VG06014 Revegetation for thrip control

Horticulturalists on the Northern Adelaide Plain continue to experience serious crop losses due to Tomato Spotted Wilt Virus (TSWV).

A key source of TWSV are the pest thrips including Western Flower Thrip (Frankliniella occidentalis) which transmit the virus are exotic weeds which infest land around horticultural production facilities in the region.

In addition, the region has a degraded natural landscape and there is a serious lack of commercial incentives to improve biodiversity in the area. By 1889 exotic weeds had infested parts of the region and remaining woodlands in the Angle Vale and Virginia areas were cleared for market gardens after World War I.

Previous research, has shown that TSWV vectoring thrips are rare on a range of native broadleaf plants and grasses. In addition, a number of potentially beneficial arthropods were present on native plants in the region.

Here we build on these findings by examining how key insect species interact with native plants and nearby crops, in attempts to understand how we can manipulate the environment at a property scale, to suppress/enhance specific insect species.

As part of this project we established native revegetation plots near several horticultural production facilties in the region.

This report details the research and extension undertaken in this project and covers the key findings, industry implications and recommendations.

Key Findings :

• Key findings confirm that judicious placement of select endemic plant species near horticultural facilities has potential for positively impacting on pest management and is likely to be more effective than traditional bare-earth buffers.

• A new parasitic wasp (Ceranisus sp.) was identified that has been shown to efficiently parasitise western flower thrips in culture. This wasp is closely associated with the saltbush Rhagodia parabolica and may also use native thrips species as an alternative host.

• We have also identified a Telenomus sp. wasp sampled from native vegetation that parasitises the well known pest Nysius vinitor, the Rutherglen bug. These wasps are likely candidates for delivering biological control of both of these wide spread pests.

• Breeding of a lacewing generalist predator Micromus tasmaniae is shown to be associated with a native grass, Austrodanthonia linkii, suggesting this will be key species for manipulating M. tasmaniae populations at property scale.

  Indications are that different endemic plant species will become important for different crops to enhance/suppress particular beneficial/pest species.

Top – saltbushes – Rhagodia parabolica and Enchylaena tomentosa
Bottom – native grass – Austrodanthonia linkii

Key Findings (cont) :

• Growers investing in native plant refuges to enhance natural enemy populations should see this as a marketing opportunity rather than simply another expense.

• At property scale, select native plants used in the context of best practice Integrated Pest Management systems, can contribute to suppression of western flower thrips and subsequent reduction of TSWV is possible.

• Feedback from growers on the NAP indicates that the benefits of native vegetation are well understood. Therefore grower acceptance of these principles has increased with time, however large-scale adoption remains the key to positioning the industry to achieve significant benefits.

• Growers must be willing to be proactive in increasing the level of integration of non chemical controls. Reduced efficacy and tolerance of chemical use for pest control will have long term consequences industry wide. In the current economic climate, integrating new technologies that increase agricultural sustainability by reducing losses generated by pests, disease and pesticide use are urgently required for the industry to move forward.

SEE ALSO :

VG05014  Native Vegetation and Pest Control – part 1 (2006)

  VegeNote : Native Vegetation and Pest Control (2008)

Acknowledgements :

Special thanks go to Nick Stevens for his valued contribution to identifying our parasitoids. Thanks to consultants Mr Bill Doyle (botanist) and Mr Mario Niesingh (revegetation provider – Environmental Revegetation Australia) for assistance and advice on planting native plants.

We would also like to thank members of the ‘Revegetation at property scale’ project management team Tony Burfield, Domenic Cavallaro, Bill Doyle, Gavin Limbert and Stacee Brouwers for their considerable knowledge, advice and practical support towards the delivery of the project on the Northern Adelaide Plains.

Thank you also to the vegetable growers and their families Mr Thien Vu and Mr Dino Mussolino who kindly hosted two of our on-farm trials in Virginia, and for the constant support provided by the Virginia Horticulture Greenhouse Modernisation Project.

To the City of Playford revegetation staff, Green Corps and the Youth Conservation Council for planting hundreds of native plants.

Special thanks to Liz Millington, Anthony Fox, and Jeanette Chapman for working so tirelessly with us to close the gap between Horticulture and Natural Resources Management on the Northern Adelaide Plains.

We thank all SARDI Entomology Unit staff who generously provided a diverse range of support over the previous 6 years.

This project has been facilitated by the South Australian State Government, Rural Industries Research and Development Corporation (RIRDC), Virginia Horticulture Centre, The
City of Playford and Horticulture Australia Limited (HAL)
in partnership with AUSVEG through the National Vegetable Research and Development Levy.

The Australian Government provides matched funding for all HAL’s R&D activities.