Details of this species in China Status: Alien
Invasiveness: Invasive
Occurrence: Present/controlled
Source: Jianqing et al. 2001 Arrival Date: early 1900s
Introduction: Species Notes for this Location:
Water hyacinth was introduced into China in the early 1900s. As an ornamental plant, it was first introduced into Taiwan in 1903 from Southeast Asia. In the 1930s it was introduced to the mainland (Diao 1989, in Jianqing et al. 2001). But the first scientific record appeared for the mainland in 1954 in the book, ‘Taxonomy Catalogue for China’s Plants: Families and Genera’ (Anon. 1954, in Jianqing et al. 2001). In the 1950s and 1960s, water hyacinth was distributed widely into almost all provinces for animal food. After artificial transplanting and mass rearing and breeding, water hyacinth was distributed to further areas in the 1970s and began to cause damage in the 1980s. Increasing damage has been reported since the 1990s as nutrient levels increased in water bodies and the use of water hyacinth plants began to fall.
Water hyacinth is now distributed naturally in 17 provinces or cities in China. In several other provinces water hyacinth is still utilised but cannot overwinter. Water hyacinth causes damage in more than 10 provinces (Ding et al. 1995). Great damage has been reported in five provinces: Yunnan, Guangdong, Zhejiang, Fujian, Taiwan. Management Notes for this Location:
Manual removal has been employed in most areas in China in the past 10 years. It is estimated that more than 100 million RMB yuan (US$12m) was spent on artificial control of water hyacinth each year but the practice was neither economic nor effective. Mechanical control is used in only a few places and cannot provide long term control. In some areas, herbicides such as Roundup and paraquat were used, but they are prohibited in places where the water is used by people and animals.
In China, biological control activities for water hyacinth were initiated in early 1995, when the Biological Control Institute (BCI) introduced two weevils Neochetina eichhorniae and N. bruchi from the USA and Argentina, respectively. Upon the request of the local government, host range tests for the two weevils were conducted in Kunming, Yunnan Province in 1995. Forty-six plant species from 23 families representing local economic, ornamental, and ecologically important plants (Ding et al. 1998, in Jianqing et al. 2001). were tested. As they had done previously in the USA, Australia, India and other countries, host range tests showed the weevils attacked and completed their life cycles only on water hyacinth and they were safe to other local plant species. After host-specificity tests, the weevils were released in the Wenzhou (1996), Zhejiang (1996) and Fujian (1998) Provinces.
The bug Eccritotarsus catarinensis was introduced into China in the early spring 2000 from the Plant Protection Research Institute (PPRI), South Africa but, for unknown reasons, failed to establish. BCI (Biological Control Institute) plans to re-introduce it. Pathogen surveys started in Fujian and Zhejiang provinces in May 2000. Several promising isolates have been screened.
In order to control the weed rapidly, an integrated control system was developed in 1996 by BCI scientists. Several herbicides, e.g. Roundup (41% IPA salt of glyphosate) and Caoganlin (10% salt of glyphosate), were screened to supplement the activity of the weevils. Bioassay tests showed that Roundup and Caoganlin had almost no adverse effect on the weevils. The tests of integrating Roundup at different concentrations with weevils indicated that herbicides had to be used at a lower concentration than normal, so as to not kill the plants too rapidly and not deprive the insects of food and habitat. The details of those tests were reported in the first IOBC water hyacinth workshop in Zimbabwe in 1998 (Ding et al. 1999, in Jianqing et al. 2001).
Water hyacinth is still a big problem in South China despite great efforts at control over the past 10 years. As more and more attention from central and local governments is paid to improvement of the environment, control of water hyacinth is becoming one of their objectives. Biological control will be increasingly employed but the public and government officials need to be made aware of the importance of biological control. BCI research on biological and integrated control of water hyacinth will focus on the following subjects in the next few years by means of national and international collaborations: (1) Study of the factors influencing the level of control of water hyacinth achieved by weevils, (2) Distribution of the weevils into more areas and introduction of new insects from abroad. An agreement between the South African and Chinese governments has been signed for collaboration on water hyacinth over the next three years. BCI will obtain help from PPRI for the importation of new natural enemies e.g. E. catarinensis, (3) Conduct of field tests of integrated control on a large scale, (4) Survey of pathogens in South China and introduction of promising fungi from abroad. In BCI a pathogen laboratory has been set up for the study of control of the weed by this means. Last Modified: 24/07/2006 3:28:36 p.m.
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