Biological control of oxeye daisy
Although closely related, Oxeye daisy is an invasive weed in places like North America and Australia, while Shasta daisy remains a garden favourite, especially in North America. CABI is investigating whether specialist natural enemies from oxeye daisy’s area of origin in Eurasia could be introduced in North America and Australia as biological control agents. In North America the popularity of Shasta daisy makes this a challenge because any introduced agent must damage oxeye daisy but not Shasta daisy.
Hope for biological control of houndstongue in the USA?
An invasive weed with close relatives among native species is a challenge for biological control. Houndstongue was introduced accidentally to North America from Eurasia in the mid-19th century. It has since invaded most Canadian provinces and adjacent US states. There are many native plants in the USA in the same family as houndstongue. CABI staff in Switzerland are investigating specialized natural enemies in the area of origin of the weed that could be introduced as biological control agents.
Controlling hoary cress in North America
Trade in seed brought crops to new regions, but many weeds were spread by this route too. Whitetops, also known as hoary cresses, arrived in the USA as contaminants of seed from Eurasia. They are now aggressive invaders of crops, rangeland and riverbanks. One reason for this is the absence of the natural enemies that keep them in check in their area of origin. CABI staff in Switzerland are looking into the prospects for biological control of these invasive plants.
Controlling swallow-worts the sustainable way
Swallow-worts (Vincetoxicum nigrum and V. rossicum) are Eurasian plants that have become invasive in North America. The overall goal of the project is to identify specific natural enemies that can be introduced to North America as biological control agents for swallow-worts.
An old problem revisited: biological control of toadflaxes
Native to Europe, toadflaxes were introduced to the USA and Canada over 100 years ago as ornamental plants. They now occur over much of temperate North America and are declared noxious in eight US states. CABI identifies specific natural enemies that can be introduced into North America as biological control agents to reduce the vigour, density and spread of this invasive plant.
Stemming the spread of Russian olive
Russian olive is a significant invasive weed in North America but is perceived as a useful and attractive tree by some stakeholders. It is especially a problem in western parts of the USA where it affects many natural habitats, altering the ecosystem and its functions. Biological control is a useful approach in such circumstances because scientists can look for natural enemies that damage reproduction, and thus future spread, without damaging established trees.