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Biological control of bridal creeper with the bridal creeper leafhopper | LC0168 |
Keith Turnbull Research Institute, Frankston
July, 1999 |  |
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This Landcare Note describes the bridal creeper leafhopper and its use in biological control.
Common name
Bridal creeper leafhopper
Scientific name
Zygina sp., Family Cicadellidae
Background
Bridal creeper, Asparagus asparagoides (L.) is native to South Africa. It was introduced into Australia during the 1870s as an ornamental garden plant and was popular for use in bridal bouquets, giving rise to its common name. It is now found in all southern states of Australia in a wide range of habitats.
Bridal creeper is a highly invasive environmental weed and unlike most environmental weeds can establish in undisturbed native vegetation. The climbing stems of bridal creeper form a dense canopy which smothers other vegetation, and the masses of underground roots can extend to form a thick, dense mat which destroys understorey plants.
Effective treatment of bridal creeper with herbicides or manual removal is expensive and labor intensive. These control methods are not feasible in many areas of Victoria because of the size and inaccessibility of infestations. Biological control is viewed as the preferred management option for bridal creeper infestations of this type. The Australian Quarantine and Inspection Service and Environment Australia have approved the release of the leafhopper as the first biological control agent for bridal creeper.
Description
Adults - Yellowish-white 2.5 to 2.6 mm long. Males are shorter than females and can be identified by the presence of genital claspers. Females develop a dark brown ovipositor prior to egg laying.
Eggs - Transparent, oblong, 0.5 to 0.6 mm long by 0.1 mm wide. Older eggs turn deep yellow and red eyespots become visible when the nymphs are ready to hatch.
Nymphs - Five nymphal instars (growth stages) with each instar progressively larger and whiter than the previous one. The fragile first instar nymphs are 0.8mm long and have soft yellow bodies. Wing buds appear at the third instar and sex identification is possible at the fifth instar.
Figure 1. Adult bridal creeper leafhopper.
Figure 2. Adult bridal creeper leafhopper (left) and five nymphal instars.
Life cycle
Bridal creeper leafhoppers feed and lay eggs on the under side of bridal creeper leaves. Nymphs tend to remain on the same leaf from egg to adulthood unless they are disturbed or their food is depleted. Adults live for 6 to 8 weeks and the females lay an average of 180 eggs in their lifetime. Eggs are laid just under the surface of mature leaves and hatch after 2 weeks. The nymphs require another 2 weeks to reach adulthood.
This short life cycle enables the bridal creeper leafhopper to have several generations per year. They breed more quickly at higher temperatures. In areas where bridal creeper grows all year round, either in summer rainfall areas or near watercourses, the leafhopper will remain on the host and continue to breed. However in most areas bridal creeper foliage dies back during summer and the populations go into decline until new growth appears in autumn.
Figure 3. Leafhopper egg inserted in a leaf.
Impact
Bridal creeper leafhoppers have sucking mouthparts that pierce the individual cell walls of bridal creeper leaves and extract the cell contents. They generally feed on adjacent cells, producing a zigzig damage pattern of white spots. Feeding damage increases with each nymphal moult. The greatest damage is caused by the adults. Although the leafhoppers live on and feed from the underside of leaves, they actually consume the contents of the upper layer of cells in the leaf, so their damage is usually only obvious on the upper surface. Dense populations of leafhoppers can remove all the cell contents of bridal creeper leaves, leaving them completely white.
Releases
The leafhopper is released at carefully selected nursery sites which are managed to enable the insect to multiply. Sites appropriate for releases are easily accessible for monitoring purposes, will not be affected by herbicides and preferably maintain foliage over the summer. Leafhoppers can later be harvested from these sites for redistribution to other infestations.
Integrated control
The leafhopper is the first biological control agent to be released on bridal creeper in Australia.Three other potential agents are being investigated. A leaf beetle Crioceris sp. and a seed wasp Eurytoma sp. were introduced to Perth for host specificity testing in October 1998. A rust fungus, Puccinia myrsiphylli, is currently undergoing host specificity testing in quarantine conditions in Canberra and is likely to be the next agent to be released. These organisms are all from South Africa, where bridal creeper originated, and are expected to limit the spread of bridal creeper by reducing biomass and directly or indirectly reducing seed production.
Biological control cannot eradicate a weed but can 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 considered the complete answer to a bridal creeper problem. It is a technique that should be used in conjunction with other control measures in an integrated management program.
Figure 4. Foliage of bridal creeper showing heavy leafhopper damage (left) and moderate damage (centre).
Further information
If you wish to be part of the biological control of bridal creeper program please contact you local Department of Natural Resources and Environment (NRE) officer or:
Emma Wills
Keith Turnbull Research Institute
PO Box 48, Frankston, Victoria 3199
Tel (03) 9785 0111 Fax (03) 9785 2007
Email Emma.Wills@nre.vic.gov.au
Further information on bridal creeper management is available in the NRE Landcare Note – bridal creeper.
Acknowledgements
The biological control program for bridal creeper has been funded by the Australian and New Zealand Environment and Conservation Council, the Cooperative Research Centre for Weed Management Systems, the Parks, Flora and Fauna Division of NRE and government departments in other States. Host specificity testing of the bridal creeper leafhopper was carried out by CSIRO Entomology. The Victorian biological control agent release program is funded by the Catchment Management and Sustainable Agriculture Division of NRE.
Prepared by Emma Wills. Edited by Ian Faithfull. Photos courtesy of CSIRO Entomology.
This note replaces note number BC0037
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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