Host preference of adult Caligus elongatus Nordmann in the laboratory and its implications for Atlantic cod aquaculture     

Oines O  Simonsen JH  Knutsen JA  Heuch PA 《Journal of fish diseases》2006,29(3):167-174

The sea louse Caligus elongatus utilizes a range of marine fish species as hosts, and it has been suggested that fish farms are infected with adult C. elongatus from wild fish hosts. We assessed experimentally whether dislodged lice return to their original host species. Adult lice from wild lumpfish and saithe were presented to lumpfish, sea trout, Atlantic cod, saithe and European plaice. All fish species became infected. Lumpfish and cod were strongly preferred, followed by saithe, trout and plaice. Lice from wild saithe showed a preference for saithe and lumpfish, followed by cod, sea trout and plaice. The mtCO1 gene was used to determine the genotypes of the lice. Lice from lumpfish were genotype 1. Lice from saithe were mainly genotype 2. The two genotypes of C. elongatus differed slightly in their host preferences: lice from saithe were less discriminating. The data support the hypothesis that adult C. elongatus may transfer between different host species. Cod is an attractive host for lice from both lumpfish and saithe, which suggests that C. elongatus may become a serious pest of farmed cod.  相似文献   

Laboratory and field investigations of salmon lice [Lepeophtheirus salmonis (Krøyer)] infestation on Atlantic salmon (Salmo salar L.) post-smolts   总被引：1，自引：0，他引：1  

B Finstad  P A Bjørn  A Grimnes  & N A Hvidsten 《Aquaculture Research》2000,31(11):795-803

Hatchery‐reared 1‐year‐old Atlantic salmon post‐smolts (Salmo salar L.), artificially infected with salmon lice [Lepeophtheirus salmonis (Krøyer)] copepodids, were found to suffer from primary alterations (increased cortisol levels) at early lice stages. Secondary alterations, such as osmotic stress (increased chloride levels), first occurred after the preadult stages of the lice appeared. Fish with the highest salmon lice infections died throughout the experiment. Seven years of field investigation of Trondheimsfjorden showed that Atlantic salmon post‐smolts descending coastal waters can become heavily infected with salmon lice. The migrating post‐smolts were only infected with the chalimus stages, showing that the fish had only recently left the rivers. The infection level, however, varied considerably between the years, and, in 1998, the infection was higher than previous years. The experimental results have been combined with the field data to appraise the consequences of the infection.  相似文献   

五种鸟体羽虱卵扫描电镜观察（Ⅱ）     

周淑君  施新泉 《中国兽医寄生虫病》1999,7(2):12-14

本文对采自兰马鸡、黄鹂、金雕（小型卵、大型卵）、白鹇体上５种羽虱卵的亚微结构进行了扫描电镜观察。结果证实：低倍镜下卵壳表面较光滑；３００倍以上观察时，不同种类结构各异，有呈斑块状、鳞片状凹花纹、瘤状突等；卵盖的形状亦因种而异，呈帽状或圆锥状；有的种类卵体周缘有锚钩形长丝状物等。这些形态结构可作为种间分类特征之一。  相似文献   

Serial invasive signal amplification reaction for genotyping permethrin-resistant (kdr-like) human head lice, Pediculus capitis     

Hyo Jeong Kim  Steven B. Symington  Si Hyeock Lee  J. Marshall Clark   《Pesticide biochemistry and physiology》2004,80(3):173-182

Permethrin resistance in the human head louse, Pediculus capitis De Geer (Anopulura: Pediculidae), has been reported worldwide, is associated with the knockdown phenotype, and elicits cross-resistance to DDT and the pyrethrins. Two point mutations, T929I and L932F, in the voltage-sensitive sodium channel α-subunit gene are responsible for permethrin resistance as a resistant haplotype (kdr-like). We have optimized a serial invasive signal amplification reaction (SISAR) protocol for the detection of these mutations using PCR amplified DNA fragments. SISAR distinguished all genotypes with high accuracy in a head louse population from Texas that was heterogeneous in terms of permethrin sensitivity. Using SISAR, resistance-conferring mutations are detected in a high throughput format, facilitating the efficient monitoring of permethrin resistance allele frequency in field populations.  相似文献   

Upper susceptibility threshold limits with confidence intervals: a method to identify normal and abnormal population values for laboratory toxicological parameters, based on acetylcholinesterase activities in sea lice     

Fallang A  Larsen S  Horsberg TE 《Pest management science》2006,62(3):208-213

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Salmon lice infection of wild sea trout and Arctic char in marine and freshwaters: the effects of salmon farms   总被引：2，自引：0，他引：2  

P A Bjørn  B Finstad  & R Kristoffersen 《Aquaculture Research》2001,32(12):947-962

The abundance of salmon lice and the physiological effects of infection were examined in two stocks of sympatric sea trout and anadromous Arctic char in northern Norway. One stock feed in a coastal area with extensive salmon farming (exposed locality), while the other feed in a region with little farming activity (unexposed locality). The results showed that the lice infection was significantly higher at the exposed locality, at which the mean intensity of infection peaked in June and July at over 100 and 200 lice larvae per fish respectively. At the exposed locality we also observed a premature return to freshwater of the most heavily infected fish. Such behaviour has previously been interpreted as a response by the fish to reduce the stress caused by the infection and/or to enhance survival. Blood samples taken from sea trout at sea at the exposed locality showed a positive correlation between intensity of parasite infection and an increase in the plasma cortisol, chloride and blood glucose concentrations, while the correlations from sea trout in freshwater were more casual. Several indices pointed towards an excessive mortality of the heaviest infected fish, and 47% of the fish caught in freshwater and 32% of those captured at sea carried lice at intensities above the level that has been shown to induce mortality in laboratory experiments. Furthermore, almost half of all fish from the exposed locality had lice intensities that would probably cause osmoregulatory imbalance. High salmon lice infections may therefore have profound negative effects upon wild populations of sea trout. At the unexposed location, the infection intensities were low, and few fish carried more than 10 lice. These are probably within the normal range of natural infection and such intensities are not expected to affect the stock negatively.  相似文献   

No evidence of Bartonella quintana but detection of Acinetobacter baumannii in head lice from elementary schoolchildren in Paris     

Bouvresse S  Socolovshi C  Berdjane Z  Durand R  Izri A  Raoult D  Chosidow O  Brouqui P 《Comparative immunology, microbiology and infectious diseases》2011,34(6):475-477

The human body louse is the only known vector of Bartonella quintana. However, the presence of this bacterium has recently been detected in the head lice of homeless individuals and Nepalese slum children. Previous studies have reported the isolation of Acinetobacter baumannii from the body lice of homeless individuals. An epidemiological survey including 74 schools was conducted between 2008 and 2009 in Paris. After a first visual examination, the hair of children with suspected pediculosis was combed with a fine-tooth comb to collect live adult head lice. Molecular studies were performed on randomly selected DNA samples to detect B. quintana and A. baumannii by specific quantitative real-time PCR. Among a collection of 288 DNA samples, B. quintana was not detected, but A. baumannii was detected in 95 DNA samples (33%). Further study is needed to determine the significance of the finding of A. baumannii in head lice.  相似文献   

Management actions in relation to the controversy about salmon lice infections in fish farms as a hazard to wild salmonid populations     

Alasdair H McVicar 《Aquaculture Research》2004,35(8):751-758

Risk analysis provides a logical strategy for the identification of hazards in an area of concern leading to their management. This approach has rarely been used for research studies on the possible links between salmon lice in fish farms and variations in wild salmonid populations. Although correlation has been found between some data sets, a series of international meetings of experts has not been able to establish cause–effect relationships between lice on farms and the current low level of salmonid stocks in Europe and eastern Canada. Research in this area is currently in progress in western Canada. Views on the meaning of the correlations found have become highly polarized in both the scientific and non‐scientific communities, with the same data often being interpreted in different ways. Farm lice levels are being managed by industry codes and by official strategies in Europe, but these programmes have not so far resulted in associated benefit to the size of wild salmonid stocks. The large array of factors that cause variations in both the size of fish stocks and the level of fish diseases is frequently overlooked. Using a risk analysis approach, the key contributory factors may be identified and appropriate remedial management actions designed to meet achievable objectives. Regular assessment of the effectiveness of the measures introduced would then be possible.  相似文献   

Parasites and hepatic lesions among pink salmon, Oncorhynchus gorbuscha (Walbaum), during early seawater residence     

Saksida SM  Marty GD  Jones SR  Manchester HA  Diamond CL  Bidulka J  St-Hilaire S 《Journal of fish diseases》2012,35(2):137-151

Juvenile pink salmon, Oncorhynchus gorbuscha (Walbaum), in the Broughton Archipelago region of western Canada were surveyed over 2 years for sea lice (Lepeophtheirus salmonis and Caligus clemensi), gross and microscopic lesions and evidence of infections with viruses and bacteria. The 1071 fish examined had an approximate ocean residence time no longer than 3 months. A high prevalence of degenerative liver lesions, renal myxosporean parasites and a low prevalence of skin lesions and sea lice were observed. No indications of viral or bacterial diseases were detected in either year. The monthly prevalence of sea lice in 2007 (18-51%) was higher than in 2008 (1-26%), and the infestation density exceeded the lethal threshold in only two fish. Degenerative hepatic lesions and renal myxosporean parasites occurred in approximately 40% of the pink salmon examined in June of both years, and the peak monthly prevalence of hepatocellular hydropic degeneration was greater in 2007 (32%, in May) than in 2008 (12%, in June). Logistic regression analysis found skin lesions and hepatocellular hydropic degeneration significantly associated with sea lice. Most parasites and lesions occurred during both years, but the prevalence was often higher in 2007. Fish weight was 35% less in June 2007 than in June 2008, but condition factor was not different. Further research is required to monitor inter-annual variations and aetiology of the liver lesions and to assess their potential role on pink salmon survival.  相似文献   

Experimental challenges of Atlantic salmon Salmo salar with incremental levels of copepodids of sea louse Caligus rogercresseyi: effects on infestation and early development     

Angélica Araya  Melinka Mancilla  Jean Paul Lhorente  Roberto Neira  José Andrés Gallardo 《Aquaculture Research》2012,43(12):1904-1908

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