Design and performance of a recirculating aquaculture system for oyster larval culture

The major objective of this study was to introduce a newly designed recirculating aquaculture system (RAS) for oyster (Crassostrea angulata) larval culture. The system includes a culture tank, a suspended circular inlet‐pipe, an upwelling aeration pipe, combined “banjo” sieves and a bioreactor chamber containing microalgae life keeping installation. The system was designed to resolve three problems: (i) stranding of larvae caused by water level changes and aeration, (ii) physical clogging of the screens and also (iii) deterioration of diet microalgae. The culture tank, “banjo” sieve size, water flow rate and light intensity for maintaining microalgae activity were all designed according to the pattern of larval movement and feeding behaviour. Results of this study showed the best average SGR for larval length was 6.36%/d (9.5 μm/d) and survival rate was 80%, with initial rearing density of 50 larvae/ml, indicating the problems above were fully resolved. Consequently, the system is fit for larval culture in mass production of oysters.     

番茄潜叶蛾成虫触角及幼虫头部感受器的超微结构

为明确番茄潜叶蛾Tuta absoluta(Meyrick)成虫触角及幼虫头部感受器的种类、分布和形态结构,采用扫描电镜法观察番茄潜叶蛾雌雄成虫触角和4龄雌雄幼虫触角及口器上的感受器种类和形状。结果显示,番茄潜叶蛾成虫触角上共有8种类型感受器,分别为B?hm氏鬃毛、毛形感受器、鳞形感受器、锥形感受器（Ⅰ型和Ⅱ型）、刺形感受器、腔锥形感受器、栓锥形感受器和耳形感受器。其中,雌成虫的Ⅰ型和Ⅱ型锥形感受器数量、刺形感受器数量、B?hm氏鬃毛长度、鳞形感受器长度及基部直径、Ⅰ型锥形感受器长度及基部直径、Ⅱ型锥形感受器长度、刺形感受器臼状窝直径、腔锥形感受器基部直径和耳形感受器基部直径均显著大于雄成虫;而雄成虫的毛形感受器数量和腔锥形感受器中心锥长度显著大于雌成虫。幼虫头部共计有6种类型感受器,主要着生在触角、下颚和下唇上,分别为毛形感受器、锥形感受器、刺形感受器、栓锥形感受器、指形感受器和感觉锥;幼虫触角、下颚和下唇的感受器类型和数量在雌雄间完全相同。而雌性幼虫触角鞭节上的锥形感受器SB5和下颚须上的锥形感受器SB2的长度显著大于雄性幼虫;雄性幼虫下颚茎节上的刺形感受器Sch1和下颚须上的锥形...     

云南松毛虫越冬代幼虫自然种群空间分布型的研究

通过样方调查计算，采用聚集度指标法，测定云南松毛虫越冬代幼虫的空问分布型，建立了最适抽样数关系式，并对其进行了序贯抽样分析。结果表明：云南松毛虫越冬代幼虫种群在林内呈聚集分布，其Iwao回归方程为m*=5．2181 1．0207x^-、复相关系数R=0．9918；最适抽样株数为：N=621．81/x^- 2．07。     

鞭角华扁叶蜂滞育幼虫空间密度估计的研究

利用生物地理统计学的原理和方法研究鞭角华扁叶蜂滞育幼虫的虫口密度与其所处的空间位置之间的关系，创建了鞭角华扁叶蜂滞育幼虫虫口密度的半方差函数模型.在此基础上，用不同空间位置上的已知种群密度观测值估计其他空间位置上的未知种群密度，取得了令人满意的估计效果。     

竹织叶野螟Algedonia coclesalis Walker越冬幼虫的真菌病

粉质拟青霉Paecilomyces farinosus (Dicks.ex.Fr.)Brown et Smith是竹织叶野螟越冬幼虫的重要病原菌,林间自然发病率为23.08％～42.84％。用5.5×10~6/ml孢子悬液感染越冬幼虫,死亡率达91.7％。在24～26℃下,病程约10～14d。林间罹病虫尸上,可见粉质拟青霉被寄生黑孢壳Melanospora parasitica Tulasne寄生。本文还从病原菌的生理性质及侵染环境的角度,讨论了疾病的流行条件和病原菌利用的前景。     

樟叶蜂生物学特性及温度对幼虫发育历期的影响

樟叶蜂在上海地区1 a发生2~3代,以蛹越冬。1龄、2龄、3龄、4龄幼虫平均头壳宽分别为(0.037±0.002)mm,(0.080±0.004)mm,(0.126±0.008)mm,(0.175±0.016)mm。雌雄成虫寿命分别为(4.75±1.22)d和(4.70±0.96)d。雌雄性比1∶1.74。     

Combined effects of water temperature and daily food availability period on the growth and survival of tench (Tinca tinca) larvae

A 16‐day experiment was designed to find the best combination of water temperature (27, 30, 33°C) and daily duration of food availability (12, 18, 24 h) for larval tench (Tinca tinca) growth and survival. Larvae with an initial mean size of 5.7 mm total length (TL) and 0.7 mg wet body weight (BW) were stocked at 15 L^?1. Larvae were fed in excess with live Artemia nauplii with the period of food availability lasting 12, 18 or 24 h daily. The largest final larval size was recorded at 27 and 30°C in groups fed for 24 h a day (17.7 and 17.9 mm TL, 76.1 and 77.7 mg BW, respectively). The combination of the highest temperature and the longest daily food availability was the only set of conditions under which final larval survival was affected (95.4% survival; 98.7–99.9% under all other conditions). The combination of water temperature of about 28.6°C and continuous food availability is recommended as the optimum combination for rearing T. tinca larvae under controlled conditions. Providing continuous food supply to fish larvae under aquaculture conditions was also advantageous in helping to mitigate the effects of slower growth relative to developmental progress, which can occur at high water temperatures. However, should one wish to limit the daily feeding period to 12 h per day, the use of a water temperature between 27.4 and 27.9°C would be the best solution.     

Winter monsoon promotes the transport of Japanese temperate bass Lateolabrax japonicus eggs and larvae toward the innermost part of Tango Bay,the Sea of Japan

Northwesterly cold winds characteristic of the East Asian Winter Monsoon (EAWM) dictate winter climatic conditions over the Japanese Archipelago. Japanese temperate bass Lateolabrax japonicus is a commercially important coastal fish that spawns offshore in winter and uses shallow waters as nursery habitats. To investigate the effects of EAWM on the planktonic period of L. japonicus, eggs, larvae, and juveniles were quantitatively collected in Tango Bay on the Sea of Japan side in winter and spring from 2007 to 2017. Although eggs occurred close to the mouth of the bay, planktonic larvae occurred further inside as they developed. The horizontal distribution of planktonic larvae, combined with water velocity data obtained from mooring observations, indicated that planktonic larvae are transported south‐ to westward through Ekman current and an anticyclonic circulation, which are driven by northwesterly winds. To evaluate survival during the planktonic period in each year class, the abundance of benthic larvae/juveniles was divided by winter total landings of Lateolabrax spp. (proxy of the spawning stock size). This survival index exhibited a positive correlation with the northwesterly component of winter winds, and a negative correlation with winter air temperature (average from December to February, Spearman's correlation, p < .05). There was, however, no significant correlation with winter water temperature or winter freshwater discharge in the bay. We conclude that northwesterly cold winds of EAWM play a critical role in transporting L. japonicus eggs and larvae toward nursery habitats, specifically beaches and estuaries fringing the innermost part of Tango Bay.     

方斑东风螺肉壳分离病病因的初步研究

螺肉与螺壳分离病是方斑东风螺养殖中的常见病害，主要发生在壳高0．5cm以下的稚、幼螺阶段，严重时可造成螺苗在短时间内大量死亡。本文报道了方斑东风螺中间培育过程中由于养殖水体中混入以婆罗异剑水蚤（Apocyclops borneoensis）为主的桡足类对稚、幼螺的攻击，导致稚、幼螺受伤部位发生溃疡性病变，进而诱发稚、幼螺肉壳分离疾病发生的镜检检查结果。通过采取杀灭螺池中桡足类的措施后，病情很快得到控制，研究结果验证了桡足类对方斑东风螺稚、幼螺的危害性。