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Thirty eight isolates of Phytophthora cinnamomi from five counties in Michoacan, Mexico, were genetically analyzed using amplified fragment length polymorphisms (AFLP) to determine the genetic variability and the existing relationships among the avocado isolates. The amplifications showed 296 bands. A genetic dissimilarity matrix was obtained in this trial by means of the multiple coupling coefficient and the hierarchical grouping method, also called non-weighted average method. The resulting dendogram showed two levels of association. The isolates were classified within two main groups associated with the geographical location from which they were obtained. The analysis and determination of the confidence levels demonstrated that these geographical groups are strong. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa es una de las enfermedades más importantes a nivel mundial, el manejo de sus vectores es una de las estrategias más viables para su control. La presente investigación se realizó en el Laboratorio de Entomología y Acarología del Departamento de Parasitología Agrícola de la Universidad Autónoma Agraria Antonio Narro (UAAAN). Se evaluaron 21 extractos de plantas sobre Cuerna costalis proveniente de muestreos de vid y nogal, estos se multiplicaron sobre frijol bajo condiciones de laboratorio. Para el establecimiento del ensayo se utilizó el método de prueba 005 del IRAC con ligeras modificaciones, en un arreglo completamente al azar con 8 concentraciones y 10 repeticiones evaluando a las 120 h. La mortalidad se corrigió acorde a Abbott (1925) y se realizó un Análisis Probit, asimismo se determinaron los principales compuestos fitoquímicos presentes en los extractos mediante el espectrofotómetro infrarrojo. Los resultados muestran una alta susceptibilidad a los extractos de uña de gato (Mimosa zygophylla), sangre de drago (Jatropha dioica), pimienta negra (Piper nigrum), canela (Cinnamomum verum), y mezquite (Prosopis laevigata) con una CL50 de 1166, 1275, 1433, 1459, y 1478 ppm, respectivamente. Los metabolitos presentes en la mayoría de los extractos eficientes fueron ácido tartárico, 1,8-cineol, eugenol, grupos de saponinas, flavonoides, y compuestos fenólicos. Xylella fastidiosa is a very important disease worldwide. Vector management is one of the viable strategies for control. This research was done in the Entomology and Acarology Laboratory of the Department of Agricultural Parasitology at Universidad Autónoma Agraria Antonio Narro (UAAAN). Twenty-one plant extracts were evaluated on Cuerna costalis from grapevine and pecan samples, subsequently multiplied on beans under laboratory conditions. IRAC test method 005 was used with slight modifications, using a completely randomized design with eight concentrations and 10 replications evaluated at 120 hours. Mortality was corrected according to Abbott (1925) and a Probit analysis was done. The main phytochemical compounds in the extracts were determined using an infrared spectrophotometer. Results showed high susceptibility to cat's claw extracts (Mimosa zygophylla), dragon's blood (Jatropha dioica), black pepper (Piper nigrum), 1166, 1275, 1433, 1459, 1478 ppm, respectively. The metabolites in most of the extracts were tartaric acid, 1, 8-cineole, eugenol, saponin groups, flavonoids, and phenolic compounds. [ABSTRACT FROM AUTHOR]

Introduction: Bactericera cockerelli is an insect pest that damages Solanaceous crops, mainly potato (Solanum tuberosum L) and tomato (Solanum lycopersicum Mill). The B. cockerelli management has been the chemical control, however, attempts have been made to implement other control strategies with less toxic insecticides for the environment, human health, and non-white insects. This implementation consists of including biological control organisms such as predators, parasitoids, insecticides of natural and botanical origin, entomopathogenic fungi and chemical insecticides with less impact on beneficial fauna. In order to deepen these interactions, the present work determined the median lethal concentration (LC50) of insecticides on B. cockerelli populations and its parasitoid Tamarixia triozae. With these data, the selectivity percentage (SP) of different insecticides with the parasitoid T. triozae was calculated. Method: Bioassays were performed using the immersion method evaluating six different insecticides; Profenofos and Cypermethrin of chemical origin; Azadirachtin and AEC (Essential oils of citrus with cinnamon and soap of vegetable oils) of botanical origin; strains of Beauveria bassiana and Metarhizium anisopliae from biological origin. With the data obtained, selectivity was determined using the Selectivity Ratio (PS), dividing the LC50 of the product over the natural enemy by the LC50 of the product over the pest insect, where values equal to or greater than one indicates selectivity. Results: The insecticide products evaluated showed mortality in B. cockerelli and its parasitoid T. triozae. The lowest selectivity ratio was for Cypermethrin (PS = 0.01) and only M. anisopliae showed selectivity with T. triozae when obtaining a value of PS = 3.58. The other insecticides showed PS values less than one, so they were considered non-selective for parasitoids. Conclusion: The lowest proportion of selectivity was for Cypermethrin (PS = 0.01) and only M. anisopliae showed selectivity with T. triozae when obtaining a value of PS = 3.58. The other insecticides showed PS values lower than one, so they were considered non-selective. [ABSTRACT FROM AUTHOR]

Bactericera cockerelli is an economically relevant pest of solanaceous crops. The presence of leaf trichomes that certain wild species have constitutes important genetic resources for plant breeding programs in terms of resistance to pests. In this study, the influence of leaf trichomes of wild species and commercial tomato cultivars on the preference, development and fecundity of B. cockerelli was evaluated. The results showed that wild species were less preferred by the psyllid than commercial cultivars. Insects showed a lower settlement percentage in S. habrochaites compared to the other species. Regarding survival, the lowest percentage developed in S. habrochaites with 24% and S. arcanum with 40%. The lowest oviposition average was found in S. habrochaites with two eggs, which did not hatch, in addition to being the only species that showed the presence of glandular trichomes type IV (113.86 ± 48.1) and VIc (27.3 ± 2.3) per mm2, and its presence was negatively correlated with the number of perched adults. S. arcanum was another species that negatively influenced the behavior and development of the insects; however, these attributes were not due to the presence of trichomes. The defense mechanisms expressed by S. habrochaites and S. arcanum towards B. cockerelli can be used as a resource for gene introgression for the management of this pest by reducing its biological potential. [ABSTRACT FROM AUTHOR]

The objective was to determine differences in antioxidant enzyme activity and total phenol concentration in Mexican lime plants (Citrus aurantifolia (Christm.) Swingle), Persian lime (Citrus latifolia Tanaka); and Valencia sweet orange (Citrus sinensis (L.) Osbeck). Infected under natural field conditions with Candidatus Liberibacter asiaticus (CaLas), in Bustamante, Tamaulipas, Mexico. The presence of CaLas was determined by qPCR. We determined the enzymatic activity of phenylalanine ammonia lyase (PAL), which is activated by pathogen attack; the peroxidase involved in wall lignification in response to infection; the α-amylase which degrades starch and accumulates in vascular tissue; and phenolic compounds involved in defense functions. A contrasts analysis was performed. Total protein concentration showed significant differences between species (P<0.0001). With a mean of 6.1 and 6.37 mg of protein per g of fresh tissue for infected Mexican lime trees, and sweet orange negative CaLas. The peroxidase activity presented a significant difference for Persian lime (P=0.0341), with a mean of 1.96 U.mg of protein-1. In sweet orange, higher α-amylase activity was observed in CaLas infected trees (1.19 U.mg protein-1). The concentration of PAL and total phenols did not show significant differences between species. In the present study it was observed that CaLas influences the enzymatic activity of Citrus species. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum L.) plants have developed or adapted over time efficient defense mechanisms against insect attack. Because the mechanisms often fail to be effective enough, alternatives are needed to help counteract attacks by pests. Sodium menadione bisulfite (MBS), a compound derived from vitamin K3, possesses insecticidal properties. In this work, bioassays were done to verify insecticidal effect of MBS on Bactericera cockerelli (Sulc) and Bemisia tabaci (Gennadius). MBS killed more than 80 and 60% of the insects evaluated, with LC50 of 54.79 and 521.72 ppm, respectively. MBS also deformed B. cockerelli adults hatched from nymphs exposed to concentrations of MBS tested under in vitro conditions. Therefore, menadione can be considered an alternative for integrated management of B. cockerelli and B. tabaci. [ABSTRACT FROM AUTHOR]

Xanthomonas axonopodis pv. Phaseoli (Xap) (Smith) is the bacterium that causes common bacterial blight in bean plants (Phaseolus vulgaris L.) characterized by irregular necrotic staining with yellow halo on leaves, stems, and fruits with crop yield reduction. The taxonomy of this pathogen has been changing due their genetic variability. Infected seeds are one of the most efficient forms of disease dispersal between cultivated areas, the infection and bacterial multiplication in the host tissue often depend on the virulence factors and their secretion system. Management methods that are used to counter the disease in the field have not been effective, however, the constant search for new approaches as the use of biocontrol agents and resistance inducers, open new prospects for control. [ABSTRACT FROM AUTHOR]

Xanthomonas axonopodis pv. phaseoli (Xap) (Smith) es la bacteria que ocasiona el tizón común bacteriano del frijol (Phaseolus vulgaris L.) síntoma que se caracteriza por la aparición de manchas con aspecto de tizón con un halo amarillo en hojas, tallos, y frutos reduciendo así el rendimiento del cultivo. La taxonomía de este patógeno ha sido muy cambiante debido a su variabilidad genética. La semilla infectada es la forma más eficiente de dispersión de la enfermedad entre las áreas cultivadas, el éxito de la infección y la multiplicación bacteriana en el tejido hospedero frecuentemente depende de factores de virulencia y del sistema de secreción. Los métodos de manejo que se emplean para contrarrestar la enfermedad en campo no han sido efectivos, no obstante, la constante búsqueda de nuevos enfoques como el empleo de agentes de biocontrol e inductores de resistencia, abren nuevas expectativas para su control. [ABSTRACT FROM AUTHOR]

Pesticides are considered substances of interest and targets of study due to the secondary effects they have on the environment and on human health. The monitoring of pesticide residues is important to trace the possible contamination of the food we consume daily. The objective was to compare two techniques for the validation of spectrophotometry as a detection alternative. Soil, water and chili samples from the states of Aguascalientes, Sinaloa and Tamaulipas were evaluated by high efficiency liquid chromatography and spectrophotometry. The data was compared with the R 3.6 program and the 1.3 Agricolae package. Statistical similarity was observed in the monitored pesticides: Malathion, methamidophos and chlorpyrifos, for which, spectrophotometry is recommended as an alternative detection technique for these; however, for monocrotophos further studies are suggested. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is the most representative crop of Mexico, mainly because of its social, cultural, and economic importance. The objective of this research was to identify genotypes with natural resistance to damage by fall armyworm, Spodoptera frugiperda (J.E. Smith), and corn earworm, Helicoverpa zea (Boddie), and their relationship with ear rot caused by Fusarium spp. Link (Nectriaceae). Samples were collected from September to November 2019 from hybrids and native maize in nine plots in Puebla and Morelos states. Ear rot pathogens and Lepidoptera found in plots were morphologically identified; ear rot incidence, severity, and damage caused by the pests were evaluated. Data of ear rot, leaf damage, and ear damage were adjusted by arcsine square root and analysis of variance (ANOVA), and means were compared by a Tukey multiple range test (p = 0.05). Fusarium spp. was found with 15.04 to 32.01% severity; damage by fall armyworm and corn earworm ranged from 23.63 to 46.96%, with galleries as long as 4.77 cm. The amount of ear rot was proportional to damage by Lepidoptera, demonstrating relationship between injury by these insects and ear rot severity caused by Fusarium spp. in hybrids and native cultivars in different areas, cultural practices, and production systems. Genotypes more resistant to damage by pests were Black Native from San Miguel, Teotlalco, Puebla; Pioneer 30F35 from Contla, Puebla; Pioneer P4028W from Tetelilla, Morelos; and Pioneer P4028W from Tepalcingo, Morelos. [ABSTRACT FROM AUTHOR]

Antifungal activity of zinc oxide (ZnO) and ZnO nanoparticles (ZnO NPs) was evaluated on the control of Fusarium oxysporum Schltdl. (Nectriaceae) under laboratory and greenhouse conditions. In vitro evaluation, poisoned culture media was prepared, and an explant was placed in the centre of solid medium. The experimental design was completely randomized with 18 treatments. Mycelial growth and conidia concentration were evaluated. Subsequently, three treatments (3,000, 1,500, 100 ppm) of ZnO NPs and ZnO were chosen for their evaluation in the greenhouse in tomato plants of Floradade variety under a randomized block design. Inoculation was carried out with a 1x107 conidia per mL suspension of F. oxysporum, when the plants presented the third pair of true leaves. Later, the application of different concentrations of ZnO and ZnO NPs was carried out; in this investigation, the incidence and severity and plant height were evaluated into account to determine the treatment effect on F. oxysporum. In vitro, the best treatments in mycelial growth inhibition were the high concentrations of ZnO NPs from 1,600 to 3,000 ppm with 81%–83%, and in the sporulation of the fungus, they were also those that inhibited from 82.57% to 83.85%. In greenhouse, the treatments that reached the highest plant height were ZnO NPs from 1,500 to 3,000 ppm, with a range of 166.0–175.40 cm, with a severity on the scale of 0.40–0.80 and an incidence of 20%–40%. ZnO NPs have a potential application as an antifungal agent and can be used to control the spread of F. oxysporum in tomato plants, in addition to improving the promoter effect related to the Zinc activity as a precursor in auxins synthesis, cytokinins and gibberellins biosynthesis, as well as the induction of higher activity of antioxidant enzymes useful in response to the pathogens attack. [ABSTRACT FROM AUTHOR]

Reduction in pests targeted by Bt cotton is widely studied; however, other phytophages not affected by Bt cotton-expressed toxins are increasing, suggesting these potential pests might occupy ecological niches of primary pests and become new key pests requiring use of broad-spectrum insecticide. During the 2017 springsummer crop season, insects were collected on 10 genetically modified (GM) hybrids of cotton (Gossypium hirsutum L.), planted at “Rincón del Buitre” ranch, belonging to “Universidad Autonoma Agraria Antonio Narro” (UAAAN) at San Pedro, Coahuila, Mexico. The 13,422 phytophagous insects collected from GM cotton were in five orders: Coleoptera, Diptera, Hemiptera, Lepidoptera, and Thysanoptera; ≈12,766 of the individual insects were in Hemiptera, mainly whiteflies (Aleyrodidae), for a total of 657 other insects collected. Coleoptera were 18.5% of the families, 19.4% of species, and 6.6% of individuals; Diptera had 29.6, 27.8, and 17.2%, respectively; Hemiptera (without Aleyrodidae) had 25.9, 27.8, and 18.9%, respectively; Lepidoptera had 18.5, 19.4, and 44.6%, respectively, and Thysanoptera had 3.7, 2.8, and 2.5%, respectively. Species with more individuals than 5% of the total were Anagasta kuehniella Zeller (32.7%), Spodoptera exigua Hübner (11.0%), Epichlorops sp. Becker (10.7%), Lygus oblineatus Say (9.0%), Diabrotica balteata Leconte (6.9%), Anthonomus grandis Boheman (5.9%), and Bemisia tabaci Gennadius (≈12,766 individuals). Species with greatest incidence among cotton hybrids were Epichlorops sp. (70%), L. oblineatus and D. balteata (each 60%), and A. grandis and Aphis gossypii Glover (each 30%). Monitoring increasing abundance of secondary pests on Bt crops can indicate if the pests threaten sustainable production of the crop. [ABSTRACT FROM AUTHOR]

Candidatus Liberibacter solanacearum is a Gram-negative bacterium, obligate parasite of the phloem in Solanaceus crops, not cultivable in vitro. It is transmitted vertical and horizontally by Bactericera cockerelli. In Mexico, CLso is a pathogen asociated with the diseases "permanente del tomate", "punta morada de la papa" (Zebra chip) and "variegado del chile". The symptoms caused by CLso depend on the farming and the stage of growth of the host but it mainly consists in yellowing and deformation of the leaf blade, due to the feeding of the vector and the colonization of the pathogen. Infections caused by CLso reduce the quality and the commercial value of the product in the market. The presence of this bacterium has been detected in the states of Coahuila, Sinaloa and Guanajuato Mexico through molecular techniques, the control of the diseases is focused on the control of the vector, by means of cultural practices and the application of chemical and biological agents. Therefore, the objective of this work is to stand out the current situation of the distribution of CLso in Mexico, the diagnostic methods and the strategies for the integrated management of the disease and the vector. [ABSTRACT FROM AUTHOR]

The maize weevil, Sitophilus zeamais Motschulsky, is the most important pest of stored maize, Zea mays L. The pest causes estimated losses of 5-10% worldwide. Oil extracts from plants show promise to control maize weevil with important advantages over conventional insecticide, such as non-toxicity to humans, biodegradability, and ecosystem safety. The objective of this research on maize weevils in laboratory conditions was to determine the insecticidal effect of 10 plant oils: garlic, Allium sativum L.; cinnamon, Cinnamomum verum J.; hot pepper, Capsicum annuum L.; clove, Syzygium aromaticum L.; mint, Mentha piperita L.; black pepper, Piper nigrum L.; rosemary, Rosmarinus officinalis L.; rue, Ruta graveolens L.; thyme, Thymus vulgaris L. and allyl (commercial product). Residual film was used to test plant oils at five concentrations: 9,000, 7,000, 5,000, 3,000, and 1,000 ppm. The number of weevils killed was counted at 72 hours, and treatment means were compared using a Tukey multiple separation test. PC-Probit analysis determined LC50 and LC95. Most weevils, 52.47 and 60.38%, were killed by garlic and black pepper oils, respectively; at 9,000 ppm; fewer than 50% were killed with the other plant oils. Use of garlic and black pepper oil might be an alternative method to manage this insect pest in stored maize. [ABSTRACT FROM AUTHOR]

Brenneria nigriluens and B. rubrifaciens cause superficial and deep canker in walnut bark, respectively. B. nigriluen causes necrosis in the outer bark and scattered dark brown exudate spots. The symptoms of Brenneria nigriluens involve holes in the wood, deep longitudinal cracking in the trunk; dark brown bacterial exudate flowing through branch cracks, and eventually the two diseases can cause loss of vigor and death of the trees. Walnut canker caused by Brenneria species has been reported in USA, France, Spain, Italy, Hungary, Persia and Iran. These symptoms have not been reported in Mexico; however, SENASICA (National Service of Health, Food Safety and Food Quality) has developed risk maps to prevent Brenneria, since walnut in Mexico is a profitable crop that reached 125 758.45 tons in 2014, equivalent to more than 6 173 538 million pesos. Due to Brenneria's bacterial pathogenicity timely diagnosis is crucial to achieve good disease management. The main diagnosis methods for Brenneria genera are: Traditional techniques, biochemical test (API system, Biolog and fatty-acid cell analysis); the serological technique; molecular methods such as end-point PCR and real-time PCR; as well as chromatographic techniques (HPLC, CCD) for the detection of specific metabolites like rubrifacine. The purpose of this work is to provide an outlook of domestic and global walnut canker, as well as reviewing the diagnosis techniques for this disease. [ABSTRACT FROM AUTHOR]

Brenneria nigriluens y Brenneria rubrifaciens, causan el cancro superficial y profundo de la corteza del nogal, respectivamente. B. nigriluen ocasiona necrosis en la corteza exterior y manchas dispersas de exudado marrón oscuro. Los síntomas de B. nigriluens involucra hoyos en la madera, grietas profundas longitudinales en el tronco, exudado color oscuro marrón con bacterias que fluyen de las grietas de las ramas. Finalmente, las dos enfermedades pueden ocasionar pérdida de vigor y muerte de los árboles. El cancro del nogal ocasionado por especies de Brenneria se ha reportado principalmente en Estados Unidos, Francia, España, Italia, Hungría, Persia e Irán. En México no se han reportado, sin embargo, SENASICA (Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria) ha establecido mapas de riesgo, ya que en México el nogal pecanero es un cultivo rentable, para el año 2014, se tuvo una producción de 125 758 ton, con un valor mayor a 6 173 millones de pesos. Debido a la patogenicidad de las bacterias, el diagnóstico oportuno es clave en el manejo de la enfermedad. Los principales métodos de diagnóstico del género Brenneria spp son: observación de signos y síntomas, pruebas bioquímicas como el sistema API, Biolog y el análisis de los ácidos grasos celulares; técnicas serológicas; técnicas moleculares como PCR punto final y tiempo real; así como técnicas cromatográficas (HPLC, CCD) para detección de metabolitos específicos como la rubrifacina. El trabajo tiene como objetivo presentar la situación a nivel nacional y mundial del cancro del nogal, así como revisión de las técnicas de diagnóstico de la enfermedad. [ABSTRACT FROM AUTHOR]

Se estudió la supervivencia y esperanza de vida de Tetranychus urticae y Phytoseiulus persimilis, en cuatro variedades de rosal bajo condiciones de invernadero. Se observaron diferencias en el número de hembras de T. urticae por variedad. La curva de supervivencia de la población de T. urticae sobre las variedades Royal y Red Baiser fue de tipo I y sobre las variedades Selena y Anastasia coincide de tipo II, y entre estas curvas se encontraron diferencias significativas, dependiendo de la variedad de rosal la esperanza media de vida de T. urticae fue diferente, así como para P. persimilis. Phytoseiulus persimilis fue más eficiente sobre las variedades Selena y Anastasia, reduciendo la población de hembras adultas de T. urticae en 7 semanas. [ABSTRACT FROM AUTHOR]

The flufenoxuron is a product considered as a growth regulator with acaricide effect, however it is unknown how much influence this has inherent ecological population increase of Tetranychus urticae Koch. The aim of this study was to determine the effect of sublethal concentrations of flufenoxuron on T. urticae using as substrate bean leaves. For this purpose we chose concentrations of 17.7, 59.9 and 106.7 ppm of flufenoxuron. Same as in concentration regression line -72 hours mortality- corresponded to CL5, CL20, and CL40, respectively. Exposure responses to sublethal concentrations of these mites indicated significant changes in some of the population parameters, especially in gross reproductive rate (GRT), net reproductive rate (Ro), cohort duration time (Tc) and generation time (TG). [ABSTRACT FROM AUTHOR]