影响库蚊幼虫摄食鱼腥藻的因素

在实验室条件下,致乏库蚊幼虫可大量摄食鱼腥藻,并能消化利用,完成生活史。鱼腥藻在蚊幼虫肠道中滞留时间约6h,酵母约5h,鱼腥藻比酵母稍难消化。对比幼虫孵化至化蛹周期,饲喂鱼腥藻为194h,而饲喂酵母则为142h,饲喂鱼腥藻比饲喂酵母延缓了蚊幼虫期52h。致乏库蚊幼虫摄食鱼腥藻的适宜条件为:pH7-8,温度25-30℃,藻液浓度愈高,摄食越多。随着蚊幼虫的生长,摄食量递增。     

苏云金芽胞杆菌杀蚊基因在鱼腥藻中克隆和表达的初步研究

将苏云金芽胞杆菌以色列亚种的杀蚊晶体蛋白基因cry11A亚克隆到大肠杆菌－蓝藻的穿梭质粒载体pRL25C,然后用三亲本杂交的方法将重组质粒转移到一种具有固氮能力且可被蚊幼虫吞食的鱼腥藻（Anabaena）PCC7120中。Southernblot及Westernblot分析表明cry11A基因在鱼腥藻PCC7120中得以克隆和表达,但生物测定未能检测到转基因鱼腥藻对库蚊（Culex）的毒性,可能是因为带有苏云金芽胞杆菌自身启动子的Cry11A基因在鱼腥藻PCC7120中表达量不够高的缘故。     

苏云金芽胞杆菌杀蚊基团在鱼腥藻中克隆和表达的初步研究

将苏云金胞杆菌以色列亚种的杀蚊晶体蛋白基因ｃｒｙ１１Ａ亚克隆到大肠杆菌－蓝藻的穿梭质粒载体ｐＥＲＬ２５Ｃ然后用三亲本杂交的方法将重组质粒转移到一种具有固氮能力且可被蚊幼虫蚕食的鱼腥藻（Ａｎａｂａｅｎａ）ＰＣＣ７１２０中,Ｓｏｕｔｈｅｒｎｂｌｏｔ及Ｗｅｓｔｅｒｎｂｌｏｔ分析表明ｃｒｙ１１Ａ基因在鱼腥藻ＰＣＣ７１２０中得以克隆和表达,但生物测定未能检测到转基因鱼腥藻对库蚊（Ｃｕｌｅｘ）的毒性,可能是因     

白鲢鱼种对螺旋鱼腥藻摄食量和利用率的研究

在通过示踪试验肯定了白鲢鱼种能消化利用螺旋鱼腥藻之后,我们继续用放射性磷做了白鲢鱼种对螺旋鱼腥藻摄食量和利用率的示踪试验,同时做了鱼体自射线显影。通过以上的研究工作,证实了螺旋鱼腥藻是白鲢鱼种易摄食和消化利用的良好食物,是白鲢鱼种快速生长的主要物质基础。       

白鲢鱼种对螺旋鱼腥藻摄食量和利用率的研究

在通过示踪试验肯定了白鲢鱼种能消化利用螺旋鱼腥藻之后,我们继续用放射性磷^32做了白鲢鱼种对螺旋鱼腥藻摄食量和利用率的示踪试验,同时做了鱼体自射线显影。通过以上的研究工作,证实了螺旋鱼腥藻是白鲢鱼种易摄食和消化利用的良好食物,是白鲢鱼种快速生长的主要物质基础。     

利用鱼腥藻作为饲料的研究

鱼腥藻粉作为肉鸡、全雌鲤、青虾和对虾的饲料研究结果表明:2％的鱼腥藻粉替代鱼粉作为肉鸡饲料试验,肉鸡的个体平均增重效果与对照相当,屠宰率、半净膛率和全净膛率都有所提高;同时还具有改善肉质色泽的效果。对重金属的含量分析发现,食鱼腥藻的鸡除锌的含量略高外,铜、铁、锰、镉及铝的含量都低于对照组。添加2％的鱼腥藻粉在网箱中进行小试和大面积试验,结果都表明鱼腥藻粉对全雌鲤的生长有明显的效果,并能提高全雌鲤鱼种的成活率和降低饵料系数,利用鱼腥藻粉配合饲料在网箱和大面积养殖青虾试验表明,具有促进生长,提高产量的作用.对虾试验结果表明,在饵料中添加2％的鱼腥藻粉,饲喂45d后,对虾的体长增加了14.49％;体重增加了10.43％。这些研究结果表明利用鱼腥藻作为家禽及水产养殖动物的饲料具有相当大的应用前景。     

几种因素诱导鱼腥藻7120短藻丝体的形成

丝状蓝藻鱼腥藻7120（Anabaena sp.PCC7120）中可成功表达外源基因,但其转化和表达效率不高,改变细胞的生理状态可能会影响外源基因的转化和表达效率。将鱼腥藻7120藻丝体通过几种因素诱导形成短藻丝体（具有25个左右细胞）,并对其光合活性进行了测定。结果表明：红光和高温对鱼腥藻7120短藻丝体较为有效,且红光诱导在48h时,短藻丝体细胞数占总细胞数的比例达到85％;DCMU单独诱导效果不明显,适当浓度的DCMU＋红光诱导时诱导效率略有增加;高温以45℃诱导12h比例最高,约达87％;高温45℃诱导时,对数生长后期的鱼腥藻7120较易形成短藻丝体。光合活性测定结果显示,诱导形成的短藻丝体光合放氧速率比正常营养藻丝体的低,这种具有光合放氧能力的短藻丝体显示出作为表达外源基因受体的可能性。     

不同光照度对3种藻生长的影响（简报）

不同光照度和相同的最适营养、温度(25±1)℃以及光周期(12h/12 d)培养铜绿微囊藻、多变鱼腥藻和斜生栅藻的实验结果表明,在15 000 lx和21 000～25 000 lx的光照度下,3种藻的比增长率和现存量最高.15 000 lx是铜绿微囊藻和多变鱼腥藻生长的最适光照度,21 000～25 000 lx是斜生栅藻生长的最适光照度范围.     

过滤螺旋鱼腥藻清液养鱼试验

螺旋鱼腥藻(Anabaena Spiroides)对鲢(Hypophthalmichthys molitrx)、鳙(Aristichthys nnobilis)鱼种的促长作用,经多年试验,业已证实,目前正在生产实践中推广应用。螺旋鱼腥藻营养丰富,易被滤食性鱼类摄食,消化利用良好,这是该藻能促进鲢、鳙等鱼种生长的重要因素。     

转基因鱼腥藻中hTNF-α基因表达与光合作用间的相关性研究

分析了培养光强对转基因鱼腥藻生长和hTNF-α基因表达的影响,以及转基因鱼腥藻IB02的光合放氧活性、光系统Ⅰ及光系统Ⅱ活性。发现光强对转基因鱼腥藻IB02的生长和hTNF-α基因表达都有促进;hTNF-α基因在鱼腥藻中的表达率与真正光合、光系统Ⅰ和光系统Ⅱ活性存在一定的联系。hTNF-α基因表达同时对宿主的光合放氧特性也产生了显著的影响,与正对照相比转基因藻光呼吸速率增强68%,饱和点降低66%,说明转基因鱼腥藻的代谢负荷增加,并在低光强下生长比野生型快。     

Laboratory evaluation of six algal species for larval nutritional suitability of the pestiferous midge Glyptotendipes paripes (Diptera: Chironomidae)

Glyptotendipes paripes Edwards midge larval growth, development, survival, emerging adult size, and food digestibility when provided with six species of algae as food were studied in the laboratory. For the study, eggs from G. paripes adults maintained in the laboratory were reared to the adult stage at 30 degrees C for 60 d on pure culture of each algal species at densities of 0.4, 0.1, and 0.02 mg of algae (fresh weight) per milliliter, as a sole food source. All larvae reared on Microcystis sp., Botryoccocus braunii, and Scenedesmus quadricauda died before completing development. The only larvae to complete development to adult were those reared on 0.4 mg/ml Lyngbia cf. aeruginosa (44.0 d), Anabaena flos-aquae (29.7 d), and Chlorella keslerii (44.8 d). No significant differences in body size of the adults achieving complete development on the three algal species were found. Algal digestion, measured by comparing amounts of live and dead algal cells in remains of cultures used for feeding and in larval excrement, revealed that >95% of all L. cf. aeruginosa, A. flos-aquae, and Microcystis sp. cells were digested; for C. keslerii, 13% of cells were digested, whereas little or no digestion of B. braunii and S. quadricauda was observed. To evaluate the effects of algal species on larval growth, laboratory-reared (on artificial food) late third/early fourth instars of G. paripes were fed individual algal species, and 10 d later, body mass changes were recorded and compared with nonfed larvae. Body mass of larvae reared on L. cf. aeruginosa and A. flos-aquae significantly increased, whereas those provided Microcystis sp. and the nonfed larvae showed significant body mass reductions. Overall, B. braunii and S. quadricauda were not suitable as larval food, probably due to their low digestibility, and Microcystis sp. because of its toxicity. This study identifies some algae that do and others that do not support G. paripes larval growth. The information is useful in understanding the feeding habits of G. paripes larvae as some of these algae occur in the larval environments of this pestiferous midge.     

幼虫食物对甜菜夜蛾生长发育、繁殖及飞行的影响

报道了人工饲料、圆白菜和玉米苗三种食物对甜菜夜蛾Spodoptera exigua发育历期、蛹重以及成虫产卵和飞行能力的影响。幼虫取食人工饲料时发育历期最短,蛹最重(138 mg),产卵量最高(643粒);在12 h的吊飞测试中,成虫飞行距离最远(25.5 km),飞行时间最长(6.2 h),飞行超过10 km的个体占67.9%,超过5 h的占60.7%。幼虫取食玉米苗时发育历期最长,蛹最轻(52 mg),产卵量最低(416粒),成虫仅能飞行3.3 km,1.7 h,飞行超过10 km或5 h的个体均仅占4.2%,各项指标均显著低于人工饲料组。幼虫取食圆白菜时各项指标与人工饲料组基本相似(幼虫历期和蛹重除外),而显著优于玉米苗组(幼虫历期除外)。这些结果表明,幼虫食物对甜菜夜蛾的生长发育、产卵及飞行能力均有显著的影响,因而是影响其个体发育、种群增长及种群动态的重要因素之一。同时,由于取食本人工饲料的各项指标均优于其它两种食料植物,因而可作为饲养甜菜夜蛾的实用饲料。     

Protists and detrital particles as prey for the first larval stage of the brachyuran crab, Hemigrapsus oregonensis

Newly-hatched larvae of the brachyuran crab, Hemigrapsus oregonensis, were raised in the laboratory on an autotrophic dinoflagellate (Prorocentrum micans), a heterotrophic dinoflagellate (Noctiluca milaris), a green alga (Dunaliella tertiolecta), an unfed control, and a fed control of Artemia sp. nauplii. Larvae also were fed preparations of seagrass detritus that had been cultured both to promote microbial colonization and to discourage it. Detrital diets were used both alone and in combination with sub-optimal applications of Artemia sp. nauplii. Larvae raised on P. micans showed survival to zoeal stage II equal to those raised on the Artemia sp. nauplii control, although development was delayed. Larvae raised on N. milaris showed substantial (34.7%) survival to zoeal stage II; however survival was lower and development slower than for Artemia sp. nauplii-fed larvae. Survival on D. tertiolecta was less than 3%. Larvae fed microbially-enriched detritus showed a delay in mortality as compared to unfed controls. No larvae fed solely on detritus survived to zoeal stage II. When larvae were fed a sub-optimal diet of Artemia nauplii, supplemented by detrital particles, survival to zoeal stage II increased, although not to the level shown by Artemia-fed larvae in optimal application. Development was not accelerated over the sub-optimal diet in either treatment. The potential for larval crabs to utilize a wide variety of potential prey immediately upon hatching is significant given their susceptibility to early starvation. Such omnivory also suggests a trophic link between carbon sources of the microbial loop and crab larvae.     

Allometric growth and functional development of the gut in developing cod Gadus morhua L. larvae

The development of the gut epithelium in cod Gadus morhua was studied during the larval period in intensive rearing systems. Cod larvae were fed enriched rotifers from mouth opening. On 17 days post‐hatch (dph) one group of larvae were fed Artemia sp. nauplii while another group were fed both rotifers and a formulated diet (co‐fed). At the end of the experiment (30 dph) larvae receiving live feed were almost three times larger than the co‐fed larvae, although no clear signs of pathological effects due to feeding regime were found in any larvae sampled for morphological studies. The midgut volume in larvae fed live feed increased by a factor of 38 during the experiment, and in particular volume increased rapidly between 24 and 30 dph. The enterocyte size increased between 12 and 24 dph from 652 ± 64 to 1479 ± 144 μm³ (mean ±s .e .). When enterocytes reached their maximum size, several morphological changes in the gut epithelium were initiated, such as increased number of mitochondria per enterocyte, increased size of the nuclei and a considerable increase in microvilli surface area. The mitochondrial membrane structures changed during the experiment, suggesting a maturation process of the mitochondria. The midgut development was strongly related to larval size rather than age. On 30 dph co‐fed larvae were equal in size to Artemia sp. fed larvae on 24 dph. This was reflected by equal values of estimated midgut volume, midgut length and total number of enterocytes and the number of mitochondria per enterocyte. The microvilli surface area, however, was significantly larger in co‐fed larvae on 24 dph compared to live‐feed larvae on 30 dph. This increase in absorptive surface was probably a response to suboptimal feeding conditions. The strong correlation between gut development and larval size and the lack of clear pathological effects, suggested that the gut tissue is flexible and can withstand periods of suboptimal nutrition at this stage.     

METHODS FOR THE STUDY OF BLOWFLY POPULATIONS

1. A simple method of radioactive labelling of L. sericata larvae is described.
2. More uniform count levels are obtained in individuals which have fed entirely on radioactive foods than in those which first feed on non-active food.
3. The radioactive count rates of the larvae are correlated with larval live weight and the counting rates of resulting imagines correlated both with corresponding larval counting rates and with imaginal live weight.
4. The loss of ³²P in the larvae due to causes other than decay of the isotope is traced from the prepupal stage to 3 weeks after emergence. The first and major loss occurs at emergence, when about 10% of the original ³¹P is shed as empty puparium and meconium. Adults lose about 1.5% per day.
5. The distribution of ³²P in the adult body of L. sericata labelled in the larval stage has been determined. The abdominal tissues have a lower activity than the rest of the body.     

The impact of food type, temperature and starvation on larval development of Balanus amphitrite Darwin (Cirripedia: Thoracica)

The impact of diatom food species (Chaetoceros calcitrans and Skeletonema costatum), temperature and starvation on the larval development of Balanus amphitrite was evaluated. Starvation threshold levels for different ages of larvae (0- to 5-day-old) fed with C. calcitrans and S. costatum and then starved at 5, 15 and 25 °C temperature were estimated as ultimate recovery hour (URH; denoting the starvation point in hours at the end of which larvae can recover and continue development). Effect of temperature on starvation threshold varied significantly with larval age and food species. The URH declined with larval age at 5 °C, but not at 15 and 25 °C. The URH and grazing rates were high for early instars fed on C. calcitrans, and for advanced instars fed on S. costatum. Carbon gain through feeding was maximum for 2-day-old larvae when fed with C. calcitrans and decreased with larval age. However, when fed with S. costatum carbon gain increased with larval age. This confirms that with development the utility of food types changes. The differences in the carbon gain can be attributed to differences in grazing rate due to variations in the size of the diatom cells, larval intersetular distance, diatom sinking rate and the photo-taxic behavior of larvae. Molting was observed at times when larvae were undergoing starvation and this could be viewed as stress-induced molting, and it differed with the larval age and food organisms.     

豆野螟的生物学特性及其防治

豆野螟Maruea testulalisGeyer(1832)是我国豆类蔬菜,特别是长豇豆Vigna sesguipedalis的主要害虫。在杭州,一年发生七代,以预蛹越冬。以1—3代为害为主。一龄幼虫头宽0.197毫米,Dyar常数为1.653。随虫龄增加,取食场所从花器转向豆荚。产卵前期为3—4天,羽化后6—8天卵量最集中。幼虫、蛹发育历期与日平均温度间的对数回归方程为Y₁=3.5825—1.7766x,Y_p=3.8118-2.0800x。卵期2—4天。田间为害以6—8月为主;灯下威虫有7月和9—10月两个高峰。有分距姬蜂Cremastus sp.和稻苞虫寄蝇Pseudoperiehaeta insidiosa二种天敌。应用80%敌敌畏800倍等农药,在百花虫数达40头上下、二龄幼虫约占50%时,兼喷植株、落地花,能达到降低花、荚被害率,提高鲜荚产量、品质和降低成本的效果。     

Origins of carbon sustaining the growth of whitefish Coregonus lavaretus early larval stages in Lake Annecy: insights from fatty-acid biomarkers

The hypothesis that diatom carbon (C) produced during the spring peak supported spring zooplankton production and, ultimately, the growth of Coregonus lavaretus early larval stages from March to May 2006 in Lake Annecy, France, was tested using gut content analyses and fatty acid biomarkers. Gut content results showed that C. lavaretus larvae from stages 1 to 4 preferentially fed on copepods with Daphnia sp. only a minor proportion of larval diet. The levels of diatom-marker fatty acids (C16:1n-7 and C20:5n-3) were high in Daphnia sp., but lower in both copepods and C. lavaretus larvae from stages 0 to 4. These results indicated that the spring diatom biomass was actually grazed by Daphnia sp., but, contrary to what was expected, the spring bloom was not the only C source supporting copepods secondary production and, consequently, the growth of C. lavaretus early larval stages. In contrast, levels of terrestrial fatty acid marker (C24:0) were low in Daphnia sp. but high in copepods and C. lavaretus larvae, indicating a significant contribution of terrestrial carbon to copepods and, ultimately, to the growth of C. lavaretus early larval stages.     

棉花单宁-黄酮类化合物对棉铃虫的抗性潜力

陆地棉棉叶甲醇提取物包含了棉花的大部分单宁-黄酮类化合物。这些化合物对棉花多种病虫害具有抗性作用。将这些化合物定量加入人工饲料中饲养棉铃虫龄幼虫5d,结果表明,培儿茶素、缩合单宁、芸香苷和异槲皮苷在饲料中的浓度增加均与幼虫体重生长呈显著负相关,ED50分别为0．81％,0．49％,0．57％和0．83％;儿茶素则不存在这种关系;用含0．8％的浓度桔儿茶素、缩合单宁,芸香苷和异槲皮苷的饲料测试棉铃虫,发现随取食量的增加,相对生长率的增加显著低于对照(不含次牛物质),即这些物质属于慢毒剂,而儿茶素仅有阻食作用。