Biological Control of Paterson's Curse with the Tap-Root Flea Beetle (DSE Vic)

January 1999 Biological control of Paterson's curse LC0155 with the taproot flea beetle ISSN 1329-833X Keith Turnbull Research Institute, Frankston

Common and scientific names laying within a few weeks. Some adults may survive until late in spring. Paterson’s curse taproot flea beetle Eggs are laid on and around the crown of the plant. Larvae Longitarsus echii Koch (grubs) hatch after about three weeks, depending on the Family Chrysomelidae, leaf beetles environmental temperature. Background The larvae initially feed on the plant crown and leaf stalks, and then descend into the taproot where they feed Paterson’s curse (Salvation Jane), Echium plantagineum, is internally. After three months the larvae leave the root and a noxious weed of European origin found through much of pupate in the soil. Around one month later, they transform Victoria. It is a Regionally Controlled Weed in all into adults, which remain inactive in earthen cells in the Victorian Catchment and Land Protection Regions except soil until winter. Mallee. Landholders in these areas must take all reasonable steps to control and prevent the spread of this weed on their land and the roadsides which adjoin their land. A national program for biological control of Paterson’s curse involves the establishment of populations of the weed’s natural enemies and the redistribution of them to other sites as populations increase. A cooperative project between CSIRO and DNRE has led to the release of the Paterson’s curse taproot feeding flea beetle, Longitarsus echii, in Victoria. The flea beetle has been tested to ensure it is specific to Paterson’s curse and presents no danger to native plants or plants of economic importance. Description Adults - 2 to 4 mm long, shiny black, with a touch of bronze (Figs. 1 and 2). They have enlarged hind legs which enable them to jump considerable distances, hence the name ‘flea beetle’. The appendages, particularly the tarsi (feet) and antennae are reddish in colour. The antennae are almost as long as the body of the beetle. Eggs - Minuscule, reddish-brown and difficult to find. Larvae - Slender, cylindrical, up to 10 mm long by 2 mm wide, cream in colour with a dark head capsule. Larvae are rarely seen unless the taproot is cut open. Pupae - 5 mm by 2 mm, white to cream in colour, formed in an earthen cocoon in soil around the roots of Paterson’s curse. Figure 1. Adult of the Paterson’s curse taproot flea beetle, Life cycle The flea beetles have one generation per year. Adult beetles emerge from the soil in early winter and begin egg

released in Victoria in 1997. The complementary effects of these agents are expected to make the weed less competitive. Other insects, which will attack different parts of the plant, are being investigated. Biological control cannot totally eradicate a weed but may reduce the spread and density of infestations. In some cases control is achieved to the level where the weed is no longer of concern and no other control is necessary. More commonly, other methods are still required to achieve the desired level of control. Biological control should not be Figure 2. Adult Paterson’s curse taproot flea beetle. considered the complete answer to a Paterson’s curse problem. It is a technique that should be used in Impact conjunction with other control measures in an integrated Internal damage to the taproot caused by the feeding of management plan. mature larvae is the most important impact of the flea beetle. Root damage interferes with the flow of water and Further information nutrients from the soil to the plant, causing it to weaken. More information on Paterson’s curse is available in the For much of the year infested plants may show no external The Paterson’s Curse Management Handbook, the signs of beetle damage apart from wilting and poor general Landcare Notes: Paterson’s curse, Paterson’s curse condition. identification and Biological control of Paterson’s curse In winter and spring adult beetles feed on the leaves, with the stem-boring beetle, and in the pamphlets producing small “shot holes”. These holes are smaller and Biological control of Paterson’s curse using the leaf more irregular than those produced by the crown and root mining moth and Biological control of Paterson’s curse weevils, Mogulones larvatus and Mogulones with crown and root boring weevils, available from KTRI. geographicus, which have also been released to control For further information on Paterson’s curse please contact Paterson’s curse. your local NRE Catchment and Agricultural Services staff. Adult flea beetles cause only superficial damage to the For further information on the biological control of plant. Similar shot holes can also be produced by other Paterson’s curse contact: small animals, so are unreliable indicators of flea beetle presence. For example several species of native flea Keith Turnbull Research Institute, beetles may feed on Paterson’s curse and related plants in PO Box 48, Frankston, Victoria, 3199. summer, but their occurrence is patchy and damage to the Tel (03) 9785 0111 plant is insignificant. Fax (03) 9785 2007 email [email protected] Releases Acknowledgments The Paterson’s curse taproot flea beetle was first released Prepared by Blair Grace, Ian Faithfull and Tom Morley in Victoria in 1996. It is released onto the weed in large (KTRI) and Anthony Swirepik (CSIRO Division of cages at 'nursery sites'. Populations of the beetle are Entomology), 1996. Revised December 1998. Biological expected to build up within the cages, and to be harvested control of Paterson’s curse has been funded by Meat and for later re-distribution to other infestations. Nursery sites Livestock Australia, The Woolmark Company and NRE are selected by researchers and local NRE staff in and is supported by the Cooperative Research Centre for consultation with land owners and Landcare groups. Weed Management Systems. A release site should have a dense and persistent Paterson’s curse infestation and be connected to other neighbouring infestations so that the flea beetle can disperse more readily. The site should have a low priority for control by other techniques.

Integrated control The advice contained in this publication is intended as a source of Four other species of insect which attack Paterson’s curse information only. The State of Victoria and its officers do not guarantee that the publication is without flaw of any kind or is have been released in Victoria. The leaf mining moth, wholly appropriate for your particular purposes and therefore Dialectica scalariella, was first released in Victoria in disclaims all liability for any error, loss or other consequence which 1988 and was well established by 1992. The crown weevil, may arise from you relying on any information in this publication. Mogulones larvatus, was widely released from 1994 and redistributed from 1996 to 1998. The root weevil, Mogulones geographicus, was first released in early 1996. The stem-boring beetle, Phytoecia coerulescens, the larvae of which eat-out and girdle flowering stems, was first