Assessment of population structure and management of Cordia dodecandra A. DC. in homegardens and tropical forest in Yucatan, Mexico

Cordia dodecandra A. DC. is an arboreal component of forests and Maya homegardens in the state of Yucatan, México. Changes in land use and landscape fragmentation have led to declines in wild populations. Understanding this species’ population structure is relevant to determining the current state of its populations and proposing strategies for its conservation. The population structure of C. dodecandra in forest and homegardens in Yucatan, and the management practices associated with the species were documented with interviews. Relative importance of the tree species in the associated vegetation was estimated. Seedling density (< 1m of height) was higher in the homegardens than the forest with an evident decrease in the density of juvenile individuals caused by practices such as weeding. In contrast, the forest contained a greater number of adult and larger individuals than in the homegardens. Individual C. dodecandra were taller in the forest, but those in the homegardens had a larger diameter at breast height. Although it has multiple uses (e.g. food, ornamental, wood) the C. dodecandra in homegardens received only minimal maintenance, possibly threatening its permanence in this system. This is concerning since the homegardens function as de facto germplasm banks for this species. Highlights Cordia dodecandra trees from homegardens have a diameter at breast height (DBH) larger than those that live in the dry forest. Cordia dodecandra trees in tropical dry forests, are taller than in homegardens. Succession data showed that tropical dry forests have more adult trees of Cordia dodecandra, and homegardens have a higher density of seedlings.Cordia dodecandra A. DC. is an arboreal component of forests and Maya homegardens in the state of Yucatan, México. Changes in land use and landscape fragmentation have led to declines in wild populations. Understanding this species’ population structure is relevant to determining the current state of its populations and proposing strategies for its conservation. The population structure of C. dodecandra in forest and homegardens in Yucatan, and the management practices associated with the species were documented with interviews. Relative importance of the tree species in the associated vegetation was estimated. Seedling density (< 1m of height) was higher in the homegardens than the forest with an evident decrease in the density of juvenile individuals caused by practices such as weeding. In contrast, the forest contained a greater number of adult and larger individuals than in the homegardens. Individual C. dodecandra were taller in the forest, but those in the homegardens had a larger diameter at breast height. Although it has multiple uses (e.g. food, ornamental, wood) the C. dodecandra in homegardens received only minimal maintenance, possibly threatening its permanence in this system. This is concerning since the homegardens function as de facto germplasm banks for this species. Highlights Cordia dodecandra trees from homegardens have a diameter at breast height (DBH) larger than those that live in the dry forest. Cordia dodecandra trees in tropical dry forests, are taller than in homegardens. Succession data showed that tropical dry forests have more adult trees of Cordia dodecandra, and homegardens have a higher density of seedlings

Evaluation of the use of glyphosate and legumes in valen-cia orange (Citrus sinensis L. Osbeck), in the north of Vera-cruz: case study.

ABSTRACT Evaluation of the use of glyphosate and legumes in valencia orange (Citrus sinensis L. Osbeck), in the north of Veracruz: case study. The objective of the case study was to contribute to the knowledge of herbicides (mainly glyphosate) and legumes by valencia orange producers in northern Veracruz. The study was carried out in the year 2021, with producers from three municipalities located in the North of Veracruz: Papantla, Alamo Temapache and Ixhuatlan de Madero. A total of 55 interviews were carried out. The interview that was conducted was structured around three sections: personal information of the interviewee, information about herbicides and information about legumes. The characteristics found in this work indicate that the majority of producers continue to use herbicides, 80% do not know the term glyphosate even though it turns out to be the main active ingredient of several of the herbicides that they apply and despite knowing that these turn out to be very dangerous due to for various reasons, they continue to use them without any protective equipment, due to how easy, fast and cheap their application turns out to be, but regardless of everything, the producers are in the greatest disposition to know and cultivate leguminous plants in their plots to observe their characteristics, benefits and advantages in weed control. Keywords: glyphosate, legumes, presidential decree, valencia orange, weeds.Evaluation of the use of glyphosate and legumes in valencia orange (Citrus sinensis L. Osbeck), in the north of Veracruz: case study. The objective of the case study was to contribute to the knowledge of herbicides (mainly glyphosate) and legumes of valencia orange producers in northern Veracruz. The study was carried out in the year 2021, with producers from three municipalities located in the north of Veracruz: Papantla, Álamo Temapache and Ixhuatlan de Madero. A total of 55 interviews were carried out. The interview that was conducted was structured around three sections: personal information of the interview respondent, information about herbicides, and information about legumes. The characteristics found in this study indicate that the majority of producers continue to use herbicides, 80% do not know the term glyphosate even though it turns out to be the main active ingredient of several of the herbicides that they apply and despite knowing that these can be very dangerous due to various reasons, they continue to use them without any protective equipment, due to how easy, fast and cheap their application is. However, regardless of everything, the producers are in the best disposition to know and cultivate leguminous plants in their plots to observe their characteristics, benefits and advantages in weed control.

First record of entomopathogenic nematodes from Yucatán State, México and their infectivity capacity against Aedes aegypti

Background Biological control using entomopathogenic nematodes (EPN) has demonstrated good potential to contribute to the integral control of mosquito larvae, which as adults are vectors of diseases such as Dengue fever, Zika and Chikungunya. However, until now there are no records of the presence of EPN or their killing capacity in Yucatán state, southern México. The objectives of the current study were: (1) to report the entomopathogenic nematodes present in Yucatán soils and (2) to determine the killing capacity of the most frequent and abundant EPN against Aedes aegypti mosquito larvae and the microbial community developed by Ae. Aegypti exposed to this EPN. Methods The nematodes were collected by the insect trap technique using the great wax moth Galleria mellonella. Internal transcribed spacer (ITS), 28S gene of ribosomal DNA and phylogenetic analyses were performed to identify the EPN. For the bioassay, four concentrations of the most frequent and abundant EPN were tested: 1,260:1 infective juveniles (IJs) per mosquito larvae, 2,520 IJs:1, 3,780 IJs:1 and 5,040 IJs:1. High-throughput sequencing of the 16S rRNA gene was used to identify bacterial amplicon sequences in the mosquito larvae infected with EPN. Results Six isolates of Heterorhabditis were recovered from 144 soil samples. Heterorhabditis indica (four isolates) was the most frequent and abundant EPN, followed by Heterorhabditis n. sp. (two isolates). Both nematodes are reported for the first time for Yucatán state, Mexico. The concentration of 2,520 IJs:1 produced 80% of mosquito larvae mortality in 48 h. Representative members of Photorhabdus genus were numerically dominant (74%) in mosquito larvae infected by H. indica. It is most likely that these bacteria produce secondary toxic metabolites that enhance the mortality of these mosquito larvae

Perspectivas de la empresa y la economía mexicana frente a la reestructuración productiva

1 archivo PDF (404 páginas)Este texto se presenta una reflexión de investigadores de la UAM, así como de otras Instituciones de Educación Superior respecto al marco en el que se han desenvuelto las empresas mexicanas en los últimos años, así como del desarrollo en algunos de sus sistemas organizacionales. PALABRAS CLAVE: Mexico Economic policy 1970-1994

Planeación, gobernanza y sustentabilidad Retos y desafíos desde el enfoque territorial

Frente a la compleja realidad actual, resulta ineludible el desarrollo de la investigación científica de los fenómenos y procesos urbanos, territoriales y ambientales, que contribuya a su comprensión y la construcción de alternativas de solución a los retos y desafíos vigentes. En este contexto, el abordaje de las ciudades y regiones metropolitanas, el ordenamiento del territorio y la ocupación del espacio, así como la relación sociedad-naturaleza y la complejidad ambiental, precisa la generación de metodologías y procesos de investigación multi e inter disciplinarios que contribuyan a la comprensión de los procesos socioterritoriales, el mejoramiento de las condiciones de vida y la conservación ambiental.Programa de Fortalecimiento de la Calidad Educativa PFCE-2016 proyecto K0313101

Source water, phenology and growth of two tropical dry forest tree species growing on shallow karst soils

Seasonally dry tropical forests are dominated by deciduous and evergreen tree species with a wide range of leaf phenology. We hypothesized that Piscidia piscipula is able to extend leaf senescence until later in the dry season due to deeper and more reliable water sources than Gymnopodium floribundum, which loses leaves earlier in the dry season. Physiological performance was assessed as timing of leaf production and loss, growth, leaf water potential, depth of water uptake determined by stable isotopes, and leaf stable isotopic composition of carbon (δ¹³C) and oxygen (δ¹⁸O). P. piscipula took water primarily from shallow sources, whereas G. floribundum took water from shallow and deep sources. The greatest variation in water sources occurred during the onset of the dry season, when G. floribundum was shedding old leaves and growing new leaves, but P. piscipula maintained its leaves from the previous wet season. P. piscipula showed greater relative growth rate, greater leaf expansion rates, and more negative predawn and midday water potentials than G. floribundum. P. piscipula also exhibited greater leaf organic δ¹³C and lower δ¹⁸O values, indicating that the decrease in photosynthetic carbon isotope discrimination was associated with greater stomatal conductance and greater photosynthesis. Our results indicate that the contrasting early and late dry season leaf loss phenology of these two species is not simply determined by rooting depth, but rather a more complicated suite of characteristics based on opportunistic use of dynamic water sources, maximizing carbon gain, and maintenance of water potential during the dry season

La sequía de la península de Yucatán

La sequía es uno de los fenómenos naturales más difíciles de estudiar debido a que no se cuenta con una definición lo suficientemente clara ni con los recursos técnicos para poder predecirla. Es un problema que, en el mundo, se ha incrementado en las últimas décadas como consecuencia del cambio climático. En México, la sequía afecta a más personas que cualquier otra contingencia natural, por lo que se requiere estudiarla para poder prevenir y mitigar sus efectos. En la península de Yucatán (PY), zona privilegiada por tener un vasto manto acuífero, la sequía no se presenta de manera tan catastrófica como en otros estados de la república. La sequía produce pérdidas y bajo rendimiento de cultivos, cabezas de ganado y colmenas, disminución de la calidad de los productos, así como incremento en los costos de producción, lo que produce reducción en el ingreso de los productores. A nivel de los organismos operadores no se registra baja en la disponibilidad de agua durante la época de sequía y sólo se reporta su disminución para consumo humano en algunas localidades en donde el acuífero se encuentra muy profundo o la calidad natural del agua no es adecuada para consumo humano. Sin embargo, al depender la PY casi en su totalidad del acuífero para el abasto del agua, su disponibilidad podría disminuir súbitamente por problemas en la infraestructura del sistema operador o de contaminación (importante por la permeabilidad del sustrato geológico y porque no existen sistemas de drenaje y potabilización de agua suficientes)

Moving carbon between spheres, the potential oxalate-carbonate pathway of Brosimum alicastrum Sw.; Moraceae.

Aims The Oxalate-Carbonate Pathway (OCP) is a biogeochemical process that transfers atmospheric CO2 into the geologic reservoir as CaCO3; however, until now all investigations on this process have focused on species with limited food benefits. This study evaluates a potential OCP associated with Brosimum alicastrum, a Neotropical species with agroforestry potential (ca. 70–200 kg-nuts yr−1), in the calcareous soils of Haiti and Mexico. Methods / results Enzymatic analysis demonstrated significant concentrations of calcium oxalate (5.97 % D.W.) were associated with B. alicastrum tissue in all sample sites. The presence of oxalotrophism was also confirmed with microbiological analyses in both countries. High concentrations of total calcium (>7 g kg−1) and lithogenic carbonate obscured the localised alkalinisation and identification of secondary carbonate associated with the OCP at most sample sites, except Ma Rouge, Haiti. Soils adjacent to subjects in Ma Rouge demonstrated an increase in pH (0.63) and CaCO3 concentration (5.9 %) that, when coupled with root-like secondary carbonate deposits in Mexico, implies that the OCP does also occur in calcareous soils. Conclusions Therefore this study confirms that the OCP also occurs in calcareous soils, adjacent to B. alicastrum, and could play a fundamental and un-accounted role in the global calcium-carbon coupled cycle

Compromising between European and US allergen immunotherapy schools: Discussions from GUIMIT, the Mexican immunotherapy guidelines

Background: Allergen immunotherapy (AIT) has a longstanding history and still remains the only disease-changing treatment for allergic rhinitis and asthma. Over the years 2 different schools have developed their strategies: the United States (US) and the European. Allergen extracts available in these regions are adapted to local practice. In other parts of the world, extracts from both regions and local ones are commercialized, as in Mexico. Here, local experts developed a national AIT guideline (GUIMIT 2019) searching for compromises between both schools. Methods: Using ADAPTE methodology for transculturizing guidelines and AGREE-II for evaluating guideline quality, GUIMIT selected 3 high-quality Main Reference Guidelines (MRGs): the European Academy of Allergy, Asthma and Immunology (EAACI) guideines, the S2k guideline of various German-speaking medical societies (2014), and the US Practice Parameters on Allergen Immunotherapy 2011. We formulated clinical questions and based responses on the fused evidence available in the MRGs, combined with local possibilities, patient's preference, and costs. We came across several issues on which the MRGs disagreed. These are presented here along with arguments of GUIMIT members to resolve them. GUIMIT (for a complete English version, see Supplementary data) concluded the following: Results: Related to the diagnosis of IgE-mediated respiratory allergy, apart from skin prick testing complementary tests (challenges, in vitro testing and molecular such as species-specific allergens) might be useful in selected cases to inform AIT composition. AIT is indicated in allergic rhinitis and suggested in allergic asthma (once controlled) and IgE-mediated atopic dermatitis. Concerning the correct subcutaneous AIT dose for compounding vials according to the US school: dosing tables and formula are given; up to 4 non-related allergens can be mixed, refraining from mixing high with low protease extracts. When using European extracts: the manufacturer's indications should be followed; in multi-allergic patients 2 simultaneous injections can be given (100% consensus); mixing is discouraged. In Mexico only allergoid tablets are available; based on doses used in all sublingual immunotherapy (SLIT) publications referenced in MRGs, GUIMIT suggests a probable effective dose related to subcutaneous immunotherapy (SCIT) might be: 50–200% of the monthly SCIT dose given daily, maximum mixing 4 allergens. Also, a table with practical suggestions on non-evidence-existing issues, developed with a simplified Delphi method, is added. Finally, dissemination and implementation of guidelines is briefly discussed, explaining how we used online tools for this in Mexico. Conclusions: Countries where European and American AIT extracts are available should adjust AIT according to which school is followed

Conferencia internacional. Desafíos de la Investigación e innovación en tiempos de Covid-19

En 2018, Treinta y nueve estudiantes femeninas del X ciclo del periodo 2018-1 de la escuela de Psicología de una universidad particular del cono norte de Lima, ellas han descrito el romance de su personas cercanas a ellas. Se analizaron los 266 casos de parejas de enamorados estaban el rango de 17 a 25 años. El instrumento que se usó fue una CUESTIONARIO CUPIDO que es una escala nominal de conductas donde las estudiantes de psicología clasificaban los comportamientos en categorías preestablecidas, claramente definidas y mutuamente excluyentes. La conclusión más importante del estudio observacional fue que las parejas analizadas en un 64.4 % la mujer ero atrajo al varón y después el varón emo conectó con la mujer. También han observado otro estilo de romance cuando el varón ero atrajo a la mujer por su cuerpo atracción y después la mujer fue la que emo conectó con el varón y observaron este hecho en un 35.6 % de los casos