Prebiotic Mannan Oligosaccharide Diet Improves Health Status of the Digestive System of Marron,Cherax tenuimanus (Smith 1912)

The aim of this experiment was to determine the effects of dietary supplementation with mannan oligosaccharide (MOS; BioMos, Alltech, USA) on the gut microbiota and histology of marron, Cherax tenuimanus. Marron were fed six different diets supplemented with 0%, 0.05%, 0.1%, 0.2%, 0.4%, and 0.8% of MOS for a duration of 112 days. Total bacteria in the gut were highest when marron were fed diets which included 0.1% to 0.4% BioMos, whereas total bacteria/Vibrio spp. ratio was highest in the marron fed 0.4% BioMos diet only. The marron fed 0.2% and 0.4% BioMos diets showed normal morphology and higher densities of microvilli, and thicker layer of gut epithelium than other inclusion rates. The results suggest that application of 0.2% to 0.4% of MOS in the diet improves digestive system health in marron.     

The estimate of world demand for Pangasius catfish (Pangasiusianodon hypopthalmus)

ABSTRACT

This research described in this article aimed to investigate international market potentials for Pangasius catfish (Pangasianodon hypopthalmus). The monthly export data from Vietnam, which accounts for more than 95% of the global export value, in the period 2007 to 2014, were used to estimate a non-linear Inverse Almost Ideal Demand System of the seven market regions. Prices in all markets are found very inflexible, with own-price flexibilities on ?0.200 to ?0.917, or ?0.419 on average, revealing the option of expanding global production and export without inducing a substantial price reduction. Consumers in all markets except Latin America evaluate Pangasius as a necessary good, indicating that the Pangasius industry is relatively little affected by recessions and booms in the world economy. The major markets are substitutes for each other; therefore, if demand at one market region is reduced, the presence of substitution leads suppliers to find other markets. The results reveal that demand provides stable framework conditions for the Pangasius industry.     

Implicit price of mussel characteristics in the auction market

This study explores desired and undesired characteristics of mussels in wholesale market by applying hedonic price analysis. Transaction data in auction market in Yerseke, the Netherlands, was used to estimate linear and semi-log price models. Meat content and size count, which are measured as the ratio of the weight of cooked meat to the total weight and the number of mussel per kg of raw mussels, respectively, are the most important characteristics determining the price. At the sample mean, if the meat content increases by 1%, farmers can get a premium price of 5.5 eurocents kg^?1 of raw mussel. Mussel lots with size counts below 50 pieces kg^?1 can command the highest implicit price of size. Processors prefer mussel lots in which the size of mussels is more or less heterogeneous. The impurity of mussel lots, which is measured by the percentage of tare, the amount of barnacles and limpets per kg of raw mussels are significant discounting factors on the price. The study also investigates the impact of farming locations and seasons on the price and the price trend during the period of 2002–2009.     

Emerging pests and diseases of South‐east Asian cassava: a comprehensive evaluation of geographic priorities,management options and research needs

Cassava is a major staple, bio‐energy and industrial crop in many parts of the developing world. In Southeast Asia, cassava is grown on >4 million ha by nearly 8 million (small‐scale) farming households, under (climatic, biophysical) conditions that often prove unsuitable for many other crops. While SE Asian cassava has been virtually free of phytosanitary constraints for most of its history, a complex of invasive arthropod pests and plant diseases has recently come to affect local crops. We describe results from a region‐wide monitoring effort in the 2014 dry season, covering 429 fields across five countries. We present geographic distribution and field‐level incidence of the most prominent pest and disease invaders, introduce readily‐available management options and research needs. Monitoring work reveals that several exotic mealybug and (red) mite species have effectively colonised SE Asia's main cassava‐growing areas, occurring in respectively 70% and 54% of fields, at average field‐level incidence of 27 ± 2% and 16 ± 2%. Cassava witches broom (CWB), a systemic phytoplasma disease, was reported from 64% of plots, at incidence levels of 32 ± 2%. Although all main pests and diseases are non‐natives, we hypothesise that accelerating intensification of cropping systems, increased climate change and variability, and deficient crop husbandry are aggravating both organism activity and crop susceptibility. Future efforts need to consolidate local capacity to tackle current (and future) pest invaders, boost detection capacity, devise locally‐appropriate integrated pest management (IPM) tactics, and transfer key concepts and technologies to SE Asia's cassava growers. Urgent action is needed to mobilise regional as well as international scientific support, to effectively tackle this phytosanitary emergency and thus safeguard the sustainability and profitability of one of Asia's key agricultural commodities. © 2016 Society of Chemical Industry     

Quantification and ecological study of ‘Candidatus Liberibacter asiaticus’ in citrus hosts,rootstocks and the Asian citrus psyllid

The use of proper management strategies for citrus huanglongbing (HLB), caused by ‘Candidatus Liberibacter asiaticus’ (Las) and transmitted by Asian citrus psyllid (ACP) (Diaphorina citri), is a priority issue. HLB control is based on healthy seedlings, tolerant rootstock cultivars and reduction of ACP populations. Here, dynamic populations of Las in different citrus hosts and each instar of ACP were studied, together with the seasonal growth and distribution of Las in different tissues, using conventional and TaqMan real‐time PCR. Different levels of susceptibility/tolerance to HLB were seen, resulting in different degrees of symptom severity and growth effects on hosts or rootstocks. Troyer citrange, Swingle citrumelo and wood apple were highly tolerant among 11 rootstock cultivars. Regarding distribution and seasonal analysis of Las, mature and old leaves contained high concentrations in cool temperatures in autumn and spring. Las was detected earlier through psyllid transmission than through graft inoculation, and the amounts of Las (AOL) varied in different hosts. Thus, different AOL (10⁴–10⁷ copy numbers μL^?1) and Las‐carrying percentages (LCP; 40–53.3%) were observed in each citrus cultivar and on psyllids, respectively. Furthermore, both AOL and LCP were lower in nymphs than in adult psyllids, whereas the LCP of psyllids were not affected by increasing the acquisition‐access time. The present study has significant implications for disease ecology. The combination of early detection, use of suitable rootstocks and constraint of psyllid populations could achieve better management of HLB disease.     

A Natural Forest of Commercial Timber Species: Logging or Not Logging

Most tropical forests outside protected areas have been or will be selectively logged because the timber industry is a main income-generating resource for many developing countries. Therefore, understanding the composition of commercial timber species and logging types is key for sustainable forest management in countries like Vietnam as they move toward fulfilling Reducing Emissions from Deforestation and Forest Degradation (REDD+) agreements. Seven 1-ha plots were surveyed in the Central Highland of Vietnam, and 18 commercial tree species from these plots, whose timber is widely used by local people for housing and furniture making and timber is easily sold at local markets for high prices, were analyzed. In total, 151 tree species with a diameter at breast height (DBH) of ≥?10 cm were recorded. The 18 commercially valuable species assessed in this study accounted for 33.2% of all stems (total of 524 stems ha^?1 for all species), 47.1% of basal area (total of 34.35 m² ha^?1 for all species), and 50.8% of aboveground biomass/AGB (total of 262.68 Mg ha^?1 for all species). Practicing diameter-limit harvesting of all commercially valuable species with DBH of ≥?40 cm, which is widely performed in Vietnam, will reduce the number of stems by 7%, basal area by 31.6%, and AGB by 38.2%. Because such harvesting practices cause severe ecological impacts on the remaining forest, logged forests may require >?40 years to recover the structure status of a pre-logged forest. In addition, the recovery of the 18 commercially valuable species may require a much longer time because they comprised 33.2% of stems. Permission for logging natural forests should be given in Vietnam to sustain lives of local communities, where logging has been prohibited. However, alternative harvesting systems, such as reduced-impact logging systems, should be considered. The systems selected must simultaneously generate economic returns for local people and respect the REDD+ agreements with regard to protecting biodiversity and reducing carbon emissions.     

不同薏苡品种光合特性及其与氮素利用效率的关系

为明确薏苡品种的光合特性及与氮素利用效率间的关系。2015年早季和晚季,分别以从大田试验中筛选出来的氮素利用效率较高和较低品种各2个为材料进行盆栽试验,在分蘖期、抽穗期和成熟期测定功能叶片光合速率及叶绿素荧光参数,抽穗期测定顶部4片功能叶的光合速率,成熟期测定氮素积累量和氮素利用效率。结果表明,氮高效品种西林1号(XL)与黔饮1号(QL)早季和晚季成熟期单株氮素吸收量平均分别比氮低效品种隆林1号(LL)与品种10号(CU)高125.5%和96.0%,其氮素利用效率平均比品种LL与CU分别高出17.7%和18.0%,品种间差异显著。氮高效品种在分蘖期、抽穗期和成熟期功能叶片的光合速率和叶绿素含量均明显高于氮低效品种。同时,氮高效品种在分蘖期后的光合速率、叶绿素含量衰减速率比氮低效品种小。不同品种在分蘖期、抽穗期和成熟期功能叶片的叶绿素荧光参数及抽穗期顶部4片功能叶光合速率也存在一定的差异,但品种间的变化规律不明显。综上所述,氮高效薏苡品种各生育期功能叶片的光合速率和叶绿素含量较高,其中后期光合速率及叶绿素含量衰减较慢。薏苡品种氮素利用效率与功能叶片的叶绿素荧光参数及顶部4片功能叶光合速率的变化没有显著的相关关系。     

油菜花叶病毒15号和菸花叶病毒间干扰作用的研究

 TMV与YMV₁₅在系统感染寄主——菸(Nicotiana tabacum)上的相互干扰作用是很微弱的。同时接种二病毒时,在感染的早期(接种后2-3天) YMV₁₅占优势,在此时间以后TMV的浓度就超过YMV₁₅。二病毒以相同的侵染力同时接种心叶菸(Nicotiana glutinosa)时,则大部分的局部斑点是由YMV₁₅形成的。上述结果表明,YMV₁₅竞争侵染点的能力较TMV为大。试验并证明完整的YMV₁₅及其蛋白都能干扰TMV侵染菜豆(Phaseoluss vulgaris),因而这种干扰似决定于病毒蛋白质部分对于侵染点附着的特异性。     

卫星RNA作为黄瓜花叶病毒的生防因子——Ⅲ.含有卫星RNA的黄瓜花叶病毒S51的某些生物学特性的研究

 1982~1983年比较了含有卫星RNA的黄瓜花叶病毒(CMV)S51和CMV分离物的寄主范围、症状反应和蚜虫传染的特性。对属于8科25种以蔬菜为主的植物的接种和回接实验证明:S51比CMV的寄主范围窄得多,只侵染茄科、葫芦科和藜科中的10种植物,CMV侵染6科的20种植物。S51除在西葫芦的部分植株上有花叶症状外,均无症状;而CMV能引起重花叶、畸形和坏死等症状。桃蚜对S51的传染效率比CMV低,潜育期延长2~6天。     

Medicinal plants popularly used in the Brazilian Tropical Atlantic Forest

A survey of medicinal plants used by rural and urban inhabitants of the three cities of the Tropical Atlantic Forest, Region of Vale do Ribeira, State of S?o Paulo, Brazil was performed by means of 200 interviews with medicinal plant users and extractors and, traditional healers. One hundred fourteen herbal remedies were recorded and the following information reported: Latin, vernacular and English names, plant part used, forms of preparation and application of the herbal remedies, medicinal or food uses, areas of plant collection, economic importance (when available) and other data.