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In Mexico, Theobroma cacao is affected by the black pod rot (BPR) caused by Phytophthora capsici. Currently, an epidemiological study of this disease is lacking. The objective was to determine the influence of climate, fruit set and the incidence of cacao frosty pod rot (Moniliophthora roreri) on the epidemic intensity of BPR in five locations in southeastern Mexico. The temporal structure of BPR epidemics was analyzed and the correlation of absolute change of BPR incidence with temperature, relative humidity (RH), precipitation, and fruiting flows was studied. The possible competition between P. capcisi and M. roreri was also analyzed correlatively. The epidemics had a duration of 15 to 25 weeks restricted to September - February with 6 to 24% final incidence (Yf ). The curves were best fitted to the Gompertz model (r = 0.059 - 0.123, R2 0.97 - 0.99) with an exponential phase in October corresponding with the highest rainfall. BPR was positively associated with RH greater than 90%, precipitation, temperature periods lower than 19.9, and 20 - 26.9 °C, and with fruiting intensity. P. capcisi had less parasitic f itness than M. roreri, which induced earlier epidemics, with greater duration and intensity. The characterization of BPR as a polycyclic epidemic justifies management strategies aimed at reducing the secondary inoculum.

App-ExploraCitricos v2.0 is an application for assessing epidemiological variables with a spatio-temporal, multicrop, multivariety-species, multivariable, multi-pest, multi-user and multi-criteria approach for risk analysis in the citrus productive chain. This work aimed to develop an application for Android® mobile devices higher than 5.0, allowing in situ evaluations associated with epidemiological or phytosanitary processes through a flexible design customized to the user's criteria. The process is initiated by logging into the application with passwords, previously registered, for authentication. Before an assessment, users are required to register only once n-pests and/or n-diseases associated with the citrus crop(s)/species concerned, providing the common and scientific name, and organism type (fungus, virus, bacterium, etc.). Entries are stored locally available for future assessments. Later, set up assessment n-scales with n-classes to quantify damage/severity. Versatility allows entry of qualitative (e.g. healthy, sick, dead) or quantitative scales (e.g. 0, 50%). It also enables to assess presence/absence and quantify vector if required. By customizing the assessment, choose the pest(s) concerned and associated scale. At the moment of evaluation, a plantation is parameterized by 26 epidemiological-productive variables, e.g., agronomic condition, age, crop, variety/cultivar, irrigation type, nutrition, management, etc. Assessment is performed for n-plants defined by the user. Per plant, the selected pathogen-pest(s) and scale class is assessed. Optionally, up to three geo-referenced photographs of symptoms or other aspect of concern can be taken. At the end, assessment(s) are sent to a database web platform. Assessments per planting are exported in MS-Excel for sharing via email, bluetooth, social networks or other device tools.

Research objective was to assess phytosanitary response and epidemiological behavior in 12 Phaseolus vulgaris genotypes and develop etiological-epidemiological methodologies applicable to plant breeding studies. In 2020 spring-summer season, assessments were conducted at flowering (June) and fructification stages (August). Severity was evaluated with a 6-class logarithmic-diagrammatic scale setup in App-Monitor® v1.1. Genotype health was determined using an Integrated Damage Index (IDI), weighted and adjusted for disease severity and coverage-plant vigor (IV), which was estimated with images (RGB, 14mpx) captured with dron-Phantom-3 at 5 m height from genotype centroid. In SAS v9.4, t-test and ANOVAs, followed by Tukey (p = 0.05), were performed for different experimental settings. Disease spatial patterns were analyzed with kriging and omnidirectional variograms in SURFER v10. Forty-three total samples were used for isolation, pathogenicity testing, and molecular identification with universal primers ITS1/ITS4, NIb2F/NIb3R, PBL1v2040/PCR1c for eukaryotes, Potyvirus and Begomovirus, respectively. Final data matrix included 22 variables, 859 observations and 18,898 metadata. Alternaria alternata and Bean common mosaic virus (BCMV) were identified in 100% of samples analyzed with 99% homology. Vaquita Negro, Garrapato and Canario were statistically the most susceptible genotypes (37.3 - 58% severity) for BCMV, while Canario and Tipo Flor de Mayo (41.4-42.7%) were for A. alternata (p = 0.05). Oti and Negro Perla had higher climatic adaptability and tolerance to both pathogens with IV > 0.7 and IDI < 0.43. Spatially, BCMV presented random dispersion of foci and a block-edge effect with continuous contagion of up to 5.6 meters. Vaquita Negro and Bayo Mecentral showed uniform virus spread, presumptively due to high viral transmissibility by seed. In contrast, except for Tipo Flor de Mayo and Canario, which exhibited significant coalescence of foci, A. alternata had spatial dependence of less than 8 plants. Wind and hail damage significantly favored A. alternata infection (p = 0.05) suggesting its opportunistic condition.

The objective of this work was to determine the impact of COVID-19 on productive activities of farmers and extensionist, and the level of application of Integrated Pest Management (IPM) in urban agriculture in Xochimilco, Milpa Alta, Tláhuac, Tlalpan, Magdalena Contreras and Cuajimalpa at Mexico City, a metropolitan area with a high SARS-CoV-2 positive cases. In 2020, a digital survey was applied to a total of 108 farmers and extensionists during the first COVID-19 epidemic wave. The sanitary emergency reduced the continuity of the extension service. However, this was carried out with digital technologies including photographs submitted by WhatsApp for pest diagnosis purposes. During the maximum COVID-19 peak (July, 2020), only 14% of farmers declined to sowing the summer fall season 2020. The majority established corn and, to a lesser extent, vegetables in mixed topologies. However, the activity of agricultural workers was reduced to 50%. Up to 75% of farmers reported losses of 20% derived from the epidemic. The major pest control strategy was mechanical, mainly for preventive purposes (67%) followed by chemical control (52%), biological at both preventive (8%) and curative (25%) levels, and the combination of more than one strategy in less than 10%. The data indicate an intuitive understanding of the IPM benefit, although the farmer is unaware of its principles. Faced with the growing demand for fresh, quality and safe food as a COVID-19 preventive strategy, urban agriculture has great development prospects by supplying local markets without transport problems caused by regional and global contingencies such as that caused by SARS[1]CoV-2. However, public and institutional policies of great vision are required. This work recognizes the work of farmers, as well as extensionists in favor of food security.

Food and health are vital needs and legitimate human rights. Agriculture, exceeded by the Industrial Revolution and subsequent economic development has been fundamental to face the SARS-CoV-2 / COVID-19 health contingency. Its essentiality, in contrast to most economic sectors’ shutdown, implied the uninterrupted agricultural production to guarantee worldwide food supply despite the farmer’s risk. Consequently, the Mexican agricultural segment had sustained growth with a global food production contribution of 59.2%, ranking 12th in the world in 2020. Phytosanitary activities have been fundamental in the production and global mobilization of healthy and safe food through safety programs and pest-free status certifications. The regional-crossboundary phytosanitary-international preventive model has strengths applicable to Public Health Systems whose current trend favors the patient-client curative approach in the hospital-outpatient environment. The COVID-19 pandemic represents a multidimensional problem that exceeds the Public Health Systems. The development of a preventive Pansystemic Model to address integral human health, involving causes and effects for this and future epidemics is urgent. The necessity of a new agricultural production paradigm that balances the growing global demand for healthy food, with sustainable and resilient ecosystem services with comprehensive human and environmental health indicators is also recognized. This work analyzes 31 contributions of the Mexican Journal of Phytopathology integrated into the Special Issue ‘COVID-19 and Plan Heath’, promoted internationally among producers, researchers, and academia to communicate the phytosanitary contribution to the society, with emphasis on Phytopathology, at the multidimensional COVID-19 solution.

Although the SARS-CoV-2 virus can survive in various environments for 28 days or more, and that the virus dispersion by microdroplets in the air can be a risk of contagion, there is no evidence that food carries it. However, the authorities have recommended measures in the handling of food, to avoid the possible spread of the disease through it or its packaging. In addition, current certification models such as ISO 22000 and Good Manufacturing Practices have generated a culture of prevention and food safety also applicable to the SARS-CoV-2 risk.

Global retrospective human/plant epidemiology analysis exhibits a reactive cognitive development influenced by casuistic phenomena. Epidemic outbreaks of XXI century evidenced regression of the population-based approach to risk prevention and erosion of Public Health model, successful between 1950-1970. After 19 pandemics and 200 historical outbreaks, neither WHO nor public or private institutions, have not consolidated sustainable preventive models. Urban expansion and agricultural colonialism during the Industrial Revolution accelerated pandemic processes such as Black Death (Yersinia pestis), Cholera (Vibrio cholerae), Potato Blight (Phythopthora infestans) or Coffee Rust (Hemileia vastatrix). These factors contributed to the conception and application of the contagion and prevention principles by Snow/1854 or de Bary/1857, in the hygienism of Proust/1873, and the sanitation of Marshall/1882, before the etiological principle developed by Pasteur/1862 and Koch/1882. The contemporary scientific revolutions strengthened the reductionist hospital vision, with emphasis on cure as a principle, and on health privatization as a business strategy. The central epidemiology paradigm’s population is limited to the individual-patient or plant-damage. The COVID-19 cases curve (‘epidemic wave’) is not inherent to preventive epidemiology, ‘flattening’ lacks infectious basis, ‘healthy distance’ or ‘confinement’ are not sustainable mitigation strategies. The immunological emphasis did not generate the expected individual protection and ‘herd immunity’. Instead, it exacerbated the pharmaceutical-mercantilized vaccine ‘race’ to new variants; geopolitical protectionism; and unequal distribution of immunologicals. The SARS-CoV-2/COVID-19 pandemic evidenced the rational epidemiological framework deterioration; the absence of Surveillance Systems that articulate clinical detection and viral variants with community risks follow-up, enhanced with genomic and digital technology; the systematic failure of Public Health Systems; and the absence of a pansystemic model to integrate regional preventive models. Maximum case-fatality reduction from 15.2% in 2020 to 2.5 world average 2021, suggests an endemic transitional process. Worldwide reproduction rates Rt > 1 are consistent with more transmissible variants, such as Delta and Omicron, as sublethal survival ability of the virus. The pandemic has not been successfully intervened and its momentum is determined by biological attributes inherent to SARS-CoV-2.

La comúnmente llamada Fusariosis de las musáceas es un patógeno que representa una amenaza para la seguridad alimentaria global. Es responsable de pérdidas considerables en la producción de plátano y banano en el mundo. Por casi 30 años, su presencia se restringió al Sureste asiático, sin embargo, en agosto de 2019 se detectó por vez primera en Colombia y se consideró un nuevo riesgo fitosanitario en América. Se modelaron los patrones espaciales de Fusarium oxysporum, f. sp. cubense raza 4 tropical (FocR4T) a nivel global y subcontinental (América pantropical) bajo un enfoque que integró los componentes epidémico y espacial, e incluyó la distribución potencial (patógeno/hospedante) y el potencial de daño económico por asociación espacial de nodos comerciales (origen/destino), lo cual se integró mediante la evaluación multicriterio (MCDA). A nivel territorial se caracterizaron cinco niveles de riesgo fitosanitario (muy alto, alto, medio, bajo y muy bajo). A escala global se determinó la existencia de cuatro áreas focales donde existen condiciones para la ocurrencia de la enfermedad. En la América pantropical se determinó la existencia de 26 598 km2 en riesgo fitosanitario muy alto (>0.9) ubicado por mayor extensión en Ecuador, Brasil, México, Guyana, Guatemala, Venezuela, Panamá y Colombia, aunque también existen 15.8 millones de km2 con un nivel de riesgo inferior. La cartografía obtenida representa una herramienta valiosa para fortalecer y direccionar las acciones preventivas en la dispersión de este patógeno en la región y se considera un insumo técnico/científico que fortalece el análisis de riesgo de plagas realizado por las organizaciones regionales y nacionales de protección fitosanitaria.

Estimate the probabilistic potential of introduction of the causative agent of influenza type A in Mexico, using geo-intelligence applied to health.Ecological study of 1,973 influenza outbreaks with a high degree of pathogenicity, worldwide during the period 2014-2016. Geospatial modeling was developed with geo-intelligence tools such as spatial representation, a relational model, spatial characterization of the inoculum source with the maximum entropy model and the receiver operating characteristic (ROC) curve, using multicriteria spatial analysis. This was validated with the Moran index and geographically weighted regression.Isochrones (at an initial distance of 548 km) were estimated for health risks and their exponential growth; at the fourth isochrone, the east and west coasts of the United States of America and a part of Central America were identified as possible areas that favor the introduction of the pathogen. Also, a COR curve = 0.923 was obtained; two risk periods for introduction were identified (September-March and April-August, with north-south and south-north trajectories, respectively) with high positive autocorrelation for geospatial modeling; and in one scenario, more than half of Mexico was found to be at high risk of introduction, with an estimated 78 million people exposed. A positive association was identified between significant risk areas (More than 50% of Mexican territory was found to be at risk of introduction of the causative agent of influenza type A, with approximately 70% of the population exposed.Estimar o cenário probabilístico em potencial de introdução do vírus da influenza A no México com o uso de inteligência geográfica em saúde.Estudo ecológico de 1.973 surtos mundiais de influenza de alta patogenicidade ocorridos no período 2014–2016. Foi desenvolvido um modelo geoespacial com ferramentas de inteligência geográfica, como representação espacial, modelo de conexidade, caracterização espacial da fonte de inóculo com o modelo de máxima entropia e curva ROC (receiver operating characteristic) com avaliação espacial por múltiplos critérios e validação com o índice de Moran e regressão geograficamente ponderada.Foram estimadas isócronas do risco de saúde com uma distância de 548 km e o crescimento exponencial destes linhas; até a quarta isócrona, foram identificadas as costas leste e oeste dos Estados Unidos (EUA) e parte da América Central como possível superfície que favorece a introdução do vírus. Foi também estimada uma curva ROC de 0,923, sendo identificados dois períodos de risco de introdução do vírus (setembro–março e abril–agosto) com trajetórias de norte-sul e sul-norte, respectivamente, com elevada autocorrelação positiva para o modelo geoespacial. Foi estimado um cenário em que mais da metade do México apresenta alto risco de introdução do vírus da influenza, com 78 milhões de pessoas expostas. E foi observada uma associação positiva entre as áreas de risco significativo (Observa-se que mais de 50% do território mexicano está sob risco de introdução do vírus da influenza A, com cerca de 70% da população exposta.

Plant-pathogenic viruses cause physiological and biochemical changes in the host plant as well as direct and indirect effects on the biology and behaviour of the vector. Brevipalpus yothers...

El avance de la tecnología digital ha permitido concebir Sistemas de Vigilancia Epidemiológicos (SVE) automatizados con un enfoque holístico-sistémico favoreciendo la planeación, operación, gestión y procesamiento de datos fitosanitarios de manera efectiva y oportuna para toma de decisiones en la prevención y manejo regional de plagas. Este tipo de sistemas se enfocan en la salud del cultivo superando la visión reduccionista de plaga en la vigilancia normativa convencional. Un SVE web implica la definición clara del marco regional, objetivos, plaga(s) en su amplia acepción, recursos humanos/financieros, contexto normativo, líneas de investigación de soporte, estructura operativa y modelos de innovación. Estos elementos determinan la precisión, frecuencia y tipo de muestreo y monitoreo, así como las variables de medición relativas a un novel sistema epidemiológico. A diferencia de la vigilancia normativa, un SVE web holístico-sistémico tiene capacidad descriptiva y de pronóstico de riesgos, incluyendo alertas tempranas a partir de análisis espaciales y temporales. La interfaz web SVE asegura la generación flexible y dinámica de reportes y/o análisis automatizados. Un SVE operado en plataformas web, con énfasis en lenguajes de programación y herramientas de uso libre puede ser alojado en servidores genéricos o dedicados para almacenamiento de metadatos configurados con tecnologías Linux/Apache y funcionalidad 24/7 (h día-1). Programas de uso libre incluyen MySQL/MariaDB y otros como gestores de bases de datos; PHP / Node.js, y JavaScript, Ajax, HTML5 y CSS, como tecnologías web de maquetado base ‘back-end’ y ‘front-end’, respectivamente. Esta revisión se enfoca en principios, atributos conceptuales, enfoques metodológicos generales y objetivos de SVE base web. Aplicaciones generales se ilustran con un SVE desarrollado en México para el cafeto (Coffea spp.), el cual permitió operar la vigilancia de 19 plagas, nueve con estatus cuarentenario, mediante la generación, gestión y análisis de 87.4 y 15.7 millones de registros climáticos y epidemiológicos, respectivamente, obtenidos entre 2013-2019.

Una posible alternativa para el control de CTV y CLas en Citrus sinensis es el empleo de resistencia genética adquirida. El estudio de este mecanismo, requiere normalizar con genes de referencia. Por lo tanto, se desarrolló un protocolo de cuantificación de expresión génica mediante RT-qPCR para evaluar el uso potencial de GAPDH, ACTINA, F-BOX, COX y 18S rRNA como genes de referencia en cítricos. Un total de nueve plantas infectadas con CTV (3), CLas (3) y sanas (3) se emplearon para seleccionar una muestra compuesta de ocho hojas/planta. El protocolo no comercial se desarrolló y optimizó en todas sus etapas variando concentración de reactivos, iniciadores y sustrato de reacción. La extracción del ARN total con CTAB al 2% estuvo en el rango de 200-1000 ng ?L-1. La retrotranscripción produjo en promedio 1069 ng ?L-1 ADNc. Los productos de los genes de referencia GAPDH, ACTINA y F-BOX exhibieron curvas de disociación sin expresión de dímeros, Ct ? 28 y eficiencias de reacción en el rango de 90-110%. En todas las expresiones de genes, muestras con CTV tuvieron los Ct´s más tardíos (25-27) seguido de las muestras sanas (24-25). Sin embargo, GAPDH y ACTINA presentaron la expresión génica más estable (ln 1/M = 2.83) por lo que estos genes se proponen para normalización. El protocolo RT-qPCR fue también específico y eficiente para el gen CDR13, putativamente asociado a resistencia sistémica adquirida a CLas, lo que sugiere su viabilidad en estudios de resistencia de C. sinensis/C. aurantium en respuesta a la infección de CTV y CLas.

Urban green areas provide various services to society and the environment. The Bosque San Juan de Aragón is one of the few green areas in the northeast of Mexico City and the current condition of its trees in terms of health is not known with precision. In the present study, the protocol for the crown condition indicator was implemented and adapted in 28 circular plots of 0.1 ha, randomly established in the aforementioned forest. All trees within each plot were measured for normal diameter (ND) and total height (TA), and their taxonomic classification, crown condition and plantation density were determined. For crown condition, six variables were measured: proportion of live crown (PLC), crown density (CD), crown transparency (CTR), dieback (DB), crown position (CP) and light exposure (LE). The first four were measured in 5% classes and the remaining two were measured on an ordinal scale. A total of 760 trees were evaluated, grouped into 10 families, 11 genera and 12 species. The average values for the crown variables were 56.37% PLC, 44.38% CD, 4.04% DB and 38.4% CTR. Only PLC reached the established standards of tree health found in other studies, while CD was low and CTR and DB values were high.

Esta investigación tuvo como objetivos identificar la especie(s) de Fusarium asociada(s) a hijuelos comerciales de Agave tequilana y desarrollar una metodología para cuantificar la carga de inóculo en hijuelos provenientes de plantaciones madre de Jalisco con inductividad epidémica diferencial al síndrome marchitez y pudrición seca del cogollo (SMAP). La finalidad fue proporcionar criterios para la certificación de plantaciones madre. La fase de campo se realizó entre marzo-mayo 2018 y 2019 en 21 plantaciones comerciales en 14 municipios de Los Altos, Sur y Valles de Jalisco. Se estimó el número de plantas enfermas (PE) y severidad SMAP (S) en 63 y 200 plantas/plantación mediante App-SIVEA para 2018 y 2019 respectivamente. Se desarrolló y aplicó el método CIFUSAG en 7055 hijuelos y 46 656 colonias fungosas obtenidas de 2364 siembras de lavado basal de la ‘piña’, secciones de tejido interno y macerado total de hijuelo. Unidades formadoras de colonia de Fusarium spp. (Fsp) y hongos totales (HT), purificación, monospóricos, caracterización morfológica y cultural se realizó con los medios Komada, agua-agar, Sabouraud, SNA y Sabouraud, respectivamente, diferenciando 557 aislados. La mayor inductividad epidémica en Los Altos significó moderado Índice de Fusarium [(IF) = (?Fsp) / (?HT)] (0.30 y 0.40) y Fsp (20 y 72UFC) respecto al Sur que tuvo valores más altos (0.69, 0.50; 23, 84UFC, respectivamente) (Tukey p=0.05). Calibre de hijuelo no tuvo influencia en IF y Fsp (p=0.183). IF y Fsp de lavado basal no estuvieron correlacionadas con S de plantas madres (r2 = 0.036 y 0.13), mientras que PE únicamente se correlacionó con Fsp (r2 =0.94). La carga de inóculo obtenida por lavado fue superior al de tejido interno con un total de 17,828 UFC (93%) e IF=0.42. Análisis molecular con el gen EF-1a evidenció asociación de 23 cepas con cuatro complejos filogenéticos: Fusarium oxysporum, F. fujikuroi, F. solani y F. incarnatum-equiseti con identidad superior al 98%. El hijuelo comercial de Agave tequilana constituye un factor de dipersión de al menos cuatro especies de Fusarium spp. en el rango de 3.3±3 y 6.83±4.2 UFC/hijuelo.

El picudo del nopal, Metamasius spinolae (Gyllenhal), es una de las plaga más importantes en nopal verdura (Opuntia ficus-indica (L.) Miller) en México y en especial en Tlalnepantla, Morelos, la segunda región de importancia en la producción de este cultivo con alrededor de 2 500 ha. Tanto adultos como larvas causan daño al cultivo, la larva realiza galerías en las pencas maduras y el adulto daña los márgenes de los nopalitos. A pesar de que no existen plaguicidas autorizados en México para su control, este hecho no limita a los productores para el uso de productos químicos sin conocer su efectividad. Por esta razón, en este trabajo se evaluó la efectividad de ocho insecticidas pertenecientes a dos grupos, organofosforados y piretroides, sobre adultos de este curculiónido. Las pruebas de laboratorio y campo realizadas durante 2007 mostraron que el Malatión causó una mortalidad similar a otros productos del mismo grupo que son más tóxicos (Paratión Metílico y Metidatión). Por otro lado, sólo un insecticida piretroide (Permetrina), proporcionó una mortalidad cercana a 86%, en comparación con los tres restantes (Cipermetrina, Deltametrina y Fenvalerato) que lograron mortalidades menores a 20%. Existió una respuesta diferencial del sexo del insecto a los insecticidas, las hembras mostraron menor susceptibilidad que los machos a algunos productos, tales como Diazinón, Permetrina y Cipermetrina. Este es el primer reporte formal de la evaluación de productos químicos en este insecto y se discuten algunos problemas relacionados con su manejo.

Una característica de Salmonella es su capacidad para formar biopelículas. Estas estructuras pueden convertirse en focos de contaminación en la producción de alimentos inocuos, ya que resisten tratamientos con antimicrobianos y son difíciles de remover en procedimientos normales de limpieza. Por lo anterior los objetivos del presente estudio fueron: 1) determinar la capacidad de cepas de Salmonella, aisladas de nopal verdura (10 cepas), muestras de agua (2 cepas) y suelo (3 cepas), para formar biopelículas y 2) evaluar el efecto bactericida de los desinfectantes ácido cítrico, ácido láctico e hipoclorito de sodio sobre cepas formadoras de biopelículas. Se utilizó el método de O ́Toole y Kolter (1998) y placas de poliestireno (Coster®) con medio esencial mínimo con glucosa (MEM) y se determinó la densidad óptica (D.O) para estimar la producción de biopelículas. Los desinfectantes se aplicaron a placas con formación de biopelículasenMEMsimplede48ha37°C.Todaslascepas registraron producción de biopelículas desde las 24 h aunque se obtuvieron diferencias significativas (Tukey α= 0.05), dependiendo del tiempo de incubación con respecto a los valores de D. O. Las cepas de suelo expresaron su capacidad más rápidamente que las de agua y nopal. El hipoclorito de sodio (200 ppm) y el ácido láctico (1.5 X 10-4) inhibieron el crecimiento de células cuando se aplicaron por 20 min sobre las biopelículas. Los resultados aquí obtenidos evidencian la importancia de implementar las buenas prácticas agrícolas en la producción de nopal, como estrategia para prevenir la contaminación por cepas de Salmonella formadoras de biopelículas in vivo, donde el efecto de los tratamientos con sanitizantes pudiera variar.

This study provides a safe and low-cost in-house protocol for RT-qPCR-based detection of SARS-CoV-2 using mouthwash–saliva self-collected specimens to achieve clinical and epidemiological surveillance in a real-time web environment applied to ambulatory populations. The in-house protocol comprises a mouthwash–saliva self-collected specimen, heat virus inactivation, and primers to target virus N-gene region and the human RPP30-gene. Aligning with 209 SARS-CoV-2 sequences confirmed specificity including the Alpha variant from the UK. Development, validation, and statistical comparison with official nasopharyngeal swabbing RT-qPCR test were conducted with 115 specimens of ambulatory volunteers. A web–mobile application platform was developed to integrate a real-time epidemiological and clinical core baseline database with mouthwash–saliva RT-qPCR testing. Nine built-in algorithms were generated for decision-making on testing, confining, monitoring, and self-reports to family, social, and work environments. Epidemiological and clinical follow-up and SARS-CoV-2 testing generated a database of 37,351 entries allowing individual decision-making for prevention. Mouthwash–saliva had higher sensitivity than nasopharyngeal swabbing in detecting asymptomatic and mild symptomatic cases with 720 viral copy number (VCN)/mL as the detection limit (Ct = 37.6). Cycling threshold and viral loading were marginally different (p = 0.057) between asymptomatic (35 Ct ± 2.8; 21,767.7 VCN/mL, range 720–77,278) and symptomatic (31.3 Ct ± 4.5; 747,294.3 VCN/mL, range 1433.6–3.08 × 106). We provided proof-of-concept evidence of effective surveillance to target asymptomatic and moderate symptomatic ambulatory individuals based on integrating a bio-safety level II laboratory, self-collected, low-risk, low-cost detection protocol, and a real-time digital monitoring system. Mouthwash–saliva was effective for SARS-CoV-2 sampling for the first time at the community level.

La presencia de Huanglongbing y su vector: Diaphorina citri Kuwayama (Hemiptera: Liviidae) en México, aunado a la gran dispersión de la citricultura, dificultan su detección, control y manejo. Con el propósito de generar herramientas que faciliten la aplicación de estrategias para confrontar la problemática asociada al Huanglongbing y su vector, el presente estudio se desarrolló con el objetivo de implementar una metodología práctica y de uso sencillo para clasificar la presencia y abundancia potencial del vector y generar un mapa con la delimitación de las zonas potenciales de riesgo de desarrollo del insecto en el país. Se modelaron tres índices, dos basados en la temperatura (índice de generaciones potenciales, y días con condiciones favorables), y uno en la disponibilidad del hospedero (superficie plantada con cítricos). En el mapa final, cada índice fue ponderado respecto a su máximo, interpolado mediante el método de inverso de la distancia optimizado, y promediado con los demás para obtener el índice de riesgo promedio. Se encontró que los municipios con mayor índice de días con condiciones favorables fueron: Tuzantán, Chiapas, y Atoyac de Álvarez, Guerrero. Referente al índice de generaciones potenciales, los municipios de Rosario, Sonora, y Pichucalco, Chiapas, resultaron con 34 y 28 generaciones potenciales anuales, respectivamente. El máximo riesgo, índice de riesgo promedio, se encontró en los municipios de Álamo Temapache, Martínez de la Torre, y Papantla, Veracruz, y Atoyac de Álvarez, Guerrero. El método propuesto es práctico, económico y sin cálculos complicados; para mejorarlo, sería necesario incorporar información de humedad relativa, precipitación, fenología y especie de cítricos. Su utilidad radica en que auxilia en la toma de decisiones relacionadas con acciones de detección, monitoreo, muestreo y control del vector.

La investigación tuvo por objetivo analizar la sintomatología visual y nutrimental en nopal verdura Opuntia ficus indica (L.) por medio de la inducción de deficiencias nutrimentales mediante la técnica del elemento faltante bajo condiciones de hidroponía. Para cumplir con esta meta, se planeó trabajar en un invernadero del Colegio de Postgraduados en el Estado de México, a partir de junio de 2008 hasta que en la plantas se observaran las deficiencias nutrimentales buscadas. Los materiales vegetales utilizados fueron cladodios de un año provenientes de la zona productora de Tlanepantla, Morelos, que se secaron y trasplantaron en macetas con tezontle promoviendo su enraizamiento. Se probaron 11 tratamientos de distintas soluciones nutritivas con tres repeticiones cada una, cada maceta constituyó una unidad experimental y los tratamientos se distribuyeron de acuerdo a un diseño completamente al azar. Se analizaron los datos a través de un ANOVAconpruebasdecomparacióndemediasdeTukey(α= 0.05). En los resultados se destaca que las plantas presentaron deficiencias nutrimentales a los 13 meses de iniciado el experimento, se observaron diferencias morfológicas con la presencia o ausencia de hojas subuladas y la coloración de las mismas resaltando el tratamiento que no contenía nitrógeno. Asimismo, se apreciaron diferencias significativas en número de cladodios, peso seco y concentración nutrimental. Se concluye que esta metodología sirve para inducir la deficiencia de macronutrimentos.

Cladode brown spot (CBS) is an important disease of prickly pear cactus (Nopalea cochenillifera) in Brazil. No standard method exists for sampling in the field. A study was conducted in 30 fields of prickly pear (cv. Miuda) in Pernambuco state, Brazil, to determine the optimal sample size to assess severity of CBS. In each field, a 0.3 ha (45 × 68 m) test area consisting of 30 rows and 45 plants per row (1350 plants per test area) was arbitrarily chosen. In each test area, 50 plants were sampled using a systematic method and the disease severity was assessed with the aid of a standard area diagram set on 2, 4 and 6 cladodes/plant. The spatial pattern of the disease was examined by spatial autocorrelation analysis and the optimal sample sizes were determined based on three levels of error (5, 10 and 20%). CBS severity in the fields ranged from 0.4 to 8.7%. In 15 fields the disease severity of CBS was >4.0% and in 20 fields the spatial pattern of CBS was aggregated. There was a positive correlation (r = 0.59, P = 0.0001) between disease severity and strength of aggregation, and a negative correlation (r = −0.39; P = 0.0001) between disease severity and sample size (number of plants). There was no significant effect (P = 0.3) of the number of cladodes assessed per plant (2, 4 or 6 cladodes) on sample size. Considering a sample of two cladodes per plant and an acceptable error of 5, 10 or 20%, the optimal sample size was 253, 63 and 16 plants, respectively, for each 0.3 ha of cultivated field.

Epidemiological studies are important for successful use of entomopathogens for pest management. Although microbial control of insects is applied epidemiology, there are few epidemiological-ecological studies, which partially explains why the use of entomopathogens has ended in failure. Isolated studies using preserved strains of entomopathogens in a laboratory might contribute to lack of efficacy under field conditions. An option is regional exploration of entomopathogens as the basis for epidemiological diagnoses, because this would enable identifying the most prevalent species and isolates that presumably have greater potential for use in pest management. Field epidemiological/ecological diagnoses allow identifying factors that induce the development of epidemics, including the range of hosts, plants, and cropping systems. Understanding their prevalence, dispersal, and pathogenicity is key to successfully detect pathogens in the field. Basic epidemiological characterization includes measuring...

La marchitez y pudrición seca del cogollo del agave (Agave tequilana var. azul) son enfermedades de alto impacto económico para este cultivo. En este trabajo se planteó determinar la implicación de Fusarium spp. en ambas enfermedades bajo un enfoque regional. Se colectaron muestras de raíz y suelo en 40 plantaciones comerciales ubicadas en 13 municipios de Los Altos Jalisco, importante región de cultivo de agave azul en México. De cada plantación de colecta se estimó carga de inóculo mediante un índice de Fusarium obtenido de unidades formadoras de colonias (Fusarium vs hongos totales) y se analizó su relación con pH y materia orgánica. Se obtuvieron 109 aislados caracterizados morfológicamente como Fusarium spp. de los cuales se seleccionaron 25 para identificación molecular con ITS y EF-1a. La selección consideró sintomatología, caracteres macro y microscópicos y prevalencia de tipologías de colonia observadas in vitro en medios Komada, Sabouraud, SNA y CLA. Los caracteres culturales y morfológicos evaluados fueron: coloración micelial, tamaño, forma y septación de macro y microconidios, y longitud y número de fiálides. Se asociaron cinco especies con marchitez y/o pudrición seca ubicadas en tres complejos filogenéticos: F. oxysporum del complejo de especies Fusarium oxysporum (FOSC) con 56% (46.2% suelo y 66.7% raíz) de representatividad regional; F. solani, F. falciforme y Fusarium sp. del complejo Fusarium solani (FSSC) (40%); y Fusarium sp. del complejo Fusarium fujikuroi (FFSC) (4%). MO y pH tuvieron correlación inversamente proporcional con Índice de Fusarium (r2 = 0.68-0.70). Se postula que la marchitez y pudrición seca del cogollo de agave azul constituyen un síndrome en el cual se asocian y especializan parasíticamente diversas especies de Fusarium. Se encontró un aislado de los tres complejos de Fusarium asociados específicamente a cada tipo de síntoma y la combinación de ellos. La mayoría se asociaron a marchitez con predominancia de F. oxysporum.

Candidatus Liberibacter asiaticus (CLas), agente causal del huanglongbing (HLB), y el Citrus tristeza virus (CTV) constituyen amenazas para la citricultura mexicana por su condición endémica en cítricos agrios de algunas regiones del pacífico y de focos recientes de razas severas, respectivamente. La identificación y clonación de genes relacionados con la Resistencia Sistémica Adquirida (RSA) de la planta podrían coadyuvar como parte de una estrategia de manejo integrado. Este trabajo tuvo como objetivo desarrollar construcciones con genes específicos inherentes a la planta como primera etapa en la generación de plantas transgénicas resistentes a CLas. Los genes seleccionados con base a la respuesta de cítricos a una amplia gama de patógenos, fueron AZI-1, 1-inductor del ácido ‘Azelaic’ y CsNDR-1, 1-resistencia no específica a enfermedades en cítricos, ambos genes reguladores de la señalización del ácido salicílico (SA), y el gen asociado con la síntesis de proteína 1 relacionada con la patogenicidad (PR-1). Los tres genes (AZI-1, PR-1 y CsNDR-1) se insertaron independientemente en pUC118-FMV-Poly-2-1. Posteriormente estos tres genes fueron subclonados individualmente en el vector pCAMBIA 2301, mientras que en pCAMBIA 2201 se clonó el gen AZI-1. La clonación de los genes en los vectores pCAMBIA2301 y pCAMBIA2201 permitió incorporar a las construcciones un gen de selección de transformación (35S-nptII-35S) y un gen reportero (35S-GUS-NOS). La construcción CsNDR-1 fue clonada en las cepas EHA5 y AgL1 de Agrobacterium tumefaciens. Los genes AZI-1 y PR-1 no se lograron integrar a estas cepas de Agrobacterium. Estas construcciones representan el primer paso para generar cítricos transgénicos como una alternativa para enfrentar a CLas y CTV.

Introduction: The US-Mexico region is at high risk of elevated tuberculosis (TB) incidence due to mobility and migration. Knowledge of how socio-demographic factors varies geographically, provides clues to understanding the determinants of tuberculosis and may provide guidance for regional prevention and control strategies to improve public health in Mexico. The aim of the present study was to describe the epidemiologic characteristics and spatial patterns of the incidence of tuberculosis in Tonala, Jalisco (Mexico) from 2013-2015. Methodology: The Surveillance System Database from the Health Department, complemented by information from the National Institute of Statistics and Geography, was used to obtain data for a spatial-temporal analysis of TB cases. For the geographical analysis map creation and geoinformation storing, ArcGIS software was used. Results: This study sought to characterize problem areas and jurisdictional locations of TB via a spatial approach based on analyses of case distributions and individual patient variables. The study found that tuberculosis cases were dispersed throughout Tonala County and were mainly concentrated on the Guadalajara city border. The TB cases were mainly individuals between 31 and 45 years old. Most of the cases reported during the observation period were male patients, and most cases primarily had lung involvement; however, there were quite a few cases with lymph node and intestinal disease. Conclusion: Our findings show that TB cases are essentially located in areas close to the city of Guadalajara and that most TB cases were pulmonary cases spread throughout the whole jurisdiction.

El estado de Colima es productor importante de limón, las afectaciones por efecto del Huanglonbing (HLB) han ocasionado pérdidas en forma progresiva. Hasta el momento no se conoce cura y los productores han decidido realizar cambios en la dinámica de cultivos. El objetivo de este trabajo fue cuantificar los cambios, mediante análisis espacial (PR) y herramientas del sistema de información geográfica (SIG); se realizaron clasificaciones supervisadas de imágenes Landsat 7 y Landsat 8, comprobando un progresivo aumento en la sustitución de cultivos en los últimos cinco años. Hasta el momento se han sustituido alrededor de 5000 ha de cítricos, lo que ha significado una reducción de 84 721.88 t en el volumen de producción del limón mexicano y una pérdida de 302 636 729 pesos aproximadamente.

Hyperaspis trifurcata (Coleoptera: Coccinellidae) is a native predator of the wild cochineal scale, Dactylopius opuntiae (Hemiptera: Dactylopiidae) in North America. Here we have determined its life cycle and voracity when reared on first instar nymphs of D. opuntiae and estimated its population parameters using five diets based on different developmental stages of its prey: (a) first instar nymphs, (b) second instar nymphs, (c) young adults, (d) gravid adult females, and (e) a mixed diet which included all the developmental stages. The tests were conducted under laboratory conditions: 25 ± 2 °C, 60 ± 10 % RH and 12:12 (L:D) h. H. trifurcata developmental times were 5.9, 3.1, 3.6, 3.1, 8.9 and 11.4 days for the eggs, first, second, third and fourth instar larvae, and pupae, respectively. Overall there were 36.6 days from egg to adult emergence. Females consumed a mean of 5293 ± 361 first instar D. opuntiae nymphs during their lifetime, and there was no significant difference in developmental time between males and females. H. trifurcata could complete its life cycle when reared on any developmental stage of D. opuntiae. Nevertheless, the highest fecundity (237.4 ± 25.8 eggs) was obtained when they were fed the mixed diet, and the lowest fecundity and fertility were obtained when they were fed first or second instar nymphs, with a fecundity of 57.8 ± 10 and 140.5 ± 13 eggs and a fertility of 72 and 80 %, respectively. Moreover, the mixed diet increased the net reproduction rate (Ro = 112) and prolonged the generation time (T = 68.4 days) compared with females reared on first or second instar nymphs where Ro = 27.3 and 66.3 and T = 56.2 and 62.4 days, respectively. These parameters indicate that H. trifurcata has potential as a biological control agent of D. opuntiae.

La producción de cacao (Theobroma cacao L.) en el sureste de México es afectada por la moniliasis (Moniliophthora roreri) con pérdidas superiores al 75 %. Actualmente se carece de estudios completos que analicen la relación inóculo-fructificación en la estructura epidémica para mejorar el control efectivo de la enfermedad. El objetivo del presente estudio fue evaluar el efecto de condiciones climáticas y la implicación de diferentes flujos de fructificación en el incremento de intensidad epidémica durante un ciclo productivo en el estado de Tabasco y norte de Chiapas, México. En seis plantaciones, se etiquetaron 10,621 frutos de 8 a 10 cm, asociados a seis flujos de fructificación, durante el ciclo 2011-2012. Se evaluó la incidencia de la enfermedad. Las curvas de progreso de la incidencia acumulada del ciclo productivo total y las epidemias parciales por flujo de fructificación se ajustaron a modelos temporales. Adicionalmente, se estimó el área bajo la curva de progreso de enfermedad (ABCPE) y Yf. Se analizó la relación de la incidencia con la temperatura, humedad relativa y número de frutos. La enfermedad ocurrió durante 10 meses, con incidencia promedio de 75.8 %. La incidencia absoluta semanal se relacionó positivamente con el número de frutos (r = 0.55-0.82), número de horas/semana de temperatura en el intervalo de 20 a 26 °C (r = 0.41-0.87) y humedad relativa mayor a 60 % (r = 0.40-0.67). El ABCPE (14,132-8186), Yf (54.5-88.7 %) y tasas Weibull (0.003-0.005) de epidemias anuales indicaron epidemias policíclicas. El análisis epidémico parcial por flujos de fructificación evidenció tasas contrastantes (P = 0.05) entre una epidemia monocíclica (R2 = 0.92-0.99) del primer y segundo flujo, y epidemias policíclicas de flujos subsecuentes (R2 = 0.93-0.99), indicativo del efecto del inóculo primario, seguido de una combinación de éste con el inóculo secundario, con incrementos significativos a través del ciclo productivo. Los resultados sugieren que un control efectivo de la moniliasis debe considerar estas dos fuentes de inóculo, así como el empleo de alertas predictivas climáticas y la dinámica de fructificación subregional.

Cercospora agavicola, agente causal de la mancha gris del agave azul (Agave tequilana), es un hongo reglamentado bajo control oficial en estados bajo Denominación de Origen del Tequila (DOT). Este trabajo se desarrolló en Jalisco, México, principal región DOT, para determinar la inductividad epidémica espacio-temporal del hongo y desarrollar modelos estocásticos de pronóstico de la mancha gris con el fin de sustentar acciones preventivas regionales. De octubre 2016 a diciembre 2017 se evaluó mensualmente la severidad, incidencia y número de plantas enfermas en 41 parcelas establecidas en plantaciones comerciales de agave de 3-4 años de edad seleccionadas con criterios ponderados de riesgo en Los Altos (20), Valles (11) y Sur (10). La inductividad epidémica regional de C. agavicola fue heterogénea con mayor riesgo para al menos nueve municipios de Los Altos. Sin embargo, bajas tasas epidémicas (0.0008-0.006 unidades semana-1), fuerte restricción de contagio (1-4 plantas), reducido incremento anual de incidencia (0-32 plantas/0.5 ha) y nula captura de esporas evidenciaron la baja aptitud parasítica y epidémica del hongo. Consecuentemente, se encontró limitada capacidad predictiva aun con los mejores modelos generados (R2adj 0.51-0.60). Las horas favorables (HFav) de enero-abril, respecto a la infección, fue consistente entre modelos por lo que puede integrarse como algoritmo preventivo en SIVEA (www.sivea.org.mx). Las pérdidas regionales, bajo los parámetros epidémicos establecidos, se estimaron entre 98.01 MDD y 237 mil dólares americanos. La cercosporina, toxina asociada al género Cercospora, puede estar implicada en el progreso temporal lineal atípico y debe integrarse en futuras investigaciones.

Este trabajo tuvo la finalidad de investigar la presencia de fitoplasmas asociados a síntomas similares al HLB, enfermedad causada por CLas, con el propósito de optimizar los procesos de muestreo y diagnóstico en el marco de acciones fitosanitarias oficiales en la citricultura Mexicana. A partir de alertas de resultados negativos a CLas en árboles de Citrus spp con síntomas putativos de HLB se realizaron muestreos dirigidos en huertos comerciales y traspatios en Hidalgo, Colima, Puebla y Veracruz en 2012, 2013 y 2018. El ADN total se analizó por PCR con los iniciadores P1/P7 anidados con R16F2/R16R2 y D7f2/D7r2. La infección de CLas se determinó con los iniciadores A2/ J5. Se confirmó en México la presencia del Brazilian Huanglongbing disease-associated phytoplasma, miembro del grupo 16Sr IX, asociado a C. latifolia (NCBI, MK282760) y C. aurantifolia (NCBI, MK282761) induciendo síntomas similares pero contrastantes a los causados por CLas. Estos hospederos se reportan por primera vez en adición al original reporte en C. sinensis en Brasil. También se reporta a Bidens odorata y Cajanus cajan como probables hospederos arvenses alternos y la presencia de especímenes de Graphocephala y Acinopterus (Cicadellidae), géneros reconocidos con especies vectoras de fitoplasmas de los grupos 16Sr III-A y Aster Yellow, respectivamente.

The Asian citrus psyllid (ACP), Diaphorina citri , is an important pest of citrus, which transmits the disease Huanglongbing (HLB) and has had devastating effects on the citrus industry around the world. Control relies mainly on synthetic pesticides, but biological control using entomopathogenic fungi may provide an alternative strategy. We evaluated sixteen fungal isolates in total; three of Beauveria bassiana , two of Metarhizium anisopliae , three of Isaria fumosorosea (Group 1); and eight isolates of Hirsutella citriformis (Group 2). The in vitro growth, germination (after different incubation times) and sporulation were assessed for all isolates at four temperatures: 20, 25, 30 and 35 °C. Overall, the Group 1 isolates achieved the greatest growth, germination rate and sporulation compared with the H. citriformis isolates In Group 2. Among the Group 1 isolates, B1, M2 and I1 had the greatest performance in the biological attributes evaluated. Group 2 isolates were not competitive under in vitro assessment; however, they cannot be dismissed entirely until in vivo experiments are done as this species was the most common pathogen infecting ACP in the field.

The Asian citrus psyllid, Diaphorina citri, is an important pest of citrus, which transmits the disease Huanglongbing with devastating effects on the citrus industry around the world. Control relies mainly on synthetic pesticides, but biological control using entomopathogenic fungi may provide an alternative strategy. Based on previous in vitro experiments, we selected four isolates, one from each of the species Beauveria bassiana, Metarhizium anisopliae, Isaria fumosorosea and Hirstella citriformis. With these isolates, we carried out in vivo experiments to select an isolate based on its infection ability against adult D. citri. Using only H. citriformis isolates, we evaluated the mortality in D. citri achieved using blastospores. As a potential cause of the low mortality achieved with H. citriformis, we evaluated the effect of inoculum carrier (Tween 80 or distilled water) on conidial germination. We also compared the pathogenicity of dry conidia (not suspended in 0.03% Tween 80) of H. citriformis and M. anisopliae against adult D. citri. Using conidial suspensions, all isolates caused mortalities above 80% in adult D. citri cohorts, except H. citriformis, which caused a maximum of 40% mortality. The mortality caused by blastospore suspensions of H. citriformis, were 60%. Tween 80 solution and distilled water significantly reduced the germination of H. citriformis conidia. Dry conidia of H. citriformis and M. anisopliae caused 100% mortality. Our results suggest that using a combination of biological control approaches, both inundative (using M. anisopliae or I. fumosorosea isolates in suspension) and inoculative (using H. citriformis as dry conidia in autoinoculation devices), has good biological control potential. The suitability of the combined use of these two biological control approaches for management of D. citri is discussed.

Objectives The objectives of this study were to analyse the frequency of gene mutations associated with antitubercular drug resistance in clinical samples from the population of Jalisco State (Mexico) and to evaluate the genetic variability of Mycobacterium tuberculosis and multidrug-resistant (MDR) M. tuberculosis strains to describe the frequency of various families. Methods Clinical isolates of M. tuberculosis obtained from Jalisco State were analysed. Isolates were subjected to drug susceptibility testing, and mutations were characterised by sequencing, followed by genotyping using spoligotyping and mycobacterial interspersed repetitive units–variable-number of tandem repeats (MIRU-VNTR). Moreover, the prevalence of mutations was analysed by phylogenetic lineages. Results Resistant strains were analysed by sequencing of katG , inhA and rpoB genes to determine the presence of mutations associated with isoniazid and rifampicin resistance. In MDR, monoresistant and polyresistant isolates, mutations were found in 17 (54.84%) of 31 strains. Spoligotyping identified six different strain lineages [T1 (25.40%), H3 (7.94%), MANU (4.76%), X1 (3.17%), EAI5 (1.59%) and LAM1 (1.59%)], with the remaining strains identified as orphans. In additional tree-based identification, a dendrogram of spoligotype patterns generated five different similarity clusters. When combining 24-loci MIRU-VNTR and spoligotyping approaches, the results shows that there is no cluster formation, indicating low transmission of the samples. Conclusions This study using spoligotyping and MIRU-VNTR showed that the analysed strains were not related to each other since no two identical strains were found. Families with the highest prevalence in the study were orphans followed by T family.

The spatiotemporal distribution of strawberry wilt, caused by Fusarium oxysporum, Phytophthora sp., Pythium aphanidermatum and Rhizoctonia fragariae, was studied with the aim to establish the effect of some technological components of the strawberry crop cv. Camarosa (Fragaria x ananassa Duch.) and sustain their use in an integral management of the disease. Epidemics were characterized in two cropping seasons at three localities in Valle de Zamora, Michoacan, Mexico, in commercial plantations with plastic mulch and drip irrigation (A+G), and non-mulch and gravity irrigation (T) on a 100 m2 area per site. Temporal parameters were contrasting between both management techniques. A+G plantations had significantly lower final incidence (Yf =12.8±5.6%) than T (22.5±5.9%) (p=0.05) and were consistent with estimators of area of curve (ABCPEa and ABCPEe). The range of epidemic intensity reduction induced by A+G was 22.21 to 76.7% day, which was reflected in lower apparent infection rates (b-1=0.0015-0.0027, R2=0.92-0.99). Lloyd’s Index of Patchiness and Morisita Index (1.01 to 1.17) indicated a slightly aggregated dispersion pattern. Autocorrelation and geostatistical analysis confirmed lower aggregates in A+G (up to 5 plants) vs. T (8 plants), but an apparent higher mobility of inoculum in A+G up to 6.5 m. Plastic mulch and drip irrigation are proposed as technological components of an eventual integrated management program of dry wilt in Michoacan. Key words: Epidemiology, plastic mulch, drip irrigation, strawberry dry wilt.

During 2006, laboratory studies were conducted to evaluate the pathogenicity of seven isolates of Pandora neoaphidis (Remaudiere & Hennebert) against the cabbage aphid, Brevicoryne brassicae (L.). Two isolates were obtained from the aphids Rhopalosiphum padi (L.) (TEXRP1), and Myzus persicae (Sulzer) (TEXMP1), infesting broccoli (Brassica napus (L.)) in Texcoco, Mexico; the rest of the isolates were obtained from Rhopalosiphum maidis (Fitch) infesting sorghum (Sorghum bicolor (L.) Moench), in five localities in Tamaulipas, Mexico. The greatest percentages of mortality were caused by isolates RBF, TEXRP1, y RBB, at a rate of 87, 76, y 72%, respectively, 240 hours after the initiation of the treatments. These results show the potential of P. neoaphidis as an agent of biological control against B. brassicae, depending of the place and the origin of the isolate.

Aims: To evaluate different entomopathogenic fungal isolates against the cactus weevil Metamasius spinolae under laboratory and field conditions, and select an isolate to be used as a tool in the management of this insect pest. Methods and Results: Four experiments were carried out. The effect of temperature on the in vitro growth of eight isolates of entomopathogenic fungi (two Metarhizium anisopliae and six Beauveria bassiana) was assessed. The susceptibility of adult M. spinolae to the same isolates was evaluated. Using three selected isolates, the interaction between susceptibility and sex of the insect was studied. Finally, a field experiment was carried out to evaluate infection of adult M. spinolae by the same three isolates under natural abiotic conditions. Overall, growth rate was greatest at 25°C for all the isolates. In vitro growth of M. anisopliae was greater than B. bassiana. Mortality of adult M. spinolae was greater when inoculated with B. bassiana compared with isolates of M. anisopliae. Susceptibility had no interaction with the sex of the insect. The proportion of insects succumbing to infection was smaller when incubated under field conditions than when incubated under laboratory conditions. Conclusions: The experiments described here showed a complex interaction between entomopathogenic fungi and M. spinolae, and these data allows us to select isolate Bb107 as a first step towards its use in the management of this pest insect. Significance and Impact of the Study: Our results showed that entomopathogenic fungi can be used for the control of M. spinolae, which may help reduce the use of chemical insecticides and, therefore, the exposure of Opuntia ficus-indica producers to pesticides.

El nopal Opuntia ficus-indica se cultiva con diversos propósitos en el mundo, mientras que en México, principal productor y consumidor mundial, particularmente se consume como verdura (nopalitos). La producción de nopalitos se ubica, principalmente, en los alrededores de la Ciudad de México donde las cochinillas silvestres Dactylopius spp. son de los insectos más nocivos para el cultivo. El control químico es el método de más uso por los productores, aunque el control biológico podría ser útil para un manejo integrado de plagas. No obstante, los estudios taxonómicos sobre las especies de cochinilla y sus enemigos naturales en México no son abundantes. En esta investigación se planteó conocer las especies presentes de Dactylopius y sus enemigos naturales en Tlalnepantla, Morelos, una de las áreas de mayor producción de nopalitos en México. Se seleccionaron 30 sitios distribuidos en esta región y se establecieron cinco sitios para monitoreo de enemigos naturales cada dos semanas durante un año. La única especie de cochinilla silvestre del nopal que se encontró correspondió a Dactylopius opuntiae (Cockerell), los enemigos naturales en orden de abundancia fueron Leucopis bellula, Sympherobius barberi, Laetilia coccidivora, Hyperaspis trifurcata, Salpingogaster cochenillivorus, Sympherobius angustus y Chilocorus cacti. Se proporcionan descripciones de biología de los enemigos naturales en campo y laboratorio. Diversos factores relacionados con el manejo del cultivo tuvieron un efecto sobre las poblaciones de D. opuntiae y sus enemigos naturales.

1 INIFAP-Campo Experimental Rio Bravo, Km 61 Carretera Reynosa-Matamoros, Apdo. Postal 172, 88900, Rio Bravo, Tamaulipas, Mexico Departments of Seed Production, Genetics, Phytopathology, and Botany, Colegio de Postgraduados, Campus Montecillo, Km. 36.5 Carretera Mexico-Texcoco, 56230, Montecillo, Estado de Mexico (E-mail: leopoldo@colpos.mx) 5 INIFAP-Campo Experimental Bajio, Km. 65 Carretera Celaya-San Miguel Allende, Apdo. Postal 112, 38810, Celaya, Guanajuato, Mexico

Sorghum ergot (caused by Claviceps africana) is a disease that affects sorghum seed development and yield. The interaction between pollen tube growth and hyphal development determines whether ovaries will be fertilized or colonized. Thus their respective deposition times on the stigma are critical. The effect of the time interval between pollination and inoculation on stigma receptivity and seed production was measured under field conditions in the male-sterile line A9 at Montecillo, State of México (2240m altitude). Pollination and inoculation treatments, from simultaneous application to 2 and 4h difference, were imposed when all stigmas on the panicle had emerged. Control panicles were either only pollinated or only inoculated. Eighteen hours later, pollen grains that adhered to, and germinated within the stigma, pollen tubes in the style and ovary, and fertilized pistils were counted. Pistils showing some disease expression (germinated spores, mycelium growth, or tissue necrosis) at 18, 48, and 72h were recorded. The number of diseased florets was registered at the dough growth stage, while number of seeds, grain yield and 100-seeds weight was measured at the physiological maturity. The pathogen applied in a water suspension of macro and secondary conidia caused a decrease in stigma receptivity; the greatest decrease (40-60%) occurred when the pollen and the inoculum were deposited almost simultaneously, regardless of which was deposited first. The route of the pollen tube was also the route for fungal infection. On average, treatments first inoculated had 60% more diseased florets and 36% less grain yield, 30% fewer seeds and seed size decreased 8%, than those first pollinated.

In A-lines of sorghum (Sorghum bicolor L. Moench), seed production under field conditions with manual pollination is generally lower than that in self- pollinated B-lines. This may be associated with floral differences. Six pairs of A/B-lines and four R-lines were evaluated during 2005 and 2006 at Montecillo, State of Mexico (2240 m altitude). Rachis length, number of primary branches and fertile flowers per panicle, 100-seed weight, seed number, seed yield and seed set per panicle were evaluated. In the A-lines, the pistil characteristics were also measured and in the male-fertile lines, the size of anthers and the amount and size of viable pollen were recorded. Compared with the A- and B-lines, the R-lines exhibited significantly higher (P £ 0.05) numbers of flowers, seed set and seed yield per panicle and they also produced more pollen grains of larger size and with greater viability during their longer flowering period (FP). Between A- and B-lines, there were differences (P £ 0.05) in most of the yield traits, which also interacted with year. The proportion of viable pollen in B- and R-lines (75 %) was not considered to be a factor that might account for their low seed production. Chilling temperatures (3.5-8.4 � C) during the FP could have affected stigma receptivity in the three different line types and thus may have reduced seed set in the male-fertile lines.

SUMMARYSix pairs of isogenic lines of sorghum (Sorghum bicolor L. Moench) were sown in field plots in Montecillo, State of México (2240 m altitude), in 2005 and 2006. Crosses A (♀)×B (♂) were done in each pair. In A-lines, the length of pistil, stigma, style and ovary, as well as the ovary width, were measured. In B-lines, pollen diameter, viability (cytoplasm density) and production were evaluated. Pollen germination and pollen tube growth in the pistils of the A-lines, were quantified in vivo with aniline blue and epifluorescence 18 h after pollination (HAP), while fertilized pistils were counted at 96 HAP. Histological studies on both pollinated and non-pollinated pistils were performed in one male-sterile line. Seed yield, mean-seed weight, seeds per panicle and seed set (SS; seeds/flower/panicle) were determined at harvest. Pollen viability was the variable most related to pollen germination and pollen tube growth. Stigma receptivity was not associated with its morphology. Growth of the pollen tube in stigma, style and ovary was observed in the transmitting tissue 18 HAP, running parallel to the vascular tissue. Yield under chilling field temperatures (minimum average of 6 and 8°C) prevailing during flower development and pollination ranged from 7 to 12 g/panicle. The differences in seed production and SS among A×B crosses did not depend on the amount and viability of pollen.

Se analizó la sobrevivencia de Salmonella typhimurium sola y asociada con Rhizopus sp. en frutos de melón 'Cantaloupe' (Cucumis melo L.) var. reticulatus durante el almacenamiento en frío con atmósferas controladas (AC). Frutos de tamaño uniforme se inocularon con 8.2 log10 UFC de una cepa de S. typhimurium ATCC2356, resistente a kanamicina (Km), y se almacenaron en las atmósferas: AC1 con O2 3 %, CO2 12 % y N2 85 %; AC2 con O2 5 %, CO2 15 % y N2 80 %; y aire con O2 20.95 %, CO2 0.03 % y N2 78.08 %, a 3.7 ºC y humedad relativa (HR) de 93.6 ± 5.9 % por 192 h. Cada 48 h se extrajo un fruto en el que se tomaron muestras de tejido inoculado para pruebas de detección en agar entérico Hektoen con Km (50 μg mL-1). Los resultados mostraron que S. typhimurium puede sobrevivir en la superficie del fruto en las atmosferas refrigeradas AC1, AC2 y aire; sin embargo, bajo estas condiciones la población bacteriana registró un decremento (P ≤ 0.05) de 3.7, 4.3 y 4.75 log10 UFC por fruto, respectivamente. La presencia de Rhizopus sp. no afectó la capacidad de sobrevivir de la bacteria ni el nivel de su población en AC2 y aire en condiciones similares de temperatura y HR. Se evidencia así la capacidad de S. typhimurium para sobrevivir en atmósferas con alta concentración de CO2 y condiciones adversas de temperatura, así como de la importancia de prevenir la contaminación del melón 'Cantaloupe' durante su producción y comercialización.

El Virus de la tristeza de los cítricos (VTC) causa una enfermedad de interés regulatorio para la citricultura mexicana. El diagnóstico y un muestreo oportuno y confiable es esencial para aplicar estrategias de manejo ante el avance en territorio nacional del pulgón café, su principal vector. Con el fin de contar con un método eficaz y eficiente para el muestreo y detección del VTC, se evaluó el desempeño del método de inmunoimpresión-ELISA con respecto a DAS-ELISA, el método oficial de diagnóstico, debido a su economía, facilidad y rapidez. Con este propósito se evaluaron 7,421 árboles, considerando la edad del brote y de infección, provenientes de 11 huertos comerciales de Tamaulipas. El método de inmunoimpresión-ELISA superó en sensibilidad y capacidad de pronóstico de positivos a DAS-ELISA en el diagnóstico de árboles con infección reciente o desconocida del VTC (P¿0.028). La disposición de brotes positivos en el dosel fue heterogénea siendo descrita por la función beta binomial (P¿0.16-0.23). Con base en esta función y la reproducción de los resultados de impresiones dobles por pecíolo (93.2 %) se sugiere un tamaño óptimo de muestra de 10 pecíolos por árbol en impresiones simples. Este método fue 54.9 % más económico que DAS-ELISA y los diagnósticos se realizaron en una sexta parte del tiempo requerido en esta última prueba. Sin embargo, por el requerimiento de la norma oficial mexicana vigente (NOM- 031-FITO-2000), se recomienda el método de inmunoimpresión-ELISA como un método rápido para discriminar árboles positivos en muestreos de campo que deben posteriormente ser verificados por el método oficial de diagnóstico.

El efecto de barreras vegetales como componente de un programa de manejo integrado (MI), se validó y adaptó en 1999 en Michoacán, México, para controlar la Mancha Anular del Papayo, enfermedad causada por el Papaya ringspot potyvirus type-P (PRSV-P). Se estableció un experimento en parcelas divididas con dos factores experimentales: barreras vegetales (Hibiscus sabdariffa), y componentes de MI: MI sin aspersión de citrolina (1.5%) (MI-A), MI sin eliminación de plantas con síntomas iniciales de virosis antes de floración (MI-D) y MI. Las barreras vegetales sembradas 20 días antes del trasplante del papayo y el desplante retrasaron en 19 días el inicio del progreso de epidemias en el MI lo que resultó en una mayor producción (14.2%) que el resto de tratamientos, aunque fue superado por MI-A en vigor (4% en diámetro de tallo). La citrolina fue fitotóxica, disminuyó el vigor de plantas (5.3%) y no limitó significativamente el desarrollo de la enfermedad ya que la intensidad de las epidemias (X0 = 47días, Yf = 84% y ABCPE = 3220% días) fue similar al testigo. El uso de barreras vegetales por si sola aparentemente no es suficiente para la reducción de la incidencia y dispersión de la enfermedad. Los áfidos más abundantes, con reconocida capacidad transmisora del PRSV-P, fueron Aphis gossypii, A. nerii, A. spiraecola y Macrosiphum euphorbiae, los cuales representaron aproximadamente el 13% del total de áfidos capturados.The effect of plant barriers as a component of an integrated management program (IM) was validated and adapted in 1999, in Michoacan, Mexico, to control papaya ringspot, caused by papaya ringspot potyvirus type-P (PRSV-P). A split-plot design was established with two experimental factors: plant barriers and components of IM: IM without oil sprinkling (IM-O), IM without plant rouging (IM-R), and complete IM. Plant barriers (Hibiscus sabdariffa), sowed 20 days before papaya transplanting, and plant rouging delayed the epidemics onset in 19 days thus IM resulted in the highest yield (14.2%) than the rest of the treatments, but it was less effective than IM-O in vigor (4% in stem diameter). Oil sprinkling was phytotoxic and caused a 5.3% vigor reduction. The oil effect on the disease progress was not clear, since the epidemic intensity (epidemic onset X0 = 47 days after transplanting, final incidence Yf = 81% and area under disease progress curve ABCPE = 3220 %days) was similar to the control treatment. Plant barriers alone may not be sufficient to reduce disease incidence and spreading. The more abundant winged aphids known as PRSV-P vectors were Aphis gossypii, A. nerii, A. spiraecola and Macrosiphum euphorbia, which represented approximately 13% of the total captured aphids.

The Toluca Valley, located in the central highlands of Mexico, has optimal climatic conditions for the development of Phytophthora infestans as well as for sexual reproduction due to the presence of two mating types (1:1, ratio). Therefore, it is a suitable place to study late blight epidemics on cultivated potatoes. In order to quantify oospore formation on foliage during the progress of late blight epidemics and to establish the implications of (a) genetic resistance of the host, (b) disease management (fungicide application), and (c) environmental conditions, a study was conducted in the summer of 2002 and 2003 on two potato cultivars during the progress of the epidemic under rainfed and natural infection conditions in the Toluca Valley. The cultivars were exposed to 0.0, 0.5, and 1.0× doses of the protectant fungicide chlorothalonil (1.0× = 1.15 kg a. i. ha−1). Oosporulation started 56 and 46 days after planting (2002 and 2003, respectively) with a maximum peak at 72 days in the two growing cycles. The total number of oospores in both years on cultivar Zafiro, resistant to P. infestans, was higher than on susceptible cv. Alpha (101 vs. 67). However, there were no statistically significant differences (P = 0.40), which suggests that the resistance level of the host did not have a direct influence on oospore formation. The epidemics obtained from each of the treatments were characterized through multivariate analysis. Initial severity (Yo), as a percentage of damage from total foliage, time of total epidemic duration (T t ), and average of apparent infection rate (b −1) were the variables that best explained the epidemics. These epidemics were organized into four groups. The group with an average rate of apparent infection of 0.010–0.015 units day−1 and a duration of more than 50 days allowed higher oospore formation, regardless of host genotype. The nine days accumulated rainfall prior to the formation of oospores had a significant positive correlation (r ≥ 0.7) with the absolute number of oospores per leaflet. It is concluded that oosporulation depended more on environmental factors (rain) and on the induction of slow epidemics (disease management), than on the genetic makeup of the host.

Sixteen barley cultivars with a suscep- tible infection type (IT = 7-8) in the seedling stage to an isolate of race 24 of Puccinia striiformis f. sp. hordei were planted at two locations in Mexico. Disease severity (DS) parameters were assessed for the flag leaf and for the upper three leaves. The cultivars represented at least five levels of quanti- tative resistance ranging from very susceptible to quite resistant. ''Granado'', ''Gloria/Copal'' and ''Calicuchima-92'' represented the most resistant group and had an IT of 7 or 8. The culti- var · environment interaction variance, although significant, was very small compared with the cultivar variance. The disease severity parameters were highly correlated. The monocyclic parameter DSm, measured when the most susceptible cultivar had reached its maximum DS, was very highly correlated with the area under the disease progress curve (AUDPC), r being 0.98. Components of quantitative resistance were evaluated in two plant stages. In the seedling stage small cultivar effects for the latency period were observed, which were not correlated with the quantitative resistance measured in the field. In the adult plant stage the latency period (LP), infection frequency (IF) and colonization rate (CR) were measured in the upper two leaves. The LP was much longer than in the seedling stage and differed strongly between cultivars. The differences in IF were too large, those in CR varied much less. The components showed association with one another. The LP and IF were well correlated with the AU- DPC (r = 0.7-0.8).

A ferrugem branca, causada pelo fungo Puccinia horiana, é considerada a principal doença do crisântemo no Brasil, induzindo severas perdas aos produtores. Apesar da importância, inexistem estudos epidemiológicos no país, e para que estes estudos sejam realizados, é necessário o desenvolvimento de métodos padronizados de quantificação da severidade da doença no campo. Visando atender a essa demanda, foi elaborada uma escala diagramática com os níveis de 1, 3, 6, 10, 18 e 30% de área foliar lesionada, testando-se a acurácia, a precisão e a reprodutibilidade das estimativas de severidade da ferrugem branca com e sem a sua utilização. Na validação da escala diagramática, 50 folhas com diferentes níveis de severidade da doença, mensurados previamente com o programa AutoCADâ, foram avaliadas por 10 pessoas sem e com a utilização da escala diagramática. Foram realizadas duas avaliações com a utilização da escala, com intervalo de sete dias, onde seqüências diferentes das mesmas folhas foram estimadas visualmente pelos mesmos avaliadores. A acurácia e a precisão de cada avaliador foi determinada por regressão linear simples, entre a severidade real e a estimada. Sem o auxílio da escala, todos os avaliadores superestimaram consistentemente a severidade, indicando a presença de desvios positivos constantes para todos os níveis de severidade da doença. As avaliações realizadas com a escala diagramática foram mais acuradas nas estimativas da maioria dos avaliadores e mais precisas para todos os avaliadores, além de proporcionar boa repetibilidade e elevada reprodutibilidade entre avaliações de diferentes avaliadores. A escala diagramática mostrou-se adequada para avaliação da severidade da ferrugem branca do crisântemo.White rust, caused by Puccinia horiana, is considered the major disease of Chrysanthemum in Brazil, which results in severe losses for the growers. Despite of its economic importance, very few epidemiological studies have been carried out in Brazil. In order to conduct these studies it is necessary to develop standard methods to quantify disease severity under field conditions. Therefore, a diagrammatic key, including the levels 1, 3, 6, 10, 18, and 30% of diseased leaf area, was elaborated. The severity of the white rust was estimates using the key or not in order to test its accuracy, precision and reproducibility. The diagrammatic key was validated by 10 raters using 50 leaves with different levels of severity, which were previously measured by the AutoCAD® software. Two evaluations were performed with the key at 7-day intervals when different sequences of the same leaves were visually estimated by the same raters. The accuracy and precision of each rater were determined by using simple linear regression between actual and estimated severity. When the key was not used, all raters overestimated disease severity indicating the presence of constant positive errors for all levels of disease severity. The evaluations using the diagrammatic key were more accurate for the great majority of the raters and more precise for all the raters. In addition, the key also showed good repeatability and high level of reproducibility among the evaluations from the different raters. The diagrammatic key is suitable for the evaluation of severity of white rust of Chrysanthemum.

Abstract Population densities, population fluctuations, yield loss and disease incidence caused by Nacobbus aberrans on tomato (Lycopersicon esculentum) were studied, using an epidemiological approach, in a field experiment that included three different control regimes: an integrated control (IC) scheme, which included fertilisation, nematicide (ethoprop) and chicken manure; a technical control (TC) scheme, based on the best local practices of fertilisation and use of carbofuran for nematode control; and a check treatment (AC), with no application of fertilisers or nematicide. At least three generations of N. aberrans occurred through the cropping season and the numbers of galls/plant and females/g of root through the crop season were used to define the area under a disease progress curve (AUDPC). The variables b−1 (Weibull's apparent infection rate), AUDPC and Yf (final disease incidence) indicated less crop damage under the IC scheme than under the other two schemes (TC and AC). The IC scheme resulted in increased plant height (41-49%), foliage dry weight (37-53%) and stem diameter (31-41%) compared with the TC and AC schemes. Tomato yields in IC surpassed those from TC and AC by 34 and 83%, respectively, while TC exceeded AC by 73%. The yield loss attributed to N. aberrans was 12, 29 and 83% in IC, TC and AC, respectively. The IC scheme improved commercial production by 20 and 81% in comparison to the TC and AC schemes. This was largely due to effective control of the initial inoculum density, which affects the first generation of the nematode population; control of this generation is essential for avoidance of yield loss. The first generation is completed during the period 0-60 dat (days after transplanting), i.e., during the critical stages of flowering, fruit initiation and fruit set (40, 50 and 60 dat). Data on plant performance taken every 10 days were used to derive a multiple point model for calculation of production loss.