Seed production of Charybdis feriatus (Linnaeus)

Some aspects of the reproductive biology of Charybdis feriatus (Linnaeus) were investigated to identify suitable techniques for broodstock management and seed production. Likewise, factors such as ablation, water depth and light requirements affecting survival or reproductive performance were tested. Production of megalops in tanks and juveniles in net cages installed in earthen ponds was conducted. Wild‐caught berried females produced a significantly higher number of zoeae per gram body weight (BW) of the female (3300±600) than captive spawners (867±58). Ablated and unablated crabs spawned after a month and ovaries of both had oocytes in all developmental stages after spawning, indicating that ablation was not necessary. Broodstock survived higher when stocked in 1 m‐deep water and kept in dark conditions compared with shallow (0.5 m depth) water or ambient lighting. There were six zoea and one megalopa stage. Megalops were produced (survival of 2–22% in 1 tonne or 23–55% in 3 L tanks) when methods for the mud crab Scylla serrata (Forsskål) were used, but feeding with Artemia started only at the Z4 stage. Survival of megalops after 1 month was higher when stocked in net cages installed in an earthen pond (32–82%) than when reared continuously in land‐based tanks (5–11%).     

球孢白僵菌MZ041016菌株对平菇厉眼蕈蚊的毒力

利用球孢白僵菌MZ041016菌株5种孢子悬浮液浓度(3.6×104～3.6×108个/mL)对平菇厉眼蕈蚊成虫和幼虫进行室内毒力测定。在3.6×108个/mL浓度下成虫死亡率最高达86.72%,幼虫死亡率最高达87.69%,成虫的LC50为2.319×105个/mL,幼虫的LC50为3.082×105个/mL。在3.6×104～3.6×108个/mL浓度处理下成虫的LT50依次为8.57、6.14、5.18d和4.28d,幼虫的LT50分别为8.09、6.03、4.96d和4.53d。球孢白僵菌MZ050724菌株在室内对平菇厉眼蕈蚊的成虫和幼虫有较强的毒力。     

斜纹夜蛾幼虫存活过程的神经网络模型的建立

利用BP神经网络对斜纹夜蛾幼虫的存活过程进行建模分析,给出了BP神经网络建模的Matlab算法程序。结果表明,BP神经网络能充分逼近斜纹夜蛾幼虫的存活过程曲线,使用BP神经网络可对斜纹夜蛾幼虫的存活过程进行有效的建模。利用所建立的模型,得到了关于斜纹夜蛾幼虫存活过程的模拟预测结果。不同温度下斜纹夜蛾幼虫种群的死亡过程有所不同。在20,24,36和40℃温度下,斜纹夜蛾幼虫种群的死亡高峰分别出现在卵孵化后20d左右,5～20d,5～10d及3～6d。最后,对神经网络建模的特点,以及影响BP神经网络建模效果的主要因素进行了分析讨论。     

不同温度和温湿度组合对米蛾的影响

不同温度处理对米蛾有不同饲养效应。试验结果表明:以26℃饲养米蛾效果最好,幼虫存活率,平均蛹重,平均蛹长,成蛾率,产卵量,繁殖倍数均居首位。25℃和28℃对米蛾的生长发育和生殖产卵均有不利影响,21℃不适合米蛾生长发育的需要。在26℃条件下,采用人工加湿的办法,使相对湿度保持在84％左右,对米蛾生长发育和繁殖均有明显促进作用,各项生物学指标分别达到:幼虫存活率95.8％,平均蛹重31.54毫克.平均蛹长9.64毫米;成蛾率55％,单雌产卵量370粒,群体繁殖倍数达59倍。降低湿度,不但延缓米蛾的发育进度,还直接降低了米蛾的产卵量和繁殖倍数。     

春蚕5龄立体条桑一日两回育研究

针对农村养蚕房屋紧、投入成本高、效益低的实际情况,在春蚕期进行了5龄立体条桑一日两回育研究,结果表明立体条桑育具有节省养蚕用房、生产用具简单、用桑量少、蚕茧产质量高于对照区等优点。     

对虾的免疫机制及其疾病预防策略的研究

在对虾的细胞免疫中血细胞是主要的作用因素,而体液免疫是血淋巴中的一些酶和调节因子,机体还可以被诱导产生特殊的免疫保护反应.应用免疫增强剂、疫苗和基因工程技术为预防对虾病害提供了有效的途径.本文根据国内外的有关资料,就对虾的免疫机制和疾病预防策略进行了综述.     

Effect of parental origin on early life history traits of European eel

Establishment of European eel (Anguilla anguilla) hatchery production will rely on selectively bred individuals that produce progeny with the best traits in successive generations. As such, this study used a quantitative genetic breeding design, between four females and nine males (four wild‐caught and five cultured), to investigate the effect of paternal origin (wild‐caught vs. cultured) and quantify the relative importance of parental effects, including genetic compatibility, on early life history (ELH) performance traits (i.e. fertilization success, embryonic survival at 32 hr post‐fertilization, hatch success and larval deformities at 2 days post‐hatch) of European eel. Wild‐caught males had higher (56%) spermatocrit values than cultured males (45%), while fertilization success, embryonic survival, hatch success and larval deformities were not significantly impacted by paternal origin. This demonstrates that short‐term domestication of male eels does not negatively affect offspring quality and enables the consideration of cultured male broodstock in future breeding programmes. Moreover, paternity significantly explained 9.5% of the variability in embryonic survival, providing further evidence that paternal effects need to be taken into consideration in assisted reproduction protocols. Furthermore, maternity significantly explained 54.8% of the variation for fertilization success, 61.7% for embryonic survival, 88.1% for hatching success and 62.8% for larval deformities, validating that maternity is a major factor influencing these “critical” ELH traits. At last, the parental interaction explained 12.8% of the variation for fertilization success, 8.3% for embryonic survival, 4.5% for hatch success and 20.5% for larval deformities. Thus, we conclude that eggs of one female can develop more successfully when crossed with a compatible male, highlighting the importance of mate choice for successful propagation of high‐quality offspring. Together, this knowledge will improve early offspring performance, leading to future breeding programmes for this critically endangered and economically important species.     

淡水鱼虾华支睾吸虫囊蚴感染情况调查

采集吉林省白城地区镇赉县周边6个鱼塘的各种鱼类,用直接压片镜检法和人工消化法分别对采集回来的麦穗鱼感染华支睾吸虫囊蚴的情况进行统计调查,结果表明,感染率最高、感染强度最大的鱼塘是四方坨六分场。随即对四方坨六分场鱼塘中各种鱼类华支睾吸虫囊蚴感染情况也采用同样方法进行调查,结果显示,感染率最高的是麦穗鱼、银飘鱼、尖头鱥,均为100%;其次是细鳞鱼,为80%;其他种类的鱼虾均未检测到有华支睾吸虫囊蚴寄生。     

A synthesis of large-scale patterns in the planktonic prey of larval and juvenile cod (Gadus morhua)

Data from 40 published studies of the diet composition of larval and juvenile cod (Gadus morhua) from around the northern North Atlantic were summarized to assess generic patterns in ontogenetic and regional variability in the key prey. The results showed that larvae at the northern edge of the latitudinal range of cod depend primarily on development stages of the copepod Calanus finmarchicus, whilst those at the southern edge depend on Para‐ and Pseudocalanus species. Juvenile cod preyed on a wider range of taxa than larvae, but euphausiids were the main target prey. Analysis of regional variations in the relative abundances of C. finmarchicus and Para/Pseudocalanus spp. in the plankton, as estimated by the continuous plankton recorder (CPR) surveys, showed a similar geographical pattern to the larval cod stomach contents. Comparison of CPR data from the 1960s and 70s with data from the 1990s showed that the boundary between C. finmarchicus and Para/Pseudocalanus spp. dominance has shifted northwards on both sides of the Atlantic, whilst the abundance of euphausiids in the southern cod stock regions has declined. The results are discussed in relation to regional differences in the response of cod stocks to climate variability.     

水温和盐度对南美白对虾幼虾能量收支的影响

用室内生态实验法测定了南美白对虾幼虾在不同盐度(5,15或25)和水温(20～23℃,25℃,30℃或33℃)下摄食水丝蚓的能量收支方程。在盐度5～25时,随盐度降低,对虾的能量转换效率升高,同化率降低。在盐度为5时,K1最高(29.02%),同化率最低(77.89%)。对虾具补偿机制来补偿调节渗透压的能耗。盐度对同化率的影响,主要是通过影响呼吸代谢实现的。对虾的特定生长率(y)(%·d-1)随水温(X)(℃)上升而增加,其关系式为:y=0.0168LnX 0.0831(R2=0.9324)。对虾在较高温度下生长快,主要是增加绝对摄食量,提高吸收效率,减少粪便排泄量。在相同温度下,变温时对虾的摄食量高于恒温时。