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

Background. Resistance to an insecticide is what determines its effectiveness and the lack of information limits effectiveness in the control of the boll weevil in cotton crops. Objective. The objective of the study was to determine the susceptibility of the boll weevil (Anthonomus grandis Boheman) to malathion in the Laguna, Mexico. Currently, this pest is considered as the one with the highest economical impact on cotton cultivation in the region. Methodology. Three bioassays were carried out, one in the state of Coahuila in the 2017 agricultural season and in the 2018 and 2019 seasons in the states of Coahuila and Durango. Boll weevils reared in the laboratory, as well as those collected in the field were used to obtain DL50 and DL95. The mortality data was analyzed using the Probit analysis. Results. The mean lethal dose after 48 hours in the three agricultural cycles fluctuated between 0.19 and 0.39 µg/µl for adults raised in the laboratory and the data observed for adults collected in the field was between 0.37 and 0.44 µg/µl. Implications. Periodic bioassays are suggested to detect populations resistant to malathion. Conclusion. It was determined that the boll weevil populations in the Laguna Region were susceptible to malathion, since the mean lethal dosage for the 3 agricultural seasons was < 1 µg/µl.

Background. Ruminants have been related to greenhouse gas production. Therefore, it has been necessary to find alternatives by using natural additives to reduce their production by modulation of rumen fermentation. Objective. It was to evaluate the effect of the addition of condensed tannins (CT) and different levels of essential oregano oil (Lippia graveolens) (EOO) in sheep's diets on in vitro fermentation products such as total gas production, methane (CH4), carbon dioxide (CO2), pH, ammoniacal nitrogen (N-NH3), and volatile fatty acids (VFA). Methodology. There were evaluated six experimental diets: the control diet with 4% of CT kg/DM, and 0.02, 0.04, 0.06, 0.08 or 1% de EOO kg/DM, respectively. Total gas production, CH4, CO2, pH, N-NH3, and AGV were measured at different in vitro incubation times. Results. Total gas production was not affected (P > 0.05) due to treatment or the interaction treatment*time. An exponential increment was observed (P < 0.05) according to incubation time. CH4 and CO2 production increased at 48 h. The lowest emissions of these gases were recorded when 0.04, 0.06, 0.08, and 1% of EOO were added to the diet. Nevertheless, no differences were found (P > 0.05) due to treatment or the interaction treatment*time. Acetic and butyric acid concentrations were affected due to incubation time and the interaction treatment*time; however, there was no effect due to treatment (P > 0.05). Propionic acid production and pH were not affected (P > 0.05) due to treatment, time, or interaction treatment*time. N-NH3 production increased through incubation time (P < 0.05), with the highest concentration at 48 h for all treatments, without differences (P > 0.05) due to treatment or interaction treatment*time. Implications. These results suggest that the inclusion levels of TC and EOO in the diet were not enough to affect rumen fermentation or methane production. Therefore, it is necessary to evaluate higher levels of these compounds in sheep's diets. Conclusion. The addition of CT or the different levels of EOO included in sheep's diets evaluated in this study did not affect total gas production, CH4, CO2, pH, concentration of N-NH3, AGV, and pH.

Background: Saprophytic micromycetes are recognized for their extraordinary ability to biosynthesize various metabolites with biological properties that can be modified when interacting with other organisms. Objective: To evaluate the antibacerial and antifungal activity of extracts obtained from dual interactions of Acremonium masseei CICY029 (Am), Beltraniella portoricensis MR42 (Bp), Cylindrium elongatum MR45 (Ce) y Stachybotrys sp. MR33 (Ssp) and to obtain the chemical profile of the most active interaction. Methodology: The ethyl acetate extracts of the four strains and their six dual interactions were evaluated against ten pathogens by the microdilution method to determine their antifungal and antibacterial capacity.  The most active extracts were partitioned, and the minimum inhibitory concentration (MIC) o their fractions were determined. The chemical profile of the most active interaction was analyzed by gas chromatography coupled to mass spectrometry. Results: The highest mycelial growth inhibitory activity (MCI = 100%) was obtained from the fungal extracts of the single culture of Stachybotrys sp., and the dual Ce-Ssp interaction against Colletotrichum gloeosporioides, Mycosphaerella fijiensis at the concentration of 2000 µg/mL, as well as against Candida albicans and Xanthomonas campestris at 400 µg/mL. The acetonitrile fraction of Stachybotrys sp. showed high effectiveness against Alternaria tagetica, C. gloeosporioides, M. fijiensis and X. campestris (MIC ≤ 250 -1000 µg/mL). A mixture of fatty acids and three unidentified components not observed in the single cultures were detected by GC-MS in the Ce-Ssp extract. Implications: Biological interactions between two saprophytic fungi are a viable alternative for inducing the production of new metabolites with the potential to control pathogenic bacteria and fungi. Conclusions: The antifungal and antibacterial potential of saprophytic micromycetes can be improved in their dual interaction, particularly between C. elongatum MR45 and Stachybotrys sp. MR33, is a promising option for further investigation as potential natural antimicrobials.

Background. Bamboo species is characterized by their rapid growth; therefore, they have been used in commercial forest plantations in Mexico under several environments. This study aimed to evaluate the survival and growth of two bamboo species: Otatea acuminata, and Otatea rzedwoskiorum, in plantations in Ziracuaretiro, Michoacán. Methods. An experimental design with randomized blocks, two treatments, four replicates, and 25 plants as experimental units was used. Variance (p= 0.05) and Tukey-test analyses were performed for the variables height (AT), diameter at stem base (DBT), and relative growth rate (TCR) in the program Statistica version 13. Results: After two years, there were differences between both species ( ), where O. rzedwoskiorum stood out in survival (96%), but O. acuminata had more AT (2.04 m), DBT (8.30 mm), and TCR (0.013 mm day-1). Implications: O. acuminata can be established adequately in commercial forest plantations in the temperate region of Michoacán. Conclusions: In survival, Q. rzedwoskiorum was better; however, O. acuminata had better growth.

Background. Pigeon peas (Cajanus cajan) produce large amounts of high protein leaves that make it suitable for cultivation in arid and semiarid regions. Objective. To evaluate the biomass production and chemical composition of three pigeon pea varieties (ICEAP 00557, ICEAP 01514 and CIMMYT 100/01). Methodology. A completely randomized design was used. In two growing seasons, the plots were harvested at flowering and biomass yields were measured for fresh forage and dry matter (DM). Harvested leaves were either shade or oven-dried to a constant weight before being milled for chemical analyses. The proximate composition, mineral content, phenolic, tannin and saponnin contents were determined. Results. Varieties ICEAP 01514 and CIMMYT 100/01 yielded the highest fodder of 2620.6 and 4458.3 kg DM/ha in 2016 and 2017, respectively. Variety ICEAP 00557 produced the lowest amount of fodder in both 2016 and 2017 at 1997.6 and 2933.3 kg DM/ha, respectively. There were interactions among varieties, seasons and drying methods on proximate composition. The DM, organic matter (OM) and neutral detergent fibre (NDF) were higher for ICEAP 01514 at 96.0, 88.0 and 55.3 %, respectively and digestible dry matter (DDM) (67.8 %) and metabolizable energy (ME) (9.8 MJ/kg DM) were higher for variety ICEAP 00557 in 2017.  Shade drying recorded higher crude protein (CP) values (24.2-27.0 %) across all varieties with higher values occurring in 2017 compared to 2016. The interactive effect of season, pigeon peas varieties and drying method had little effect on both macro and micro- minerals except for copper (Cu) values. The ranges in macro-minerals were: calcium (Ca) (1.21-2.35), magnesium (Mg) (0.33-0.89), sodium (Na) (0.1-0.7) and phosphorus (P) (0.13-0.31 %). The ranges in micro-minerals were: iron (Fe) (206.7-283.4) and Cu (5.94-7.95 mg/kg DM). The tannins, phenolic and saponin contents were different (P< 0.05) among varieties and between drying methods. Their ranges were: 2.7-8.0 mg catechin equivalent (CE)/g, 13.6-15.9 mg gallic acid equivalent (GAE)/g and 3.4-6.1 %, respectively. Implications. Pigeon peas are suitable for farming systems in the drylands and these varieties are suitable diets for ruminants in the subtropics, where CP in the diets are low. Conclusions. Air-drying under a shade was recommended to preserve the nutritional quality of pigeon peas fodder. The macro and micro-nutrients in the pigeon peas satisfied the animal requirements, except for the deficiency in Na and Cu. The concentration of the anti-nutritive compounds in the pigeon peas will not limit animal performance.

Antecedentes. Uno de los problemas clásicos de degradación de la tierra que ha tenido que enfrentar el hombre, es controlar, prevenir o mejorar los suelos afectados por la salinidad. Objetivo. El objetivo de esta investigación fue evaluar la respuesta fisiológica y morfométrica de plantas de Origanum vulgare L. sometidas a cinco concentraciones de NaCl (0, 50, 100, 150 y 200 mM). Metodología. El experimento se estableció en un diseño completamente al azar con cinco tratamientos a base de diferentes concentraciones de NaCl (0, 50, 100, 150 y 200 mM) con cuatro repeticiones por tratamiento. Cada repetición estuvo conformada con 14 plantas. Las variables evaluadas fueron peso fresco y seco de hojas, área foliar, peso fresco y seco de tallo, longitud de tallo, peso fresco y seco y longitud de raíz, el contenido de clorofila a y b, contenido relativo de agua y el potencial hídrico. Resultados. Los resultados mostraron que el peso fresco y seco de hojas, tallo y raíz, área foliar, así como la longitud de tallo y raíz presentaron diferencias significativas entre tratamientos, disminuyendo conforme las concentraciones de NaCl se incrementaron, al igual que el contenido de clorofila a, b, contenido relativo de agua y el potencial hídrico fue más negativo conforme la concentración de NaCl se incrementó. Implicaciones. El estudio permite determinar la tolerancia de orégano a la salinidad, al someter las plantas a diferentes concentraciones de NaCl y valorar si tiene capacidad de absorber Na+ del medio de cultivo. Asimismo, muestra que es posible cultivar orégano en condiciones de hidroponía en raíz flotante, considerando todas las ventajas que este sistema ofrece, como ahorro de agua y nutrientes, siendo posible obtener rendimiento adecuado utilizando agua de salinidad moderada (50 mM de NaCl) que representa una conductividad eléctrica de 5.8 dS∙m-1. Conclusiones. Todas las variables disminuyeron conforme las concentraciones de NaCl se incrementaron en el medio de cultivo. El orégano mostró capacidad de absorber el Na+ del medio de cultivo en 50, 100 y 150 mM de NaCl.

Background. The study of space allowance (m2) per animal is important, due in current production systems different group sizes are used throughout the year, without knowing their possible effects on daily weight gain and growth during the fattening period. Objective. The effect of space allowance on the growth of hair lambs in raised-slatted floor cages was determined. Methodology. Data from 527 daily weight gains (DWG) and weights adjusted at 60 (P60) days post-weaning of female lambs from commercial crossbreds between hair breeds were analyzed. The statistical model included fixed effects of space allowance (AL; 0.69, 0.64-0.60 and 0.56 m2/animal), year (A; 2012 and 2013), seasons of the year (EA; rainy and north) and the interaction on DWG and P60. The initial body weight was included as co-variate. Results. AL, A and interactions A × EA affected the dependent variables evaluated (P <0.05). AL larger (0.69 m2) and intermediate (0.64-0.60 m2) had similar growth (P >0.05); these groups, in turn, were the ones that obtained the highest DWG and P60 compared to smaller AL (0.56 m2). Higher growth of the female lambs was observed in the year 2012 compared to 2013. EA had no significant effect (P >0.05). Implications. The availability of the space allowance implies the quantity and quality, including the area occupied by the feeder and drinker. Conclusion. Under the conditions of the present study, AL should be adjusted between 0.69 and 0.60 m2/female lambs and that A and A × EA interaction can play an important role in animal growth.

Antecedentes. La superficie cultivada de camote en la costa peruana ha crecido en los últimos 10 años debido al incremento de la demanda del mercado; en este contexto de intensificación del cultivo, se desconoce su nivel de sostenibilidad en los sistemas de producción predominantes.  Objetivo. Determinar el nivel de sostenibilidad de las unidades de producción de camote (UPC), considerando aspectos económicos, ambientales y sociales, aplicando técnicas y propuestas metodológicas de análisis multivariado. Metodología. Se aplicaron encuestas con preguntas estructuradas a agricultores responsables del manejo de sus UPC. Los valores de los indicadores económicos, ambientales y sociales se hallaron en función a una propuesta metodológica de análisis multidimensional. Los datos se adecuaron a una escala ordinal de 1 a 5, en el cual 1, se consideró como el menos sostenible y 5 un nivel de sostenibilidad ideal. Implicaciones. El valor de los indicadores económicos, ambientales y sociales definen el valor de la sostenibilidad de los sistemas de producción agrícola. Conclusiones. Los indicadores económicos, sociales y ambientales contribuyen con un Índice de Sostenibilidad General (ISGen) de 2.93; valor que ubica a las UPC en una condición crítica debido a que el valor de los indicadores ambientales no logra superar el umbral mínimo de sostenibilidad establecida en la metodología aplicada.

Background: The identification of the relationship between the particular traits of the body development of the rabbit could help the understanding of the biological growth and the application in different areas of livestock and veterinary study. Objective. To evaluate the relationship between osteometry of the limbs, live weight (LW), hot carcass weight (HCW) and anatomical cuts; and generate equations to predict PV, PCC and anatomical cuts in New Zealand White (NZW) rabbits at different ages. Methodology. A total of 113 rabbits of seven different ages (9, 11, 14, 17, 20, 24 and 28 weeks) were used. The data obtained were LW, carcass characteristics: PCC and anatomical cuts (front, middle and back); and osteometry: length and diameter of the humerus (LH and DH), radio-ulna (LR-C and DR-C), femur (LF and DF) and tibia-fibula (LT-P and DT-P). The information was analyzed using Pearson's correlation coefficients (r) and linear and multiple regression models. The accuracy of the models was evaluated using the coefficients of determination (r2) and the square root of the mean square error (RCCME). Results. The correlations expressed between LW, carcass characteristics and bone lengths were higher (r= 0.90 – 0.95; p= < 0.0001) compared to diameters (r= 0.38 – 0.72; p= < 0.0001). The regression equations for PV had a RCCME that varied from 186.86 to 197.70 g using LR-C and LF. While for the PCC it presented RCCME from 130.4 to 138.58 g with LH, LR-C and DH. Regarding the anatomical cuts, the progressive order of rear, middle and front using LF and LH was RCCME= 21.66 to 25.67. The LF and LH explained 92 and 91% of the variation of the PV and PCC, although it decreased slightly in the anatomical cuts from 85 to 92%. Implications. The osteometry of the extremities reflects security in the application of equations to calculate general and particular data of body mass in the rabbit, this contribution of knowledge can be extrapolated for animal production and forensic veterinary studies. Conclusion. The close associations obtained between limb lengths (exception LT-P) with PV, PCC and anatomical cuts gave equations with high capacity to estimate these body changes of growing NZB rabbits.

Background: Soil hydraulic parameters in non-saturated conditions are crucial for explaining soil water dynamics in the field. It is therefore necessary to understand the link between soil water potential and hydraulic conductivity in the soil in order to estimate plant available water and hence simulate its movement within the soils. However, measurement of such hydraulic properties in the field and laboratory is somehow difficult, laborious and costly. Objective: To determine soil hydraulic properties of Ferro-chromic Luvisols in Katumani using the RETC code based on pedo-transfer functions; % sand, silt, clay and soil bulk density. Methodology: Undisturbed soil samples were collected from a profile pit at 0-15, 16-30, 31-45 and 46-60 cm depths using core rings for bulk densities and texture determination. Soil water retention curves and saturated hydraulic conductivities (Ksat) were estimated for all the samples using standard suction apparatus and the constant head method, respectively. The air entry suction (α) and pore size distribution (n) were generated using the RETC code. Results: The permanent wilting point and field capacity were at 0.081, 0.102, 0.107 and 0.121 and 0.188, 0.225, 0.241, 0.262 m3m-3 H2O, whilst its soil water diffusivity ranged from a low of 6.39, 6.94, 9.03 to a high of 12.5 cm2min-1 in the 0-15, 16-30, 31-45 and 46-60 cm depth, respectively. Ksat values from RETC code ranged from 29 - 48 cm day-1, while the total and readily available water within the soil profile were 330.4 and 214.7 mm H2O, respectively. Implication: The air entry value (α) and pore size distribution (n) implied an almost even distribution from the top and subsequent horizons. The soils ‘field capacity was achieved at pF 2.0 whilst PWP was arbitrary indicated at pF 4.2 reducing the time it takes to calculate irrigation cycles based on the amount of water available to the crops. Conclusion: The data indicates that pedo-transfer functions; especially high bulk densities negatively impact on soil hydraulics conductivity.