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。

Classical biological control of exotic weeds

Biological invasion has become a serious ecological and economic concern in the international community as well as in China. Invasive exotic plants have caused vast damage to the biodiversity and the economy in China. Classical biological control of weed aims to suppress and achieve long term regulation of weed populations by introducing host-specific natural enemies from the native range of the weed. It is a self-sustainable and self-regulating management approach widely used in the world, while being systematically explored in China since the 1980's. This paper reviews the current status, main challenges and prospect of classical biological control of weeds in the world, highlighting some important and successful cases, and discusses the priorities, recent development and successes, and main challenges in China. More than 70 countries have developed weed biological control programs. The U.S.A., Australia, South Africa, Canada and New Zealand have actively been using more agent species against target weeds than the other countries. There have been at least 63 families 369 species of invertebrates and fungi utilized against 133 species of target weeds belonging mainly to the plant families of Astereae, Cactaceae and Mimosaceae. One case reviewed in the paper has demonstrated to be successful for more than 100 years in biological control of weed history. And more successful cases are recognized as examples in controlling exotic weeds by classical biological control, such as Opuntia inermis & O. stricta, Hypericum perforatum, Alternanthera philoxeroides, Salvinia molesta, Hydrilla verticilla, Chondrilla juncea etc.. Biological control of Eichhornia crassipes remains the most difficult and important program in the world.Classical biological control of weeds began to be systematically studied and practiced since the mid 1980's in China, although there had been attempts and even community campaigns of using fungus as bioherbicides in the 1960's. So far, 14 species of biocontrol agents have been introduced to control 4 species of target weeds, viz. Eupatorium adenophorum, Alternanthera philoxeroides, Ambrosia spp. and Eichhornia crassipes. The introduction of Agasicles hygrophila from USDA to control Alternanthera philoxeroides has been by far the most successful in China. Through collaboration with USA and Canada by the Chinese Academy of Agricultural Sciences, 23 species of insects and fungi were found in China and exported to North America for the control of Euphorbia esula, Tamarix spp., Cirsium arvense, Myriophyllum spicatum,Hydrilla verticillata,Trapa natans, Polygonum perfoliatum. Introducing Agasicles hygrophila to control Alternanthera philoxeroides is by far the most successful case in China. Classical biological control as a promising approach for the long-term control of invasive exotic weeds is faced with many challenges in China, such as the development of the science, research in host specificity testing, biosafety issues, funding for the long-term programs, just to name a few. With its rich and unique biodiversity, China needs to develop and implement a sound management system to conserve and protect the biodiversity. Classical biological control against invasive exotic weeds will, if given a priority and support, play a promising and important role in the protection and utilization of the biodiversity.