Allelochemical mediated invasion of exotic plants in China

Invasion of exotic species is a global ecological problem and has tremendous impact on economy, environment and human health. The success of invasion for exotic plants depends on many mechanisms and in recent years the novel weapons hypothesis has been argued as an important mechanism to elucidate the invasion process. This review summarizes a large body of research including the observations of potential allelopathic phenomenon, isolation and identification of allelochemicals and the role of allelopathy in invasion of common exotic invasive plants in China such as Eupatorium adenophorum, Eucalyptus spp., Spartina anglica, Chromolaena odoratum, Eichhornia crassipes, Solidago canadensis, Alternanthera philoxeroides, Ambrosia artemisiifolia, Ambrosia trifida, Lantana camara, Wedelia trilobata, Bidens pliosa, Ageratum conyzoides and Mikania micrantha. We suggest that allelopathy plays a vital role in successful invasion of alien species in new areas. The allelochemicals of invasive alien species also serve as defence chemical weapons against native plant pathogen and herbivorous insects.