Integrating fish and azolla into rice-duck farming in Asia

Several countries in Asia practice integrated rice-duck farming. On-farm resources such as duck manure and feed waste are not adequately used and recycled in the system. This indicates the potential for research to increase the productivity of the rice-duck system. The integration of fish and the nitrogen-fixing aquatic fern azolla show promise for increasing the production potential of the system. Fish, azolla and ducks integrated with rice farming can result in nutrient enhancement, pest control, feed supplementation and biological control. Some of the results of a case study on integrated rice-fish-azolla-duck farming systems conducted in the Philippines are presented in this paper.

The introduction of exotic fish in Sri Lanka with special reference to tilapia

Introductions of exotic finfish between 1948 and 1953 are reported in this paper, with a brief reference to earlier and later introductions. Exotic fish were introduced principally to develop the potential for aquaculture in fresh and brackish waters in order to increase the availability of fish for rural communities through the biological control of aquatic vegetation. The algal feeding tilapia (Sarotherodon mossambicus) has created a new food industry in inland and brackishwaters. It has supplemented marine fishery production in a community where animal protein intake consists mainly of fish. It is also being cultured in flooded rice fields and used in the control of malaria. This excellent table fish has not had any adverse environmental impact.

Seroprevalence of Triatoma virus (Dicistroviridae: Cripaviridae) antibodies in Chagas disease patients

Background: Chagas disease is caused by Trypanosoma cruzi, and humans acquire the parasite by exposure to contaminated feces from hematophagous insect vectors known as triatomines. Triatoma virus (TrV) is the sole viral pathogen of triatomines, and is transmitted among insects through the fecal-oral route and, as it happens with T. cruzi, the infected insects release the virus when defecating during or after blood uptake. Methods: In this work, we analysed the occurrence of anti-TrV antibodies in human sera from Chagas disease endemic and non-endemic countries, and developed a mathematical model to estimate the transmission probability of TrV from insects to man, which ranged between 0.00053 and 0.0015. Results: Our results confirm that people with Chagas disease living in Bolivia, Argentina and Mexico have been exposed to TrV, and that TrV is unable to replicate in human hosts. Conclusions: We presented the first experimental evidence of antibodies against TrV structural proteins in human sera.

The potential for crop rotation in controlling diseases in shrimp culture

The use of antibiotics and other chemicals in controlling shrimp pathogens become ineffective as the strains grow more resistant to these chemicals. Moreover, the bacterial pathogen (Vibrio harveyi) produced biofilm coating that protects it from dying and disinfection procedures that are followed during pond preparation. Biological control is being considered as an alternative means of preventing shrimp disease outbreak. The main principle behind biological control is to enhance the growth of beneficial microorganisms which serve as antagonists or target pathogens. The paper discusses shrimp and tilapia crop rotation as a form of effective biological control, a technique which is already being practiced in Indonesia and the Philippines.

果实采后病害生物防治及其机理研究

　　分离和筛选了5种能有效防治采后果实病害的拮抗菌。其中，季也蒙假丝酵母(Candida guiliermondii(Cast) Langeroret Guerra)从引种拮抗菌中筛选获得，枯草芽孢杆菌（Bacillus subtilis）B-912从土壤中分离筛选获得，膜醭毕赤酵母（Pichia membranefaciens hansen）从桃果实伤口上分离获得，隐球酵母(Cryptococcus albidus (Saito) Skinner)和丝孢酵母（Trichosporon sp.）从桃果实表面分离获得。本文主要研究了这些拮抗菌对桃、油桃、苹果、梨和柑桔等我国主要水果采后病害的防治效果，并对其可能的抑菌机理进行了初步研究。结果如下： 1. Sx108 CFU/mL的C．guiliermondii和P．membranefaciens悬浮液可完全抑制病菌孢子浓度为5x104个/mL时桃和油桃果实软腐病(Rhizopus stolonifer(Ehrenb.ex Fr.) Vuill.)在25℃，15℃和3℃下的发生。lx108 CFU/mL的C．albidus和Trichosporon sp.悬浮液可完全抑制孢子浓度分别为lx105个/mL和5x104个/mL时苹果灰霉病(Botrytis cinerea)和青霉病（Penicillum expansum）在23℃-25℃和1℃下的发生。C．albidus和Trichosporon sp.对梨灰、青霉病也有一定抑制效果。B-912对柑桔果实青霉病(Penicillium italicum)、绿霉病(Penicillium digitatum)和核果类果实褐腐病(Monilinia fructicola)也有极好的抑制效果。生物防治效果与拮抗菌的浓度成正比，与病菌孢子浓度成反比。 2．拮抗酵母菌在室温和冷藏条件下都能迅速在果实伤口定殖，接种酵母菌48 h后，数量可增加20倍以上。拮抗菌和病菌孢子的接种时间与生物防治效果有关，先接种拈抗菌的抑菌效果显著地好于同时或后于病菌接种的效果。 3．温度对拮抗酵母菌的抑菌活力没有明显影响，无论是在室温还是在冷藏条件下，拮抗酵母菌都有同样的抑菌效果。但拮抗细菌B-912的抑菌效果与温度有一定关系。较高的温度有利于细菌拮抗作用的发挥。 4．拮抗菌能与常规的果实采后处理措施如钙处理、化学杀菌剂、冷藏和气调贮藏相结合。酵母菌与2% CaC12配合能明显地增强其抑菌能力;拮抗菌与低浓度的杀菌剂如扑海因混合使用，可达到高浓度杀菌剂的抑病效果;C．albidus和Trichosporon sp.对果实采后气调贮藏环境有良好的适应性，它们在气调下对采后苹果、梨的灰霉病和青霉病的抑制效果比冷藏条件下的好。 5．细菌B-912的抑菌机理与其产生抗菌素有关，B-912的滤液在in vitro上能有效地抑制病菌孢子的萌发，在invivo上也能明显地抑制果实采后病害的发生。拮抗酵母菌的抑菌机理则较复杂，但主要与病菌竞争营养有关，同时，C．guilliermondii和P．membranefaciens对软腐菌的抑制还通过产生水解酶如β-1，3一葡聚糖酶和几丁酶与病原菌直接作用，并参与诱导寄主产生抗性等

提高生物拮抗菌对果实采后病害的生防效力研究

摘要 　　"随着人们对身体健康和环境污染的日益重视，化学农药作为控制果实采后病害的主要方法受到了很大限制，科学研究者不得不寻求更加安全有效的防治果实采后病害的新方法。生物防治以其对环境和人类健康不造成危害的优点而逐渐受到人们的青睐。然而，由于生物防治是以活菌为基础，有其局限性和时效性，单独使用拮抗菌很难达到化学药剂完全控制果实采后病害的效果，因此，提高拮抗菌的生防效力成为当今生物防治领域的研究重点。本文主要研究了拮抗菌与不同外源物质配合使用的抑病效果及协同抑病机理;拮抗菌对采前田间和采后贮藏环境条件的适应能力;以及采前应用拮抗菌对果实采后贮藏期间病害的生物防治效力。研究结果表明： 　　1、酵母拮抗菌Cryptococcus laurentii与低浓度化学杀菌剂imazalil（25g/ml）和kresoxim-methyl（50g/ml）配合使用可以显著提高对冬枣果实采后黑霉病（Alternaria alternata）和褐腐病（Monilinia fructicola）的防治效果，杀菌剂并不影响拮抗菌在冬枣果实伤口的生长动态。 　　2、酵母拮抗菌Pichia membranefaciens和C. laurentii 与钼酸铵（NH4-Mo，5 mmol/L）和碳酸氢钠（NaHCO3，2%）配合能够显著提高对甜樱桃果实采后褐腐病（M. fructicola）的抑病能力。通过in vitro和扫描电镜观察结果表明，NH4-Mo和NaHCO3能够显著地抑制病原菌M. fructicola在培养基和果实伤口的生长，具有杀菌作用。 　　3、酵母拮抗菌C. laurentii和Rhodotorula glutinis与硅酸钠（Na2SiO3）配合使用对甜樱桃果实采后青霉病（Penicillium expansum）和褐腐病（M. fructicola）以及对冬枣果实青霉病（P. expansum）和黑霉病（A. alternata）的防治效果更好。经in vitro和扫描电镜观察表明，Na2SiO3对病原菌在培养基和果实伤口的生长有明显的抑制作用。同时，Na2SiO3还能诱导果实苯丙氨酸解氨酶（PAL）、多酚氧化酶（PPO）和过氧化物酶（POD）等抗性相关酶活性的提高。 　　4、酵母拮抗菌R. glutinis与水杨酸（SA，0.5mmol/L）配合可显著提高对甜樱桃果实采后青霉病（P. expansum）和黑霉病（A. alternata）的抑病能力。SA不影响拮抗菌在果实伤口的生长，in vitro实验中低浓度的SA对病原菌孢子萌发和芽管伸长也没有抑制作用。SA可能是通过诱导果实产生抗性来协同提高拮抗菌的抑病效果，而不是直接抑制病原菌生长。 　　5、酵母拮抗菌C. laurentii和R. glutinis在气调（Controlled atmospheres, CA）贮藏条件下对樱桃果实采后青霉病（P. expansum）和黑霉病（A. alternata）的防治效果显著提高。气调贮藏不抑制拮抗菌在甜樱桃果实伤口的生长。 　　6、采前应用酵母拮抗菌C. laurentii 和R. glutinis能够显著抑制甜樱桃果实在采后不同贮藏环境下的发病率。拮抗菌能够在田间果实表面生长并一直保持较高的数量。在试验的三种酵母拮抗菌中，C. laurentii的防病效果最好，该菌不仅能在果实表面迅速生长，也能适应低温和CA贮藏环境。"

酵母拮抗菌的抑病机理及生防效力改良的研究

相对于酵母拮抗菌的使用来说，人们对其作用机理了解得还不是很清楚。而了解拮抗菌的抑菌机理却是增强拮抗菌的生防效果以及进行拮抗菌筛选标准的重要前提。本文主要研究了酵母拮抗菌Pichia membranefaciens、Cryptococcus albidus以及Crytococcus laurentii对水果采后软腐病、褐腐病以及青霉病的防治效果，拮抗菌与病原菌之间的相互作用，并对酵母拮抗菌与外源物质配合使用，以及通过遗传改良途径来提高酵母拮抗菌生防能力等进行了初步研究。实验结果如下： 1、酵母拮抗菌P. membranefaciens、C. albidus以及C. laurentii能在果实伤口大量繁殖。采用扫描电镜技术，观察发现在桃果实伤口处P. membranefaciens能紧密地吸附在软腐病菌Rhizopous stolonfier的菌丝体上;C. laurentii与青霉病菌Penicillium expansum在苹果果实伤口处也存在着直接的拮抗作用;但P. membranefaciens和C. albidus对P. expansum的直接作用不明显。 2、酵母拮抗菌P. membranefaciens能够有效地抑制甜樱桃果实在常温和低温贮藏条件下褐腐病的发生。在常温贮藏条件下，P. membranefaciens和褐腐病菌Monilinia fracticola 处理都能够提高果实β-1,3-葡聚糖酶、POD、以及PAL酶的活性，但在低温贮藏条件下，拮抗菌和病原菌处理对甜樱桃果实β-1,3-葡聚糖酶、POD酶活性的升高有促进作用，对PAL和PPO酶活性的诱导作用不明显。 3、梨果实采后经过水杨酸，CaCl2，UV辐射和草酸等各种激发子处理以后，再接种病原菌Alternaria alternata，可以显著降低梨果实的发病率。其中，水杨酸处理的果实发病率最低。不同的激发子均可以诱导梨果实β-1,3-葡聚糖酶、POD、PAL和PPO酶活性的升高，但对果实乙烯含量的影响不明显。 4、氨基糖甙类抗菌素G418能够抑制P. membranefaciens的生长，其最低抑制浓度为100g ml-1。将G418抗性基因Neor插入到酵母-大肠杆菌穿梭表达载体pFL61中，构建PGK启动子驱动的表达载体pFL61-neo，利用醋酸锂转化法转化P. membranefaciens。酵母转化子在非选择性培养条件下连续生长50代后，仍有67.87%的细胞保留该质粒。这表明穿梭表达载体pFL61-neo能稳定地存在于P. membranefaciens中，并且该酵母细胞能有效地识别PGK启动子和终止子指导Neor的表达。 5、酵母拮抗菌C. laurentii和Rhodotorula glutinis与2%的碳酸氢钠混合使用，对冬枣果实青霉病的防治效果明显比单独使用拮抗菌或化学物质的防病效果好。其中，107CFU ml-1的拮抗菌与238 mmol l-1的碳酸氢钠配合使用可以达到单独使用108CFU ml-1拮抗菌的防病效果。另外，钼酸铵作为一种添加剂也能提高R. glutinis对梨果实青霉病和黑霉病的防治效果，但将钼酸铵与Trichosporon sp.配合使用的防病效果不明显。碳酸氢钠和钼酸铵在果实伤口对酵母拮抗菌的生长都有一定的抑制作用。 6、酵母拮抗菌P. membranefaciens在不同碳源、氮源中生长情况表明：在几种氮源中，大豆蛋白胨、酵母提取物、牛肉浸膏对P. membranefaciens的生长有显著的促进作用，其中，大豆蛋白胨的效果最好。在检测以葡萄糖、果糖和麦芽糖作为碳源的生长实验中，发现这几种碳源都能够被拮抗菌很好的利用，其中葡萄糖的利用率最好。小球藻生长因子（CGF）能够明显地促进了P. membranefaciens的生长。但是，CGF的浓度从0.5%增加到1%并没有促进酵母菌细胞数量的增加。

Feeding stimulatory effects of Cyperus rotundus tuber on Cirrhinus mrigala

Traditionally tubers of cyperus (Cyperus rotundus) and its extracts have been used for alluring fish during harvesting in India. An experiment was conducted to evaluate its feeding stimulatory activity and effect on the growth of a commercially important freshwater fish, Cirrhinus mrigala. Three isonitrogenous and isocaloric formulated diets viz. plant ingredient based control and control supplemented with cyperus tuber (CS) at 1% and 5% levels were fed to the fingerlings of mrigal, C. mrigala (2.68+0.20 g) for a period of 45 days. The growth performance and the activity of metabolic enzymes, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), in liver, gill and muscle tissues of mrigal were studied during every 15 days interval. Highest relative growth (72.28%) was obtained in the mrigal fed with the diet containing 5% cyperus (5% CS), while the relative growths were 66.18% and 43.40% for the fish fed with the 1% CS diet and control respectively. The activities of AST and ALT were significantly higher (p<0.01) in both 1% and 5% CS diets as compared to the control in all the tissues studied. Higher aminotransferase activities were observed in the tissues of 5% CS group than in those of 1% CS group throughout the experimental period. The observed higher enzymatic activity was concomitant with the higher growth rate in fish. The results suggested that cyperus tuber supplementation increased feed palatability and growth.

Observations on the biology of Nothobranchius guentheri (Pfeffer) (Cyprinodontidae), an annual fish from the coastal region of East Africa

Nothobranchius guntheri is found in seasonal pools and streams in the coastal region of Tanzania. A population recurring annually in a pond near Kilosa has been studied. Growth in length was rapid and maximum mean lengths were attained within 11-12 and 7-8 weeks of hatching by males and females respectively. Males grew larger and exhibited wider variation in length than females. N. guentheri shows clear sexual dichromatism. No significant inequality in the sex ratio was found. Females with ripe eggs were found 7-8 weeks after hatching. Spawning continued throughout adult life and fecundity increased markedly with increasing length. In laboratory aquaria, aggressiveness between adult males was noted and females were actively driven on to the substratum preparatory to spawning. The diet of the fish pond consisted chiefly of aquatic and terrestrial insects, of which midge larvae and pupae were the most common. N. guentheri is exploited by man in the aquarist trade and for the biological control of mosquitoes. An extended redescription of the species is appended which includes N. melanospilus (Pfeffer) as a synonym.

Lysis of Aphanizomenon flos-aquae (Cyanobacterium) by a bacterium Bacillus cereus

A phytoplankton-lytic (PL) bacterium, Bacillus cereus, capable of lysing the bloom-forming cyanobacterium. Aphanizomenon flos-aquae was isolated from Lake Dianchi of Yunnan province, China. This bacterium showed lytic activities against a wide range of cyanobacteria/algae, including A. flos-aquae, Microcystis viridis, Microcystis wesenbergi, Microcystis aeruginosa, Chlorella ellipsoidea, Oscillatoria tenuis, Nostoc punctiforme, Anabaena flos-aquae, Spirulina maxima, and Selenastrum capricornutum. Chlorophyll a contents, phycocyanin contents, and photosynthetic activities of the A. flos-aquae decreased evidently in an infected culture for a period. Bacterium B. cereus attacked rapidly A. flos-aquae cells by cell-to-cell contact mechanism. It was shown that the lysis of A. flos-aquae began with the breach of the cyanobacterial cell wall, and the cyanobacterial cell appeared abnormal in the presence of the PL bacterium. Moreover, transmission electron microscope examinations revealed that a close contact between the bacterium and the cyanobacterium was necessary for lysis. Some slime extrusions produced from B. cereus assisted the bacterial cells to be in close association with and lyse the cyanobacterial cells. These findings suggested that this bacterium could play an important role in controlling the Aphanizomenon blooms in freshwaters. (c) 2006 Elsevier Inc. All rights reserved.

The status and causes of alien species invasion in China

Data of classification, origin, pathway and environmental impacts of invasive alien micro-organisms, invertebrates, amphibians and reptiles, fish, birds, mammals, weeds, trees, and marine organisms in terrestrial, aquatic and marine ecosystems of China, were analyzed, based on literature retrieval, field survey and consultation. Some 283 invasive alien species were recorded in China, including 19 invasive alien micro-organisms, 18 aquatic plants, 170 terrestrial plants, 25 aquatic invertebrates, 33 terrestrial invertebrates, 3 amphibians and reptiles, 10 fish, and 5 mammals. Of the invasive alien species, 55.1% originated from North and South America, 21.7% from Europe, 9.9% from Asia, 8.1% from Africa and 0.6% from Oceania. Many institutions and individuals in China lack adequate knowledge of ecological and environmental consequences caused by invasive alien species, with some ignorance of the dangerous invasion in the introduction of alien species. For instance, 50.0% of invasive alien plants were intentionally introduced as pasture, feedingstuff, ornamental plants, textile plants, medicinal plants, vegetables, or lawn plants, 25% of alien invasive animals were intentionally introduced for cultivation, ornament, or biological control, In addition, more efforts are being made in the introduction of alien species, and little attention is paid on the management of introduced alien species, which may cause their escape into natural environment and potential threats to the environment. There were also gaps in quarantine system in China. All microorganisms were unintentionally introduced, through timber, seedling, flowerpot, or soil; 76.3% of alien invasive animals invaded through commodity or transportation facility because of the failure of quarantine. Therefore, quarantine measures should be strictly implemented; and meanwhile the intentional introduction of alien species should be strictly managed and a system of risk assessment should be implemented.

Controle biológico da podridão de raízes causada por Pythium spp. em cultivos hidropônicos.

2009