Evaluación de los impactos en la calidad de la energía por la compensación de potencia reactiva con bancos de condensadores y D-STATCOM

This paper presents an assessment of capacitor banks and Distribution Static Compensator (D-STATCOM) with respect to their impact on energy quality. Tests were done with capacitor banks built with electrolytic capacitors commonly used in industrial applications and a D-STATCOM. Experimental tests were performed for power factor correction in order to reduce the reactive power demanded from the electrical grid for inductive-resistive loads. For comparative purposes, the control of the D-STATCOM was set to operate with similar compensation conditions to that of the capacitor banks. Results show that under the same test conditions capacitor banks produce higher Total Harmonic Distortion (THD) than D-STATCOM.Este artículo presenta una evaluación de los bancos de capacitores y el Compensador Estático de Distribución (D-STATCOM) con respecto a su impacto en la calidad de la energía. Las pruebas fueron hechas con bancos de capacitores construidos con capacitores electrolíticos comúnmente usados en aplicaciones industriales y un D-STATCOM. Las pruebas experimentales fueron realizadas para corrección del factor de potencia, con el fin de reducir la potencia reactiva demandada por la red eléctrica con cargas resistivo-inductivas. Por propósitos comparativos, el control del D-STATCOM se programó para operar en similares condiciones de compensación respecto al banco de capacitores. Los resultados muestran que, bajo las mismas condiciones de prueba, los bancos de capacitores producen mayor Distorsión Armónica Total que el D-STATCOM

Susceptibility of biological stages of the horn fly, Haematobia irritans, to entomopathogenic fungi (Hyphomycetes)

The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC(50) against adult horn flies (8.08 &times 10(2)conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults

Use of the entomopathogenic fungi \u3ci\u3eMetarhizium anisopliae, Cordyceps bassiana\u3c/i\u3e and \u3ci\u3eIsaria fumosorosea\u3c/i\u3e to control \u3ci\u3eDiaphorina citri\u3c/i\u3e (Hemiptera: Psyllidae) in Persian lime under field conditions

The Asian citrus psyllid Diaphorina citri Kuwayama is a destructive insect pest in citriculture, because it is an efficient vector of the proteobacteria ‘Candidatus Liberibacter asiaticus’ (Las), ‘Ca. L. africanus’ (Laf) and ‘Ca. L. americanus’ (Lam). These bacteria cause the ‘huanglongbing’ disease or ‘greening’ or ‘yellow dragon’ disease. The disease kills the plant and reduces fruit production. This insect pest is susceptible to entomopathogenic fungi, and we report the use of different strains of Metarhizium anisopliae, Cordyceps bassiana and Isaria fumosorosea against the nymphs and adults of D. citri under field conditions. The fungi were applied four times using a concentration of 2 £ 1013 conidia/ha with a time interval of 15 days between applications. The percentage of control of Cb 108, Ma 65, Ma 14 and Ifr 4 was 60, 50, 40 and 35% in nymphs, and 50, 50, 42 and 22% in adults, respectively. Metarhizium anisopliae, C. bassiana and I. fumosorosea applied on Persian lime groves are more effective in reducing higher density of nymphs than adults of D. citri

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

Nutritional quality of sun-dried swine excreta for beef cattle

The effect of drying fresh swine excreta (FSE) previously mixed with ground corn (GCS) or sorghum straws (GSS) by sun exposure (10, 15, 20 cm deep bed; 10, 20, 30 and 40 h) on its nutritional quality and acceptance by beef cattle was studied in a 3x3x4 factorial arrangement. The reduction in protein content of the excreta mixed with ground straw was slightly lower as compared with excreta alone at 40 hours of sun exposure. In a second experiment, two groups of nine Bos indicus x Brown Swiss growing bulls (235-243 kg) were allotted randomly and fed with either fresh or dried swine excreta mixed with whole ground dried corn plant (WGDC). There were no significant differences on average daily gain or intake of feed. Results of this study suggest that the sun dried swine excreta previously mixed with whole, ground dried corn plant might be included in ruminant diets

Susceptibility of Biological Stages of the Horn Fly, \u3ci\u3eHaematobia irritans\u3c/i\u3e, to Entomopathogenic Fungi (Hyphomycetes)

The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC50 against adult horn flies (8.08 x102conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults

Virulence of Mexican isolates of entomopathogenic fungi (Hypocreales: Clavicipitaceae) upon \u3ci\u3eRhipicephalus = Boophilus microplus\u3c/i\u3e (Acari: Ixodidae) larvae and the efficacy of conidia formulations to reduce larval tick density under field conditions

The first objective was laboratory evaluation of the virulence of 53 Mexican isolates of fungi against larvae of Rhipicephalus (Boophilus) microplus. Thirty-three isolates of Metarhizium anisopliae var. anisopliae (Metschnickoff) Sorokin (Hypocreales: Clavicipitaceae) and 20 isolates of Isaria (Paecilomyces) fumosorosea (fumosoroseus) (Wize) (Eurotiales: Trichomaceae) were tested on 7-day-old larvae under laboratory conditions. Larvae were immersed in a suspension containing 108 conidia/mL and the CL50 values were estimated. Then, field tests were conducted to determine the efficacy of formulations of the isolate with the highest virulence. M. anisopliae (Ma 14 isolate) was formulated with four carriers: Tween, Celite, wheat bran, and Citroline (mineral oil) and applied on pasture beds of Cynodon plectostachyus (L.), at a dose of 2×109 CFU/m2. In the first trial, M. anisopliae was applied on plots naturally infested with larvae; in the second trial, tick populations in the experimental plots were eliminated and then re-infested with 20,000 7-day-old larvae. In the laboratory, all M. anisopliae isolates infected larvae with a mortality range between 2 and 100%; also, 13 of 20 I. fumosorosea isolates caused mortality rates between 7 and 94%. In the first field trial, 14 days post-application, conidial formulations in Celite and wheat bran caused 67.8 and 94.2% population reduction, respectively. In the second trial, the Tween formulation caused the highest larval reduction, reaching up to 61% (28 days post-application). Wheat bran formulation caused 58.3% larval reduction (21 days post-application) and was one of the most effective. The carriers and emulsifiers have a large impact on the effectiveness of conidial formulations