Reducing sea lice (Lepeophtheirus salmonis) infestation of farmed Atlantic salmon (Salmo salar L.) through functional feeds          下载免费PDF全文

L.B. Jensen  F. Provan  E. Larssen  J.E. Bron  A. Obach 《Aquaculture Nutrition》2015,21(6):983-993

Health diets for Atlantic salmon have become an important component of the integrated pest management strategies targeting sea lice. A challenge trial was performed to examine the effect of supplementing salmon diets with either immunostimulants or essential oils. One control and four experimental diets containing immunostimulants or natural identical extracts were fed to Atlantic salmon in triplicate tanks for 4 weeks before challenging the fish with the sea lice copepodids. Prevalence of infection was 100%, and the mean abundance of infection was 21.2. The lowest mean lice count of 17 per fish (P < 0.05) was found in the group fed a mix of natural identical plant extracts (PX I). This represents a 20% reduction in infection, showing the potential for health diets to be employed as a tool to help control sea lice. To gain an understanding of the mechanisms of action underlying this protection, fish fed the control diet and fish fed the PX I diet were compared using quantitative histology of the epidermis and proteomic analysis of epidermal mucus. No significant differences were seen in the thickness of the epidermis or mucous cell percentage area, but differences in expression were seen for a number of proteins, including heat shock proteins, in epidermal mucus.  相似文献   

Sea lice population and sex differences in P‐glycoprotein expression and emamectin benzoate resistance on salmon farms in the Bay of Fundy,New Brunswick,Canada     

Okechukwu O Igboeli  John F Burka  Mark D Fast 《Pest management science》2014,70(6):905-914

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果树木虱防治的研究概述     

李斌  杨茂发 《贵州农业科学》2009,37(8)

我国的果树木虱主要有中国梨木虱(Psylla chinensis Yang et Li)、柑桔呆木虱(Diphorina citri Kuwayama)、龙眼角颊木虱(Cornegenapsylla sinica Yang et Li),危害的果树主要有梨、柑桔和龙眼.木虱的防治技术已有一定的研究成果,应用较为广泛,但研究不够深入,尚待完善.综述了危害果树的木虱种类、危害情况及综合防治技术,并提出了防治对策.  相似文献   

Esterase-mediated malathion resistance in the human head louse, Pediculus capitis (Anoplura: Pediculidae)     

Jian-Rong Gao  Kyong Sup Yoon  Gerald C. Coles 《Pesticide biochemistry and physiology》2006,85(1):28-37

Resistance in a dual malathion- and permethrin-resistant head louse strain (BR-HL) was studied. BR-HL was 3.6- and 3.7-fold more resistant to malathion and permethrin, respectively, compared to insecticide-susceptible EC-HL. S,S,S-Tributylphosphorotrithioate synergized malathion toxicity by 2.1-fold but not permethrin toxicity in BR-HL. Piperonyl butoxide did not synergize malathion or permethrin toxicity. Malathion carboxylesterase (MCE) activity was 13.3-fold and general esterase activity was 3.9-fold higher in BR-HL versus EC-HL. There were no significant differences in phosphotriesterase, glutathione S-transferase, and acetylcholinesterase activities between strains. There was no differential sensitivity in acetylcholinesterase inhibition by malaoxon. Esterases from BR-HL had higher affinities and hydrolysis efficiencies versus EC-HL using various naphthyl-substituted esters. Protein content of BR-HL females and males was 1.6- and 1.3-fold higher, respectively, versus EC-HL adults. Electrophoresis revealed two esterases with increased intensity and a unique esterase associated with BR-HL. Thus, increased MCE activity and over-expressed esterases appear to be involved in malathion resistance in the head louse.  相似文献   

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil     

Madeira NG  Amarante AF  Padovani CR 《Tropical animal health and production》2000,32(4):225-232

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.  相似文献   

Monooxygenase mediated pyrethroid detoxification in sea lice (Lepeophtheirus salmonis)     

Sevatdal S  Fallang A  Ingebrigtsen K  Horsberg TE 《Pest management science》2005,61(8):772-778

The role of monooxygenases in detoxification of the pyrethroids cypermethrin and deltamethrin was examined. Four strains of sea lice (Lepeophtheirus salmonis Krøyer) with normal or moderately reduced sensitivity towards the pyrethroids were tested in bioassays by exposure to the pyrethroid alone and in combination with an oxygenase inhibitor, piperonyl butoxide (PBO). The normal (baseline) sensitivity was considered as the sensitivity range for the two most sensitive strains. Pre‐treatment with PBO elevated the sensitivity (P < 0.01) compared with groups exposed to the pyrethroid only. A positive, but not statistically significant, correlation between the activity of haem peroxidases and the pyrethroid concentration immobilizing 50% of the parasites was demonstrated (ρ = 0.500 for deltamethrin and ρ = 0.310 for cypermethrin). The results indicate that cytochrome P450 monooxygenases are involved in detoxification of pyrethroids in sea lice. ¹⁴C‐Deltamethrin was absorbed in a lesser amount in a group of sea lice exposed to a mixture of the compound and PBO than in a group exposed to ¹⁴C‐deltamethrin alone. A significant difference could be demonstrated both immediately after exposure (P < 0.01) and 24 h after exposure (P < 0.05). No significant differences were found between groups pre‐treated with PBO and groups exposed to ¹⁴C‐deltamethrin only. ¹⁴C‐Deltamethrin was taken up mainly through the cuticle, especially the cuticle on the extremities of the ventral surface, and subsequently distributed throughout the body of the parasite. Copyright © 2005 Society of Chemical Industry  相似文献   

Effect of timing of count events on estimates of sea lice abundance and interpretation of effectiveness following bath treatments          下载免费PDF全文

R Gautam  R Vanderstichel  A S Boerlage  C W Revie  K L Hammell 《Journal of fish diseases》2017,40(3):367-375

Effectiveness of sea lice bath treatment is often assessed by comparing pre‐ and post‐treatment counts. However, in practice, the post‐treatment counting window varies from the day of treatment to several days after treatment. In this study, we assess the effect of post‐treatment lag time on sea lice abundance estimates after chemical bath treatment using data from the sea lice data management program (Fish‐iTrends) between 2010 and 2014. Data on two life stages, (i) adult female (AF) and (ii) pre‐adult and adult male (PAAM), were aggregated at the cage level and log‐transformed. Average sea lice counts by post‐treatment lag time were computed for AF and PAAM and compared relative to treatment day, using linear mixed models. There were 720 observations (treatment events) that uniquely matched pre‐ and post‐treatment counts from 53 farms. Lag time had a significant effect on the estimated sea lice abundance, which was influenced by season and pre‐treatment sea lice levels. During summer, sea lice were at a minimum when counted 1 day post‐treatment irrespective of pre‐treatment sea lice levels, whereas in the spring and autumn, low levels were observed for PAAM over a longer interval of time, provided the pre‐treatment sea lice levels were >5–10.  相似文献   

High marine survival rates of sea‐ranched Atlantic salmon smolts (Salmo salar) that had previously matured as male parr     

O. T. SKILBREI  M. HOLM 《Fisheries Management and Ecology》2011,18(5):384-391

Abstract The growth and recapture rates of Atlantic salmon, Salmo salar L., smolts that had previously matured as parr were compared with those of immature siblings in a sea‐ranching experiment in western Norway. The smolts were the offspring of three river populations. They were individually tagged, transferred to cages in a small bay where estuarine salinity gradients had been established and released on four dates from mid‐May to early June after either 3 or 7 days of acclimatisation. The previously mature male parr (PMMP) were smaller than their siblings before release, but performed much better during their time in the sea. As grilse, they reached sizes comparable with the formerly immature fish, and their recapture rate was more than four times higher (8.6 vs 2.1%). This difference decreased somewhat during the following years because 0.85% of the immature fish and only 0.1% of PMMP were recaptured as multi‐sea‐winter salmon. The highly successful marine performance of the PMMP demonstrated that this life history strategy may be more flexible than previously believed.  相似文献   

Seasonal epizootics of sea lice, Caligus spp., on southern bluefin tuna, Thunnus maccoyii (Castelnau), in a long-term farming trial     

C J Hayward  N J Bott †  B F Nowak 《Journal of fish diseases》2009,32(1):101-106

Within the typical 2–8 month (January to August inclusive) farming cycle for southern bluefin tuna, Thunnus maccoyii (Castelnau), in Spencer Gulf, South Australia, counts of a sea louse, Caligus chiastos Lin et Ho, 2003, were strongly statistically associated with both fish condition and severity of eye damage. During a trial examining the feasibility of maintaining T. maccoyii in farms for more than 1 year, including over the summer season when temperatures may exceed 24 °C, we collected additional epidemiological data on burdens of sea lice over a 17-month period (April 2005 to August 2006 inclusive), on a total of 200 T. maccoyii and 40 'control' T. maccoyii farmed and harvested within 2006. In the first farming season, an epizootic of C. chiastos was characterized by a significant increase in prevalence from 0% to 55% in the first 6 weeks after transfer to farms from the wild, which was followed by a significant decline to zero over the next 12 weeks. A single specimen of a second species of Caligus was also detected within this 4.5-month period. In the second farming season, we recorded a third species of sea louse, C. amblygenitalis Tripathi, 1961. In March 2006, a second epizootic peak occurred, this time with mixed infections of C. chiastos and C. amblygenitalis , with a combined prevalence of 100%. The prevalence of both sea lice species then declined significantly over the second winter period (June to August inclusive). On all but one date that sea lice were detected, sea lice counts were significantly associated with the severity of gross eye damage. Because both peaks in infection occurred in summer months (December to February inclusive), we conclude that infections of sea lice pose a risk to the farming of T. maccoyii under certain summer conditions within Spencer Gulf.  相似文献   

Sea lice infestation rates on wild and escaped farmed Atlantic salmon (Salmo salar L.) entering the Magaguadavic River, New Brunswick     

Jonathan Carr  & Frederick Whoriskey 《Aquaculture Research》2004,35(8):723-729

A monitoring program for the prevalence and intensity of sea lice infestations of wild and escaped farmed salmon has been underway on the Magaguadavic River since 1992. Fish are screened in a fish ladder trap located in freshwater a short distance above the head of tide. No trends with time were evident in observed sea lice burdens, and in all years the majority of salmon, both wild and escapees, had no or low levels of infestation with sea lice. In the spring of 2002, 23 landlocked salmon moving to sea from the Magaguadavic River were acoustically tagged. Two fish returned to the river after a brief period of residence in Passamaquoddy Bay, with significant dermal damage from sea lice. These fish were tracked to areas close to commercial salmon farms.  相似文献