克氏原螯虾雄性生殖系统的超微结构

采用透射电镜研究了克氏原螯虾输精管的超微结构,采用石蜡切片法研究了克氏原螯虾的精巢、输精管和精荚的显微结构,并对精巢做了周年变化研究。结果表明,精巢由许多生精小囊和收集管组成,其结构呈葡萄串状,生殖细胞在生精小囊内发育成熟后由收集管输送到输精管;输精管有左右两条,相对于左侧输精管,右侧输精管比其约长一半,直径更大,卷曲程度更高,内容物含量更多,分泌细胞内的内质网含量更丰富;输精管根据形态不同分为前、中、后、生殖突4段,前中段具有分泌精荚壁物质的功能,后段具有储存、射出精荚的功能,末端生殖突为输精管出口;精荚呈长囊形或椭球形,由精子团、精荚基质和两层精荚壁组成,精子团偏向精荚一侧分布;克氏原螯虾雄虾精巢在一周年中的5—8月和10月处于精子细胞期的生精小囊比例很高,具有两个成熟时期。     

克氏原螯虾几种动植物饵料的培育

针对克氏原螯虾天然性饵料的合理利用问题,阐述了几种适于克氏原螯虾养殖的常用动植物饵料及其培育技术,具体包括小浮萍移植、采收、日常管理和防病除害,伊乐藻的栽培与栽后管理,红虫的施肥培育与捞取等,为克氏原螯虾养殖生产提供借鉴。     

Acute toxicity of chlorantraniliprole to non‐target crayfish (Procambarus clarkii) associated with rice–crayfish cropping systems

BACKGROUND: Chlorantraniliprole, a novel anthranilic diamide insecticide, was recently introduced into the United States where rice–crayfish crop rotations are practiced to control rice water weevil (Lissorhoptrus oryzophilus Kuschel) infestations. Chlorantraniliprole has high margins of mammalian safety and excellent insecticidal efficacy, but its toxicity to non‐target crayfish is uncertain. In this study, the acute toxicity of chlorantraniliprole to the red swamp crayfish Procambarus clarkii Girard was determined using aquatic and feeding assays. RESULTS: The aquatic 96 h median lethal toxicity (LC₅₀) data indicate that technical‐grade chlorantraniliprole is highly toxic (US EPA category) to crayfish with an LC₅₀ of 951 µg L^?1 (95% CL = 741–1118 µg L^?1). A no observed effect concentration (NOEC) of 480 µg L^?1 was recorded. Neither the 36 day chronic feeding study, where crayfish fed on chlorantraniliprole‐treated rice seed in aquaria, nor the 144 h acute feeding test, where crayfish fed on rice seeds treated with chlorantraniliprole, produced mortality or abnormal behavior. CONCLUSION: Chlorantraniliprole is three orders of magnitude less acutely toxic to P. clarkii than lambda‐cyhalothrin and etofenprox, two pyrethroid insecticides also used in rice, and is less likely to cause acute crayfish toxicity in rice pond ecosystems. Based on acute toxicity data, the use of chlorantraniliprole should be more compatible with rice–crayfish crop rotations than pyrethroids. Copyright © 2010 Society of Chemical Industry     

Comparative acute toxicity of neonicotinoid and pyrethroid insecticides to non‐target crayfish (Procambarus clarkii) associated with rice–crayfish crop rotations

BACKGROUND: Most insecticides used to control rice water weevil (Lissorhoptrus oryzophilus Kuscel) infestations are pyrethroids. However, pyrethroids are highly toxic to non‐target crayfish associated with rice–crayfish crop rotations. One solution to the near‐exclusive reliance on pyrethroids in a rice–crayfish pest management program is to incorporate neonicotinoid insecticides, which are insect specific and effective against weevils but not extremely toxic to crayfish. This study aimed to take the first step to assess neonicotinoids as alternatives to pyrethroids in rice–crayfish crop rotations by measuring the acute toxicities of three candidate neonicotinoid insecticides, clothianidin, dinotefuran and thiamethoxam, to juvenile Procambarus clarkii (Girard) crayfish and comparing them with the acute toxicities of two currently used pyrethroid insecticides, lambda‐cyhalothrin and etofenprox. RESULTS: Neonicotinoid insecticides are at least 2–3 orders of magnitude less acutely toxic (96 h LC₅₀) than pyrethroids to juvenile Procambarid crayfish: lambda‐cyhalothrin (0.16 µg AI L^?1) = etofenprox (0.29 µg AI L^?1) ? clothianidin (59 µg AI L^?1) > thiamethoxam (967 µg AI L^?1) > dinotefuran (2032 µg AI L^?1). CONCLUSION: Neonicotinoid insecticides appear to be much less hazardous alternatives to pyrethroids in rice–crayfish crop rotations. Further field‐level neonicotinoid acute and chronic toxicity testing with crayfish is needed. Copyright © 2009 Society of Chemical Industry     

克氏原螯虾对3种不同生长型沉水植物清水态系统的影响

原产美国南部和墨西哥东北部的克氏原螯虾（Procambarus clarkii）是目前全球入侵最广的小龙虾,也是对淡水生态系统最具破坏性的物种之一,研究克氏原螯虾对以沉水植物为初级生产力的清水态系统的影响,有助于认识其入侵浅水湖泊带来的生态风险。本文通过受控实验,研究了克氏原螯虾对三种生长型沉水植物轮叶黑藻（Hydrilla verticillata,直立型）、穗花狐尾藻（Myriophyllum spicatum,冠层型）和密刺苦草（Vallisneria denseserrulata,莲座型）的影响以及不同植物培养系统理化因子的响应变化,结果表明直立型轮叶黑藻和莲座型密刺苦草的生物量降低大于冠层型穗花狐尾藻;克氏原螯虾进入后均导致三种生长型沉水植物清水态系统的总悬浮物浓度、叶绿素a和营养盐显著增高,其中实验结束时密刺苦草组、穗花狐尾藻组和轮叶黑藻组的总悬浮物浓度均值在实验组比对照组分别增加了41.4、11.3和29.7 mg/L,总磷分别增加了0.056、0.024和0.032 mg/L。研究表明克氏原螯虾进入3种生长型沉水植物草型清水态系统后均会导致水体悬浮物浓度和营养盐增加,也会通过直接牧食或扰动破坏降低沉水植物生物量,最终影响草型清水态系统的稳定性。     

克氏原螯虾不同发育阶段卵巢中EST同工酶比较

[目的]研究克氏原螯虾(Procambarus clarkii)卵巢成熟过程EST的变化。[方法]采用聚丙烯酰胺凝胶电泳方法,分析了卵黄形成期和成熟期卵巢中酯酶同工酶(EST)的表达情况。[结果]所研究的两个阶段卵巢中EST同工酶的表达可分为Ⅰ、Ⅱ、Ⅲ共3个区。其中Ⅰ区和Ⅱ区卵黄形成期EST表达较强,酶带明显比成熟期浓,尤其是Ⅰ区,卵黄形成期EST同工酶的表达最强。相反,在Ⅲ区,成熟期EST酶带明显比卵黄形成区浓。[结论]在克氏原螯虾卵子成熟过程中,EST基因的表达存在时间差异性。     

克氏原螯虾大颚器的超微结构研究

克氏原螯虾的大颚器为一对,位于左右大颚的背面,大颚几丁质腱外侧基部。大颚器含丰富的血淋巴管和血窦,大颚器细胞围绕血窦成短束状排列,典型大颚器细胞超微结构最显著的特征;（１）线粒体和光面内质网广泛分布于胞质中,光面内质网明显分成小池状和小管状两种类型;（２）细胞质膜内陷并作不同程度的卷绕;（３）质膜外侧的基膜增厚,富含微丝。在泡状化的大颚器细胞中,光面内质网几乎消失,线粒体形态变异,胞核中的异染色质     

江苏四个典型克氏原螯虾养殖区抗生素污染特征与生态风险评估

为揭示江苏克氏原螯虾养殖环境中抗生素的分布特征和污染现状,利用超高效液相色谱-串联质谱法(UPLC-MS/MS)调查浦口和盱眙两个地区4个典型养殖塘水和沉积物中抗生素的残留情况。共检出14种抗生素(包括4种大环内酯类、2种四环素类、4种喹诺酮类和4种磺胺类),除浦口两养殖塘水体中的CTCHCL、OFL和AZI(浓度分别为16.528~57.140ng L-1和9.803~47.400 ng L-1),其他抗生素均以低浓度存在。抗生素浓度与水质指标的相关性分析结果表明,抗生素在水环境中的降解可能受水体富营养化、有机污染程度等水质状况的影响。基于RQs值对养殖环境中的抗生素进行风险评估,它们对生态系统中浮游动物的生长基本不会造成威胁;对藻类等浮游植物而言,浦口养殖水体中部分大环内酯类(SP、CTM)和喹诺酮类(O FL)抗生素具有中高度风险(0.161≤RQs≤2.92),盱眙养殖环境中目标抗生素生态风险较低(RQs≤0.181)。研究表明,江苏(特别是盱眙)克氏原螯虾养殖水体中抗生素污染水平相对较低,但仍存在一定的生态风险。建议采取全面的抗生素控制措施,以保护水产养殖生态系统的健康。     

注射白斑综合征病毒对克氏原螯虾酚氧化酶活力的影响

将白斑综合征病毒(white spot syndrome virus,WSSV)、嗜水气单胞菌(Aeromonas hydrophila,Ah)、大肠杆菌(Escherichia coli)(DH5α)用注射法接种克氏原螯虾(Procambarus clarkii),在0~72 h之间定时检测克氏原螯虾血细胞和肝胰脏中酚氧化酶(Phenoloxidase,PO)活力变化。结果显示:(1)0.1 mg/m L和1 mg/m L胰蛋白酶处理样品后,样品间差异不显著。(2)加胰蛋白酶处理与未加胰蛋白酶相比,供试克氏原螯虾PO活力均升高。(3)未加胰蛋白酶与加胰蛋白酶表现出相似的特征,WSSV和Ah注射组与对照组相比均表现为,12~48 h PO活力显著高于对照组,并且在48 h达到最大值,72 h时基本恢复正常;注射DH5α组与对照组相比没有显著性变化。可见感染WSSV后,克氏原螯虾体内酚氧化酶活力发生了变化,由此推测,PO参与了螯虾体内抵御病毒的免疫反应。     

克氏原螯虾对盐度适应性试验

对克氏原螯虾仔虾采用6个不同的盐度进行了盐度突变试验,2个试验组的初始盐度为2,探讨克氏原螯虾仔虾对盐度适应性。盐度突变试验结果显示,克氏螯虾仔虾对盐度为10以下具有较强的适应性。渐变试验显示,克氏螯虾仔虾的存活率与盐度调整周期有关,3d为1次的调整周期优于2d调整周期。因此,在低盐度水平开展克氏螯虾盐度驯养是可行的。