Root weevil, Mogulones geographicus on Paterson's curse flower.

The root weevil, Mogulones geographicus is a successful biocontrol agent for Paterson's curse.

Paterson's curse

Paterson's curse is considered a great resource for apiarists but is toxic to most grazing animals and is Australia's worst broadleaf temperate pasture weed.

  • 1 September 2006 | Updated 14 October 2011

The problem

Paterson's curse, Echium plantagineum (known as Salvation Jane in South Australia) is an introduced winter annual from the Mediterranean. Free of native Mediterranean plant and insect communities, it has become a dominant pasture weed of temperate Australia.

In Australia Paterson's curse produces over 10 000 seeds by late spring which sit dormant over summer waiting for rain when they germinate in their thousands.

The seedlings grow quickly and develop a large taproot making them resistant to drought. Seedlings form a flat rosette, out-competing other germinating plant species.

Paterson's curse can completely dominate a paddock resulting in the endless fields of purple often seen in spring each year.

Although relatively nutritious in terms of digestible nutrients, and valued as a pasture plant in some places, Paterson's curse contains pyrrolizidine alkaloids that are poisonous to livestock as they can:

  • destroy the liver
  • reduce weight gain and wool clip
  • lead to death in severe cases.

In 1985, Paterson's curse was estimated to occur on over 30 million hectares in Australia, and in 2002 costing the wool and meat industries A$125 million each year.

In spring 90 per cent of pasture can be Paterson's curse producing over 30 000 seeds per square metre.

Background

Paterson's curse was first suggested as a candidate for biocontrol at the Australian Weeds Council in 1971. CSIRO Entomology started surveys in the weed's native range in 1972 from the CSIRO laboratories in Montpellier, France.

From over a hundred insect species recorded on Paterson's curse, eight were selected as possible biocontrol agents. The first was imported into Canberra quarantine by 1979.

In 1980 a small group of graziers and apiarists lodged an injunction in the Supreme Court of South Australia to stop the biocontrol program. They considered the loss of Paterson's curse a threat to their livelihoods. 

The Biological Control Act of 1984 established procedures for assessing and authorising biological control programs in Australia.

A subsequent inquiry and benefit-cost analysis was conducted by the Industries Assistance Commission, which concluded with the judgement that a biological control program on Echium should go ahead. The Supreme Court injunction was eventually lifted and the importation of insects into Australia resumed.

Six agents have now been successfully released:

  • leaf mining moth, Dialectica scalariella
  • crown weevil, Mogulones larvatus
  • root weevil, Mogulones geographicus
  • root beetle, Longitarsus echii
  • stem boring beetle, Phytoecia coerulescens
  • pollen beetle, Meligethes planiusculus.

Biological control

The six agents are spreading across the weed's distribution.

The leaf-mining moth was first released in 1988 and is widely established although providing little impact.

The crown weevil was first released in 1990 and is currently the most damaging agent, often killing the weed outright on a farm scale at a number of sites in New South Wales, Victoria and South Australia.

The root weevil and flea beetle are both established in all southern mainland states. The flea beetle is starting to kill Paterson's curse before it can flower at some sites in New South Wales and Victoria.

The flower beetle and stem-boring beetle are also established in all southern mainland states, but at this stage are not reducing the seed set of Paterson's curse.

The four most promising insects are the focus of a nation-wide redistribution program.

  1. The crown weevil is most effective in high rainfall low grazing pressure situations.
  2. The root weevil tolerates drier regions and since it feeds in the taproot below ground also performs better in more heavily grazed pasture.
  3. The flea beetle is the best insect for heavy grazing and extended summer/autumn drought conditions and can survive under ground for six months without feeding.
  4. The pollen beetle complements the damage of the root feeders by destroying seeds directly in spring and does best in regions of extended flowering, typically regions of higher rainfall.

All four species of insect are available in the southern mainland states through collaborating State Departments.

Learn more about the Ecology and management of Australian weeds.