PROGRESS AND PROSPECTS IN RESEARCH OF AN EXOTIC INVASIVE SPECIES,EUPATORIUM ADENOPHORUM

Eupatorium adenophorum, native to Mexico and Costa Rica of Central America, is a worldwide noxious invasive weed. It occurs throughout many terrestrial areas of the world and is especially rampant in Southeast Asia, Hawaii (U.S.), New Zealand, Australia, and the Pacific Islands. Since its invasion to China from the boundaries of Vietnam and Burma, the speed of its spread has been faster than anticipated, particularly in the southern and southwestern parts of the country. Presently, E. adenophorum can be found in Chongqing, Yunnan, Sichuan, Guizhou, Tibet, Guangxi, Taiwan and Hubei Provinces. A rough estimate of the annual spreading rate of E. adenophorum is about 10-60 km from south to north and from west to east in China. It is considered a threat to local economy and biodiversity. As a result, an increasing number of Chinese scientists have become interested in studying this species and much progress in understanding the biology and ecology of this species has been made to date. In particular, much is known about the underlying mechanisms of its invasion biology. This paper reviews some of the hot research topics of this invasive species in China, including its distribution, predicting its potential distribution, the mechanisms underlying its invasion and spread, and methods for control and elimination. The distribution of this invasive plant in China has been mapped and its potential distribution has been predicted using a computer model based on climatic factors. Among current research efforts, understanding the mechanisms underlying its invasion and spread is one of the hottest topics. Recent research also has studied the patterns of genetic variation within populations of the invasive weed, novel biochemical mechanisms of interspecies interactions, biological characteristics of the invasive species that explain its highly successful spread, e.g., small seed size, persistent soil seed bank, high offspring production, potential long-distance dispersal of propagules, vegetative reproduction, relatively high CO2 fixation capacity, shade tolerance, high adaptive ability, and tight link of life-history traits with climatic rhythm. Although much progress in understanding the biology and ecology of this species has been achieved, there have been no dramatic breakthroughs on how to control E. adenophorum so far. At present, control methods of E. adenophorum are divided into three general categories: manual, chemical and biological control. Biological control is considered the most promising sustainable control strategy for this weed. Several natural enemies and pathogens have been reported that might be able to control the reproduction of this weed, such as Procecidochares utilǐs, Cercospora eupatorii and Alternaria alternata. The current status of research on the invasive species, E. adenophorum, was reviewed in this paper. Five areas of future research have been proposed: 1) modeling long-distance seed dispersal; 2) allelopathic mechanisms of invasion; 3) ecophysiological adaptations of the invasive species; 4) breeding system of the invasive species; and 5) effective biological control of the invasive species, especially the potential role of genetically engineered fungi.