Larviculture of the painted river prawn Macrobrachium carcinus in different culture systems     

《Aquacultural Engineering》2021

The objective of this study was to evaluate different hatchery systems used for the larviculture of the Macrobrachium carcinus based on survival, larval development and production of post-larvae. The experimental culture was carried out in three phases designated as Phase I (Zoea VI to VIII – Z_{VI – VIII}), Phase II (Zoea VIII to X – Z_{VIII – X}), and Phase III (Zoea X to PL – Z_{X – PL}), with densities of 30, 27.5 and 25 larvae / L, respectively. The M. carcinus larvae (Z_VI) were reared in four culture systems, two being open (Greenwater – GW and Clearwater – CW) and two being closed (Biofloc – BFT and Bio-filter – RAS), distributed in twelve 10 L plastic containers, filled with 20 ppt brackish water, equipped with constant aeration, and water circulated by air lift and heated with thermostat (∼30 °C). The GW treatment was maintained with Chlorophyceae algae in the density of 3–5 × 10⁵ cells/mL. In the CW, the water was previously filtered through a 5 μm mesh screen, sterilized with 10 ppm active chlorine and, dechlorinated with vitamin C and subjected to aeration for 24 h. The BFT received water rich in bioflocs that was matured prior to the experiment and used molasses as a source of organic carbon. In the RAS, the culture water circulated through an external “Dry-Wet” biological filter. The feeding was carried out ad libitum four times daily, alternating a wet diet formula with a commercial diet, which was supplemented with newly hatched Artemia nauplii at a rate of 40–50 per larvae/day. Temperature, dissolved oxygen and pH were monitored daily and the salinity two times per week. Total ammonia, nitrite, nitrate, orthophosphate, alkalinity, total suspended solids, chlorophyll-a, COD and BOD were also analyzed. The best water quality (P < 0.05) was obtained in the RAS, with 0.49 (±0.38), 0.23 (±0.22), and 9.0 (±1.5) mg/L of TAN, NO₂-N and NO₃-N, respectively. In the GW, the nitrogen species showed high fluctuations and higher concentrations at 2.32 (±1.68), 3.53 (±3.53) and 18.2 (±12.9) mg / L of TAN, NO₂-N and NO₃-N, respectively. Considering the three phases (Z_{VI – PL}), the overall survival was 0.03, 1.97, 2.23 and 17.32 % for the BFT, CW, GW and RAS, respectively. When considering the phases separately, the survival in Phase I (Z_{VI – VIII}) was highest in the GW system at 58.7 % while the RAS was the highest in Phases II (Z_{VIII – X}) and III (Z_{X – PL}) at 70.6 % and 60.3 %, respectively. The BFT showed 8.4 (±3.5) PL/L, which was higher (P < 0.05) than that obtained in the RAS (2.8 ± 1.2 PL/L) and the GW (1.3 ± 1.1 PL/L) and similar to that obtained in the CW (5.6 ± 2.0 PL/L). Thus, the larviculture for the M. carcinus may be optimized by adopting a multiphase management strategy, which the intermediate larval stages (Z_{VI – IX}) are reared in the GW system and the final stages (Z_{X – PL}) are reared in the BFT system.  相似文献   

灌丛草地放牧山羊的牧草适口性与嗜食性及山羊采食率研究   总被引：8，自引：1，他引：7  

杨泽新  蔡维湘 《草业科学》1995,12(2):17-21,24

通过对放牧山羊的牧草适口性，嗜食性和采食率及其相互关系的分析，表明山羊放牧对灌丛草地的植物适口性、嗜食性比率和采食率均以灌木嫩枝叶，中禾草和苔草属植物较优。季节性规律为：春季山羊喜哺食灌木嫩枝叶，灌木嗜食性比率较高，采食率也较高，夏季山羊喜草本植物，草本植物的嗜食性比率高于灌木，秋季山羊较喜啃食灌木枝叶，嗜食性比率灌木高于草本植物，采食率低于春季，灌木采食率高于草本植物。  相似文献   

二化螟在茭白上的钻蛀行为及其防治方法   总被引：2，自引：1，他引：2  

俞晓平  郑许松  徐红星  陈建明  张珏锋 《植物保护学报》2004,31(1):26-32

研究了二化螟在茭白植株上的转移、钻蛀和产卵行为以及取食选择性,并根据其行为特性,制订合理的药剂喷施方法.结果表明,二化螟90%以上的卵产在茭白的叶片上,其余部分产在叶鞘上.产卵的主要叶位是心叶、倒一叶和倒二叶.超过50%的卵块集中在叶片距叶枕0～60cm的部位.幼虫孵化后,蚁螟蛀入的部位一般在叶枕以下的叶鞘内侧,多集中于倒四、倒五叶鞘.2龄后开始钻蛀内侧叶鞘,并蛀入茭白茎的内芯,二化螟幼虫在茭白植株上通常从叶片转移到叶鞘进行钻蛀危害.幼虫嗜食茭白茎部,其次为茭白果肉和叶鞘,对叶片几乎不取食.使用叶鞘喷施杀虫可达到对茭白进行全株喷雾同样的防治效果,并可节省40%～50%的用药量,经济和生态效益十分明显.  相似文献   

芽孢杆菌绿色荧光蛋白标记及其在小麦体表定殖的初探   总被引：17，自引：0，他引：17  

田涛  亓雪晨  王琦  梅汝鸿 《植物病理学报》2004,34(4):346-351

 将来自质粒pAD4412的启动子和绿色荧光蛋白基因gfpmut3a插入大肠杆菌-枯草芽孢杆菌穿梭载体pBE2,构建成芽孢杆菌表达载体pGF P4412,用其转化野生型生防芽孢杆菌83-6和A-47等8个菌株,均得到良好的发光表型。质粒稳定性实验表明重组质粒pG FP4412稳定性为92%。借助荧光显微镜对gfp标记的菌株A-47-gfp在小麦体表的定殖进行初步的研究。结果表明:A-47-gfp能够在小麦根际及小麦体表定殖(包括根表和茎叶表面);相对于在茎叶表面定殖的A-47-gf p在根表定殖的菌体与根的结合更为牢固;从根基到根尖A-47-gfp的定殖量有明显的减少趋势。  相似文献   

Endophytic-Host Selectivity of Discula umbrinella on Quercus alba and Quercus rubra Characterized by Infection, Pathogenicity and Mycelial Compatibility     

Susan D. Cohen 《European journal of plant pathology / European Foundation for Plant Pathology》2004,110(7):713-721

The fungal endophytic–host relationships of Discula umbrinella and two oak species, Quercus alba and Quercus rubra, were characterized on the basis of endophytic infection, pathogenicity, and mycelial compatibility. Isolates of D. umbrinella were cultured from leaves of Q. alba and Q. rubra collected from a hardwood forest located in Patuxent Wildlife Research Center in Laurel, Maryland, USA. Endophytic infection was observed on sterile leaf discs and living 2-month-old seedlings of Q. alba and Q. rubra. Fungal-host reciprocal inoculations revealed the presence of conidiomata on both hosts but conidiomata production was more abundant on Q. alba. Isolates from Q. rubra produced milder disease symptoms on both oak species. Mycelial compatibility studies identified seven different MCG groups. MCG groups 1–3 contained isolates from both oak species whereas MCG groups 4–7 contained host specific isolates. Field studies monitored the seasonal appearance of the sexual fruiting structures, perithecia, as a possible source of new genetic variation that might alter host specificity/pathogenicity of the D. umbrinella isolates on Q. alba and Q. rubra hosts. Only 1–2% of the leaves contained perithecia throughout the sampling period (April–September). Isolates collected from Q. alba differed from those collected from Q. rubra in endophytic infection, pathogenic response, and perithecia production. The results of this study suggest that the endophyte–host relationship is one of host selective preference for Q. alba, but that the endophyte has the ability to maintain the endophytic/pathogenic life cycle on the less preferred host species, Q. rubra.  相似文献   

Comparative bioactivity of selected seed extracts from Brazilian Annona species and an acetogenin-based commercial bioinsecticide against Trichoplusia ni and Myzus persicae     

《Crop Protection》2014

The acute and chronic toxicity of ethanolic seed extracts from selected Brazilian Annona species (Annona montana Macfadyen, Annona mucosa Jacquin, Annona muricata Linnaeus, and Annona sylvatica A. St.-Hil) and an acetogenin-based commercial bioinsecticide (Anosom^®) were investigated against the cabbage looper Trichoplusia ni Hübner (Lepidoptera: Noctuidae) and the green peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae). In the laboratory, extracts of A. mucosa and A. sylvatica as well as Anosom^® were especially active through oral and topical administration. A greenhouse trial showed that a formulated A. mucosa extract and Anosom^® were highly effective (>98% mortality) against third instar T. ni larvae, and comparable to a pyrethrin-based commercial insecticide (Insect Spray^®) used as a positive control. Similar to results with T. ni, A. mucosa extract showed the greatest aphicidal activity followed by A. sylvatica extract and Anosom^®. In another greenhouse trial, aphid population reduction from the formulated A. mucosa extract was superior to that provided by other treatments including the positive control. Though inferior to the A. mucosa extract, the acetogenin-based commercial insecticide (Anosom^®) and A. sylvatica extract also reduced aphid populations in a manner comparable to the positive control. Botanical insecticides based on these Annonaceae derivatives could be useful in the framework of Brassica IPM in Brazil and elsewhere, especially for organic production.  相似文献   

Evaluation of European corn borer Ostrinia nubilalis (Lepidoptera: Crambidae) larval movement and survival in structured and seed blend refuge plantings     

《Crop Protection》2016

Blending Bacillus thuringiensis (Bt) corn and non-Bt corn seeds in the same bag is a convenient and easier compliance solution to satisfy refuge regulations. However, there has been considerable debate and concern about larval movement of the target insects in a seed blend because of its potential effect on the development of resistance. Reported here are studies to determine the larval movement of European corn borers, Ostrinia nubilalis (Hübner), in a seed blend compared to a structured refuge and their effects on survival, feeding injury and larval fitness. Also evaluated is the relative performance of a purple-seeded corn hybrid as a surrogate host plant for tracking gene flow. Seed blend and structured refuge arrangements of Agrisure GT/CB/LL Bt corn expressing Cry1Ab and isoline plants were evaluated at two locations in 2013 and 2014 by manually infesting refuge plants with first and second generation corn borer larvae. The majority of leaf and stalk injury was recorded on the refuge plant, which amounted to 66–83% of the total tunnel length. In both refuge arrangements, plant injury and the number of larvae recovered significantly decreased on neighboring plants with increasing distance away from the refuge plant in the same row. The relative decline in injury was much more pronounced in the seed blend, with neighbor Bt plants experiencing very minor tunneling or no injury at all due to the high dose trait. Eighty-nine percent fewer live larvae were also found on neighbor Bt plants in the seed blend compared to those found in the structured refuge plots. Larvae that moved to Bt plants as well as older instars that were manually placed on Bt plants failed to complete development. Comparison of the number of tunnels and larvae recovered per refuge plant indicated that the seed blend may not produce as many susceptible individuals as those produced in a structured refuge arrangement. Although the purple-seeded hybrid showed lower levels of ear and stalk injury, it could serve as an appropriate surrogate refuge plant to track gene flow.  相似文献   

Sward characteristics,nutritive value and choice by cattle of conterminous monocultures of centipedegrass (Eremochloa ophiuroides) and bahiagrass (Paspalum notatum)          下载免费PDF全文

Masahiko Hirata  Toshiro Okuma  Yuichiro Tanaka  Manabu Tobisa 《Animal Science Journal》2016,87(5):674-680

In south‐western Japan, centipedegrass (Eremochloa ophiuroides; CG) offers a novel option for a warm‐season perennial for grazing use in areas where bahiagrass (Paspalum notatum; BG) can be grown. However, the potential of CG as a forage has not been fully explored because of the short history as a forage crop. We conducted four experiments to evaluate CG (cv. TifBlair) in comparison with BG (cv. Pensacola) in terms of sward characteristics, nutritive value and choice by animals. In each experiment, four Japanese Black cows (Bos taurus) were individually allowed to graze conterminous monocultures of CG and BG (5 × 10 m each) for 30 min. Irrespective of regrowth durations and fertilizer rates, CG was consistently shorter, leafier and denser, contained lower acid detergent fiber and cellulose, and was preferred or equally selected by cows, as compared with BG. Furthermore, CG maintained sufficient levels of crude protein (80–89 g/kg DM) to ensure voluntary intake of ruminant animals under extended regrowth^? and without fertilizer, whereas BG failed to do so (65 g/kg DM). CG provided higher digestible dry matter than BG when crude protein concentration exceeded 86 g/kg DM. The results indicate advantages of CG as a forage.  相似文献   

Horse Preference,Forage Yield,and Species Persistence of 12 Perennial Cool-Season Grass Mixtures Under Horse Grazing     

《Journal of Equine Veterinary Science》2016

Cool-season grass mixtures are rarely evaluated for preference, yield, and persistence under horse grazing. The objectives of this research were to evaluate horse preference, forage yield, and persistence of cool-season grass mixtures under horse grazing. Eight commercially marketed and four experimental perennial cool-season grass mixtures were planted in 2009 in a randomized complete block with five replicates and grazed by four adult horses during 2010, 2011, and 2012. All mixtures contained four to six cool-season perennial grass species. Specie density measurements were taken in each spring and fall, and yield was mechanically measured before each grazing period. After grazing, preference was determined by visually assessing percentage of forage removal on a scale of 0 (no grazing) to 100 (100% of vegetation removed). Data were analyzed using a mixed-model analysis of variance and liner regression. Horses preferred mixtures containing tall fescue, perennial ryegrass, Kentucky bluegrass, and timothy (P < .001). Horses had less preference for mixtures containing ≥30% orchardgrass (P < .001). Mixtures had similar (P = .11) forage yields that ranged from 6,100 to 7,082 kg ha⁻¹. After 2 years of grazing, orchardgrass and tall fescue increased; Kentucky bluegrass remained stable; and festulolium, meadow fescue, and perennial ryegrass had the greatest rate of decline in mixtures. Orchardgrass became the dominate species, regardless of initial percentage in the mixture. Mixtures containing tall fescue, perennial ryegrass, Kentucky bluegrass, and timothy should be planted in midwestern US horse pastures; however, mixtures will likely transition to tall fescue and Kentucky bluegrass–dominated pastures.  相似文献   

草栖钝绥螨对二斑叶螨的捕食作用     

侯飞  邹梦婷  倪召红  乙天慈  郭建军  金道超 《植物保护学报》2023,50(2):530-537

为明确草栖钝绥螨Amblyseius herbicolus对二斑叶螨Tetranychus urticae的控制潜能,在温度分别为19、22、25、28和31℃、相对湿度均为（85±5）%、光周期均为16 L∶8 D条件下测定草栖钝绥螨对二斑叶螨各螨态的捕食偏好性、捕食功能反应及自身干扰反应。结果表明,草栖钝绥螨对二斑叶螨幼螨和第1若螨具有嗜食性,对其捕食选择系数分别为2.22和1.27,均大于1.00,对二斑叶螨卵、第2若螨和雌成螨捕食选择系数分别为0.61、0.68和0.22,均小于1.00。在不同温度条件下,草栖钝绥螨对二斑叶螨各螨态的捕食功能反应均符合HollingⅡ型;在19～31℃范围内,草栖钝绥螨对二斑叶螨各螨态的瞬时攻击率、最大日捕食量和捕食能力均随着温度升高呈先升高后降低的趋势,在28℃时达到最大值;而草栖钝绥螨对二斑叶螨各螨态的处理时间随着温度升高呈先缩短后延迟的趋势,在28℃下处理时间最短。在相同温度下,草栖钝绥螨对二斑叶螨卵、幼螨和第1若螨的捕食作用较强。在有限的捕食空间和二斑叶螨密度固定的条件下,草栖钝绥螨单头捕食量和捕食作用率随其自身密度的增加而逐渐下降,说...  相似文献