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1.
Acute hepatopancreatic necrosis disease (AHPND) causes massive mortality in shrimp ponds within the first month poststocking. The causative agent is a specific strain of Vibrio parahaemolyticus (VPAHPND) that has acquired the capability to produce virulent binary toxins called ToxA and ToxB. This study aims to test the effect of the addition of an autoinducer‐2‐containing cell‐free supernatant (CFS) from the mutant Vibrio harveyi (VH) on growth and toxin production of VPAHPND. The relative AI‐2‐like activity in CFS was detected by luminescence assay. The effect of CFS (5 and 9%) on growth and toxin production of VPAHPND was evaluated. Compared to the control culture (without CFS‐VH addition), the addition of either 5 or 9% CFS‐VH affected the growth at the initial stage of VPAHPND. Similar growth profiles of VPAHPND were found with the addition of CFS‐VH at both concentrations. Western blot analysis suggests that the addition of CFS‐VH affected the production of both toxins. ToxA could be detected at the early hour post‐CFS‐VH inoculation, whereas the high amount of ToxB was detected when 5% CFS‐VH was added. However, interfering with the AI‐2 function with furanone, the AI‐2 antagonist resulted in a slight delay in the production of both toxins. Results from this study will help to design a novel strategy to control AHPND in shrimp culture.  相似文献   

2.
Sixteen candidate disease‐resistant parameters were selected through which to evaluate the acute hepatopancreatic necrosis disease (AHPND)‐resistant capability of Exopalaemon carinicauda after three generations of selection for AHPND‐causing strain of Vibrio parahaemolyticus (VPAHPND) resistance in our previous study. However, these parameters required further verification. In this study, another AHPND‐resistant E. carinicauda series was obtained through a short‐term selection procedure, consisting of three virulent challenge rounds of selection (about three‐week interval for each challenge) with VPAHPND infection. After this selection, the survival rate at 144 hr post infection (hpi) increased from 23.33% to 37.78% and the observed 48‐hr LD50 of VPAHPND to shrimp increased from 105.5 cfu/ml to 106.5 cfu/ml. Then, the immune response of this AHPND‐resistant E. carinicauda was studied using the 16 candidate AHPND‐resistant parameters selected for in our previous study. The improved VPAHPND clearance rate in hpi, increased total haemocyte counts, haemocyanin concentration, alkaline phosphatase activity and expressions of six immune‐related genes (Tollip and ALF in haemocytes and hepatopancreas; lysozyme, crustin and cathepsin B in hepatopancreas; and LGBP in haemocytes) at 24 hpi after the three‐round challenge selection suggest that these immune parameters may be reliable markers for the evaluation of the physiological status and potential AHPND‐resistant phenotypes in E. carinicauda.  相似文献   

3.
Outbreaks of acute hepatopancreatic necrosis disease (AHPND) have caused great economic losses to many shrimp‐producing countries in Asia since its first appearance in 2009. The causative agent was reported in 2013 as specific isolates of Vibrio parahaemolyticus (VPAHPND) that were later found to harbor a plasmid (pVA) encoding the Pir‐like binary toxin genes Pir vpA and Pir vpB. VPAHPND isolates colonize the shrimp stomach and release the binary toxins that cause massive sloughing of tubule epithelial cells followed by shrimp mortality. More recent information indicates that pVA plasmid and variants occur in many V. parahaemolyticus serotypes and also in other Vibrio species such as Vibrio campbellii, Vibrio harveyi, and Vibrio owensii. Information on such genomic and proteomic studies of different VPAHPND isolates from different countries are reviewed. A cohort study carried out in Thailand in 2014 indicated that AHPND outbreaks account for only a portion of the disease outbreaks reported by shrimp farmers as outbreaks of early mortality syndrome (EMS). It is recommended that a regional research network and surveillance program for newly emerging or re‐emerging pathogens be established to speed up the process of diagnosis and the implementation of coordinated control measures and to avoid a repeat of the EMS/AHPND scenario.  相似文献   

4.
Shrimp culture is a well‐established and fast‐growing industry that produces economic and social benefits in many countries. However, during the last years, it was severely affected by the emergence of the Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Disease (AHPND). This disease is mainly attributed to Vibrio parahaemolyticus, and currently, there is no effective cure or treatment. In this study, the use of T2A2 and VH5e bacteriophages was evaluated to control different AHPND‐positive strains (presumptively identified as V. parahaemolyticus, VPAHPND) under laboratory conditions. Lytic effect of T2A2 and VH5e bacteriophages against different strains isolated from AHPND outbreaks was corroborated. In addition, the effectiveness of the mixture of both phages was tested on a brine shrimp experimental infection model using three highly virulent VPAHPND strains. It has been found that phage‐treated brine shrimp had significantly higher survival percentage compared with non‐treated groups (p < .001). Also, phage cocktail was found to be harmless to the organisms. These results suggest that the phage mixture is worth considering as a possible control measure for positive AHPND strains, although it is clear that further and more extensive testing is needed.  相似文献   

5.
This study aimed to elucidate the effects of dietary Bacillus licheniformis ATCC 11946 (BL) on the growth, immune and antioxidant activities, intestinal morphology and microbiota, and susceptibility to Vibrio parahaemolyticus (VPAHPND) in juvenile pacific white shrimp, Litopenaeus vannamei (LV). Juvenile LV (initial weight = 0.63 ± 0.001) were fed diets containing varying BL concentrations (0 (BL0), 106 (BL1), 107 (BL2) and 108 (BL3) CFU/g feed) for 8 weeks. Growth performance, immune and antioxidant enzyme activities, and intestinal morphology significantly improved in the probiotic‐treated groups than the untreated. Regardless of the treatment group, the two dominant phyla were Proteobacteria and Bacteroidetes, whereas the two dominant genera were Ruegeria and Vibrio. Increasing inclusion of probiotics in diets led to significant increase in beneficial bacterial genera (Ruegeria, and Pseudoalteromonas) and a significant decrease in some known opportunistic pathogens (Vibrio, Tenacibaculum, Photobacterium, Kangiella and Spongiimonas) with the BL3 group witnessing the best. A 7‐day challenge study with VPAHPND showed significantly high protection in the probiotic‐treated groups, with the BL3, BL2 and BL1 obtaining 51%, 34% and 22% relative percentage survival, respectively. In conclusion, BL at 108 CFU/g feed should be used to help in shrimp production since it attained the most significant improvement.  相似文献   

6.
近年来包括急性肝胰腺坏死病(AHPND)在内的多种新发疫病的流行,使我国甲壳类养殖业遭受了严重的经济损失。为了筛查导致山东潍坊某养殖场中一虾蟹混养池塘内患病三疣梭子蟹感染的可能病原,本研究采用分子生物学检测方法,对三疣梭子蟹样品进行了白斑综合征病毒(WSSV)、传染性皮下及造血组织坏死病毒(IHHNV)、虾血细胞虹彩病毒(SHIV)、致急性肝胰腺坏死病副溶血孤菌(Vp_(AHPND))、虾肝肠胞虫(EHP)、偷死野田村病毒(CMNV)、黄头病毒(YHV)和肝胰腺细小病毒(HPV)等8种病原的检测,并对样品进行了组织病理和原位杂交分析。分子生物学检测结果显示,患病三疣梭子蟹样品呈Vp_(AHPND)阳性,而呈现WSSV、IHHNV、SHIV、EHP、CMNV、YHV和HPV阴性。对样品进行Vp_(AHPND)套式PCR第二轮扩增产物的序列测定、比对和进化树分析,结果显示,扩增产物序列与致病副溶血弧菌质粒上pirA~(vp)毒力基因片段具有99%的同源性,该序列与已报道的多个致病副溶血弧菌PirA聚在进化树的同一主分支上。组织病理学分析显示,患病三疣梭子蟹的肝胰腺小管上皮细胞坏死,心肌纤维呈溶解样病变,鳃丝上皮柱突细胞明显坏死,胸神经节的神经细胞损伤严重,并且这些组织中还可见大量的细胞核固缩现象;原位杂交结果显示,肝胰腺、心肌、鳃组织及胸神经节中的病变部位均存在Vp_(AHPND)探针的蓝紫色杂交信号。以上表明,虾蟹混养池塘中三疣梭子蟹在自然状态下感染了Vp_(AHPND),并导致肝胰腺、心肌、鳃和胸神经节发生了严重病理损伤。本研究首次在养殖三疣梭子蟹中检测到Vp_(AHPND)感染并揭示了感染所致的病理变化,相关结果为揭示Vp_(AHPND)自然宿主种类和养殖三疣梭子蟹病害防控提供了基础信息。  相似文献   

7.
Here, two monoclonal antibodies (MAbs) specific to different epitopes on ToxB, a toxin produced by Vibrio parahaemolyticus that causes acute hepatopancreatic necrosis disease (VPAHPND), were employed to develop a rapid strip test. One MAb was conjugated to colloidal gold to bind to ToxB at the application pad, and another MAb was used to capture colloidal gold MAb–protein complexes at the test line (T) on the nitrocellulose strip. To validate test performance, a downstream control line (C) of goat anti-mouse immunoglobulin G antibody was used to capture the free colloidal gold conjugate MAb. The sample in the application buffer could be applied directly to the application well, and the test result was obtained within 15 min. The sensitivity of the kit is approximately 6.25 µg/ml of toxin, which was equivalent to the toxin produced by approximately 107 cfu/ml of bacteria. This kit is convenient and easy to use since it can be used to identify VPAHPND directly using a single colony of bacteria grown on agar culture plates. Because of its high specificity and simplicity, as well as not being reliant on sophisticated equipment or specialized skills, this strip test could be used by farmers for surveillance for ToxB-producing bacteria.  相似文献   

8.
Development of an intensive culture system is presently being conducted in Kuwait as a means of farming penaeid shrimp in arid lands. Efficiency of commercial-scale hatchery production of Penaeus semisulcatus and P. japonicus showed significant improvement in 1981 over previous years. Three one-month hatchery rearing cycles in three 15 m3 concrete tanks yielded a total of 9.1 million post-larval shrimp with an average density of 160 PL/liter being obtained for one of these trials. Four other trials were discontinued due to low spawning rates and disease. Installation of a heat exchange system made it possible to begin larviculture in February, two months earlier than in previous years. Research in nursery and grow-out phases of intensive shrimp culture is being directed towards raceways, although Shigueno culture systems are also being investigated. Experimental work with six 18 m × 1.5 m raceways demonstrated that low water exchange rates (1 tank volume/day), combined with high aeration (9.5 liter/min) yielded the highest shrimp biomass. Unheated greenhouse structures constructed over the raceways showed that a single layer of 0.25 mm clear plastic sheeting could maintain water temperatures up to 2.7°C above those in unenclosed tanks. Rearing trials in two Shigueno tank systems demonstrated the importance of high water flow rates (3 tank volumes/day minimum) and adequate aeration. Due to sub-optimal conditions, survival was reduced to 7.5%, however, growth rates up to 6 g/month were obtained for P. semisulcatus.  相似文献   

9.
Two feeding trials were conducted in two stages to compare growth and performance, grow‐out (1–9 g b.w.) and fattening (13–19 g b.w.), of Penaeus semisulcatus. Shrimps were fed with two commercial feeds: P. monodon feed and P. japonicus feed. Both experiments were conducted using an indoor flow‐through tank culture system. The results reveal that the growth performance of shrimp fed with P. japonicus feeds (0.91 g shrimp?1 week?1) for the grow‐out stage was significantly better than shrimp fed with P. monodon feeds (0.63 g shrimp?1 week?1). The growth performance of shrimp fed with P. monodon feed (0.56 g shrimp?1 week?1) for the fattening stage was significantly better than shrimp fed with P. japonicus feed (0.42 g shrimp?1 week?1). The feed conversion ratios of both diets for the two sizes did not differ significantly. Thus, it is recommended that P. japonicus feeds be fed to P. semisulcatus during the grow‐out stage. During the fattening stage, the better growth performance of the shrimp fed with P. monodon feed makes it a better feed. However, colour and overall acceptability of shrimp fed with P. japonicus feed were generally higher than those fed with P. monodon feed.  相似文献   

10.
Early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND) is currently the most significant disease of shrimp in farms of Vietnam, Thailand, Malaysia, China and Mexico, and there is a great risk that it may spread to other shrimp farming countries. Although, an array of sophisticated detection tools for AHPND available, there is a need for a sensitive, simple and rapid detection method. In this study, a simple, sensitive, rapid and polyclonal antibody‐based farmer‐friendly flow‐through assay (FTA) test has been developed for the detection of AHPND pathogen. The recombinant Photorhabdus insect‐related (Pir) A toxin‐like protein of AHPND pathogen was used to immunize rabbits at 21‐day interval observed for highest antibody titre after third booster by ELISA. The raised rabbit antiserum was purified by affinity chromatography and characterized by Western blot. The antiserum showed no cross‐reactivity with AHPND‐free Vibrio parahaemolyticus, V. anguillarum, White Spot Virus (WSV), Aeromonashydrophila and Aphanomycesinvadans. This polyclonal rabbit antiserum was used to develop a farmer‐friendly FTA test for the detection of AHPND pathogen. This simple FTA testis is more sensitive and could detect PirAVP toxin up to 0.121 µg/ml, compared with 0.242 µg/ml by immunodot assay. Furthermore, FTA test requires only 8–10 min for completion, compared with 3 hr by immunodot thus found to be more sensitive, specific and cost‐effective. Collectively, sensitive FTA test would help shrimp farmers to take real‐time management decisions, especially emergency harvest and finally be a better hope for the prevention of AHPND.  相似文献   

11.
Outbreaks of multidrug-resistant pathogens have been constraint on aquaculture production in Thailand, thereby controlling shrimp pathogens by preventive probiotics being importance to sustain the aquaculture system. In this study, the effect of potential probiotics, Bacillus subtilis and Enterococcus sp. was related to growth, digestive enzyme activities (trypsin and chymotrypsin) and pathogenic resistance by postlarval black tiger shrimp (Penaeus monodon). The experiment was divided into two treatments, in triplicate, with and without supplementation of probiotics as a food additive. Shrimp fed with probiotics for a culture period of 84 days showed a significant increase (P < 0.05) in weight (2.03 ± 0.29 g) and survival (71.91 ± 3.15 %) in comparison with non-treated shrimp (1.53 ± 0.28 g and 65.20 ± 5.68 %, respectively). Trypsin activity of treated shrimp was significantly higher (P < 0.05) than that of control shrimp whereas chymotrypsin activities of the two treatments were not significantly different (P > 0.05). After challenging P. monodon postlarvae with a shrimp pathogen, Vibrio harveyi for 10 days, percentage of mortality of P. monodon postlarvae fed with probiotics was 46.67 ± 1.44 %, significantly lower (P < 0.05) than that of non-treated shrimp (61.67 ± 6.29 %). This study showed that potential probiotics was appropriate for application in P. monodon postlarvae cultivation under laboratory condition due to improvement of shrimp weight and survival, enhancement of trypsin activity and reduced mortality causing by pathogenic V. harveyi. This is the first publication reported the effect of probiotics on trypsin and chymotrypsin activities of P. monodon postlarvae.  相似文献   

12.
A 45-day feeding trial was conducted to evaluate the effects of dietary citric acid on growth, digestive enzyme and disease resistance of white shrimp, Litopenaeus vannamei. Shrimp with initial body weight of 5.57 ± 0.21 g were fed with basal diet supplemented with 0.0 g kg?1 (control), 1.0, 2.0, 3.0, 4.0 and 5.0 g kg?1 citric acid. Results showed that weight gain was increased by 15.9 % and feed conversion ratio was decreased by 0.17 by 2.0 g kg?1 dietary citric acid compared with control group (P < 0.05). Intestinal protease activity of shrimp fed 2.0 g kg?1 citric acid was significantly higher (P < 0.05) than that of control group. No significant difference was found in intestinal amylase activity among treatments (P > 0.05). The activities of serum phenoloxidase, superoxide dismutase and lysozyme in 2.0 and 3.0 g kg?1 citric acid group were significantly higher, and accumulative mortalities of the two groups on the fourth day after injection of Vibrio alginolyticus were significantly lower than those of control group (P < 0.05). Results above demonstrated that dietary citric acid could improve growth performance, immunity and resistance against V. alginolyticus. The supplementation level of citric acid in diet was suggested to be 2.0–3.0 g kg?1 for white shrimp.  相似文献   

13.
Penaeus semisulcatus (bear shrimp) was used for biological and culture studies. A peak of reproductive periodicity was shown in the months of May, June and July. Increase in body weight and in gonad weight coincided with the increase in sea water temperature. This suggested that sexual maturation might be a direct response to increased sea water temperature. Fecundity of mature female shrimp was estimated as 415,000 to 479,000 ova. In most cases, half-spent spawnings led to the production of poor eggs, characterized by irregular cytoplasmic formation and final autolysis. The embryonic and larval development of P. semisulcatus proceeded satisfactorily in a slightly alkaline medium (pH range from 7.5–8.5), and in water of salinity ranging from 28 to 35 ppt for egg and nauplius stages, and thereafter 25–35 ppt for zoea and mysis stages. The shrimps exhibited faster increase in body length than body weight in early growth. Later, after the shrimps had reached a body length of about 7.0 cm, the growth rate of body weight increased more markedly than body length. The rate of daily increase in weight was 1.01% in 7.0 cm shrimp. The feed efficiency of the formulated shrimp pellets was found to be 31.4%. During the nutritional study of P. semisulcatus, it was found that the combination of high dietary protein (about 40%) and low dietary lipid produced best growth and survival of bear shrimp. High increase of biomass of the shrimp fed with clam meat and high quality fish meal demonstrated the favorable response of shrimp to these diets. The use of cages for culturing bear shrimp was found to be practicable, but not efficient.  相似文献   

14.
The objective of this study was to investigate the effects of mixed Bacillus on growth, water quality and disease resistance against Vibrio harveyi in whiteleg shrimp (Litopenaeus vannamei). Postlarval shrimp (PL30) were fed with (a) a basal diet (the control), (b) a diet containing mixed freeze‐dried Bacillus probiotics (FB) and (c) addition of mixed microencapsulated Bacillus probiotics (MB) in culture water. Addition of FB and MB probiotics improved (p < .05) growth, feed efficiency, survival and culture water quality (ammonia and nitrite) compared to the control group although there was no difference (p > .05) between the two treated groups. Bacillus numbers in gastrointestinal tracts and culture water of FB‐ and MB‐administrated shrimp were higher (p < .05) than in the control. After a 30‐day culture, shrimp were infected with V. harveyi and monitored for 10 days. A significant reduction (p < .05) in cumulative mortality was observed in FB‐ and MB‐supplemented shrimp (43.24% and 45.05%, respectively), compared to the control (63.06%). This finding demonstrated that administration of microencapsulated probiotics was as effective as freeze‐dried probiotics for improving growth, feed efficiency, survival, Bacillus in gastrointestinal tracts, water quality (ammonia and nitrite) and conferring disease resistance to V. harveyi.  相似文献   

15.
This experiment was conducted to assess the effects of antimicrobial peptides at different levels (Diet 1 (0%), Diet 2 (0.1%), Diet 3 (0.2%), Diet 4 (0.4%), Diet 5 (0.6%) and Diet 6 (1%)), on growth, serum biochemical indices and antioxidant effect, feed utilization and disease resistance in Litopeneaus vannamei. There were four replicates in each group in the experiment (mean weight = 0.21 ± 0.00 g) and also fed with their respective diets for 8 weeks. Growth performance compared with the control group (0%) significantly increased at first and then decreased among treatment groups (p < .05) whereas the survival rate ranged from 78% to 96%. No significant differences were observed in terms of moisture, crude protein and ash content, but there was a significant increase in crude lipid (p < .05). In serum, acid phosphatase, alkaline phosphatase, polyphenol oxidase, triglyceride, glucose and total cholesterol changed as compared with 0%. Total antioxidant capacity, glutathione peroxidase, catalase, superoxide dismutase and malondialdehyde were also different from 0%. Disease resistance was increased in shrimp among treatment groups with 0.4% recording the lowest mortality percentage of 37% after the challenge test. The results from the present study suggested that supplementation of AMP at 0.4% in shrimp diet can improve growth performance, antioxidants activities and innate immune response of Pacific whiteleg shrimp.  相似文献   

16.
There has been a highly detrimental impact of the white spot syndrome virus (WSSV) on black tiger shrimp (Penaeus monodon) aquaculture in India. Currently, no cost‐effective measures are available for controlling the disease. One alternative is to improve WSSV resistance through a selective breeding programme for disease‐resistant shrimp, provided that genetic variation exists for this trait. The aim of this study was to evaluate the evidence for genetic variation in resistance to WSSV in P. monodon sourced from Indian populations. Post‐larval shrimp (n=1950) from 54 full‐sibling families were challenged with WSSV using WSSV‐infected mince meat. The heritability was estimated using four different statistical models fitted to the resulting time to death data, including two linear models and two Weibull proportional hazard frailty models. None of the estimated heritabilities were significantly different from zero. We suggest three possible explanations for these results: there actually is very little variation between P. monodon in WSSV resistance and all individuals are highly susceptible to the disease; there is genetic variation in resistance to WSSV in P. monodon but we did not find it in our experiment because the level of challenge in the experiment was too high to allow genetic differences to be expressed; the variation is due to mutations conferring resistance, which are at a low frequency in the population, and we did not sample a broad enough genetic base to capture these mutations.  相似文献   

17.
The efficacy of hot‐water extract of tropical brown seaweed, Sargassum cristaefolium (SCE), supplemented in diets on immune response, stress tolerance, and disease resistance of Litopenaeus vannamei to Vibrio parahaemolyticus was evaluated. Shrimp were fed diets containing graded levels of SCE (0, 250, 500, 750, and 1000 mg/kg). The results showed that shrimp fed all diets containing SCE had significantly higher (P < 0.05) immune response in total hemocyte count (THC), differential hemocyte count (granular and hyaline cells), and phagocytic activity than those of shrimp fed the control diet. Similarly, in low dissolved oxygen stress tolerance test and the challenge test with V. parahaemolyticus, survival rates of shrimp fed all diets containing SCE were significantly higher (P < 0.05) (83–93% in stress test and 27–47% in challenge test) than those of shrimp fed the control diet (77 and 3.3%, respectively). These results suggest that oral administration of SCE at 500 and 750 mg/kg can be effectively used to enhance immune response, stress tolerance, and resistance of white shrimp, L. vannamei, against V. parahaemolyticus infection. These findings also confirm that using dietary SCE as immunostimulant is effective at increasing the nonspecific immune system in penaeid shrimp, L. vannamei.  相似文献   

18.
In June 2019, massive mortalities of cultured Penaeus vannamei occurred in a local farm in Hainan Province, China. The diseased shrimp displayed evident black gills. Three bacterial strains 20190611001, 20190611007 and 20190611022 were isolated from hepatopancreas and gills of the diseased shrimp and identified as Photobacterium damselae subsp. damselae based on the sequence analysis of 16S rRNA and toxR genes. These three isolates showed haemolytic activities. Of them, strain 20190611022 isolated from hepatopancreas was selected and processed for pathogenic analysis. The calculated median lethal dose (LD50) was 9.75 ± 4.29 × 105CFU/g (body weight) by challenging P. vannameivia reverse gavage. The diseased shrimp displayed enlarged hepatopancreatic tubules and sloughing of epithelial cells in tubular lumens. The strain 20190611022 was also characterized by the testing of API 20NE systems and antibiotic susceptibility. The results of disc diffusion test showed that strain 20190611022 was sensitive to chloramphenicol, compound sulfamethoxazole, cefoperazone, ceftriaxone, ceftazidime and cefuroxime. To our knowledge, this is the first report of isolation and characterization of Photobacterium damselae subsp. damselae from natural diseased P. vannamei. Our findings can serve as a basis for further studies of its pathogenicity and provide technological support for disease controlling in shrimp aquaculture.  相似文献   

19.
White spot disease caused by white spot syndrome virus (WSSV) is the major issue of huge economic destruction globally in the shrimp aquaculture industry. In the present investigation, WSSV prevalence associated with disease resistance was studied among wild black tiger shrimp, Penaeus monodon (Fabricius) from four distant geographic locations along the East coast of India during 2009–2010. Results suggested that the WSSV prevalence in wild P. monodon was the highest (56.2%) in Chennai, Tamil Nadu followed by Digha, West Bengal (10.9%), Visakhapatnam, Andhra Pradesh (0.6%) and Chilika, Orissa (0%). Quantitative data suggested that the mean copy number of WSSV among these four places was 1.4 × 106, 4.6 × 104, 1.6 × 102 and 2.3 × 102 copies μg?1 shrimp genomic DNA respectively. The disease resistant prevalence using the 71 bp microsatellite DNA marker was the highest among Chilika, Orissa (63.6%) and Visakhapatnam, Andhra Pradesh (63.5%). Higher WSSV prevalence in Chennai, Tamil Nadu and Digha, West Bengal corresponded to lower disease resistant prevalence (24% and 40.2%). Conclusively, probably collection of broodstock of P. monodon from places like Chilika and Visakhapatnam would be a much safer approach for the development of specific pathogen‐resistant shrimp aquaculture.  相似文献   

20.
Heritability and genetic correlations for body weight at harvest size (BW), grow-out survival (SU), and log-transformed infectious hypodermal and hematopoietic necrosis virus (IHHNV) load (VLln) in Litopenaeus vannamei were estimated. Data were obtained in 2012 from a shrimp breeding population in Mexico using 12,440 shrimp for BW and 16,814 shrimp for SU, and quantitative polymerase chain reaction determinations from 160 full-sib families were obtained for VLln. DNA was extracted from pooled muscle samples of six shrimp per family for a total of 960 individuals. Heritability estimates for BW, SU, and VLln at the family mean and at individual levels were 0.24 ± 0.08, 0.02 ± 0.01, 0.42 ± 0.45, and 0.08 ± 0.11, respectively. Genetic correlation estimates of BW with SU, BW with VLln, and VLln with SU were 0.40, −0.04, and −0.57, respectively. Our results suggest that VLln has genetic variation and a favorable genetic association with BW and SU. No serious drawbacks were found from selection responses estimated using single-trait and multitrait indices to increase BW and SU and decrease VLln. Favorable correlated responses for IHHNV tolerance estimated as BW/VLln and SU/VLln were also found. This study offers new insights into the possibility of using IHHNV viral load as a possible selection criterion in L. vannamei breeding programs.  相似文献   

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