The factors affecting a native obligate parasite, Cuscuta australis, in selecting an exotic weed, Humulus scandens, as its host

Abstract

In weed management, using native parasites to control exotic weeds is considered a better alternative than classical biological control. But the risk must be assessed because of the potential damage caused by these agents. We conducted this project to investigate the mechanism driving the choice of a native obligate parasite, Cuscuta australis, between the exotic, Humulus scandens, and native plants as its host through field and pot experiments. The results showed that C. australis preferred the exotic weed over native (naturalized) hosts and caused a notable reduction in the biomass of H. scandens in the field. In contrast, the results of the pot experimentindicated that C. australis preferred a mix of native (naturalized) hosts over the exotic weed. Both texperiments indicated that the parasitic preference of C. australis was induced more by light irradiance than plant water, carbon (C), nitrogen (N) and phosphorus (P) contents, indicating that the native parasite can only be used to control H. scandens when the exotic weed forms mono-cultures or dominates the community. Accordingly, induction and release of C. australis to control H. scandens should be conducted with great caution.

Detection of Different Hosts From a Distance Alters the Behaviour and Bioelectrical Activity of Cuscuta racemosa

“…Furthermore, other means of perception are worthy of being explored. Light cues are recognised as important for dodder foraging ( Orr et al, 1996 ; Benvenuti et al, 2005 ; Wu et al, 2019 ). Additionally, in recent years, Haberlandt’s plant ocelli hypothesis has been revisited with new pieces of evidence ( Haberlandt, 1905 ; Baluška and Mancuso, 2016 ; Mancuso and Baluška, 2017 ).…”

“…Since the 19th century, it is known that dodders forage and make choices ( von Mohl, 1827 ; Koch, 1874 ; Peirce, 1894 ; Kelly, 1990 , 1992 ; Koch et al, 2004 ; Runyon et al, 2006 ; Wu et al, 2019 ), yet the mechanisms by which these behaviours emerge are still unclear. However, there are two likely mechanisms for host detection: volatile organic compounds (VOCs) emitted by the host plants, and/or by light cues ( Albert et al, 2008 ).…”

Responses of Rhizospheric Microbial Communities of Native and Alien Plant Species to Cuscuta Parasitism

“…By maintaining fungal interactions and altering fast growing decomposers, it is likely that Cuscuta parasitization of alien plants affects the mechanism by which alien plants benefit from their surrounding microbiota. This could then be a part of the explanation of the observed greater susceptibility of some alien host plants to novel native generalist parasitic plants than native host plants [27,97,101].…”

“…Zhang et al [96] hypothesized that the litter-and rootbased loops are coupled to generate positive feedback of alien invaders on soil systems by stimulating nutrient cycling, which in turn increases alien plant fitness. This, however, might differ in the presence of Cuscuta, because parasitization is known to severely affect the nutrient release of the host plant (~40% biomass loss reported with parasitization of the alien weed Humulus scandens, [97]). This is likely to considerably reduce litter supply and to disrupt the mechanism by which alien plants benefit from the surrounding microbiota.…”

Localised photosynthetic pigments in the node of a holoparasitic plant: support for shoot growth?

“…They do not have roots, and they absorb all their nutrients through haustoria, which are connected to the hosts (Birschwilks et al 2006;Costea & Tardif 2006). Dodders are some of the most devastating agricultural parasites worldwide; however, they are also ecologically relevant owing to the strong effect of their parasitism on the fitness of wild plants and invasive species (Costea & Tardif 2006;Albert et al 2008;Mishra 2009;Cruz Neto et al 2017;Wu et al 2019).…”