Manejo sustentable de plagas agrícolas en México

The indiscriminate use of pesticides, first out of necessity and now because of ignorance, has reduced and damaged the agricultural activity in the country. Even in small areas of cultivation, we depend on the development of new technology to manage agricultural pests. Although the pesticides, fertilizers and agricultural machinery have played an important role in the increase of agricultural production, they have proven not to be, at least for chemical pesticides, a safe and sustainable strategy for pest management. The mistrust and lack of information have hindered the adoption of environmentally friendly strategies that allow a sustainable management of pests. In this review, we provide an analysis of the main phenomena that influence the implementation of pest control measures in the country and, in turn, we propose contemplating agroecological, economic and cultural aspects from each region, based on a conscientious analysis of the attainable goals in the short and medium term, with the aim of restoring the biological equilibrium and sustainability of the Mexican countryside. Focused ex profeso on the current situation of the Mexican countryside, this study can serve as a point of departure for the design of programs that take into account the heterogeneity of the Mexican farmland. El uso indiscriminado de plaguicidas, primero por necesidad y ahora por desconocimiento, ha mermado y dañando la actividad agrícola del país. Aun en pequeñas áreas de cultivo dependemos del desarrollo de nueva tecnología para el manejo de las plagas agrícolas. Si bien los plaguicidas, fertilizantes y maquinaria agrícola han sido parte importante en el aumento de la producción agrícola, han mostrado no ser, al menos para los pesticidas químicos, una estrategia segura y sustentable para el manejo de plagas. La desconfianza y la falta de información han impedido adoptar estrategias amigables con el medio que permitan un manejo sustentable de las plagas. En esta revisión se brinda un análisis de los principales fenómenos que influencian la implementación de medidas de control de plagas en el país y, a su vez, propone que se contemplen aspectos agroecológicos, económicos y culturales de cada región, partiendo de un análisis concienzudo de las metas alcanzables a corto y mediano plazo, con miras a restaurar el equilibrio biológico y la sustentabilidad del campo mexicano. Enfocado ex profeso a la situación actual del campo mexicano, este estudio puede servir como punto de partida para el diseño de programas que consideren la heterogeneidad del agro mexicano

MECANISMOS DE INTERCAMBIOS DE K+ Y ca2+ EN EPIDERMIS DE RAICES BAJO ESTRÉS SALINO

Facultad de Medicin

ESTRÉS SALINO Y TOLERANCIA: REGULACIÓN k+/Na+ CITOSOLICO EN PLANTAS SUPERIORES

Facultad de Medicin

Na+-K+ transport in roots under salt stress

Salinity causes billion dollar losses in annual crop production. So far, the main avenue in breeding crops for salt tolerance has been to reduce Na+ uptake and transport from roots to shoots. Recently we have demonstrated that retention of cytosolic K+ could be considered as another key factor in conferring salt tolerance in plants. A subsequent study has shown that Na+-induced K+ efflux in barley root epidermis occurs primarily via outward rectifying K+ channels (KORC). Surprisingly, expression of KORC was similar in salt- tolerant and sensitive genotypes. However, the former were able to better oppose Na+-induced depolarization via enhanced activity of plasma membrane H+-ATPase (thus minimizing K+ leak from the cytosol). In addition to highly K+-selective KORC channels, activities of several types of non-selective cation channels were detected at depolarizing potentials. Here we show that the expression of one of them, NORC, was significantly lower in salt-tolerant genotypes. As NORC is capable of mediating K+ efflux coupled to Na+ influx, we suggest that the restriction of its activity could be beneficial for plants under salt stress

Survey of entomopathogenic nematodes from the families Steinernematidae and Heterorhabditidae (Nematoda: Rhabditida) in Colima, México

A survey of entomopathogenic nematodes (EPNs) belonging to the families Steinernematidae and Heterorhabditidae was conducted in three municipalities on the Pacific coast of the State of Colima, Me´xico, to determine their occurrence and recovery frequency and predominant plant species in cultivated and non-cultivated habitats. Nineteen soil samples were collected: seven from non-cultivated habitats and 12 from habitats or areas cultivated mostly with fruit and grain crops and grasses. Of the 19 soil samples, 14 were positive for EPNs; the total prevalence was 73.7%. From the 14 positive soil samples, 12 steinernematid isolates (85.7%) and two heterorhabditid isolates (14.3%) were recovered. Irrespective of the locations, EPNs from the genus Steinernema were recovered from the three municipalities; EPNs from the genera Steinernema and Heterorhabditis were recovered from Armerı´a and Ixtlahuaca´n. Only steinernematid isolates were recovered from non-cultivated habitats. Most of the isolates were recovered from cultivated habitats, and our results suggest that there is a higher prevalence of EPNs in cultivated soils

Root Plasma Membrane Transporters Controlling K+/Na+ Homeostasis in Salt-Stressed Barley1[C][W]

Plant salinity tolerance is a polygenic trait with contributions from genetic, developmental, and physiological interactions, in addition to interactions between the plant and its environment. In this study, we show that in salt-tolerant genotypes of barley (Hordeum vulgare), multiple mechanisms are well combined to withstand saline conditions. These mechanisms include: (1) better control of membrane voltage so retaining a more negative membrane potential; (2) intrinsically higher H+ pump activity; (3) better ability of root cells to pump Na+ from the cytosol to the external medium; and (4) higher sensitivity to supplemental Ca2+. At the same time, no significant difference was found between contrasting cultivars in their unidirectional 22Na+ influx or in the density and voltage dependence of depolarization-activated outward-rectifying K+ channels. Overall, our results are consistent with the idea of the cytosolic K+-to-Na+ ratio being a key determinant of plant salinity tolerance, and suggest multiple pathways of controlling that important feature in salt-tolerant plants