Anti-oxidant status in embryonic,post-hatch and larval stages of Asian seabass (<Emphasis Type="Italic">Lates calcarifer</Emphasis>)

The concentrations of anti-oxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and selenium-dependent glutathione peroxidase (SeGPx), and low molecular weight free-radical scavengers such as reduced glutathione (GSH) and ascorbic acid (vitamin C) were evaluated during the period from gastrulation (GS) to 25 days post-hatch (dph) in the larvae of Asian Seabass, Lates calcarifer. Oxidative damage due to lipid peroxidation (LPO) was also assessed, by evaluation of the formation of malondialdehyde (MDA). All the three anti-oxidant enzymes, SOD, CAT and GPx, showed high activities during gastrulation, suggesting an increased metabolic rate during the period of embryonic development. Though the SOD activity apparently decreased progressively during 3–20 dph of larval development, the difference was not significant. CAT showed high activity during gastrulation and remained constant up to 3 dph, suggesting an increased need to metabolise hydrogen peroxide (H₂O₂) and organic peroxides. In contrast, SeGPx activity increased progressively from 5 dph to 25 dph during larval development, indicating an increased need to detoxify lipid peroxides. This is evident from the observation of increased lipid peroxidation from 10 dph to 25 dph during larval development. GSH levels were low at gastrulation, indicating increased metabolic rate and formation of lipid radicals during this period, corresponding to the decrease in the level of ascorbic acid, which is consumed for regeneration of GSH.     

鳞翅目昆虫幼虫味觉感受器的研究进展

鳞翅目昆虫幼虫通过味觉感受器来感受外界的化学信息。幼虫的味觉感受器主要存在于外颚叶、下颚须和内唇上。味觉感受器对幼虫取食选择行为起着重要的作用。综述了鳞翅目幼虫的各种味觉感受器及其分布和特征,旨在为进一步研究昆虫幼虫味觉行为提供参考。     

Management of paddlefish fry and juveniles in Bulgarian conditions

When paddlefish larvae were reared in tanks and fed on zooplankton, a length of 12–15 cm and a weight of 9.2 g had been obtained by the second month after hatching. After a further 2-months of pond rearing, the survival rate was 48%, and the juveniles had reached an average weight of 27.74 g and length of 22.5 cm. Much better growth rate was achieved when both paddlefish fry and juveniles were reared only on artificial food in tanks. At the end of the first month, a weight of 11.6 g had been reached; at the second month the paddlefish weight was 33.29 g, at the third month it was 60.2 g, and at the fourth month it was 127.7 g. There were two cases in which, respectively, 1,000 and 1,500 paddlefish with an average body weight of 33–60 g were stocked in a reservoir. At the age 5 months the fish had reached, or exceeded, an average weight of 500 g, and, after 1 year, it was over 700 g, which is an indicator of the good rearing opportunities this reservoir offered.     

柠檬桉精油对小菜蛾幼虫生物活性的研究

研究柠檬桉精油对小菜蛾幼虫的杀虫活性，结果表明：柠檬桉精油对小菜蛾幼虫具有很强的拒食活性，浓度为20mg／ml时，拒食率达到91．11％；而胃毒活性和触杀活性则相对弱一些，浓度为20mg／ml的处理，小菜蛾幼虫由胃毒作用引起的死亡率为69．89％，由触杀作用引起的死亡率为62．22％。     

菲律宾蛤仔幼虫的生长速度和水温的关系

通过实验研究了菲律宾蛤仔幼虫的生长速度和水温的关系，结果表明：幼虫除９℃水温外，其它所有实验水温都能正常发育，生长速度与水温呈直线关系，其回归式为ＲＧ＝０．３７７ｔ－２．９６；幼虫生长的生物学零度经计算为７．９℃。     

杨二尾舟蛾幼虫空间分布型及抽样技术的研究

通过采用种群的聚集度指数：Ｃ、１／ｋ，λ，ｍ√ｘ、Ｌ、Ｔａｙｌｏｒ冥法则和ｍ对ｍ的回归方法测定杨二尾舟蛾幼虫的空间分布型，并用不同的抽样方法比较离抽样精确度，杨二尾舟蛾幼虫在林内呈聚集分布，其聚集的原因是由环境因素所引起，幼虫空间分布的基本成份是个体群，个体间相互吸引，分析证明杨二尾舟蛾幼虫采用平行线和“Ｚ”字型抽样方法误差最小。     

害虫体内农药积累的研究

导出了昆虫取食含药植株组织后体内农药积累的计算模型。根据悬铃术体内久效磷含量的灰色动态模型及家蚕各龄期内的取食规律。进行了理论计箅,得出了若干有指导意义的结论,据此可确定施药方式、施药时间,并可初步判断施药剂量的合理性。     

Mass production of competent larvae of the sea urchin <Emphasis Type="Italic">Lytechinus variegatus</Emphasis> (Echinodermata: Echinoidea)

We evaluated the mass production of competent larvae of the sea urchin Lytechinus variegatus cultured at three initial densities (0.25, 0.5, and 1 larvae per ml) and fed Chaetoceros muelleri. Survival, length, dry weight of larvae, and larval stage index (LSI) were estimated in each treatment as a function of the density. Density decreased during the experiment due to mortality, but the percentage was similar in all three treatments (68.5, 66.7, and 76.0%). The experiment was stopped at 13 days after fertilization, when most of the larvae were competent and had settled. There were no significant differences in survival (exceeded 65% in all treatments), length and larval stage index among treatments. However, larvae weight in the two low density treatments (1.1 ± 0.11 mg and 1.2 ± 0.05 mg, respectively) was greater than the high density treatment (0.59±0.376 mg). This study demonstrates that competent larvae of Lytechinus variegatus can be produced with less than 25% mortality in 13 days when cultures are started at densities of 0.25–1 larvae/ml. Culturing at higher densities (0.5–1 larvae/ml) had no apparent disadvantages and would reduce the cost of production.     

罗氏沼虾（Macrobrachium rosenbergii）育苗中提高单位水体出苗量的关键技术

总结了上海市水产养殖公司１９９５年度罗氏沼虾育苗工作的经验，指出罗氏沼虾育苗中提高单位水体出苗量的关键技术是适时储备育苗用水，抓好育苗用水的净化处理，强化亲虾培育，严格控制育苗池水温，合理控制幼作放养密度，科学投喂适口饵料等。     

Bacterial nutrition of great scallop larvae

Bacterial nutrition of great scallop, Pecten moximus, larvae was investigated using the radioactive tracer technique. The bacterial labelling was studied initially to obtain a high and stable specific radioactivity (¹⁴C) of bacterial cells. A higher bacterial specific ¹⁴C activity was obtained when the tracer (amino acid) was introduced in the culture medium at the beginning of the exponential growth phase. After a 12 h labelling period in a rich nutritive medium, the bacteria were depurated in seawater for 5 h (chase) to prevent further ¹⁴C excretion and then added to larval rearing vessels. The larval labelling was followed for 12 h and then larvae were placed in new vessels without radioactive bacteria. The depuration of larvae was followed for 3 days. Data obtained on ingestion and assimilation efficiency show that bivalve larvae are able to ingest and digest bacteria.