Biological Control

The Meander Valley Weed Strategy in conjunction with the Tasmanian Institute of Agricultural Research has been undertaking a biological program for ragwort for a number of years.

The ragwort flea beetle, (Longitarsus flavicornis), which is a natural predator of ragwort in Europe, was introduced to Tasmania in 1979. By the end of April 1998, field surveys indicated that the ragwort flea beetle had spread over approximately 160 sq. kms of ragwort infested land within the Meander Valley Municipality, the beetle is having a significant impact on ragwort.

Although initual spread of the beetle is slow, spread increases as populations build-up.

Also released at 11 sites in Tasmania during the 1995/96 season, was the leaf and crown boring moth, (Cochylis atricapitana). Assesments of these sites in early 1998, indicate that successful site establishment had occured at most of these nursery sites. This is indicitative that the leaf and crown boring moth may become permanentally in Tasmania.

The Cinnabar Moth (Tyria jacobaeae) which feed on the leaves and flowers of ragwort, was first released in Tasmania in 1993. Releases were made at 14 nursery sites within the Meander Valley Municipality between 1994 and 1997, as well as other ragwort infested areas of Tasmania during the same period. It would appear that due to heavy caterpillar mortality resulting from the combined effects of disease, insect predators and parasites, it is still uncertain whether populations will become permanentally established in Tasmania.