides, F. solani y F. acuminatum; las cepas de Aguascalientes identificadas como AGS1A (F. oxysporum), AGS1B (F. oxysporum) y AGSY-10 (F. acuminatum) fueron las que presentaron bajo condiciones de invernadero un mayor índice de severidad.

Garlic in Mexico is one of the most profitable vegetable crops, grown in almost 5,451 ha; out of which more than 83% are located in Zacatecas, Guanajuato, Sonora, Puebla, Baja California and Aguascalientes. Blossom-end rot caused by Fusarium spp is widely distributed worldwide and has been a limiting factor in onion and garlic production regions, not only in Mexico but also in other countries. The presence of Fusarium oxysporum has been reported in Guanajuato and Aguascalientes. Fusarium culmorum has been reported in onion cultivars of Morelos; and Fusarium proliferatum, Fusarium verticillioides, Fusarium solani and Fusarium acuminatum have been previously reported in Aguascalientes. The goal of this work was identifying the Fusarium species found in Zacatecas, Guanajuato and Aguascalientes, to assess their pathogenicity. Plants with disease symptoms were collected from hereinabove mentioned States. The samples resulted in the identification of: F. oxysporum, F. proliferatum, F. verticillioides, F. solani and F. acuminatum species; out of which Aguascalientes AGS1A (F. oxysporum), AGS1B (F. oxysporum) and AGSY-10 (F. acuminatum) strains showed higher severity under greenhouse conditions.