Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Objective: To calculate the monthly relative abundance of Thysanoptera species, according to the Margalef, Simpson and Shannon-Wiener diversity indices. Design / Methodology / Approach: The work was carried out in three geographic units with conventional management, during January-December, 2019 in the Reserva de la Biosfera Zicuirán-Infiernillo (Biosphere Reserve), Michoacán, Mexico. In each unit, 10 trees were selected through simple random sampling. Thrips counts were performed on ten shoots per tree every 15 d, for a total of 7200 shoots in the three geographic units. Thysanoptera individuals were placed in entomological jars. The variables were: number of thrips collected per shoot in sampled tree and geographic unit (orchard). To estimate the specific richness and structure of species, the program "calculation of diversity indices DIVERS" was used. Results: In the three geographical units studied, the recorded presence of Thysanoptera accounted for 12 to 17 species. For Nueva Italia 12 recorded species, two were permanent (16.66%), five abundant (41.66%), one scarce (8.3%) and four rare (33.33%). In Zicuirán, three species were permanent (17.64%), six abundant (35.29%), two scarce (11.76%) and six rare (35.29%). In Los Hoyos, four species were permanent (26.66%), four abundant (26.66%) and seven rare (46.66%). The abundance of species was represented by the genus Frankliniella and the species Scolothrips sexmaculatus and Scirtothrips citri. The highest species richness and abundance was found from January to May. In October and November, the value of the calculated indices was zero, which shows less richness and abundance of individuals. The best species uniformity was recorded during January and December, which meant a more stable and homogeneous relation. Study limitations/Implications. Pest resurgence, presence of Candidatus Liberibacter spp. and its vector Diaphorina citri. Findings / Conclusions: in Nueva Italia, 12 species were taxonomically determined; in Los Hoyos 15, and in Zicuirán 17 species, which are reported for the first time in the state of Michoacán, Mexico. At the geographic unit "Los Hoyos" diversity was higher, uniform and stable.

Objective: To determine the apparent digestibility (AD) of diets with hydroponic green corn forage (HGCF) and to evaluate its effect on the dry matter (DM) intake and daily weight gain (DWG) of lambs. Design/methodology/approach: Two experiments using four levels of inclusion (0, 20, 40, 60% DM) of HGCF in the diet were carried out. For determine the AD of diet 16 sheep were used and for the growth evaluation 20 male lambs. A completely randomized design in both studies was used. Results: A higher AD of DM and crude protein in diets with 40% and 60% of HGCF was observed (P<0.05; P<0.01). Lambs from 0 and 20% HGCF treatment had a higher DWG. A lower DM intake in 60% HGCF diet was registered (P<0.05). Limitations on study/implications: Currently there are various methods to supplement sheep during dry season, however, few are fully adapted to the needs of farmers. Hydroponic green corn forage is a valuable alternative for fast and constant production of forage with high nutritional value for sheep. Findings/conclusions: Hydroponic green corn forage has high digestibility, therefore, it can be used as an excellent source of forage in the diet of lambs, obtaining appropriate weight gains with rations that include up to 40% in the diet to replace commercial food.

Nematodes were identified in the digestive tract of 11 specimens of the lizard S. variabilis in localities of Las Altas Montanas, Veracruz. Meristic data were obtained and the intestine was dissected to obtain the nematodes, 17 nematodes belonging to the Oxyuridae family were identified. No significant differences were found in the frequency of nematodes between sexes of S. variabilis. Future studies increasing the number of samples, localities and identifying nematodes at the species level using molecular phylogeny methods will help to measure the impact of this type of relationship. Key words.- absence, frequency, .host, Oxyuridae, parasites.  

Objective: To describe the advances in the sugarcane variety selection program that is carried out by the Campus Córdoba of the College of Postgraduates in Agricultural Sciences located in Amatlán de los Reyes, Veracruz, Mexico. Design/methodology/approach: For the selection of sugarcane varieties, the methodology developed by the Institute for the Improvement of Sugar Production (IMPA) was used, and for the varietal description, the protocol of the International Union for the Protection of New Varieties of Plants (UPOV) was implemented. Results: In 2009, the Campus Córdoba started the varietal selection program with more than 6 thousand hybrids from 40 crosses, of which 4422 materials were selected after showing resistance to the sugarcane mosaic virus. From the 4422 materials of the seedling phase, 352 clones were selected and evaluated in the Furrow Phase, selecting 57 varieties for the Plot Phase. Of these 57 varieties, 36 were selected in the Adaptability Test Phase, and 27 in the following Agroindustrial Evaluation Phase. Of these last 27 varieties, estimated yields are greater than 100 t ha-1, with good quality of juices and agronomic characteristics. Study limitations/implications: The program has faced climate and budget challenges, delaying progress. Currently, the Covid-19 pandemic has drastically affected our research. Findings/conclusions: This breeding and variety selection program started with 6,000 crosses, of which to date there are 27 in advanced stages of selection, with the possibility of adaptation and good yields for the area of influence of the Campus Córdoba.

Objective: Rebuild the historical transformation of agroecosystems based on sugarcane in the sub-humid tropic, as a consequence of the change in public policies of the Mexican State in the last three decades. Design/methodology/approach: The transformation of sugar cane agroecosystems was studied in the continuum of reality, as changes in their resource management and management practices. Thus, methodologies used included life stories, field diary, and documentary review. The information collected was transcribed and classified in a database, using keywords for their previous identification by categories. The statements were identified and ordered based on their content, interpretation, and underlying concepts. Results: During the last century, public policies directed towards the sugar sector encouraged the existence of sugarcane agroecosystems as a monoculture. This implied changes in the management of time, work organization, orientation of the production, dependence on credits driven by the mills, and a process encouraged by the individualization of production, eroding the collective and solidarity work that lay behind other crops. Study limitations/implications: It is important to compare these findings with other investigations done in sugar cane producing municipalities. Findings / conclusion: Neoliberal public policies aiming the sugar sector deepened the producers' financial dependence on mills; as a consequence, they lost their autonomy in the management and use of their agroecosystems.

Objective: Analyze scientific papers close linked to the concepts of agroecosystems, rural tourism and its conceptual relationship. Design/methodology/approach: A search of papers published from 2014 up to 2020 in Science Direct (https://www.sciencedirect.com) was conducted, using key words related to the agroecosystem concept and rural tourism. Later, a bibliometric and text analysis was performed. Results: The concept of agroecosystems has been dynamic through time and related to other disciplines. However, research relating this concept with rural tourism is scarce. Limitations of the study/implication: Research proposals on agroecosystems associated to rural tourism are limited. Findings/Conclusions: Papers with the conceptual evolution of agroecosystems integrating rural tourism are scarce. So, it is suggested to study the agroecosystem in its different aspects, but considering their cultural and historical basis.

Objective: To analyze the vulnerability of citrus growers to HLB in the municipalities of San Rafael and Cotaxtla, State of Veracruz, Mexico. Design/methodology/approximation: Growers were surveyed about their knowledge, proficiency and perception of the implemented strategies of the Campaign vs the HLB. Vulnerability was integrated in the Risk Index (RI), including grower knowledge and perception towards the Campaign strategies, actions implemented and those that are willing to implement. The RI was compared between localities and was correlated with grower, orchard and confidence in social-actors variables. Organizational involvement of producers was compared. Results: Citrus growers from San Rafael and Cotaxtla have an intermediate degree of vulnerability, with no significant difference (P = 0.483) among them. RI of growers increases as social confidence decreases (r = -0.302). Organizational involvement of growers is equally low in both localities (P = 0.154). Limitations of the study/implications: This study does not apply to other communities. Findings/conclusions: Growers will not be able to respond appropriately and in a relevant way to the new conditions of vulnerability, which might risk the actions implemented with their participation in the Campaign vs the HLB

Objective: Analyze the productive development performed by two aquatic species of recent introduction in our country, the giant freshwater prawn (Macrobrachium rosenbergii) and tilapia (Oreochromis niloticus), arguing their potential under mono and polyculture systems. Design/methodology/approximation: The bibliographic meta-analysis was developed searching information on the internet, and is presented in a chronological manner with the analysis of the technological, social and political dimensions, visualizing the benefits and advantages of applying the polyculture production system. Results: A data base on the development of the tilapia-freshwater prawn polyculture in our country was obtained. Mexico presents the required physical characteristics for both species production. Thus, polyculture allows the use of the same infrastructure, resulting in a better productivity and income. Limitations of the study/implications: Polyculture information registered on electronic media was scarce. Findings/conclusions: The polyculture production of the Malaysian prawn and tilapia is a profitable option for the aquaculture producer in tropical areas of Mexico.

Objective: To identify the current knowledge about the coffee agroforestry systems, with emphasis on Mexico. Design/methodology/approach: A documentary internet search based on Google® was carried out using the keywords "agroforestry and coffee plantations”, and “coffee agroforestry systems in Mexico". Results: As a result, 88 documents were obtained; 91% of the publications were in Spanish, 40% are from Colombia, 24% from Mexico, 7% from Costa Rica and the last 29% from other countries. Limitations of the study/implications: This topic is studied by several institutions, although it is not part of a systematic line of study. Findings/Conclusions: Most of the research are focused on the importance of the coffee agroforestry system as a provider of environmental services, standing out the carbon sequestration, water catchment, biodiversity reservation and soil erosion buffering.

Objective: Assess the risk of groundwater contamination due to the application of pesticides and the amount of nitrogen leached in agroecosystems with sugar cane in the area of influence of sugar mills, La Gloria y El Modelo, Veracruz, Mexico. Methodology: The presence of pesticides at 30 groundwater sampling points was determined by using the Mexican regulation N0M-041-SSA1-1993 and the EPA 608 and EPA 608.1 methods described by the Environmental Protection Agency (EPA). Nitrogen (N) loss by leaching was assessed evaluating nine treatments by combining two factors: dose (250, 200 and 150 kg ha-1 of N) and application fractionated doses (2, 3 y 4). Results: Pesticides such as ?-hexachlorocyclohexane (?-HCH), heptachlor heptachloroepoxide, ?-endosulfan, ? endosulfan, sulfate-endosulfan, aldrin, dieldrin and dichlorodiphenyldichloroethylene (4.4’DDE) were found in groundwater of deep wells of agroecosystems with sugarcane. Application of low doses of N resulted in lower losses of N due to leaching. A dose of 150 kg ha-1 of N, applied in two, three, and four fractions, generated N losses between 15.40 to 18.18 kg ha-1, which means a loss of up to 12.1%. Conclusions: Groundwater contamination by agrochemicals, such as pesticides is indubitable; so, reducing such contamination should be a priority for crop growers involved. Also, nitrogen, soil and water management and conservation practices must be done. This will result in a less negative impact to the environment and public health. Water and nitrogen fertilizers management at plot level are to be improved in order to increase water irrigation and nitrogen efficiency in agricultural areas.