Harnessing Allelopathic Autotoxicity for Invasive Plant Management: Knowledge Gaps and Future Research Directions.

Nuisance species are typically managed using mechanical removal, biological, cultural, or chemical treatments, applied either individually or in combination. Applications of synthetic pesticides may result in significant non-target effects that reduce biodiversity or result in pesticide drift, and target organisms can rapidly develop pesticide resistance. Biological control has less physical impact on ecosystems than mechanical removal, and none of the human health concerns of synthetic pesticides, but relies on coevolved antagonists that are introduced to the invaded environments and can have non-target effects (e.g., outcompeting native species, switching to non-target native organisms, and ineffectively suppressing the target organism). Due to increasing restrictions, it is becoming more difficult to import, propagate, and release new biological control agents. These concerns, in combination with the increased rates of species invasion and economic and ecological costs of existing control methods, necessitate alternative means of nuisance species control. In this review, we examine an alternative control approach based on the principles of allelopathy and autotoxicity. Autotoxins used in this manner exploit secondary metabolites produced by a target species and/or their endosymbionts to inhibit growth or induce mortality with reduced non-target impacts. We synthesized autotoxicity-related literature to compare plant-derived autotoxins to traditional biological and chemical controls and discuss how further autotoxicity research and development can assist with the control of nuisance plant species. Although autotoxins provide a promising new frontier for nuisance species control, further research is necessary to effectively develop, test, and deploy these biochemical controls for species inhibition or mortality.