常见病害防治方法

病名：罗氏沼虾肌肉白浊病 又叫罗氏沼虾苗种肌肉白浊病、白体病、白尾病。钱冬等（2003）报道,罗氏沼虾苗种肌肉白浊病的病原是诺达病毒;姜兰等（2002）报道,病原是木糖葡萄球菌。     

罗氏沼虾肌肉白浊病

罗氏沼虾肌肉白浊病,又称白尾病（WTD）,是由罗氏沼虾野田村病毒引起的一种急性病毒性疾病,主要危害罗氏沼虾苗种,以急性死亡、病虾肌肉呈白斑或白浊状为特征。我国将其列为二类疫病,OIE将其列为必须通报疾病。     

罗氏沼虾肌肉白浊病的诊断与防治

罗氏沼虾肌肉白浊病是近年来新出现的疾病 ,有的地方又称白体病、白尾病等。主要危害罗氏沼虾苗种 ,发生于虾苗淡化后至放养到池塘 3～ 5周内。病虾表现为肌肉出现白斑或呈白浊状 ,可在较短时间内大量死亡 ,特别是高密度育苗池内 ,死亡率高达 40 %～ 90 %。该病最早于 1 996年前后出现在广东、广西一带 ,以后迅速传播到江苏、浙江等地。 2 0 0 1年起 ,该病在各主要罗氏沼虾苗种场广泛流行 ,2 0 0 2年更是呈蔓延趋势 ,成为罗氏沼虾养殖业的主要威胁。1　罗氏沼虾肌肉白浊病的诊断由于该病近几年刚刚在我国流行 ,病原的研究虽已取得一定进展 ,…     

利用卵黄抗体预防罗氏沼虾肌肉白浊病

<正>近年来由于罗氏沼虾养殖密度不断提高、养殖水体污染日益严重及品种种质退化,罗氏沼虾在育苗和养殖过程中疾病也日益流行。20世纪90年代后期,罗氏沼虾肌肉坏死病相继在我国南方各省暴发,并于2001年大面积流行,导致罗氏沼虾养殖业的重大损失。该病毒的感染对象为虾苗,主要发病时期为虾苗淡化后1~2周,死亡率高达60%以上,严重时可达100%。研究表明,该病病原为罗氏沼虾野田病毒。病毒粒子呈廿面体,无囊膜,直径为23~25纳米,病毒核酸为单链2个片段的RNA。病毒只编码一种衣壳蛋白,是病毒感染与致病力的重要蛋白,也是制备疫苗的重要抗原。由于肌肉白浊病的病原是病毒,抗生     

罗氏沼虾诺达病毒单克隆抗体的制备及应用

罗氏沼虾肌肉白浊病（whitish muscle disease of Macrobrachium rosenbergii）是一种发生在罗氏沼虾苗种阶段的流行病,发病虾苗出现肌肉白浊、白斑或白尾症状,死亡率高达60％以上,作者所在实验室在确定其病原是罗氏沼虾诺达病毒（Macrobrachiium rosenbergii Nodavirus,MrNV）的基础上,用MrNV免疫BALB／c小鼠,取小鼠脾细胞与SP2／0鼠骨髓瘤细胞融合,用间接ELISA筛选阳性孔,经有限稀释法克隆,得到12株能特异分泌抗MrNV的单兜隆抗体（Mab）的杂交瘤细胞。注射小鼠,制备腹水单克隆抗体,ELISA效价为1：10^5～10^6。亚型鉴定结果表明,有6株单抗为IgG1型,4株甲抗为IgG2a型,2株单抗为IgG2b型。12株单抗与对虾白斑综合征病毒（WSSV）和桃拉综合征病毒（TSV）均无交叉反应：挑选效价高的腹水单抗2B5,建立了检测罗氏沼虾诺达病毒的三抗体夹心酶联免疫吸附测定（TAS—ELISA）法,该方法检测灵敏度达0．98ng左右。Wesrtem blot分析表明,2B5能与MrNV 43kD的外膜蛋白特异性结合。     

罗氏沼虾肌肉白浊病的病原和组织病理

对患肌肉白浊病的罗氏沼虾进行细菌分离、寄生虫检查、组织病理观察以及虾池的水质分析和疾病的流行病学调查,排除了细菌、寄生虫以及水质环境因素造成该病的可能性,并发现病症多发生在体长0 8～3cm的幼虾中,而体长3cm以上的虾病症明显减轻。病虾的显微和亚显微组织病理观察发现,病虾腹部白浊的肌肉组织肌纤维肌浆内存在嗜碱性包涵体,肝胰腺、血细胞、心脏和鳃组织细胞胞浆内也有嗜碱性包涵体出现,包涵体内有大量以晶格状排列、无囊膜的二十面体球状病毒颗粒,直径为(23.6±3.8)nm(n=40)。在包涵体外的胞浆内,尤其在白浊肌肉组织肌纤维肌浆内也分布有大量病毒。心脏和鳃组织出现不同程度的变性,肌肉组织、肝胰腺、血细胞除变性外还出现坏死;肌肉组织病变尤为严重,肌肉白浊症状是肌肉组织变性、坏死的结果。将病虾白浊肌肉组织以口服方式感染健康虾,健康虾出现与自然发病虾一样的症状,发病率和死亡率亦与自然感染病虾相近,表明上述二十面体球状病毒是罗氏沼虾肌肉白浊病的病原。     

罗氏沼虾肌肉白浊病的防治

随着罗氏沼虾养殖年限的增加，养殖技术不断进步，放养密度及单产均有较大幅度的提高。随之而来的是各种虾病不断增多，发病频率不断加快，病情日益严重，尤其是近年来频繁暴发的罗氏沼虾肌肉白浊病，给罗氏沼虾生产（尤其是育苗期）带来了极大的损失。为此，我们于１９９９年起成立了专门的课题组，对该病进行系统的专题研究，并已取得了阶段性成果。现将有关研究结果报告如下：一、流行情况：罗氏沼虾肌肉白浊病始见于１９９４年。１９９４年，广东、广西两省区的罗氏沼虾养殖面积迅速扩大，而本地的虾苗市场出现严重的供不应求。为解决供…     

虾类肌肉白浊病病原和病理的研究进展

本文针对虾类肌肉白浊病易感染的罗氏沼虾、凡纳滨对虾、中国对虾进行了分析。从病毒、细菌、寄生虫和环境因素方面,总结了近十几年来虾类肌肉白浊病的病原和病理特征。归纳了虾类肌肉白浊病的流行病学、检测方法及综合防治。     

罗氏沼虾肌肉白浊病的防治研究

1　流行情况罗氏沼虾肌肉白浊病始见于 1994年 ,是年 ,广东、广西两省区的罗氏沼虾养殖面积迅速扩大 ,而本地的虾苗生产却很不顺利。虾苗市场出现严重的供不应求。为解决供求矛盾 ,广东的部分业者率先从泰国等地进口罗氏虾苗甚至虾苗幼体供应国内市场。罗虾白浊病的病例首先发生在泰国引进的虾苗中。此后 ,该病逐步在国内的广大罗虾养殖区和虾苗繁殖场中流行。流行面积逐年增大 ,发病程度日趋严重。 1999年的 4～ 5月间出现一个明显的暴发期 ,2 0 0 0年产区病情有所缓解 ,但到了 2 0 0 1年病情再次暴发性流行。白浊病的感染对象以虾苗为主。…     

罗氏沼虾肌肉白浊病的病症及防治

罗氏沼虾得到大面积推广养殖的原因与该虾具有生长快、个体大、抗病力强和产量高等优良性状有关,但近年来病害问题随着罗氏沼虾养殖规模的扩大而日趋严重,特别是肌肉白浊病(M.rosenbergji muscle Gonorrhea)的大面积传播使得广大养殖户对该品种的养殖前景表示出了前所未有的担忧。     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.