Institute Ecologia Ac Xalapa

Veracruz, Mexico

Institute Ecologia Ac Xalapa

Veracruz, Mexico
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In order to quickly evaluate the conservation status of threatened tree species, we assessed the density and population structure in size categories of Resinanthus aromaticus; an endangered endemic timber tree, in five study sites covering 0.67 ha in central Veracruz. The analysis of population structure was performed using three approaches: the adjustment of population size distribution to the log-normal curve, the proportion of juveniles to adults, and the skewness of population size distributions. Comparing the skewness of population size distributions was the most appropriate method to identify the population in better conservation status. The results of this study indicate that the population density of R. aromaticus shows a reduction of 57 % compared to previous studies and the analysis of population size distributions skewness could be used as a quick method to identify threatened populations of tree species. According to the IUCN Red List criteria, this species should be kept in the category "endangered".

Arrizubieta M.,Institute Agrobiotecnologia Csic Upna Gobierno Of Navarra Mutilva Baja Spain | Simon O.,Institute Agrobiotecnologia Csic Upna Gobierno Of Navarra Mutilva Baja Spain | Torres-Vila L.M.,Servicio de Sanidad Vegetal Consejeria de Agricultura DRMAyE Gobierno de Extremadura Merida Spain | Figueiredo E.,University of Lisbon | And 4 more authors.
Pest Management Science | Year: 2015

BACKGROUND: A binary co-occluded mixture (HearSP1B:LB6) of Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. RESULTS: Concentrations of 109-1011 occlusion bodies (OBs) L-1 of HearSP1B:LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 1010 OBs L-1 of HearSP1B:LB6 was as effective as Bacillus thuringiensis (Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. CONCLUSION: The efficacy and persistence of HearSP1B:LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations. © 2015 Society of Chemical Industry.

Orono L.,National University of Chilecito | Orono L.,CONICET | Paulin L.,University of Buenos Aires | Alberti A.C.,University of Buenos Aires | And 6 more authors.
Environmental Entomology | Year: 2013

Herbivore host specialization includes changes in behavior, driven by locally induced adaptations to specific plants. These adaptations often result in sexual isolation that can be gauged through detection of reduced gene flow between host associated populations. Hypothetically, reduced gene flow can be mediated both by differential response to specific plant kairomones and by the influence of larval diet on some adult traits such as pheromone composition. These hypotheses could serve as a model to explain rapid radiation of phytophagous tephritid fruit flies, a group that includes several complexes of cryptic species. The South American Fruit Fly Anastrepha fraterculus (Wiedemann) is a complex of at least seven cryptic species among which pheromone mediated sexual isolation resulted in rapid differentiation. Cryptic species also exhibit differences in host affiliation. In search of a model explaining rapid radiation in this group, we studied host plant chemical composition and genetic structure of three host associated sympatric populations of A. fraterculus. Chemical composition among host plant fruit varied widely both for nutrient and potentially toxic secondary metabolite content. Adaptation to plant chemistry appears to have produced population differentiation. We found host mediated differentiation to be stronger between populations exploiting sympatric synchronic hosts differing in chemical composition, than between populations that exploit hosts that fruit in succession. Gene flow among such host associated populations was extremely low. We propose as a working hypothesis for future research, that for those differences to persist over time, isolating mechanisms such as male produced sex pheromones and female preferences resulting from adaptation to different larval diets should evolve. © 2013 Entomological Society of America.

Simon O.,Institute Agrobiotecnologia Csic Gobierno Of Navarra Mutilva Baja Spain | Bernal A.,Institute Agrobiotecnologia Csic Gobierno Of Navarra Mutilva Baja Spain | Williams T.,Institute Ecologia AC Xalapa | Carnero A.,Instituto Canario Of Investigaciones Agrarias San Cristobal Of La Laguna Spain | And 3 more authors.
Pest Management Science | Year: 2015

BACKGROUND: Chrysodeixis chalcites (Esper) is a major pest of tomato in Mediterranean countries and attacks banana in the Canary Islands (Spain). The efficacy of Chrysodeixis chalcites single nucleopolyhedrovirus (ChchSNPV-TF1) was evaluated in plant growth chambers and greenhouse trials performed on tomato and banana plants respectively. Treatments were applied using a compressed air sprayer. RESULTS: Mean (± SE) lethal infection varied from 77±10% to 94±3% in second-instar larvae fed for 2 days on tomato plants treated with 2×106 to 5×107 virus occlusion bodies (OBs) L-1, increasing to ∼100% infection after 7 days. Mortality of larvae collected from banana at different intervals post-application varied from 54±10% to 96±4% in treatments involving 1×108-1×109 OBs L-1, whereas indoxacarb (Steward 30% WG) and Bacillus thuringiensis var. kurstaki (Biobit 16% WP) treatments produced between 22±6% and 32±5% pest mortality. All treatments significantly reduced plant defoliation compared with untreated controls. Application of 1×109 OBs L-1 was 3-4-fold more effective than chemical or B. thuringiensis treatments. Larvae acquired lethal infection more rapidly when feeding on tomato than banana plants, but this difference disappeared following >60min of feeding. CONCLUSION: This information should prove useful in the registration of ChchSNPV-TF1 as a bioinsecticide in the Canary Islands and Europe. © 2014 Society of Chemical Industry.

Bernal A.,Institute Agrobiotecnologia | Williams T.,Institute Ecologia Ac Xalapa | Hernandez-Suarez E.,Instituto Canario Of Investigaciones Agrarias | Carnero A.,Instituto Canario Of Investigaciones Agrarias | And 3 more authors.
Biological Control | Year: 2013

Chrysodeixis chalcites (Lepidoptera: Noctuidae) larvae cause up to 30% production loss in banana crops in the Canary Islands. Larvae of this species are susceptible to a nucleopolyhedrovirus (ChchNPV). This study aimed at evaluating the genetic diversity and bioinsecticidal activity of ChchNPV isolates collected from C. chalcites larvae in the Canary Islands. From a total 97 isolates collected in different banana greenhouses, restriction endonuclease analysis identified five genetic variants that differed slightly from ChchNPV isolates from Netherlands (ChchSNPV-NL) and Almería, Spain (ChchNPV-SP1). Physical maps revealed minimal differences at the genome level, mostly due to variation in the position/existence of restriction sites. ChchSNPV-TF1 was the most prevalent variant, representing 78% of isolates examined, and was isolated at all Canary Island sampling sites. This isolate was the most pathogenic isolate against C. chalcites second instars in terms of concentration-mortality metrics, compared to homologous variants or two heterologous viruses Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Anagrapha falcifera multiple nucleopolyhedrovirus (AnfaMNPV). ChchSNPV-TF1 was also one of the fastest killing variants although no differences were observed in occlusion body production among the different variants in second instars. We conclude that ChchSNPV-TF1 merits further evaluation as the basis for a biological insecticide for control of C. chalcites in banana crops in the Canary Islands. © 2013 Elsevier Inc.

Garcia A.A.,Autonomous University of Puebla | Garcia G.A.L.,Autonomous University of Sinaloa | Olivas A.R.,Autonomous University of Sinaloa | Alvarez P.C.,Autonomous University of Sinaloa | And 2 more authors.
Southwestern Entomologist | Year: 2010

The study was conducted to know the host plants of adult insects of lamellicorn beetles related to agricultural areas, such as tropical deciduous forest, spiny forest, and xerophilous brush from the northern region of Sinaloa state, México. The data were collected in the morning and evening from August to October 2008. The 18 adult species collected were included in the genera: Diplotaxis, Phyllophaga, Pelidnota, Cyclocephala, Oxygrylius, Cotinis, Euphoria, and Hybosorus, of which Phyllophaga was the genus with the highest number of host species, with 15 species of plants in total, belonging to 10 plant families. The plants used as food by lamellicorn beetles belong to 26 species and 15 families, of which the Fabacea family was the most visited. Within this family the "bacaporo", Parkinsonia aculeate was preferred by a total of 11 species of beetles.

PubMed | Federal University of Uberlandia, University of Veracruz, Institute Ecologia Ac Xalapa, Federal University of Mato Grosso and Federal University of Ouro Preto
Type: Journal Article | Journal: PloS one | Year: 2014

Despite the importance and increasing knowledge of ecological networks, sampling effort and intrapopulation variation has been widely overlooked. Using continuous daily sampling of ants visiting three plant species in the Brazilian Neotropical savanna, we evaluated for the first time the topological structure over 24 h and species-area relationships (based on the number of extrafloral nectaries available) in individual-based ant-plant networks. We observed that diurnal and nocturnal ant-plant networks exhibited the same pattern of interactions: a nested and non-modular pattern and an average level of network specialization. Despite the high similarity in the ants composition between the two collection periods, ant species found in the central core of highly interacting species totally changed between diurnal and nocturnal sampling for all plant species. In other words, this night-turnover suggests that the ecological dynamics of these ant-plant interactions can be temporally partitioned (day and night) at a small spatial scale. Thus, it is possible that in some cases processes shaping mutualistic networks formed by protective ants and plants may be underestimated by diurnal sampling alone. Moreover, we did not observe any effect of the number of extrafloral nectaries on ant richness and their foraging on such plants in any of the studied ant-plant networks. We hypothesize that competitively superior ants could monopolize individual plants and allow the coexistence of only a few other ant species, however, other alternative hypotheses are also discussed. Thus, sampling period and species-area relationship produces basic information that increases our confidence in how individual-based ant-plant networks are structured, and the need to consider nocturnal records in ant-plant network sampling design so as to decrease inappropriate inferences.

PubMed | National Autonomous University of Mexico and Institute Ecologia Ac Xalapa
Type: | Journal: Frontiers in microbiology | Year: 2015

Many strains of bacteria produce antagonistic substances that restrain the growth of others, and potentially give them a competitive advantage. These substances are commonly released to the surrounding environment, involving metabolic costs in terms of energy and nutrients. The rate at which these molecules need to be produced to maintain a certain amount of them close to the producing cell before they are diluted into the environment has not been explored so far. To understand the potential cost of production of antagonistic substances in water environments, we used two different theoretical approaches. Using a probabilistic model, we determined the rate at which a cell needs to produce individual molecules in order to keep on average a single molecule in its vicinity at all times. For this minimum protection, a cell would need to invest 3.92 10(-22) kg s(-1) of organic matter, which is 9 orders of magnitude lower than the estimated expense for growth. Next, we used a continuous model, based on Ficks laws, to explore the production rate needed to sustain minimum inhibitory concentrations around a cell, which would provide much more protection from competitors. In this scenario, cells would need to invest 1.20 10(-11) kg s(-1), which is 2 orders of magnitude higher than the estimated expense for growth, and thus not sustainable. We hypothesize that the production of antimicrobial compounds by bacteria in aquatic environments lies between these two extremes.

PubMed | National Autonomous University of Mexico, Institute Ecologia Ac Xalapa and Arizona State University
Type: | Journal: Frontiers in microbiology | Year: 2015

The increase of nutrients in water bodies, in particular nitrogen (N) and phosphorus (P) due to the recent expansion of agricultural and other human activities is accelerating environmental degradation of these water bodies, elevating the risk of eutrophication and reducing biodiversity. To evaluate the ecological effects of the influx of nutrients in an oligotrophic and stoichiometrically imbalanced environment, we performed a replicated in situ mesocosm experiment. We analyzed the effects of a N- and P-enrichment on the bacterial interspecific interactions in an experiment conducted in the Cuatro Cienegas Basin (CCB) in Mexico. This is a desert ecosystem comprised of several aquatic systems with a large number of microbial endemic species. The abundance of key nutrients in this basin exhibits strong stoichiometric imbalance (high N:P ratios), suggesting that species diversity is maintained mostly by competition for resources. We focused on the biofilm formation and antibiotic resistance of 960 strains of cultivated bacteria in two habitats, water and sediment, before and after 3 weeks of fertilization. The water habitat was dominated by Pseudomonas, while Halomonas dominated the sediment. Strong antibiotic resistance was found among the isolates at time zero in the nutrient-poor bacterial communities, but resistance declined in the bacteria isolated in the nutrient-rich environments, suggesting that in the nutrient-poor original environment, negative inter-specific interactions were important, while in the nutrient-rich environments, competitive interactions are not so important. In water, a significant increase in the percentage of biofilm-forming strains was observed for all treatments involving nutrient addition.

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