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Plan Guanajuato (La Sandía), Mexico

Vanegas-Rico J.M.,Colegio de Mexico | Lomeli-Flores J.R.,Colegio de Mexico | Rodriguez-Leyva E.,Colegio de Mexico | Perez-Panduro A.,Colegio de Mexico | And 2 more authors.
Revista Colombiana de Entomologia | Year: 2015

Dactylopius opuntiae is a key pest of the prickly pear crop, Opuntia ficus-indica, which is cultivated as a vegetable (called “nopalitos”) in Mexico and for its fruit in Mexico and other regions of the world. In this study, ladybird predators associated with D. opuntiae in Central Mexico were studied as potential natural enemies to be used in future biological control programs. Collections were concentrated at the principal prickly pear crop production areas (Tlalnepantla, Morelos), where high population density of the pest is common. In this area, systematic samples were completed every other week, from February to June, for two years (2008 and 2009) on five nopalitos sites. The list of Coccinellidae associated with D. opuntiae was complemented with non-systematic collections in Mexico City (Milpa Alta) and Mexico State (Texcoco). Entomological material from INIFAP-Celaya (Guanajuato collection), where the main Mexican Coccinellidae collection is hosted, was also checked. Hyperaspis trifurcata was the major predator collected in Tlalnepantla, Morelos, Mexico. Three hymenopteran species were obtained from larvae and pupae of this predator. Homalotylus cockerelli was the most abundant parasitoid, acting as the primary parasitoid; others species found were Pachyneuron sp. and Tetrastichus sp., which were infrequently collected and acted as hyperparasitoids. Ho. cockerelli populations increased at the same time as their host, H. trifurcata. This parasitoid emerged from 0 to 46.2% of the ladybird larvae and pupae collected. Four new Coccinellidae species associated with cochineal insect pests in central Mexico were found in the non-systematic collections undertaken in this study and the INIFAP-Celaya collection. © 2015, Sociedad Colombiana de Entomologia. All rights reserved.

Rosales M.A.,National Autonomous University of Mexico | Rosales M.A.,Institute Recursos Naturales y Agrobiologia | Ocampo E.,National Autonomous University of Mexico | Rodriguez-Valentin R.,National Autonomous University of Mexico | And 4 more authors.
Plant Physiology and Biochemistry | Year: 2012

Terminal drought is a major problem for common bean production because it occurs during the reproductive stage, importantly affecting seed yield. Diverse common bean cultivars with different drought susceptibility have been selected from different gene pools in several drought environments. To better understand the mechanisms associated with terminal drought resistance in a particular common bean race (Durango) and growth habit (type-III), we evaluated several metabolic and physiological parameters using two cultivars, Bayo Madero and Pinto Saltillo, with contrasting drought susceptibility. The common bean cultivars were submitted to moderate and severe terminal drought treatments under greenhouse conditions. We analyzed the following traits: relative growth rate, photosynthesis and transpiration rates, stomatal conductance, water-use efficiency, relative water content, proline accumulation, glycolate oxidase activity and their antioxidant response. Our results indicate that the competence of the drought-resistant cultivar (Pinto Saltillo) to maintain seed production upon terminal drought relies on an early response and fine-tuning of stomatal conductance, CO 2 diffusion and fixation, and by an increased water use and avoidance of ROS accumulation. © 2012 Elsevier Masson SAS.

Cisneros-Lopez M.E.,INIFAP Campo Experimental Rio Bravo | Mendoza-Onofre L.E.,Colegio de Mexico | Gonzalez-Hernandez V.A.,Colegio de Mexico | Mora-Aguilera G.,Colegio de Mexico | And 3 more authors.
Seed Science and Technology | Year: 2010

Ergot (Claviceps africana) is a disease that affects non- fertilized ovaries in sorghum male -sterile plants and infects commercial hybrids grown under weather conditions that favours pollen sterility. In order to analyze the relationships among floral traits, stigma receptivity, and seed yield in plants inoculated with ergot, six pairs of A/B sorghum (Sorghum bicolor L. Moench) isogenic lines adapted to the Mexican Highlands (2200 m altitude) were sown under field conditions. The percentage of viable pollen was measured in B- lines, while days to flower, flowering period, stigma and panicle lengths, florets per panicle, floral density, rate of florets opening and flowering progress, were recorded in A-lines. In handmade A×B crosses, a 1 × 106 conidia mL-1 suspension was sprayed immediately after pollination, and 18 h later in vivo pollen grains adhered and germinated in the stigma, and fertilized pistils were counted. At harvest, number and percentage of diseased florets, seed yield, and yield components per panicle, were evaluated. The early flowering A-lines, with a shorter flowering period and a faster rate of florets opening showed less infected florets than the late flowering lines or than those with longer flowering period, but the healthiest lines were those that produced more florets per panicle, so both the total number of florets and the percentage of infected florets should be considered as complementary criteria for evaluating pathogen severity. The fungus caused decreases in stigma receptivity and seed yield. Averaged over crosses, the decrease in seed yield (40%) was larger than the disease severity (11%), thus pointing out the importance to link agronomic indexes to plant pathological criteria, when evaluating pathogen resistance.

Cisneros-Lopez MA.E.,Apd Life Sciences, Inc. | Mendoza-Onofre L.E.,Colegio de Mexico | Gonzalez-Hernandez V.A.,Colegio de Mexico | Zavaleta-Mancera H.A.,Colegio de Mexico | And 3 more authors.
Fungal Biology | Year: 2010

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 (2240 m altitude). Pollination and inoculation treatments, from simultaneous application to 2 and 4 h 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 72 h 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. © 2010 The British Mycological Society.

Pecina-Quintero V.,INIFAP Campo Experimental Bajio | Anaya-Lopez J.L.,INIFAP Campo Experimental Bajio | Cortez-Mondaca E.,INIFAP Campo Experimental Valle Del Fuerte | Nunez-Colin C.A.,University of Guanajuato | And 4 more authors.
Southwestern Entomologist | Year: 2015

In the present study, fall armyworm collected in 10 states of Mexico, was characterized genetically, using AFLP markers (Amplified Fragment Length Polymorphism). High levels of polymorphism (98%) were detected and the analysis of genetic relationships and diversity index of molecular data showed wide genetic variability of this species. Two groups were formed of the genotype S. frugiperda in the dendrogram of genetic relationships, confirming the presence of two strains which may have developed biological and physiological differences. No grouping by geographical origin was observed, so it is concluded that the identified genetic variation is associated more with the presence of corn and rice strains than the geographical origin of the specimens. The E-ACT+M-CAC combination was the most efficient to estimate the differences between specimens and separate the two groups of genotypes of S. frugiperda, because it had the highest MI (80.52), RP (112.27), and PIC (0.297) values, as well as a high and significant correlation between PIC and MI (r2 = 0.91, p < 0.05) and between RP and MI (r2 = 0.99, p < 0.05).

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