CABI scientists are stepping up the fight against one of the UK’s most invasive non-native aquatic weeds.
Approval has been given for the release of a novel biological control agent – the mite, Aculuscrassulae – to assess its ability in the real-world environment to suppress Australian swamp stonecrop (Crassula helmsii), also known as New Zealand pigmyweed. This follows carefully controlled laboratory testing to ensure the safe, controlled release of the mite in the UK.
Giant hogweed (Heracleum mantegazzianum) is a monocarpic perennial herb, native to the Caucasus region. Since the late 1800s, giant hogweed has spread extensively across Europe and in eastern and western parts of North America following its likely initial introduction to the continent as an ornamental curiosity as early as 1917. Hogweed is an extremely successful invader in part due to its prolific seed production and growth rate. These attributes coupled with its large size allow giant hogweed to significantly alter natural environments and plant community structures. In addition, the plant is hazardous to humans and leaves riparian banks susceptible to erosion as it dies off in autumn.
In the late 1970s and early 1980s the group of closely-related woody plant species and hybrids known as Prosopis were seen as a ‘saviour’ for millions of pastoralists and agro-pastoralists in East Africa whose very livelihoods were threatened by the degradation of dryland ecosystems spurred on by overgrazing, and by deforestation and a shortage of firewood.
Himalayan balsam (Impatiens glandulifera) is a non-native annual plant that was introduced into parts of Europe during the mid-nineteenth century as an ornamental plant for parks and gardens.
This plant species was first recognised as an invasive species and a threat to ecological stability in the 1930’s. However, since then the problem has escalated and is now of international concern, due to its negative impact on ecosystem biodiversity. This is primarily due to its ability to out-compete and overcrowd native vegetation. Himalayan balsam has now naturalised in many countries, resulting in a shift in management strategies from attempting to remove the invasive plant, to limiting its territory and further spread.
The poisonous Parthenium hysterophorus plant is one of the world’s most destructive invasive plant species, threatening biodiversity, food security and human health across numerous countries. The herb is native to Central and South America but has spread to over 40 countries over recent decades including Australia, India, Ethiopia, Swaziland and South Africa.
It was back in the early 1990s, on my first field trip to Assam in North-east India, with invasion ecologist Dr. Sean T. Murphy, when I first encountered mikania growing as an invasive weed. Until then, I had only seen this vine in its Central and South American native range, where locating a population of the plant could sometimes take all day.
Research is currently underway to study new ways of encapsulating and applying entomopathogenic nematodes (EPN) to better combat the invasive and destructive fall armyworm in Africa.
PhD student Patrick Fallet is investigating the possibility of a novel biocontrol approach which will attract the armyworm caterpillars to beads containing biocontrol agents such as the insect-killing EPN.