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     

Inoculant plant growth-promoting microorganisms enhance utilisation of urea-N and grain yield of paddy rice in southern Vietnam

Field experiments were conducted during successive rainy seasons in 2006 in the Chau Thanh district of southern Vietnam to evaluate the effects of an inoculant plant growth promoter product called “BioGro” and N fertiliser rates on yield and N and P nutrition of rice. The results indicated that inoculation with BioGro, containing a pseudomonad, two bacilli and a soil yeast, significantly increased grain and straw yields and total N uptake in both seasons, as well as grain quality in terms of percentage N. Nitrogen fertilisation increased grain and straw yields as well as total N and P uptakes significantly in both cropping seasons. The estimated grain yield response to added N was quadratic in nature with and without added BioGro. In the first crop, BioGro out-yielded the control up to 90 kg urea N ha^?1 whilst in the second season the beneficial effect of BioGro was observed up to 120 kg urea N ha^?1, indicating either an interaction of the inoculant with higher yielding seasonal conditions or a cumulative effect of BioGro application. In the first season, the estimated N rate for maximum grain yield was 103 kg N ha^?1 with BioGro while it was 143 kg N ha^?1 without BioGro. The maximum estimated grain yields were 3.21 and 3.18 t ha^?1 with and without BioGro, respectively. This information indicates that BioGro was able to save 40 kg N ha^?1 with an additional rice yield of 30 kg ha^?1 in the season. In the second rainy season, the estimated N rates for maximum grain yields were 94 and 97 kg N ha^?1 with and without BioGro, respectively. The estimated maximum grain yields were 3.49 and 3.25 t ha^?1 with and without BioGro, respectively. The two seasons’ combined results indicate that application of BioGro improved the efficiency of N use by rice significantly, saving 43 kg N ha^?1 with an additional rice yield of 270 kg ha^?1 in two consecutive seasons at the experimental site. The extra efficiency was shown by the fact that the same yield of rice was obtained with about 40 and 60 kg less fertiliser-N that the maximum yields with urea alone in the two successive harvests on the same plots.     

Biochemical composition of New Zealand geoduck clam broodstock (Panopea zelandica) conditioned under different temperature and feeding regimes

Geoduck clams are amongst the most valuable cultured shellfish available on the world market, driving interest in the establishment of the native New Zealand species, Panopea zelandica (Quoy & Gaimard, 1835), as a candidate for aquaculture. A critical element of domestication is the effective management of breeding stock to optimize gamete and offspring quality. To develop a reliable broodstock conditioning protocol for P. zelandica, we investigated the biochemical composition of geoducks exposed to nine factorial treatment combinations of temperature (7.5, 11.5 and 16.5°C) and feeding ration [10 000, 50 000 and 100 000 cells mL^?1 of a (1:1 cell count) mixture of Tisochrysis lutea and Chaetoceros muelleri]. In addition, a reference group of geoducks was conditioned in an aquaculture pond‐nursery system, providing a dilute, mixed phytoplankton culture at ambient temperature. Glycogen, protein, lipid and fatty acid contents of flesh and viscera were measured at days 0, 36 and 73 of conditioning. Glycogen, protein and lipid analyses indicated that geoducks within all treatments achieved a positive energy balance, except for those in the treatment combining the highest temperature and lowest feeding ration. Comparisons of fatty acid profiles of animals among treatments and with the reference group revealed that eicosapentaenoic (EPA, C20:5n‐3), docosahexaenoic (DHA, C22:6n‐3) and arachidonic (ARA, C20:4n‐6) fatty acids were important contributors to gametogenic development for geoduck conditioning.     

EFFECTS OF A MULTISTRAIN BIOFERTILIZER AND PHOSPHORUS RATES ON NUTRITION AND GRAIN YIELD OF PADDY RICE ON A SANDY SOIL IN SOUTHERN VIETNAM

Field experiments during two successive rainy seasons were conducted in southern Vietnam to evaluate the effects of a commercial inoculant biofertilizer (‘BioGro’) and fused magnesium phosphate (FMP) fertilizer on yield and nitrogen (N) and phosphorus (P) nutrition of rice. Inoculation with BioGro containing a pseudomonad, two bacilli and a soil yeast significantly increased grain yield in the second season and straw yield in both seasons by 3–5%. The FMP fertilizer significantly increased grain yield from 1.72–2.33 t ha^?1 to 2.99–3.58 t ha^?1 along with total N and P accumulation at all rates in both cropping seasons. In the first season the difference in grain yield between BioGro treated and untreated plots was marginal but in the second season BioGro out-yielded the control at all the rates of added P. Overall, BioGro application did not compensate for low P fertilizer application to the same extent previously demonstrated for low N fertilizer applications.     

烘干鸡粪营养成分的分析

对两种处理方法处理的烘干鸡粪中的营养成分进行了分析.实验分析表明,烘干处理后的鸡粪含有丰富的粗蛋白、粗脂肪、粗纤维、矿物质及钙、磷等营养成分.烘干鸡粪作为养殖业饲料配料完全可行,这一资源的开发利用既有显著的经济效益,又有良好的社会和环境效益.     

Analyzing the variations in cost-efficiency of marine cage lobster aquaculture in Vietnam: A two-stage bootstrap DEA approach

ABSTRACT

This study measures cost-efficiency and its determinants for 353 marine cage lobster farms in Vietnam using a two-stage bootstrap data envelopment analysis (DEA). In the first stage, the bootstrap DEA approach was used to obtain bias-corrected technical, allocative cost-efficiencies for the farms. Then, the bias-corrected cost-efficiency scores were regressed on a set of explanatory variables using a bootstrapped truncated regression. The results show that substantial cost-inefficiency occurs in lobster aquaculture due to the overuse of inputs, which, given the prevailing input prices, are also used in inappropriate ratios. Cost-efficiency is shown to be significantly impacted by the age of the farmer, total cage volume and by variables affecting the production environment such as the cage cleaning, distance to the nearest farms and the presence of other discharges into the marine environment.     

Analysis of ITS of the rDNA to infer phylogenetic relationships among Vietnamese Citrus accessions

This study focused on clarifying phylogenetic relationships among Citrus accessions from Vietnam. Our phylogenetic analysis based on nucleotide sequences from the ITS of the ribosomal DNA included 69 accessions belonging to Citrus and related (sub)genera. Maximum parsimony and Bayesian analysis confirmed a clear separation of the three ‘true’ Citrus species (C. medica, C. maxima and C. reticulata). Confirming recent taxonomic revisions, Fortunella, Poncirus trifoliata and Citrus hystrix are clustered among the accessions of subgenus Citrus. C. × sinensis accessions revealed a close evolutionary relationship to either C. maxima or C. reticulata, thereby confirming their involvement in its hybrid origin. Also, some other hybrid taxa and their proposed parental species were investigated and their origin could in some cases be confirmed using the ITS sequence data.     

Isolation and identification of antiplatelet aggregatory principles from the leaves of Piper lolot

The methanolic extract of Piper lolot, having shown potent inhibitory activity on platelet aggregation induced by arachidonic acid (AA) and platelet activating factor (PAF), was subjected to activity-guided isolation to yield twelve new amide alkaloids, piperlotine A-L (1-12), along with twenty-nine known compounds. Their structures were elucidated on the basis of spectroscopic analysis. The isolated compounds were tested for their inhibitory activity on the rabbit platelet aggregation. The compounds piperlotine A (1), piperlotine C (3), piperlotine D (4), piperlotine E (5), 3-phenyl-1-(2,4,6-trihydroxyphenyl)propan-1-one (21), 3-(4-methoxyphenyl)-1-(2,4,6-trihydroxyphenyl)propan-1-one (22), 1-trans-cinnamoylpyrrolidine (24), sarmentine (26), pellitorine (27), methyl 3-phenylpropionate (32), and (10S)-10-hydroxypheophorbide a methyl ester (40) showed potent antiplatelet aggregation activity.     

Early interactions of Edwardsiella ictaluri, with Pangasianodon catfish and its invasive ability in cell lines

Commercial Pangasianodon catfish production is heavily impacted by Bacillary Necrosis of Pangasius (BNP) caused by Edwardsiella ictaluri. This study aimed to investigate the early bacterium-host interactions following immersion challenge and to compare the retrieved data with the invasion ability of the used isolates in fish cell lines. Firstly, Pangasianodon hypophthalmus fingerlings were challenged via immersion using E. ictaluri isolate HO2 or 223. At different times post inoculation, fish were sacrificed and gill and internal organ samples were taken for bacteriological, histological and immunohistochemical evaluation. The bacterial load was higher for fish inoculated with isolate HO2 compared with 223. Histological and immunohistochemical analysis revealed multifocal necrotic areas in kidney, spleen and liver of HO2 inoculated fish at 72 h post inoculation with short rod-shaped immunoperoxidase positive bacteria clustered inside cells respectively. Bacteria especially were present in the gills and intestinal tract of HO2 inoculated fish, suggesting the gastrointestinal tract and gills act as portals of entry. Following, the ability of HO2, 223 and four additional isolates to invade a Chinook salmon embryo cell line, a fat head minnow cell line and a rainbow trout liver cell line was tested. All E. ictaluri isolates were invasive in all cell lines albeit at different degrees. Isolate HO2 was highly invasive in all cell lines with a significantly higher invasion capacity than isolate 223 in the Chinook salmon embryo cell line. A correlation between in vivo virulence and in vitro invasiveness hence is suggested although further studies are needed to confirm this hypothesis.     

稻谷、糙米、精米在储藏期对玉米象(Sitophilus zeamais)的抗性差异研究

选用抗玉米象的4个水稻品种即花粳2号、665、浙852、鄂宜105;和2个感虫品种即秀水48、Ⅱ优46,研究其稻谷、糙米、精米对玉米象的抗虫性差异。结果表明:抗虫品种不同米型的抗虫性顺序是糙米最感玉米象,精米次之,稻谷最抗玉米象。感虫品种是糙米最感玉米象,稻谷次之,精米最抗玉米象。但其中感虫品种的稻谷和精米的抗虫性经方差分析和新复极差测验,无显著差异。