Invasive Alien Plants (Eds C.A

Policy Frameworks for the Implementation of a Classical 11 Biological Control Strategy: the Chinese Experience Jianqing Ding* School of Life Sciences, Henan University, Kaifeng, China Introduction successfully in the areas to which that plant has been introduced, owing to the ability of China is one of the mega-diverse countries the natural enemy to disperse to find its of the world, with over 30,000 species of host plant food resource. This is in sharp higher plants, 6347 species of vertebrates contrast to the use of manual, mechanical and 3862 species of fish (Chen, 1994; Xu and chemical control measures, which et al., 2000). In recent years, the conserva- typically require repeated treatment and tion of China’s biodiversity and protection provide control only at or near the site of of its environment have been critical domes- application. Although an entire research tic and international concerns (Liu and project from the screening of natural ene- Diamond, 2005), and in this context inva- mies to successful control may be relatively sive species have been recognized as posing expensive, a weed control programme based an increasing threat to China’s economy and on biological control can be inexpensive in ecosystems, largely due to escalating inter- the long term. For example, the Interna- national activities and commerce (Normile, tional Institute of Tropical Agriculture 2004). (IITA) has estimated that the biological con- Many approaches have been employed trol of water hyacinth (Eichhornia crassipes) to control invasive species and prevent fur- following the introduction, mass rearing ther pest introductions in the campaign and release of two Neotropical Neochetina against biological invasions in China and the weevils in Benin was likely to yield a wider world. Classical biological control benefit:cost ratio of 124:1 over the 20 years through the screening, introduction and following the releases (De Groote et al., release of host-specific natural enemies of 2003). Similarly, a benefit:cost ratio of 112:1 an invasive plant from its native region has has been demonstrated for the successful been regarded as one of the more promising biological control of skeleton weed (Chon- control approaches worldwide for more than drilla juncea) in Australia (Marsden et al., 100 years (Winston et al., 2014). Biological 1980). control may provide self-sustaining, broad- The exchange of natural enemies, that scale control of an invasive plant when one is, the international import or export of of its natural enemies, such as an insect potential insect/pathogen agents, is key to or fungal agent, establishes a population the implementation of a classical biological * E-mail: [email protected] CAB International 2017. Invasive Alien Plants (eds C.A. Ellison, K.V. Sankaran and S.T. Murphy) 191 192 Jianqing Ding control programme for an invasive plant. Invasive Plants in China: Current Therefore, cooperation is required between Status, Impacts and Constraints the recipient country – where the invasive to Providing Solutions plant is a problem, and the donor country – where the plant is native. An appropriate The first survey of invasive plants in China policy framework is essential to provide law- was reported by Ding and Wang (1999) in a ful guidance and regulation for the exchange Chinese government document on China’s of natural enemies between countries. biodiversity. This survey, which was largely Unfortunately, most developing countries based on published Chinese literature, lack such a policy framework, leading to reported 58 invasive plant species in the often insurmountable problems in the agriculture and forestry systems in the import and export of insects/pathogens. country. In recent years, great advances in This may have the following consequences: research on exotic plant species have been (i) the restriction of all international imports made as invasive species have become a of natural enemies because of the unfounded growing concern in China. Qiang and Chao fear that they may become pests themselves, (2000) reported that there were 108 inva- or vice versa (by allowing the import of any sive weeds, in 76 genera and 23 families. A exotic natural enemy); and (ii) forbidding general survey of the exotic plant species in all exports of natural enemies to other China conducted by the Institute of Botany countries, allegedly to protect the source and the Institute of Zoology of the Chinese country’s biological resources, or vice versa Academy of Sciences showed there were (by allowing any insect/pathogen to be about 300 exotic plants (Xie et al., 2000). exported). Hence, a country may either face The most important invasive plants in more novel threats from invasive species if China include water hyacinth, alligator weed there is no policy framework to regulate and (Alternanthera philoxeroides), Crofton weed manage the import and release of potential (Ageratina adenophora), common and giant biological control agents in place, or its ragweed (Ambrosia artemisiifolia and A. tri- biological control programmes may be fida) and mikania (Mikania micrantha); the jeopardized if all foreign introductions are latter species is also called mile-a-minute prohibited. weed, but as there are two plants found in In Asia, China is one of several develop- China that are commonly given the name of ing countries that have implemented active ‘mile-a-minute’ – the exotic invasive mikania classical biological control programmes and and the native Persicaria perfoliata (which is achieved successes in their campaign against invasive elsewhere) – the name of mile-a- invasive species. Although classical biologi- minute is not used subsequently in this cal control is still in its early stages in China, chapter to avoid confusion. Other impor- and many aspects including the policy tant invasive plants in China are tall golden- framework need to be greatly improved, the rod (Solidago altissima) and the common and experience that has been gained may be of smooth cordgrasses (Spartina anglica and value to other Asian countries. Certainly, S. alterniflora) (see Box 11.1). China shares with them many similar social, Invasive plants have been a critical issue political and scientific issues, in particular in in China for more than 30 years because of the management of invasive species. The their negative impact on the environment purposes of this chapter are: (i) to review the and economy but, until recently, the Chinese current status and impact of, and the con- government and public were unaware of the straints to providing solutions for invasive challenges that they present. There are no plants in China; (ii) to report China’s experi- specific national acts or laws to define or ences in classical biological control; and (iii) regulate the introduction of invasive spe- to review and assess the current policy cies, with the result that many exotic species framework in terms of its role in the imple- are imported into China every year, some of mentation of a classical biological control which may prove to be potentially invasive. strategy. Research on developing the appropriate Policy Frameworks for a Classical Biological Control Strategy in China 193 Box 11.1. A roll call of invasive plants in China. Invasive plants pose a great threat to China’s ecosystems, cause economic losses in agriculture, fishery, forestry and other industries and, in some instances, have even become a problem for human health. The water hyacinth (Eichhornia crassipes) has invaded 17 provinces in southern and central China, and has covered water surfaces in river courses, lakes and ponds. It alters ecosystem services and decreases soluble oxygen, leading to a decline in native aquatic biodiversity. It has aided the spread of human diseases, and has had economic impacts by impeding water flows, hindering navi- gation, and damaging irrigation and hydroelectricity facilities (Ding et al., 1995; Lu et al., 2007). Mikania (Mikania micrantha), a more recent invasive climbing plant from South America, com- petes aggressively with native plants in the Neilingding National Reserve in Guangdong Province, southern China, and this has resulted in large areas of forests being killed, land degradation and habitat loss for protected animals such as rhesus macaques (Macaca mulatta) (Zhang et al., 2004). At its peak, the plant covered some 40–60% of shrub and woodland in Neilingding (Feng et al., 2002). • In south-western China, Crofton weed (Ageratina adenophora) has driven many native plant species, such as Persicaria perfoliata, to local extinction (Ding Jianqing, Chinese Academy of Sciences, unpublished data). • Pollen from ragweed (Ambrosia artemisiifolia) causes hay fever in susceptible people in many invaded areas in China, as they are allergic to its pollen (Li et al., 2009). • The biological and ecological characteristics of alligator weed (Alternanthera philoxeroides) have been well studied owing to its threat to biodiversity and ecosystem functions (Pan et al., 2007). Although the use of a biological control agent has successfully suppressed its growth and repro- duction in aquatic habitats in many provinces in southern China, it is still problematic in terrestrial habitats. The invasion of fields by alligator weed can cause 19–63% yield losses in five crops: rice, wheat, maize, sweet potato and lettuce (Tan, 1994). • In the provinces of Zhejiang and Fujian in south-eastern China, the common and smooth cordgrasses (Spartina anglica and S. alterniflora) have invaded and occupied large coastal areas, leading to a dramatic decrease in aquaculture yields, as many of the crabs, mussels and fish have died (Huang, 1990). Alteration of the habitat structure and food resources has also led to a dramatic decline in avian species richness (Gan et al., 2010). However, a 16 year chronose- quence study has indicated that smooth cordgrass is being inhibited by an accumulation of habitat changes created by the two Spartina species themselves (Tang et al., 2012). technology for early warning and prediction food for human consumption, by many systems to prevent future invasions is at an researchers in China (Ding et al., 1995), even early stage, particularly at the national level.

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