Biology and management of the invasive weed Ageratina adenophora (Asteraceae): current state of knowledge and future research needs

Abstract

Summary Biological invasion is increasing worldwide and the management of invasive species is becoming an important priority for vegetation managers. Success of invasive species management depends on a thorough understanding of the biology of the organism in question and the effectiveness of current management efforts, in order to identify the best practices for management improvement. In this review, we synthesised current biological knowledge of a noxious invasive weed Ageratina adenophora to identify knowledge gaps and assessed management efforts to identify best practices. Finally, we proposed some priority areas for future research to fill knowledge gaps and improve management. Our analysis showed that A. adenophora has already invaded 40 countries, mainly in Asia, Oceania, Africa and Europe. Phenotypic plasticity, allelopathic interference and invasion‐mediated changes in the soil microbial community are the proposed mechanisms that facilitate rapid spread of this weed. However, allelopathy as a mechanism of invasion success of this weed has not been supported by ecologically meaningful experiments. Though mechanical, chemical and biological control measures have been used, their success remains limited and the weed continues to spread in new regions. Among seven biological control agents examined to date, gall fly (Procecidochares utilis) and leaf spot fungus (Passalora ageratinae) have been effective in limited areas to suppress growth of this weed. Some perennial native grasses (e.g. Setaria sphacellata and Lolium perenne) have shown potential to competitively suppress A. adenophora. In conclusion, understanding the invasion mechanisms, exploring further to identify effective biological control agents, combined with approaches of ecological restoration, could help in the management of this weed.

Evaluation of foliar fungus‐mediated interactions with below and aboveground enemies of the invasive plant Ageratina adenophora

“…The spread of A. adenophora is considered to be a severe problem in more than 30 countries in Asia, Africa, Oceania, Europe and North America (Datta et al., 2019). In China, this weed has been reported to reduce the diversity of native plant species, crop production in agricultural land and forage production in pastures; moreover, this weed is poisonous to domestic animals (Poudel et al., 2019). Therefore, understanding the mechanisms of successful weed invasion is ecologically and economically important.…”

“…Nevertheless, once established, A. adenophora can change the soil biota to promote its own growth (Niu et al., 2007), for example, by increasing the abundance of nitrogen‐fixing bacteria (Xu et al., 2012) and root endophytic Enterobacter bacteria (Chen et al., 2019). Moreover, A. adenophora has also been reported to host various foliar fungi, including pathogens (Poudel et al., 2019; Zhou et al., 2010) and endophytes (Mei et al., 2014, Fang et al, 2019). In addition, foliar herbivory was frequently observed in our routine investigations.…”

Origin of climatic data can determine the transferability of species distribution models

“…Ageratina adenophora (Crofton weed, Asteraceae) is a plant species native to Mexico and invasive (or even noxious) in more than 30 countries in subtropical regions across the globe (Auld and Martin 1975;Qiang 1998;Tian et al 2007;Muniappan et al 2009;Poudel et al 2019). It is a multi-stemmed, perennial herb or undershrub that grows up to 2 metres and flowers profusely in spring (Tripathi et al 2012).…”

Virulence evolution of multiple infections with vertically and horizontally transmitted fungal species in a natural plant system

“…Ageratina adenophora (Sprengel) R. M. King and H. Robinson is a perennial herb of the Compositae family that is native to Central America but is a noxious weed in Asia, Africa, Oceania and Hawaii. This plant has invaded more than 40 countries worldwide in tropical to temperate regions, resulting in serious ecological impacts and economic losses (Poudel et al 2019). Since the first record in China in the 1940s, the plant has been widely distributed in the provinces of Yunnan, Sichuan, Guizhou, Guangxi and Tibet, and it has continuously spread eastand northward with clear time information (Wang and Wang 2006).…”

“…Since the first record in China in the 1940s, the plant has been widely distributed in the provinces of Yunnan, Sichuan, Guizhou, Guangxi and Tibet, and it has continuously spread eastand northward with clear time information (Wang and Wang 2006). There is evidence that A. adenophora can infect fungal pathogens in the introduced ranges (Zhou et al 2010, Poudel et al 2019). In particular, our recent study indicates that A. adenophora accumulates diverse foliar pathogens from neighbours (horizontally transmitted); however, a primary pathogen (OTU515), which belongs to the family Didymellacea, does not occur on surrounding native plants (Chen et al 2020b).…”