Vampire vines - do they really exist?

There is a parasitic vine called a vampire vine. It sucks the sap out of feral weeds, and it is being hailed as a new agent for biocontrol. The vampire vine helps to destroy European (alien) weeds in Australia (New Scientist, 22 April 2016).

Actually the real name is not vampire vine. It is devil’s twine – Cassytha pubescens. Robert Cirocco of the University of Adelaide in South Australia says the vampire vine kills a variety of European weeds, such as gorse, Scotch broom, and blackberry. The vampire vines – the devil’s twine – attach small suckers to the stems of the weeds and sucks out their water and nutrients, leaving the weeds bloodless – well, sapless. Plants don’t have blood.  

Cirocco says that the vampire vines will save farmers and the government millions of dollars, which is the money it takes to eradicate the invasive weeds that kill native plants. For example, gorse (Ulex europaeus) costs more than US $5.5 million a year to eradicate from farmland with herbicides, mechanical removal, and burning. Vampire vines will kill weeds naturally.

The vampire vines suck out the sap, which reduces the ability of the weeds to photosynthesize. This means less carbohydrate, which means less growth – and the weed dies.

Cirocco presented his findings to the Natural Resource Management Science Conference in Adelaide in April. He conducted a study in the Mount Lofty Ranges, near Adelaide, where Cassytha was growing, and where the European gorse had virtually been eradicated due to the presence of Cassytha. He said that the vampire vines are toxic to non-native plants, but are not harmful to native plants.

The next step is to conduct field trials to confirm the effectiveness of the devil’s twine as a biocontrol agent in a variety of natural habitats. Other scientists say biocontrol agents can be difficult to predict whether they will eradicate only the invasive species of weeds and keep the native plants intact – and whether the Cassytha can be managed effectively as a biocontrol agent.

Cassytha pubescens is a hemiparasitic vine, similar to laurel, and is found in south-eastern Australia. Common names are devil’s twine or dodder-laurel. The thin dark-green stems are about 0.5mm to 1.5mm in diameter, which curl around tree branches and other plants. The suckers are called haustoria – disc organs that pierce the xylem in trees or plants to extract nutrients. To survive, Cassytha must attach itself to a host plant or weed within six weeks of germination. Scottish botanist, Robert Brown, formally identified it in 1810.

https://www.newscientist.com/article/2085389-vampire-vine-helps-to-destroy-alien-european-weeds-in-australia/

MARTINA NICOLLS is the author of:- The Shortness of Life: A Mongolian Lament (2015), Liberia’s Deadest Ends (2012), Bardot’s Comet (2011), Kashmir on a Knife-Edge (2010) and The Sudan Curse (2009).