Conclusions
Once an invader reaches a high level of abundance eradication becomes
very difficult or impossible. This means that time and resources are
continually required to manage widespread invaders. Native pathogens
could provide a low cost method for controlling some invaders if
effective pathogens can be identified
(Kotzé et al. 2015).
Using our proposed framework, we aim to help predict what invaders are
most susceptible to pathogens and therefore have the potential to be
managed with native pathogens. This management can be accomplished with
bioaugmentation of pathogens as microbial herbicides, a method that is
currently used for a limited number of native pathogen-invasive plant
combinations (Trognitzet al. 2016).
As debate continues surrounding the idea that native pathogens can
control invasive plant populations and possibly reverse negative
ecological effects, we suggest that a better understanding of the
factors that predispose invaders to pathogen decline will improve
monitoring and management efforts
(Flory et al.2018; Policelli et al. 2018). Plant traits can determine
pathogen tolerance and resistance to disease, so, logically, invader
traits should provide some power to predict pathogen accumulation. There
are many traits that are correlated with susceptibility of plants to
disease, but more studies are needed assessing the interspecific
variation in traits and plant pathogen attack, particularly among
invasive species. We found evidence for 20 cases of invasive plant
impacts due to novel pathogen interactions, but we expect that there are
additional cases that remain unidentified due to limited research, for
example where the etiology of disease has not been identified as with
most plant-soil feedback studies
(Diez et al. 2010).
Additionally, most of these examples were variable in their effects on
invader populations in the field so it is possible that cases with
insufficient population monitoring of invaders may be overlooked. These
cases could be important for management from a bioaugmentation
perspective, where native diseases are augmented on susceptible invaders
to provide control. As long-term research on invasive plants
accumulates, this framework allows us to leverage these data to better
understand patterns in dynamics of novel interactions with pathogens and
their potential to control invader populations.