17 Eighteenth Australasian Weeds Conference Summary Biological invasion is now a major threat to global biodiversity. As one of the worst invasive weeds in the world, research on various aspects of Mikania micrantha H.B.K. is increasing over the years. The plant was introduced in India after the Second World War and its profuse growth in Kerala and Assam over the years affected forests and tea plantations causing damage to the ecosystems and economy of the country. Since the 1980s it has started to spread and invade other Indian states and there is an urgent need to map and monitor the spread of this plant. This paper reviews the worldwide research trend over the years, the current status of the weed in India and reports the presence of this plant in an urban city like Kolkata in India. Keywords Mikania micrantha, worldwide research, spread in India. INTRODUCTION One of the greatest threats to global biodiversity is species invasion. Biological invasions have been considered to be one of the three most difficult envi- ronmental problems in the world. Mikania micrantha H.B.K., a climbing perennial weed of the family Aster- aceae native to Central and South America, has been listed as one of the 100 worst invasive alien species in the world (Lowe et al. 2001). The distribution of the plant in Australia has been reviewed by Day (2012) and the species has been put under high alert (Class 1 species) since 2002. The plant was introduced in Indonesia as ground cover in the 1940s and then spread to the Pacific islands, south-east Asia and New Guinea (Waterhouse 1994) and is now one of the worst exotic weeds in southwest and south Asia (Zhang et al. 2003). In Asia, M. micrantha is known to be particularly problematic in plantation crops, but also threatens natural areas and disturbed ecosystems. After estab- lishing itself in a new habitat, the plant kills all the other plants by smothering them and thus effectively reducing light beneath its canopy (Huang et al. 2000). Due to its high spreading and establishment capacity, the plant has the ability to be a potent threat to a na- tion’s biodiversity as well as its economy. In south China, the plant causes problems to tropical fruit trees Mikania micrantha H.B.K. – a potential and economical threat to global biodiversity with special emphasis on Indian context Achyut Kumar Banerjee and Anjana Dewanji Agricultural and Ecological Research Unit, Indian Statistical Institute, 203, B.T.Road, Kolkata-700108, West Bengal, India (banerjeeachyut31@gmail.com) and crops (Ye and Xia 2001) and commercial forests (Hills 1999) while in Nepal it is a threat to coconut, oil palm, banana and cacao plantations (Sapkota 2007). The seeds of the weed were found to germinate in the bare soil in coastal areas causing great damage to the mangrove forests (Yu and Yang 2011). This noxious weed cannot be eliminated by simple manual or mechanical means in places where it has posed as a potential threat—biological control is the only prob- able alternative (Ye and Xia 2001). Several aspects of the biology and ecology of M. micrantha are discussed in a review paper by Tripathi et al. (2011). The history of spread of the plant and its control in China has been extensively reviewed by Zhang et al. (2003). In India the plant has been reported to be problematic in the north-east and south- west (Parker 1972) and a classical biological control strategy for this weed using a rust fungus (Puccinia spegazzinii) from Trinidad was implemented but no satisfactory result was obtainable (KFRI 1997). There- fore, early detection of new invaders and new foci of spread would allow implementation of intervention methods at an early stage of invasion with the potential to pre-empt severe problems. The objective of the study is to chronologically review the volume of work done on Mikania micran- tha worldwide highlighting the major focus areas of research. In the absence of a proper database on the spread of the plant in the Indian context, an attempt has also been made in this paper to ascertain the current status of the plant in the Indian context with emphasis on its presence in an urban city like Kolkata in India. MATERIALS AND METHODS Data sources A total of 105 reports all over the world (1967–2012 AD) were studied and analysed. The reports containing the genus name (Mikania) and the species name of the plant (micrantha) were taken into account. The database of the journal groups [like Springer, Wiley, Taylor & Francis, ScienceDirect] were searched with the key-word Mikania micrantha. The worldwide available databases [like Asia-Pacific Forest Invasive Species Network (APFISN), CABI, Invasive Species Specialist Group (ISSG)] were also