Rubbervine infestation in Australia
The rubber vine weed was introduced to Australia from Madagascar in the 19th century as an ornamental garden plant and as a source of latex. An aggressive climber, capable of smothering trees up to 40 metres high, it was described as the single biggest threat to natural ecosystems in tropical Australia and had a huge impact on pastoral areas.By the late 1980s the rubber vine infestations were vast, covering 40,000 km2 (that’s twice the size of Wales) across often remote areas. Wide-scale chemical control was considered impractical, uneconomic and environmentally undesirable. As the weed advanced towards the prestigious national parks of the Northern Territory, urgent calls were made for its widespread control.
Natural (biological) control of the cassava mealybug in AfricaCassava, yucca or manioc was introduced from South America into Africa by the Portuguese in the 16th century and is today the staple root crop for more than 200 million people in Africa alone. This major source of carbohydrates came under threat from a devastating pest, the cassava mealybug (CMB).CMB was first recorded in Congo and Zaire (now Democratic Republic of the Congo) in the early 1970s and quickly spread over the whole of the cassava growing area of Africa, since there were no natural enemies to control it in its new habitat.
Galerucella leaf beetles
Natural (biological) control of purple loosestrife in North America
The popular European native purple loosestrife (Lythrum salicaria) was introduced to the US and Canada as an ornamental plant, however it has since invaded the natural environment forming large stands and degrading many prime wetlands. Purple loosestrife is an herbaceous perennial which grows up to about 1.5 metres in height. In its native range in Europe, the plant can be found on the margins of lakes and swamps and rarely dominates these environments.
After extensive testing, six agents proved to be safe for release in North America. Of these, two leaf-eating beetles – Galerucella calmariensis and G. Pusilla – proved to be particularly effective at controlling the invasive weed. As a result of this work, this aggressive invader is now being successfully controlled in the western and mid-western USA – 95% of purple loosestrife is destroyed within two to five years of release – allowing native wetland plants to flourish once more.