Biology and Control Methods of the Alien Invasive Weed Mikania Micrantha: A Review

Invasion of alien weed species is one of the most serious global problems. Different bioclimatic conditions of Nepal favor the introduction of different invasive alien weeds. Mikania micrantha (L.) Kunth is one of the well-established invasive alien weeds in the tropical and sub-tropical parts of eastern and central Nepal. M. micrantha was first reported in 1963 in the eastern part of Nepal and then spreading towards the western part, which is now recorded in over 20 Terai districts of Nepal. Its spread is causing a serious threat to native ecosystem and in the protected areas too, such as the Koshi Tappu Wildlife Reserve and the Chitwan National Park. It invades new areas by seed dispersal and, once established, it spreads locally by ramets produced by penetrating rosette caudices and ramet caudexes. This neotropical vine supplants other plants and reduces biodiversity significantly by swamping vegetation and out competing native plants. Regeneration of other plants in its invaded area is restricted due to its high dispersal ability and adaptability to colonize in new habitat and difficult to control if once established. Several measures have been attempted in controlling this weed, but till date little success has been achieved in Nepal. It is important to identify the control measures which are: socially acceptable; economically viable and spatially suitable. There is consumption of extra human resources and time for clearance of Mikania in their cultivated lands and also an extra expenditure is required to avoid the impact of Mikania which is affecting livelihood of local people. As M. micrantha grows rapidly and conventional control measures are costly and time consuming, biological control is seen as a feasible, environmentally friendly and self-sustaining option to control large stands of M. micrantha. Co-evolved rust pathogen, Puccinia spegazzini has been reported to be able to control the weed and introduced in countries like India, Taiwan, China, Papua New Guinea and Fiji.