| 1. |
- Corrales, Roldan, et al.
(författare)
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Population structure of Reyna Creole cattle in Nicaragua
- 2010
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Ingår i: Tropical Animal Health and Production. - : Springer Science and Business Media LLC. - 0049-4747 .- 1573-7438. ; 42, s. 1427-1434
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Tidskriftsartikel (refereegranskat)abstract
- Reyna Creole cattle originated from Bos taurus cattle brought to Latin America during the Spanish colonization in the fifteenth century and are the only remaining local breed in Nicaragua. However, the current genetic status of this breed is unknown. Therefore, the population structure of three recorded Reyna Creole herds in Nicaragua was studied to estimate their level of inbreeding, effective population size, and generation intervals. Data from 2,609 animals born between 1958 and 2007 were analyzed. A pedigree completeness index higher than 0.8 was required to obtain reliable estimates of the level of inbreeding, and this criterion was met for 367 animals (14%) in two herds. The average level of inbreeding was 13.0%, with values ranging from 0% to 43.8% for individual animals. One of the herds had an average inbreeding level of 21.6%, primarily due to long periods in which the same bulls were used for mating, leading to excessive frequencies of matings between closely related animals. The effective population size differed between years and ranged from 28 to 46 animals, showing that the Reyna Creole cattle breed is endangered, close to critical status. The average generation interval was 6.9 years with values as high as 19.1 years for some sires that were used for artificial insemination over a long period of time. Due to the high level of inbreeding and small population size, urgent actions are required for the development of a breeding program to protect the breed and support its sustainable utilization.
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| 2. |
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| 3. |
- Miranda, Freddy, et al.
(författare)
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Population Density and Killing Capacity by Predators of Eggs and Larvae of the Diamondback Moth in Nicaragua
- 2011
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Ingår i: Environmental Entomology. - 0046-225X .- 1938-2936. ; 40, s. 333-341
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Tidskriftsartikel (refereegranskat)abstract
- The diamondback moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) is a serious pest of economically important brassica crops such as cabbage (Brassica oleracea Linne). To address the current lack of baseline information concerning predators of P. xylostella, and their potential role as biological control agents, especially in Central America, we aimed to 1) identify predators in northern Nicaragua, and estimate their population densities; 2) assess their killing rate of eggs and larvae of P. xylostella; and 3) assess if predators feed more of smaller P. xylostella larvae. Individuals of selected predator groups were offered eggs, second- or third-instar larvae. Our results indicate that there exists a broad spectrum of predators, within and around cabbage fields in Nicaragua that have the capacity to feed on P. xylostella eggs and larvae under laboratory conditions. Predators with the highest killing rates were adult and larval rove beetles (Staphylinidae), sheet weaving spiders (Linyphiidae), and larger jumping spiders (Salticidae). Although all predator densities varied in space and time the consistently most abundant predator groups with the highest consumption or killing rate, and consequently the highest potential for suppressing P. xylostella populations were wolf spiders (Lycosidae) and rove beetles (Staphylinidae), although sheet weaving spiders, jumping spiders, assassin bugs (Reduviidae), and damsel bugs (Nabidae) also can be important. We conclude that those generalist predators exhibiting the highest killing rates in the laboratory should be considered for further study in the field as candidate species with a role in the management of pest P. xylostella.
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| 4. |
- Corrales, Roldan, et al.
(författare)
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Birth weight, reproduction traits and effects of inbreeding in Nicaraguan Reyna Creole cattle
- 2011
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Ingår i: Tropical Animal Health and Production. - : Springer Science and Business Media LLC. - 0049-4747 .- 1573-7438. ; 43, s. 1137-1143
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Tidskriftsartikel (refereegranskat)abstract
- Reyna Creole cattle in Nicaragua comprise about 650 purebred animals, and the breed has been shown to have a high level of inbreeding. To characterize the breed, as basis for a conservation program, information from two herds on birth weight (BW, n = 1097), age at first calving (AFC, n = 449) and calving interval (CI, n = 1,347) was analysed. Overall averages were 27.8 kg for BW, 37.4 months for AFC and 424 days for CI. Large differences between the herds were observed for all traits. Thus, there would be opportunities for management interventions to improve reproduction results. The heritability for BW was 0.34. For CI, the heritability of 0.20 and the additive genetic standard deviation of 36 days were comparatively high values. No genetic variation was found in AFC. Estimated inbreeding effects were associated with large standard errors due to the small size of the data and incompleteness of pedigrees. Nevertheless, significant effects were shown of dam inbreeding level on all traits. For each percentage of increased inbreeding, BW decreased by 0.06 kg, AFC increased by 3.5 days and CI increased by 1.4 days. The effects of the inbreeding level of the individual itself were not significant. The relatively good reproduction traits of Reyna Creole cattle shown in this study, despite high inbreeding levels, will be supplemented with a characterization of milk production traits.
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| 5. |
- Blandón-Díaz, Jorge Ulises
(författare)
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Insights into population structure and epidemiology of Phytophthora infestans from Nicaragua
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Late blight caused by Phytophthora infestans (Mont) de Bary is a constraint to both potato and tomato crops in the northern highlands of Nicaragua. This thesis describes studies on population structure and epidemiology of P. infestans from Nicaragua. The genotypic and phenotypic variation in isolates of P. infestans collected in potato and tomato growing areas of northern Nicaragua were analyzed using genotypic (SSR fingerprinting and mtDNA haplotyping) and phenotypic markers (mating type, virulence and fungicide sensitivity). Genotypic markers revealed no polymorphism among the P. infestans isolates tested. Phenotypic variation was observed. Nicaraguan population of P. infestans is dominated by a clonal lineage of the A2 mating type, Ia mtDNA haplotype and no evidence of genetic population differentiation among potato and tomato isolates was found. The aggressiveness of P. infestans isolates sampled from potato and tomato fields was determined through cross-inoculations experiments. Potato and tomato isolates both had a shorter LP, higher SP, and were more aggressive on tomato leaflets compared to potato ones. The adequacy of the late blight simulation model LATEBLIGHT (version LB2004) was evaluated under Nicaraguan conditions. During 2007-2008 field experiments were conducted in Nicaragua. The simulation model was considered adequate as it accurately predicted high disease severity in susceptible cultivars without fungicide sprays, and demonstrated a decrease in the disease progress curves with additional fungicide applications, similar to that observed in the field plots. The quantitative relationship between host resistance and the need for fungicide was also investigated using simulations performed with LATEBLIGHT, as well as field trials.
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| 6. |
- Reyes Castro, Guillermo, et al.
(författare)
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Sequence characterization of Dasheen mosaic virus isolates from cocoyam in Nicaragua
- 2009
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Ingår i: Archives of Virology. - : Springer Science and Business Media LLC. - 0304-8608 .- 1432-8798. ; 154, s. 159-162
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Tidskriftsartikel (refereegranskat)abstract
- Dasheen mosaic virus (DsMV) is an important constraint to production of cocoyam (Xanthosoma spp.) in Nicaragua. Reverse transcription polymerase chain reaction was used to amplify the coat protein (CP) region from ten Nicaraguan DsMV isolates. These isolates showed high nucleotide identity to DsMV isolates from the USA, eastern Asia and Australasia. All Nicaraguan isolates except one shared a tandem repeat in the N-terminus of the CP. Phylogenetic analyses showed that the Nicaraguan isolates formed two distinct subgroups correlated with geographic origin. This can be explained by different origins of the cocoyam genotypes grown in these regions.
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| 7. |
- Mendieta-Araica, Bryan
(författare)
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Moringa oleifera as an alternative fodder for dairy cows in Nicaragua
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The four studies comprising this thesis characterised Moringa oleifera as a fodder for dairy cows under dry tropical conditions in Nicaragua. An agronomy study examined, two planting densities (D1=100,000 and D2=167,000 plants ha-1) and four fertilisation levels (N1=0, N2=261, N3=521 and N4=782 kg N ha-1). The D2 density gave significantly higher yields of total dry matter ha-1 (TDMY) and fine fraction dry matter ha-1 (FFDM) compared with D1. There were significant interactions between fertilisation level and the variables year and cut with regard to TDMY and FFDM. However, fertilisation levels N3 and N4 gave the highest yield in both years and among all cuts. A study on Moringa leaf meal (MLM), as a protein source in concentrates to dairy cows found no significant difference in milk production when comparing isocaloric and isoproteinic concentrates with or without MLM. In an ensiling experiment, Moringa was ensiled alone with 10 g kg-1 fresh matter (FM) molasses and compared with several mixtures with Elephant grass and sugar cane. Pure Moringa biomass produced silage with a higher crude protein (CP) content and had a favourable effect on silage pH, with higher lactic acid concentrations, but the presence of Moringa decreased time to spoilage by 67 h (22%) compared with the Elephant grass silages. Feeding Moringa as the sole roughage, either fresh or ensiled, compared with feeding Elephant grass resulted in higher digestibility of both CP and fibre but milk yield did not differ (13.7 kg cow day-1). No differences in milk composition were found between treatments but when fresh Moringa was fed a grassy flavour and aroma was detected in the milk. In conclusion, to maintain high biomass yield of Moringa over time, the best planting density-fertiliser combination was D2 and N3. MLM can successfully replace commercial concentrate ingredients for dairy cows. Furthermore, Moringa ensiled alone, with only 10 or 50 g kg-1 FM molasses added, produces good quality silage that can be fed to dairy cows in large quantities while maintaining the same milk production level and milk quality as for cows fed conventional roughages.
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| 9. |
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| 10. |
- Tigabu, Mulualem, et al.
(författare)
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Germination requirements and seedling establishment of four dry forest species from Nicaragua
- 2011
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Ingår i: Tropical Ecology -Allahabad-. - 0564-3295. ; 52, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- We examined the optimal temperature and light requirements for seed germination of Bombacopsis quinata, Cordia alliodora, Lysiloma divaricatum and Tabebuia rosea and establishment of B. quinata, C. alliodora and T. rosea seedlings planted under different light conditions. Seeds of L. divaricatum germinated rapidly and to a large extent at all constant temperature regimes (15-35 degrees C) both in light and darkness. Exposure of seeds to alternating temperatures of 20/15 degrees C resulted in 58 % germination in darkness and 62 % in light. C. alliodora and T. rosea seeds germinated equally well at constant temperature regimes ranging from 20 degrees C to 35 degrees C in light and darkness. Exposure to alternating temperatures (20/15 degrees C) resulted in higher germination for seeds of C. alliodora in dark than in light, while it inhibited the germination of T. rosea seeds. Seeds of B. quinata incubated at 20 degrees C and 25 degrees C in light and 20 degrees C in darkness exhibited the highest germination while exposure to alternating temperatures completely arrested germination in this species. Survival of C. alliodora seedlings was higher on open and partially-open sites than on-the site under closed canopy. B. quinata had the lowest survival while T. rosea had the highest on the open site. The findings are discussed in relation to the restoration of abandoned sites. We concluded that while C. alliodora and T. rosea could potentially serve as framework species for the restoration of degraded and/or abandoned sites, B. quinata does not meet the requirements of a framework species for restoring degraded sites in drier regions.
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