Invasive dynamics of the crayfish Procambarus clarkii (Girard, 1852) in the international section of the River Minho (NW of the Iberian Peninsula)

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Immunostimulatory effects of dietary fructooligosaccharides on red swamp crayfish,Procambarus clarkii (Girard)

Fructooligosaccharides (FOS) are widely researched as prebiotics and immunostimulants in humans and terrestrial animals. However, limited researches on immune functions of FOS were reported in crustacean. In the present study, red swamp crayfish Procambarus clarkii were fed with different concentrations of FOS (2.0, 5.0, 8.0, 10.0 g kg^?1 diet), and then the immunostimulatory effects of FOS were evaluated by measuring immune parameters and examining immune‐related gene expression. PO and SOD activities were significantly increased in groups fed with 8.0 or 10.0 g kg^?1 of FOS compared with those in control group. In addition, significant elevations of SOD and phagocytic activities were also observed in group fed with 5.0 g kg^?1 of FOS. Among examined immune‐related genes, expressions of crustin1, lysozyme, SOD and pro‐PO were significantly up‐regulated by feeding with 8.0 or 10.0 g kg^?1 of dietary FOS. Survival rates of crayfish challenged with Aeromonas hydrophila were significantly improved by feeding with 5.0, 8.0 or 10.0 g kg^?1 of dietary FOS for 30 days. Phagocytic activities and bacterial clearance efficiencies were also significantly increased in groups fed with 8.0 or 10.0 g kg^?1 of FOS. The results indicated that dietary FOS effectively induced innate immune responses of red swamp crayfish in a dose‐dependent way and could be used as potential immunostimulant in crustacean.     

Effectiveness of Synthetic Molecules,and Animal and Vegetable Extracts as Baits for Harvesting Red Swamp Crayfish,Procambarus clarkii

Abstract

The present study was designed to evaluate the efficiency of different biogenic amines (putrescine, cadaverine, tyramine, spermine and spermidine) and their precursory amino acids (arginine, histidine, lysine and tyrosine), as well as animal extracts (from fish, crustaceans and mollusks) and vegetable extracts (Chara sp., coconut and alfalfa) as baits in traps for red swamp crayfish, P. clarkii. The methodology was conceived as a logical sequence to proceed from rapid screening of a large number of treatments and was divided into three phases: (1) chemo-detection bioassays, (2) chemattraction bioassays, and (3) field bioassays carried out under natural conditions. The attractants that showed the best performance as baits for P. clarkii, were: the fish soluble extract (included at 2.96%), the putrescine (included at 0.30%) and the red crab soluble extract (included at 2.69%). The benefits of using these attractants, when added to common pelleted feed, come from their low cost, availability and enhanced handling properties.     

四种稻田农药对克氏原螯虾的急性毒性研究

采用半静态方式水生生物急性毒性实验法,研究了在实验室常温条件下敌百虫、稻瘟灵、毒死蜱、阿维菌素四种稻田杀虫剂对克氏原螯虾（ Procambarus clarkii）的急性毒性。结果显示,敌百虫、稻瘟灵、毒死蜱、阿维菌素对体重为（34.43±7.04）g克氏原螯虾的24 h半致死浓度（24 h LC50）分别为65.07、42.16、0.71、1.23 mg/L,48 h半致死浓度（48 h LC50）分别为35.75、33.49、0.59、0.84 mg/L;96 h半致死浓度（96h LC50）分别为12.54、18.83、0.45、0.37 mg/L。其安全浓度分别为3.24、6.34、0.122、0.117 mg/L。根据国家标准和本实验数据可以看出,敌百虫和稻瘟灵对克氏原螯虾中毒,毒死蜱和阿维菌素对其高毒。     

Inducing synchronous ovarian maturation in the crayfish,Procambarus clarkii,via eyestalk interventional injection as compared with eyestalk ablation and combined injection of serotonin and domperidone

We examined the feasibility of inducing synchronous ovarian maturation in the crayfish, Procambarus clarkii, via eyestalk interventional injection (EI) using a Bletilla striata polysaccharide (BSP) gelatin containing tranexamic acid (TRA), domperidone (DOM) or serotonin (5‐HT). In total, 360 females were randomly assigned to seven experimental groups and a control group. The average survival rate (SR%) and average synchronous ovarian maturation rate (SMR%) in survivors in the EI groups, EI‐TRA, EI‐DOM, EI‐5HT were compared with bilateral eyestalk ablation (BEA), unilateral eyestalk ablation (UEA), abdominal injection (AI) of DOM (0.5 mg crayfish^?1) alone (AI‐DOM) or combined with 5‐HT (0.5 mg crayfish^?1) (AI‐DOM+5‐HT). The experiment covered a prolonged period of 32 days until two ovigerous females were observed in BEA. EI‐DOM achieved a SMR (66.67 ± 9.62%) higher than the control (22.05 ± 3.06%) (P < 0.05), but lower than BEA (88.89 ± 11.11%), UEA (63.33 ± 18.56) and AI‐DOM+5‐HT (59.26 ± 10.14%) (P > 0.05). EI‐DOM also achieved a higher SR (53.33 ± 3.85%) than BEA (15.56 ± 2.22), UEA (24.44 ± 5.88) (P < 0.05) and AI‐DOM+5HT (51.11 ± 4.44) (P > 0.05). However, EI‐TRA (SR = 28.89 ± 4.44, SMR = 37.78 ± 2.22) and EI‐5‐HT (SR = 15.56 ±4.44, SMR = 22.22 ± 11.11) failed to induce significantly higher SMR than the control. These findings suggest that EI methods, such as EI‐DOM, may have positive characteristics for the development of inexpensive and less labour‐intensive techniques for induction of ovarian maturation in decapods.     

敌百虫胁迫对克氏原螯虾免疫学相关指标的影响

在不同质量浓度(0、0.132、0.264、0.528 mg/L)敌百虫胁迫条件下,研究克氏原螯虾(Procambarus clarkii)肝胰腺T-SOD、CAT、ACP、AKP及肌肉Na+,K+-ATPase、TChE的活性变化。结果表明,敌百虫对各免疫因子影响各异;0.132 mg/L和0.528 mg/L浓度组克氏原螯虾的肝胰腺T-SOD活性分别于药浴4 d和1 d时显著高于对照组(P0.05);0.132 mg/L和0.264 mg/L浓度组克氏原螯虾的CAT活性于药浴2 d后显著高于对照组(P0.05);12 d内各浓度组ACP及AKP活性随药浴时间的延长而一直低于对照组,其中ACP在4 d内逐渐降低;肌肉TChE在0.132 mg/L和0.264 mg/L浓度组中分别于药浴1 d和4 d后活性显著高于对照组(P0.05);而Na+,K+-ATPase只有0.528 mg/L浓度组在2 d内活性显著高于对照组(P0.05),其余各组未出现诱导现象;试验组各免疫因子活性在药浴12 d时均显著低于对照组(P0.05);表明敌百虫胁迫并非仅仅作用于TChE,其对克氏原螯虾机体T-SOD、CAT、ACP、AKP及Na+,K+-ATPase均有影响,12 d后各免疫因子活性均难以恢复至对照水平。     

克氏原螯虾和红螯螯虾出肉率与可量性状的相关性

为寻找合理的方法评估比较克氏原螯虾和红螯鳌虾出肉率的高低,从而为其选育工作提供科学依据。本研究运用统计分析方法研究了2种虾的出肉率和可量性状之间的相关性。结果表明：红螯螯虾出肉率高于克氏原螯虾出肉率,第一腹节宽为影响克氏原螯虾出肉率的重点性状;体长和头胸甲长为影响红螯螯虾出肉率的重点性状,全长次之。得出结论：（1）可量性状与出肉率的相关性相较于可量性状与肉质量的相关性更能突出重点性状;（2）通过测量可量性状或通过性状比值进行克氏原螯虾和红螯螯虾出肉率方面的选育都是可行的。     

Lack of acute toxicity of an anthraquinone bird repellent to non-target crayfish (Procambarus clarkii) associated with rice-crayfish crop rotations

Aeroz™ (9,10-anthraquinone (AQ)), a chemical rice seed treatment that effectively deters birds from depredating newly planted fields, could be an important management tool that enables rice producers to plant earlier in the season and increase yields. This bird repellent, while non-lethal to birds, has unknown toxicity to crayfish that often are closely integrated with rice production in southern regions of the USA. This study was conducted to assess if AQ, the active ingredient in Aeroz™, could be acutely toxic to the red swamp crayfish Procambarus clarkii (Girard), the crayfish species most often associated with rice cultivation, via seed ingestion and/or through their contact with chemical in pond water. Mortality data from a 96 h feeding study indicate that AQ-treated (1.76% by wt) rice seed was not acutely toxic to juvenile (∼3 mo.) crayfish through the ingestion exposure route. In addition, a 96 h aquatic acute toxicity test showed that the LC₅₀ of AQ in juvenile crayfish is >85 μg L⁻¹ and above the water solubility limit of AQ. These results indicate that very minimal, if any, acute toxicity would be observed in juvenile crayfish if exposed to AQ via ingestion or dissolved or suspended in the water column.     

全价配合饲料条件下克氏原螯虾幼体及成体消化酶的活力研究

[目的]探讨全价配合饲料条件下克氏原螯虾幼体及成体消化酶的活性。[方法]取克氏原螯虾幼体全消化道组织,成体胃、肠组织,对克氏原螯虾蛋白酶、淀粉酶、脂肪酶、纤维素酶等消化酶活性进行测定。[结果]克氏原螯虾幼体的淀粉酶活性较高,胃蛋白酶活性较低;纤维素酶和脂肪酶活性相差不大,且活性均小于淀粉酶活性。成体的胃和肠中蛋白酶及淀粉酶比活力均较高,而纤维素酶和脂肪酶的比活力较低,且蛋白酶比活力为胃大于肠,淀粉酶比活力为肠略大于胃,纤维素酶和脂肪酶比活力在胃和肠中无明显差异。[结论]该研究为克氏原螯虾的水产养殖中专用饲料的开发提供了参考资料。     

克氏原螯虾自相残食特性及人工繁育中的关键技术研究

研究了不同体长、密度、雌雄配比条件下克氏原螯虾自相残食的情况。结果表明:克氏原螯虾自相残食特性与体长、群体密度、性别配比等因素之间存在明显相关性。虾苗饲养密度提高,自相残食率相应提高。在相同密度条件下,体长越大的虾苗其自相残食率越高。体长1.0~1.5、2.0~2.5、3.0~3.5 cm的虾苗,培育密度分别为667万、400万和267万只/hm2时,其自相残食率均在7%左右,人工培育虾苗时可以此为参照;在不同规格虾苗混养情况下,个体间体长相差越大,体长小的个体被残食的概率越高。人工培育虾苗时,应根据虾苗大小分群培育;成虾饲养密度小于16只/m2时,其自相残食率低于5%。人工养殖成虾时,养殖密度以15万只/hm2为宜。在雌雄比为(2~3)∶1时,克氏原螯虾自相残食率为5%左右。在克氏原螯虾人工繁育配种时,适宜雌雄比应为(2~3)∶1。