Mateo Vargas

The bean is one of the basic grains for the diet of the Mexican population. The objectives of this research were to evaluate the agronomic behavior of the black Jamapa and American pinto beans in Huitzuco de los Figueroa (Mexico), and determine the effect of commercial microbial inoculants on the crop. The treatments were commercial inoculants: Bacillus subtilis, Trichoderma spp., and Streptomyces lydicus (BTS); Glomus spp. (GSP); Trichoderma harzianum, Pisolithus tinctorius, beneficial bacteria and fungi (TPB) and control; which were evaluated in the two genotypes, so there were eight treatments distributed in a completely randomized block experimental design, with four repetitions. The experiment ended at 97 days after planting and the weight of the dry plant, grain yield and its components were evaluated. Which were subjected to analysis of variance, regression and the Tukey test (P≤0.05). The results indicate that the black Jamapa and American pinto beans genotypes adapted to the soil, climate and agronomic management conditions in Chaucingo, Guerrero, Mexico. Inoculation with rhizogenic microorganisms to bean seeds significantly influenced all growth parameters and biomass accumulation in both genotypes. In the control treatments, the black Jamapa and American Pinto beans genotypes achieved yields of 1,218.2 and 1,408 kg ha-1, respectively. The TPB treatment was the most effective, achieving a 37.28% increase in black Jamapa bean (1,672.5 kg ha-1) and a 34.41% increase in American Pinto (1,892.4 kg ha-1), compared to their respective controls.

Background Johnsongrass (Sorghum halepense (L.) Pers.) is one of the most problematic weeds worldwide, and in recent years, control failures with herbicides inhibiting the enzyme acetolactate synthase (ALS) have been reported. Objective Determine the resistance in different biotypes of Johnsongrass to nicosulfuron, as well as elucidate its possible resistance mechanism. Methods Dose-response bioassays were conducted with four biotypes, three of them from corn fields with consecutive history of nicosulfuron applications (Veracruz-Mexico) and a susceptible biotype (Guanajuato-Mexico). A partial sequence [...] Abstract Background Johnsongrass (Sorghum halepense (L.) Pers.) is one of the most problematic weeds worldwide, and in recent years, control failures with herbicides inhibiting the enzyme acetolactate synthase (ALS) have been reported. Objective Determine the resistance in different biotypes of Johnsongrass to nicosulfuron, as well as elucidate its possible resistance mechanism. Methods Dose-response bioassays were conducted with four biotypes, three of them from corn fields with consecutive history of nicosulfuron applications (Veracruz-Mexico) and a susceptible biotype (Guanajuato-Mexico). A partial sequence

Turcicum leaf blight (TLB) of maize is caused by Exserohilum turcicum . The TLB resistance is mainly associated with qualitative race‐specific resistance that is linked to several Ht genes namely Ht1 , Ht2 , Ht3 , HtM , HtN , HtNB and HtP . However, quantitative TLB resistance also occurs, but its mechanisms are poorly understood. In this study, tolerance or insensitivity to chlorosis and necrosis of E . turcicum culture filtrate was associated with quantitative TLB resistance. A novel detached maize seedling assay was developed for E . turcicum culture filtrate using methanol‐treated modified Fries medium. Screening of E . turcicum isolates of races 2, 3, 23, 3 N, 23 N and 123 N against 61 maize inbred lines with diverse levels of resistance to TLB was conducted in the greenhouse by fungal inoculation and the detached seedling culture filtrate assay. Using an isolate of race 123 N, which can overcome all the qualitative resistance genes, a simple linear regression model ( R ² = 0.68, p = .90) for the 61 inbred lines was established between disease severity from foliar inoculations and culture filtrate symptom rating of the detached seedling assay. Two maize lines CML474 and CML483 had relatively high culture filtrate symptom ratings but very low disease severity with foliar inoculation indicating that these sources of quantitative TLB resistance may be unrelated to tolerance to E . turcicum culture filtrates, whose effect on seedlings could be due to the toxin known as HT‐toxin or monocerin.

La capacidad de intercambio catiónico (CIC) es una de las propiedades más importantes al evaluar la fertilidad del suelo. El método más usado es mediante acetato de amonio 1 N, pH 7.0; sin embargo, este método presenta errores durante la determinación. Se compararon varios métodos para medir la CIC: acetato de amonio (NH₄OAc) 1 N pH 7.0, acetato de sodio (NaOAc) 1 N pH 8.2, sumatoria de cationes extraídos con NH₄OAc 1 N a pH 7.0 (CICE), cloruro de bario (BaCl2) 0.01 M y tiourea de plata (AgTU) 0.01 M. Los suelos analizados tenían características variables en pH, textura, materia orgánica y carbonatos. Los mayores valores de CIC se obtuvieron con la sumatoria de cationes, seguidos por acetato de amonio y tiourea de plata. El método de acetato de sodio presentó valores intermedios debido a los errores del método. Hubo asociación entre la CIC mediante AgTU y NH₄OAc a diferencia de CICE y NH₄OAc; el costo de determinación con NH₄OAc superó en ocho al de AgTU. Los cationes Mg2+, K+ y Na+ extraídos mediante cloruro de bario, acetato de amonio y acetato de sodio presentaron alta asociación; sin embargo, no hubo relación entre K+ y Na+ extraídos con NH₄OAc y AgTU. El calcio fue el catión que más se sobreestimó, seguido del magnesio y potasio extraído con NH₄OAc 1 N a pH 7.0, donde la sobreestimación varió de 10 a 498 veces con relación al que originalmente está en los sitios de intercambio, mientras que el magnesio y potasio se sobreestimaron de 11.2 a 141.7 y de 3.7 a 33.3 veces, respectivamente. El método de AgTU fue la mejor alternativa para determinar la CIC, ya que es rápido, de bajo costo, minimiza errores y es aplicable a suelos con diferentes características de pH, textura, materia orgánica y contenido de carbonatos.

Sorghum is cultivated in tropical and subtropical regions of the world and is an important cereal for Mexico. However, it is affected by different pests, especially the yellow aphid. The objective of the research was to evaluate the effectiveness of biological, botanical and chemical insecticides in reducing Melanaphis sacchari populations in sorghum plants under greenhouse conditions. Planting was conducted in a greenhouse, using the sorghum hybrid 945-M. Pests, diseases and weeds management were implemented. The incidence of the yellow aphid was induced artificially. A total of 13 treatments were applied. The following variables were assessed: the number of aphids per leaf, the biological effectiveness of the treatments, plant height, diameter of the plant stem, number of leaves, and the weight of fresh and dry plants. An analysis of variance was conducted for each variable under study, as along with a comparison of means using the Tukey method (α=0.05) and correlation analysis using the SAS^® 9.4 software. The chemical, biological and organic insecticide that exhibited the greatest control of the yellow aphid (more than 95%) were: Toretto® (sulfoxaflor), PHC® Meta Tron® (M. anisopliae), Bio-Die® (Argemonin, Berberine, Ricinin and a-Terthienyl). Adequate management strategies are needed to avoid health problems in people, environmental contamination and resistance or multiple resistance.

Euphorbia pulcherrima is a plant with colorful bracts sold mainly at Christmas time, and is the most important ornamental container plant in the world. To produce healthy plants with high-quality standards, growers intensively apply pesticides and fertilizers, which increases production costs and promote environmental pollution. Plant growth-promoting rhizobacteria (PGPR) represent an environmentally friendly technological alternative for ornamental production. Therefore, this work evaluated the effect of three bacteria (Pseudomonas sp. CPO 2.78, Enterobacter sp. CPO 2.5, and Bacillus megaterium CPO 2.35) isolated from the rhizosphere of E. cyathophora on the vegetative and reproductive growth of E. pulcherrima var. Prestige Red in the presence of three doses of multipurpose Ultrasol fertilizer (0, 50% and 100%) after 236 days under greenhouse conditions. At vegetative stage (118 days), bacterial inoculation produced greater leaf area and higher leaf weight, total dry weight, and relative chlorophyll content, especially with the 50% fertilizer combination. At reproductive stage (236 days), inoculating a mixture of the three bacteria combined with 50% fertilizer increased leaf area, chlorophyll content, total dry weight, plant width, and number of branches. Overall, using PGPR plus 50% fertilizer improved growth and production of E. pulcherrima, and obtained a plant quality similar to that achieved without inoculation plus 100% fertilization.

The insecticide industry has developed more bee-safe active ingredients such as flupyradifurone. However, recent research provides evidence of the negative effects of this and its possible influence on the deterioration of the health of pollinators. During the experiment, mixed-age worker bees of A. mellifera were exposed to a single, sublethal oral dose of flupyradifurone (645 ng/bee) and were assessed only for the first day after exposure to 0.5, 1, 3, 6, and 24 hours. Using reverse transcriptase polymerase chain reaction (RT-qPCR), the alteration in gene expression caused by exposure to this insecticide was quantified. A total of five genes were quantified: three primary antioxidant genes (Catalase (CAT), Superoxide dismutase (SOD1) and Thioredoxin dismutase (Trxr1)), one detoxification gene (Cytochrome P450 9Q3 (CYP9Q3)) and one gene with neuronal activity (Acetylcholinesterase, AChE1). The endogenous ribosomal protein S18 (RPS18) gene allowed the estimation of relative gene expression as the response to insecticide exposure. The AChE1 gene was overexpressed up to six hours after exposure; the remaining CYP9Q3, CAT, SOD1 and Trxr1 genes presented a similar behavior. At a sublethal dose and at short time intervals, flupyradifurone causes alteration in the relative expression of five genes in individual honeybees after oral exposure, which could cause a long-term adverse effect on hive health. La industria de los insecticidas ha desarrollado ingredientes activos más seguros para las abejas como la flupiradifurona. Sin embargo, investigaciones recientes proporcionan evidencia de los efectos negativos de esta y su posible influencia en el deterioro de la salud de los polinizadores. Durante el experimento, abejas obreras de edades mixtas de A. mellifera fueron expuestas a una dosis oral, única y subletal de flupiradifurona (645 ng/abeja) y se evaluaron solo durante el primer día tras la exposición a 0,5, 1, 3, 6 y 24 horas. Mediante la reacción en cadena de la polimerasa con transcriptasa inversa (RT-qPCR, siglas en inglés), se cuantificó la alteración de la expresión génica relativa ocasionada tras la exposición a este insecticida. Un total de cinco genes fueron cuantificados: tres genes antioxidantes primarios (Catalasa (CAT), Superóxido dismutasa (SOD1) y Tioredoxin dismutasa (Trxr1)), un gen de detoxificación (Citocromo P450 9Q3 (CYP9Q3)) y un gen con actividad neuronal (Acetilcolinesterasa, AChE1). El gen endógeno proteína ribosómica S18 (RPS18) permitió estimar la expresión génica relativa como la respuesta a la exposición al insecticida. El gen AChE1 fue sobreexpresado hasta las seis horas tras la exposición; los restantes genes CYP9Q3, CAT, SOD1 y Trxr1 presentaron un comportamiento similar. En una dosis subletal y a intervalos de tiempo corto, la flupiradifurona causa alteración en la expresión relativa de cinco genes en individuos de abejas melíferas tras la exposición oral, lo cual podría causar a largo plazo un efecto adverso en la salud de las colmenas.

Se evaluó un nuevo sistema de monitoreo para Hypothenemus hampei Ferrari en el cultivo de café Coffea arabica L. en la región de Coatepec, Veracruz, México. Los tratamientos con atrayentes probados fueron: T1=metanol+etanol (3:1), T2=vinagre de manzana+etanol (3:1), T3=vinagre blanco+etanol (3:1), T4=vinagre de manzana+etanol (1:1), T5=vinagre blanco+etanol (1:1) y T6=etanol al 96° colocados en trampas artesanales durante un año. Con la prueba de Tukey se demostró que el mejor tratamiento fue el T5 con una media de 52,00 capturas, le siguió T3 con 39,65 individuos y T1 con 24,15 hembras, el T2, T4 y T6 no mostraron una respuesta significativa. La investigación aporta a los cafeticultores de subsistencia, un nuevo atrayente para el monitoreo de la broca del café con vinagre blanco más etanol en la proporción 1:1, ya que resultó efectivo, económico, no tóxico para la salud humana y amigable con el ambiente.

Turcicum leaf blight (TLB), is a common foliar disease of maize in Mexico that is caused by the fungal pathogen Exserohilum turcicum. The most effective management strategy against TLB is monogenic race-specific resistance. Among the 140 E. turcicum isolates from symptomatic leaves collected from maize fields in Mexico, 100 were obtained from tropical (Veracruz) and temperate areas (Estado de México) between 2010 and 2019, and 40 isolates were obtained from tropical (Sinaloa, Tamaulipas, Veracruz, and Chiapas), subtropical (Nayarit, Jalisco and Guanajuato) and temperate areas (Estado de Mexico, Hidalgo, and Puebla) collected in 2019. All the isolates caused TLB symptoms on the positive control (ht4) showing that they were all pathogenic. Six physiological races of E. turcicum (2, 3, 23, 3N, 23N, and 123N) were identified based on resistant or susceptible responses displayed by five maize differential genotypes (A619Ht1, A619Ht2, A619Ht3, B68HtN, and A619ht4). The most common was race 23 accounting for 68% of the isolates, followed by races 23N, 123N, 3, 2, and 3N at 15%, 8%, 6%, 2%, and 1%, respectively. Race 123N was able to infect the greatest number of maize differential genotypes used in the study. Race 123N was detected in Sinaloa and Estado de México. Race 3 was detected in Nayarit and Jalisco. Race 2 was detected in Jalisco, Estado de México and Veracruz, and race 3N was detected in Tamaulipas. Race 23 was equally dominant in the tropical, subtropical, and temperate regions, while race 123N was more common in the tropical environment and race 23N was more common in the tropical and temperate environments. There was no evidence for shifts in the races between 2010 and 2019.

Comadia redtenbacheri (Hammerschmidt, 1847) is an insect highly regarded for its commercial and nutritional value. Adult fluctuation in a plantation of Agave salmiana Otto ex Salm-Dyck was determined using ultraviolet light traps. Trapped adults were counted weekly during three periods (December 2013 to December 2014, December 2014 to December 2015, and December 2015 to June 2016), and temperature and relative humidity were recorded. Adult population was present 157 days on average, from December to May, with peak capture on day 83. The average sex ratio of females to males was 1:14. Average environmental conditions that favoured the highest capture in the three periods were 17.8º C and 47.1% relative humidity. Knowledge of the period of adult presence and the influence of temperature and relative humidity are important for management and conservation of the insect population by farmers and gatherers.