外来入侵杂草传统生物防治的生态风险及其防范对策

长期大量实践说明,引进天敌防治外来入侵杂草的传统生物防治方法是治理外来入侵杂草的一条切实可行的有效途径,但对其潜在的生态风险——对本土生物的直接或间接不良影响不容忽视。利用传统评价方法预测候选天敌的生态风险存在缺陷,主要表现在：（1）寄主专一性测定过分依赖室内进行的生理寄主范围测定结果,对生态寄主范围（实际寄主范围）问题重视不够,后者指在新环境中的一系列物理和生物条件下的寄主利用预测;（2）在生理寄主范围测定中,过分依赖完成生长发育的可能性,对行为、遗传性状以及系统发育关系重视不够;（3）在风险评估中,过多强调对经济作物的风险,而对自然生态系统的风险重视不够。对此,建议：（1）鼓励对已释放的天敌进行回顾性跟踪研究,从而为杂草生物防治实践提供生态学理论支撑;（2）在运用生物防治手段对付外来入侵杂草实践中,建议采用“有害推论”的预防性原则,以避免在面临入侵生物重大威胁时草率做出释放天敌的决策;（3）在评估候选天敌风险中重视生态效应的风险评估。     

外来入侵杂草的生物防治及生防因子对本地非目标种的影响

随着生物入侵所引起的生态及经济问题日益严重,对有害入侵生物的防治问题也备受人们关注。生物防治因具有持续、高效、安全等优点,已成为防治有害入侵生物的重要方法。传统生防是防治有害入侵杂草的一种重要方法。在简单介绍生物防治的基础上,重点阐述了传统生物防治的理论基础——天敌逃逸假说,生防因子对外来人侵种的影响及其对本地非目标种的直接和间接效应,并针对这些问题,对我国开展生物防治工作提出几点建议。     

杂草间的他感作用及其在杂草生防中的应用

动、植物所产生的有机化合物,除了营养自身之外,还在很多方面影响着其它植物和动物的生长、健康、行为及种群生物学特征。很多人都熟悉由微生物如放线菌、细菌、真菌所产生的抗生素,它们影响着其他微生物的生长     

红薯对农田杂草群落及其多样性的影响

为了解红薯(Ipomoea batas)对农田杂草群落和生物多样性的影响, 作者研究了云南省东南部红河州建水县5种不同覆盖度红薯田的杂草种类、密度、重要值及多样性。结果表明, 5种红薯田共统计到25种杂草, 隶属18科。其中4种入侵植物藿香蓟(Ageratum conyzoides)、鬼针草(Bidens pilosa)、牛膝菊(Galinsoga parviflora)、牛筋草(Eleusine indica)和2种本地植物马齿苋(Portulaca oleracea)、马唐(Digitaria sanguinalis)的密度较高, 为红薯田杂草群落的优势物种。随红薯覆盖度增加, 杂草优势物种的密度和重要值显著降低(P<0.05), 然而2种本地物种打碗花(Calystegia hederacea)和早熟禾(Poa annua)密度却显著增加, 2种本地物种铁苋菜(Acalypha australis)和稗(Echinochloa crusgalli)重要值与红薯覆盖度成正相关(P<0.05)。红薯覆盖度为1-25%和26-50%时, 杂草群落的物种丰富度(23.5、24.5)、Simpson指数(0.89、0.85)、Shannon-Wiener指数(2.36、2.35)和Pielou均匀度指数(0.75、0.73)较高, 说明中低水平的红薯覆盖度有利于提高群落的物种多样性。可以推断, 红薯种植改变了农田杂草的群落结构, 有利于限制优势杂草和入侵杂草的发生危害, 中低水平的红薯覆盖度可作为一种有效的旱田替代化学除草剂的生态控草措施。     

贝莱斯芽孢杆菌生防次级代谢产物研究进展

贝莱斯芽孢杆菌（Bacillus velezensis）是生防芽孢杆菌中的重要代表,作为微生物农药的核心菌种,已被广泛应用于作物病害生物防治。贝莱斯芽孢杆菌具有植物内生性,其生防作用机制主要包括产生次级代谢产物对抗植物病原物;改善宿主植物根际微生物群落,促进宿主营养和生长;激发宿主植物产生防御反应,诱导植物获得系统抗性。其中,产生次级代谢产物是其最重要的生防作用机制。贝莱斯芽孢杆菌含有多个编码生物合成次级代谢产物的基因簇,其中包括编码聚酮化合物合酶（PKS）和非核糖体肽合成酶（NRPS）的基因簇,同时存在核糖体途径合成次级代谢产物基因簇。通过非核糖体途径可产生脂肽类化合物、聚酮类化合物、二肽和铁载体;通过核糖体途径产生小菌素、细菌素、羊毛硫抗生素。这些具有生物活性的次级代谢产物成为了天然新药和候选抗生素的储存库,对于解析生防菌作用机制具有重要意义。本文综述了贝莱斯芽孢杆菌的命名与更迭,产生次级代谢产物的类型、合成与调控基因以及靶标病原菌,以期为生防菌株的改良和生物农药的研发提供参考。     

不同除草剂的田间杂草防效及对糜子生长发育的影响

筛选糜子适宜除草剂来防范农田药害,是糜子高效安全生产和改善生态环境亟待解决的关键问题。本研究以粳性糜子品种‘榆糜2号'为材料,探究22种除草剂对糜子田间杂草的防除效果及对糜子生长发育的影响。结果表明: 1)喷施土壤封闭型除草剂谷友、丁草胺、莠去津、苄嘧·丙草胺和茎叶型除草剂苯唑·二甲钠、阔世玛、藤净、陶氏·优先、阔菲后,基本无药害作用,糜子幼苗生长正常,其余除草剂均对糜子有不同程度的药害影响;2)参试的22种除草剂在糜子田中对杂草均表现出一定的防除效果,总体而言,土壤封闭型除草剂的杂草防效相对优于茎叶型除草剂,但所有参试除草剂对糜子株高、功能叶片叶绿素含量、单株穗重均造成不同程度的影响;3)与人工除草相比,参试除草剂均导致糜子产量有不同程度的下降;但与不除草对照相比,部分除草剂有明显的增产增效作用。土壤封闭型除草剂中,谷友、丁草胺、莠去津、苄嘧·丙草胺的杂草防效较好,较不除草对照增产60%以上;茎叶型除草剂中,阔世玛、苯唑·二甲钠的杂草防效较好,较不除草对照增产50%以上。因此,在糜子出苗前可用38%莠去津或44%单嘧磺隆进行土壤封闭处理,或在出苗后喷施茎叶型除草剂3.6%二磺·甲碘隆或55%苯唑·二甲钠,农田杂草防效较好,且对糜子生长发育的负面影响较小。     

苹果树腐烂病生防真菌Z-12A的鉴定及其生防效果

[背景]由苹果黑腐皮壳菌(Valsamali)引起的苹果树腐烂病是我国苹果产区的毁灭性病害之一,具有分布广、危害重和防治难等特点,严重制约着苹果产业的发展,急需寻找一种对该病高效、安全的防治措施.[目的]明确一株分离自甘肃省静宁县苹果树根际土壤的生防菌株Z-12A的分类地位,评价其对苹果树腐烂病的生防潜力.[方法]结合...     

入侵杂草一年蓬的化感作用研究

用入侵杂草一年蓬(Erigeron annuus)地上部分的水浸提液对几种经济作物种子进行萌发培养实验,分别测定种子的最终萌发率、根长以及苗高来研究一年蓬是否存在他感作用。结果表明:(1)一年蓬的化感作用是存在的;(2)一年蓬水浸提液在高浓度下对作物种子萌发、根长和苗高均有明显的抑制作用,而在低浓度下则对长梗白菜、番茄的苗高具有促进生长的作用。     

生防解淀粉芽胞杆菌的研究进展

解淀粉芽胞杆菌(Bacillus amyloliquefaciens)因能抑制植物病害和促进植物生长而被广泛研究。随着测序技术的不断发展,解淀粉芽胞杆菌菌株的全基因组序列陆续被测定,综述了其拮抗作用相关的功能基因、生防机制及植物-病原物-生防菌的相互作用,并对后续研究趋势进行了展望,为解淀粉芽胞杆菌的深入研究及其更好的应用提供理论参考     

Methods Used to Assess Non-target Effects of Invertebrate Biological Control Agents of Arthropod Pests

The number of concerns regarding potential non-target effects of invertebrate biological control agents of arthropods has risen over the last decade and an increasing number of studies have since dealt with this topic. Despite some recent international initiatives aimed at providing guidance for risk assessment of biological control agents, detailed methods on how tests should be designed and conducted to assess for potential non-target effects still need to be provided. It is believed that this review comes at an ideal time, giving an overview of methods currently applied in the study of non-target effects in biological control of arthropod pests. It provides the first step towards the ultimate goal of devising guidelines for the appropriate methods that should be universally applied for the assessment and minimisation of potential non-target effects. The main topics that are reviewed here include host specificity (including field surveys, selection of non-target test species and testing protocols), post-release studies, competition, overwintering and dispersal. Finally, a number of conclusions that have emerged from this comprehensive compilation of studies are drawn, addressing potential non-target effects in arthropod biological control.     

Is host‐specificity of weed biological control agents likely to evolve rapidly following establishment?

Over 352 herbivore species have now been intentionally introduced into new regions as weed biological control agents. Recent evidence shows that rapid and significant evolution in host-specificity can occur. The risk of non-target use by biological control agents increasing to unacceptable levels through rapid evolution therefore needs to be considered. In addition, weed biological control offers many as yet largely unexploited opportunities for improving our basic understanding of host-specificity and its evolution. We therefore evaluate the evidence that rapid evolution (1) alters the use of existing hosts, and (2) alters the fundamental host-range. Most cited examples of so-called host shifts from weed biological control were not the result of genetic change. There was only limited evidence of genetically altered performance on a non-target host and no evidence of altered fundamental host-range. We conclude, from both theory and the available data, that only altered use of existing hosts (through quantitative genetic changes) needs be considered when evaluating the risk of rapid evolution. Host-specificity testing methodologies can be improved and adapted to better assess the risk of occurrence of post-release evolution.     

生物入侵对鸟类的生态影响

生物入侵是全球生物多样性面临的最主要威胁之一, 入侵种在改变入侵地环境的同时也使当地的生物受到极大影响。鸟类在生态系统中处于较高的营养级, 生态系统中任何一个环节的变化都可能对鸟类造成一定的影响。本文回顾了哺乳动物、鸟类、无脊椎动物和植物等不同生物类群的入侵对本地鸟类生态影响方面的研究进展。外来生物对鸟类的影响主要表现在以下几方面: (1)外来哺乳动物对成鸟、幼鸟或鸟卵的捕食作用; (2)外来鸟类与本地鸟类竞争栖息地和食物资源, 与当地的近缘种杂交而造成基因流失; (3)外来无脊椎动物改变本地鸟类的栖息环境和食物状况, 甚至直接捕食本地鸟类; (4)外来植物入侵改变入侵地的植物群落组成和结构, 造成本地鸟类的栖息地丧失或破碎化, 并通过改变入侵地生态系统的食物链结构而对高营养级的鸟类产生影响。最后, 作者还提出了该领域有待解决的问题和今后可能的研究方向。     

利用传统生物防治控制外来杂草的入侵

随着国际贸易的日益频繁,外来有害植物入侵,严重威胁我国的自然环境和生物多样性。利用从原产地引入食性较专一的天敌来控制外来杂草是杂草生物防治的主要方式之一,有保护环境一劳永逸的效果。简要介绍了国际生物防治概况,统计表明全世界至少有133种目标杂草进行生物防治,主要分布在菊科、仙人掌科和含羞草科,63科369种无脊椎动物和真菌作为杂草生物防治的天敌,利用最多的天敌是鞘翅目象甲科和叶甲科昆虫,其中大多数项目是治理外来杂草的。杂草生物防治最活跃的国家依次为美国、澳大利亚、南非、加拿大和新西兰。重点论述了利用传统生物防治方法防治外来杂草的经典项目、国内外研究概况,以及目前面临的问题和应用前景。我国杂草生物防治起步晚,传统杂草生防的目标杂草有4种,紫茎泽兰、空心莲子草、豚草和水葫芦,其中,空心莲子草的生物防治获得成功。共引进天敌14种,输出天敌23种,与世界上生物防治先进的国家比尚有距离。中国应充分借鉴国际成功经验,对外来杂草开展生物防治。中国的生物多样性在世界上占有十分独特的地位,将在生物多样性保护中发挥重要作用。     

Ecological studies to assess the efficacy of biological control on populations of alligator weed and lippia

Abstract  The risk of non-target effects from biological control agents can be reduced if we can better identify effective agents prior to release. Introducing only those agents with high potential for effective control will reduce the number of agents released and reduce the probability of both direct and indirect non-target impacts. Identifying effective agents requires understanding the roles that resources, disturbances and herbivory play in regulating plant populations under natural field conditions. Here we propose a series of experiments that will contrast the mechanisms of population regulation of two invasive wetland plants, alligator weed ( Alternanthera philoxeroides ) and lippia ( Phyla canescens ), with native congener species, Alternanthera denticulata and Phyla nodiflora . We hypothesise that the native plants will have greater growth rates when nutrients are low and herbivores are present, whereas the introduced plants will exhibit greater growth rates when nutrients are high and herbivores are absent.     

Success and safety in the biological control of environmental weeds in New Zealand

Biological control, using specialist insect herbivores and plant pathogens, can be a self‐sustaining, cost‐effective and low‐risk tool for the management of environmental weeds. Agents have been recorded attacking non‐target plants in New Zealand and elsewhere, but the effects are usually minor and/or transitory. It seems probable that only two cases, worldwide, will result in significant damage to non‐target plants (representing 0.5% of the nearly 400 insect, mite, or fungal species used in classical weed biocontrol). Both of these cases were predictable from host range testing. Negative indirect, or ‘downstream’, ecological effects from specific weed biocontrol agents are difficult to predict and measure. They are probably insignificant compared to the impacts of the invasive plants that the agents are introduced to control. However, it is necessary to balance the risks associated with any introduction against the environmental benefits from controlling a weed to a predicted level. Recent analyses suggest that success rates are better than generally perceived. For New Zealand programmes, where enough time has lapsed to allow assessment, we calculate a full/partial success rate of 83%. Many of the costs associated with environmental weeds are difficult to quantify. Detailed risk assessment will make biological control programmes more expensive and time‐consuming, so that reliance on non‐biological management methods for environmental weeds may actually increase. The costs of biocontrol programmes against some New Zealand weeds can be kept down by using research already carried out in Australia and other countries, and the process is reciprocal. Developing international consortia of sponsors is also a potential way to fund programmes against weeds shared by several countries.     

Non-target host risk assessment of the idiobiont parasitoid Bracon celer (Hymenoptera: Braconidae) for biological control of olive fruit fly in California

Non-target risk posed by an African parasitoid, Bracon celer Szépligeti (Hymenoptera: Braconidae), was assessed for a classical biological control program against olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae: Dacinae), in California, USA. Behavioral and reproductive responses to non-target tephritid species were tested with beneficial (Chaetorellia succinea [Costa] and Parafreutreta regalis Munro) (Tephritidae: Tephritinae) and native (Rhagoletis fausta [Osten Sacken]) (Tephritidae: Trypetinae) fruit fly species in successive no-choice and choice experiments under close confinement in quarantine. Non-target host-plant substrates exposed to B. celer were yellow-starthistle flower heads containing C. succinea, Cape ivy stem galls containing P. regalis, and bitter-cherry fruit containing R. fausta. The parasitoid probed all three infested non-target plant substrates, but significantly less than olives infested with B. oleae. It produced offspring from P. regalis in Cape ivy stem galls, but appeared unable to penetrate yellow-starthistle flower heads with its ovipositor. Bracon celer killed some B. oleae and R. fausta larvae without parasitism. Reproduction on P. regalis indicates that B. celer has a broad physiological host range, which, combined with the parasitoid's acceptance of all three host-plant substrates, indicates a strong potential to negatively impact non-target species. Although physical and temporal barriers to host attack may reduce risk to most non-target tephritids by B. celer in California, the parasitoid should not be released due to its risk of harming the beneficial P. regalis. Release of P. regalis is still under consideration, however, and final risk assessment should depend on whether the fly proves useful for weed control.