麦蚜对吡虫啉的敏感性及吡虫啉有效用量的评价

室内测定结果表明 ,禾谷缢管蚜对吡虫啉的敏感性比麦长管蚜高 ,其LC₅₀之比为1∶3左右。田间试验结果明确 ,吡虫啉持效性好 ,其持效期与吡虫啉用量和麦蚜种类有关。小麦穗蚜发生始盛期是吡虫啉防治麦蚜的最佳时期 ,防治禾谷缢管蚜最佳有效用药量为1g/667m²,麦长管蚜为2g/667m²。     

Effects of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia (Rachycentron canadum Linnaeus.)

An 8-week feeding trial was conducted to evaluate the effect of dietary carbohydrate sources on the growth performance and hepatic carbohydrate metabolic enzyme activities of juvenile cobia. Six experimental diets were formulated to contain 20% glucose, sucrose, maltose, dextrin, corn starch and wheat starch respectively. The results indicated that fish fed the wheat starch and dextrin diets showed significantly better weight gain, specific growth rate and protein efficiency ratio compared with those fed the other diets. However, fish fed the glucose diet had a significantly lower survival and condition factor than those fed the other diets. There were significant differences in the total plasma glucose and triglyceride concentration in fish fed diets with different dietary carbohydrate sources. Haematocrit, haemoglobin, red blood cell and leucocytes were significantly affected by the dietary carbohydrate sources. The activities of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphofructokinase (PFK) and fructose-1,6-bisphosphatase (FBPase) were significantly affected by the dietary carbohydrate sources, while fish fed the glucose diet showed higher G6PD, PFK and FBPase activities than those fed the other diets. These data indicated that dextrin and wheat starch were the most optimal carbohydrate sources for juvenile cobia.     

南疆棉田十一星瓢虫对棉蚜的生态控制

通过对南疆尉犁县两处棉田,4个品种十一星瓢虫的种群动态、人工诱集和棉蚜防治效果测试观察,发现:在南疆不同品种的棉田中,十一星瓢虫是棉田棉蚜的主要天敌,约占棉田瓢虫总数的80%左右;十一星瓢虫与棉蚜种群数量呈显著的跟随关系,发生期比棉蚜滞后1周左右。人工诱集十一星瓢虫的数量与诱集箱放置的位置和箱内的诱集物有关。放置在棉田周围林带中的诱集箱诱集的十一星瓢虫数量最多,其次是棉田埂箱,棉田内诱集的数量最少;诱集箱放入蜂蜜和花粉蜜诱集的十一星瓢虫数量最多,放入花粉诱集的十一星瓢虫数量次之,不放任何诱集物诱集的十一星瓢虫数量最少。越冬后的十一星瓢虫早期释放到棉田中心蚜株上可以有效防治蚜虫危害,中心蚜株株高比未释放瓢虫处理的增高59.5%,果枝数增加20.3%、蕾数增加100%、铃数增加81.4%,单株产量增加81.1%。     

盐度变化对军曹鱼稚鱼相关免疫因子及其生长的影响

研究了盐度(5、10、20、30及对照37)对军曹鱼(Rachycentron canadum)稚鱼生长及其血清溶菌酶、碱性磷酸酶(ALP)、旁路途径补体(ACP)溶血活性(ACH50)和总免疫球蛋白(T-Ig)含量等免疫因子的影响。实验周期为14 d。结果表明,在逐渐达到设定盐度后养殖14 d,盐度30组稚鱼特定生长率(SGR)最高(5.77%/d),而盐度5和10组的SGR(分别为4.24%/d和4.38%/d)显著低于其他组(P<0.05)。在低盐度环境中血清溶菌酶活性在第7天各组都有不同程度升高,其中以盐度20组升高最为显著,其次为盐度10和30组,但第14天各组溶菌酶活性又都回落至对照组水平;而稚鱼在低盐度环境中血清ALP活性受到明显抑制,且活性与盐度呈一定正相关;各组间ACP活性在第7天各盐度组间无明显差异,但实验结束时盐度5和10两组出现显著升高;而T-Ig含量在盐度10组中始终明显高于其他组。研究显示,军曹鱼稚鱼在盐度20~37范围内都可正常生长,尽管稚鱼有较强的低盐度耐受能力,但过低盐度明显影响其生长率并导致体色变黑、蛀鳍和应激增强等异常表现。此外,盐度变化还影响稚鱼多种免疫相关因子。[中国水产科学,2007,14(1):120-125]     

Dietary mannan oligosaccharide enhances salinity tolerance and gut development of larval cobia

The potential beneficial effects of supplementing live feeds with mannan oligosaccharide (MOS; BioMos®) upon cobia Rachycentron canadum larval performance were examined. Characteristics of fish examined included survival to weaning, growth, ability to withstand osmotic stress and the degree of development of the brush border of the intestine. Live feeds included rotifers (Brachionus plicatilis) and Artemia which were enriched for 24 h with a commercial enrichment media alone or in combination with 0.2% (dry weight basis) MOS. Salinity challenges were performed at 6 days post-hatch (dph) and at 7, 13, and 14 dph (0 and 65 g L^− 1 for 6 dph; 0 and 55^− 1 7+ dph) corresponding to transitions in feeding, to examine the ability of larval cobia to survive stress. Differences (P < 0.05) in survival, favoring cobia receiving MOS-supplemented feeds were discerned at 6 and 7 days post-hatch (dph) when fish were challenged at 0 g L^− 1 and at 13 dph when challenged with 55 g L^− 1 salinity water. Electron microscopy of the mid-intestine of developing larvae revealed that MOS-supplemented diets enhanced (P < 0.05) the height of microvilli while reducing (P < 0.05) the occurrence and size of supranuclear vacuoles. Supplementation of diets with MOS could assist cobia larvae in maintaining allostasis especially when reared at sub-optimal salinities.     

紫外线系统净化文蛤中大肠杆菌的研究

文蛤经人工方法使其体内积累埃希氏大肠杆菌达到5个对数值后,放入小型紫外线循环净化系统中,通过正交试验来研究各种环境因子对文蛤自身净化能力的影响。经36 h净化处理后,贝肉中埃希氏大肠杆菌减小约3个对数值。方差分析结果表明,影响文蛤净化效果的因子依次为水交换率、贝水比和温度;最佳的净化条件为:换水率3次/h、贝水比为1∶4、温度15℃。文蛤的净化生产证明,这些净化条件是合适的。     

不同类型林分青杨虎天牛发生状况研究

通过调查分析,得到青杨虎天牛在各种杨树及其它阔叶树种的纯林、混交林以及不同类型林分、、树干不同部位的发生状况,选择出相对抗青杨虎天牛及易受青杨虎天牛危害的杨树品种及其它阔叶树种,为利用生态方法控制青杨虎天牛的传播和蔓延提供了科学依据。     

网箱培育军曹鱼亲鱼及人工育苗研究

12月底从海上网箱挑选14尾1 5龄以上,健康、外表无伤的军曹鱼(Rachycentron cana dum),移至陆地盖有顶棚的大水泥池进行强化培育。经过4个月左右的培养,结果显示,亲鱼在陆地强化培育比在海区网箱提前约7 d成熟并自然产卵。受精卵在室内育苗池进行人工育苗,在海水比重为1. 020±0. 5,pH 8 1~8 4,水温在27. 0、29. 2 ℃时,仔鱼孵出时间分别为26、24 h,孵化率为88 .8%~93 .5%。孵出后的仔鱼在第7~9天为死亡高峰期,第11天左右的仔鱼体色有明显的变化,由棕红色变为黑色。经过1个月的培养,仔鱼的成活率约为9%。     

“红肉病”文蛤的组织病理学

利用组织学和组织化学方法,在光镜水平下研究了患“红肉病”文蛤(Meretrix meretrix Linnaeus)的组织病理学变化特征。结果显示,患病文蛤的病理学变化主要表现为组织结构紊乱,上皮膨大、脱落,鳃、外套膜、消化盲囊等组织发现异常结构及寄生物,如嗜碱性的包涵体、嗜酸性颗粒及寄生性原生动物等。另外,组织化学研究结果显示,病蛤在糖含量、磷酸酶活性等方面也有明显变化,表现为消化盲囊、肠等部位吸收细胞内糖含量增加。消化盲囊、消化管各处酸性磷酸酶(ACP)活性减弱,碱性磷酸酶活性(AKP)增强。鳃组织ACP活性增强,AKP活性减弱等。     

Partial replacement of fishmeal by soybean meal in diets for juvenile cobia (Rachycentron canadum)

An 8‐week feeding experiment was conducted in floating cages (1.5 × 1.0 × 2.0 m) to determine the potential use of defatted soybean meal (roasted and solvent‐extracted) as a partial replacement of fishmeal in the isonitrogenous (approximately 450 g kg^?1 CP [crude protein]) diet for juvenile cobia with an initial average weight of about 8.3 g. Diets were formulated to include 0, 100, 200, 300, 400, 500 and 600 g kg^?1 (diets D0, D10, D20, D30, D40, D50 and D60, respectively) of fishmeal protein being substituted by defatted soybean meal without methionine supplementation. The results showed that weight gain rate decreased significantly when the replacement level of fishmeal protein was increased from 400 g kg^?1 to 500 g kg^?1, and the D60 diet was the lowest in all groups. These results indicate that up to 400 g kg^?1 of fishmeal protein can be replaced by defatted soybean meal without causing significant reduction in growth. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by the replacement level of fishmeal protein being substituted by defatted soybean meal, when the replacement level of fishmeal protein was 200 g kg^?1 (diet, D20), FCR was the lowest and PER was the highest. There were no significant differences in the moisture, lipid, crude protein and ash content in whole body and muscle, while lipid content in liver increased as the dietary soybean meal replacement levels increased. There were significant differences in haemoglobin, haematocrit, red blood cell, plasma glucose and triglyceride concentration in fish fed diets with different soybean meal replacement levels. Results of this trial indicated that the optimum level of fishmeal protein replacement with defatted soybean meal, determined by quadratic regression analysis was 189.2 g kg^?1, on the basis of maximum weight gain.