Biological Control of Paterson's Curse with the Stem-Boring Beetle
Note Number: LC0159
Published: December 1997
Updated: December 1998
Common and scientific names
Paterson's curse stem-boring beetle
Phytoecia coerulescens (Scopoli)
Family Cerambycidae, Longicorn beetles
Background
Paterson’s curse, Echium plantagineum L. is a noxious weed of European origin found through much of Victoria. A national program for the biological control of Paterson’s curse, led by CSIRO Division of Entomology, involves the establishment of populations of the weed’s natural enemies in suitable infestations and the redistribution of them to new sites as populations increase. One of these natural enemies is the Paterson's curse stem-boring beetle,Phytoecia coerulecsens.
Description
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Figure 1. Adult stem-boring beetle. |
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Figure 2. Larva of the stem boring beetle. |
Adult - Size highly variable (12 to 25 mm long) depending on the host plant size and larval competition within the root. Colour varies from grass green to steel blue. Antennae are nearly as long as the body, curved and mobile so that they can be directed backwards above andparallel with the body.
Egg - Yellow, 2 to 3 mm long, cylindrical, inserted in a wound made by the female in the epidermis of the basalthird of the flowering stem.
Larva - Elongate, cream-coloured grub, up to 25 mm long, straight-bodied, distinctly segmented, no legs. Head brown and somewhat sunken into thorax. Mandibles large andstout.
Pupa - Cream-coloured, enclosed in a cell at the base of ahollowed-out stem which is plugged with stem fibres.
Life cycle
Females begin laying eggs in spring when the plant is bolting. Eggs are laid on the basal third of the floweringstem and take approximately one week to hatch.
During development of the first three larval stages (known as instars), the larva mines upwards and feeds on the growing stem. Once mature, the final instar larva bores down the stem, which it girdles 4 to 10 cm above the ground, and continues into the stem base or root stock. The mine is plugged at each end with fibres from the stem, forming a cell within which a single larva remains dormantthrough the winter.
Pupation occurs in early spring. Adults emerge from spring to early summer and feed on flowers and stem leaves of Paterson’s curse. Mating and egg-laying commences soonafter emergence.
Impact
Damage is most severe to small, thin-stemmed plants. The boring of larvae in stems just large enough to support a larva to maturity may cause the stems to be completely eaten out and girdled, before any seed can be produced. There is little effect on large, thick-stemmed plants otherthan stems becoming weakened and falling over.
Releases
Releases of the Paterson's curse stem-boring beetle were first made in Victoria in December 1998, focused on North East Victoria where Paterson’s curse is a major problem. Release sites are selected by researchers and local DNRE staff in consultation with land owners and Landcaregroups.
Releases are targetted at dense and persistent infestations of Paterson’s curse with a low priority for control by other methods. Release sites need to be part of large infestations, or connected to them, so that the beetle can spread easilywhen its population increases.
Integrated control
Four other natural enemies of Paterson’s curse have already been released in Victoria. The leaf mining moth, Dialectica scalariella, was the first biological control agent to be released, in 1988. The crown weevil, Mogulones larvatus, was released in 1993 and the root weevil, M. geographicus, was released in 1996. The fourth agent, the Paterson’s curse taproot flea beetle, Longitarsus echii, was also released in 1996. The combined effects of these agents is expected to have a significant impact onPaterson’s curse infestations.
Biological control is not appropriate for many infestations of Paterson’s curse. A local integrated weed management plan should be developed for each particular area. The plan should identify opportunities for integrating all available control options, including biological control, in the mostenvironmentally sensitive, economic and efficient manner.
Biological control will not totally eradicate a weed but may reduce its spread and density. In some cases control is achieved to a level where the weed is no longer considered a problem. More commonly, other methods are still required to achieve the desired level of control. Biological control should not be considered the complete answer to a Paterson’s curse problem. It is a technique that can be used in conjunction with other control measures in theintegrated management of this weed.
Further information
Biological Control Note. Biological control of Paterson’scurse using the leaf mining moth, Dialectica scalariella.
Biological Control Note. Biological Control of Paterson’scurse with crown and root boring weevils.
Landcare Note: Biological control of Paterson's curse withthe taproot flea beetle.
Landcare Note. Paterson's curse.
Landcare Note. Paterson's curse identification.
For further information please contact your local Catchment Management Officer of the Department ofNatural Resources and Environment or
Keith Turnbull Research Institute,
PO Box 48 Frankston, Victoria, 3199.
Tel (03) 9785 0111 Fax (03) 9785 2007
References
Kirk, A.A. and Wapshere, A.J. (1979). The life history and host specificity of the Echium borer, Phytoecia coerulescens [Col.: Cerambycidae]. Entomphaga 24, 423-430.
Parsons, W.T. and Cuthbertson, E.G. (1992). NoxiousWeeds of Australia. Melbourne, Inkata Press.
Acknowledgements
Prepared by Kerry Roberts, Tom Morley and Ian Faithfull, 1997. Photographs by Blair Grace. Revised 1998. Biological control of Paterson's curse is partly funded by The Woolmark Company and Meat and Livestock Australia and is a project of the Cooperative ResearchCentre for Weed Management Systems.
It was reviewed December 1998
