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Biological Control and Ecology of Cabomba and Alligator Weed Cabomba. Source: Wikipedia Alligator weed. Source: Wikipedia www.rirdc.gov.au Biological Control and Ecology of Cabomba and Alligator Weed by Shon Schooler and Richard Chan, CSIRO Ecosystem Sciences May 2011 RIRDC Publication No 11/029 RIRDC Project No 08-53 © 2011 Rural Industries Research and Development Corporation All rights reserved. ISBN 978-1-74254-215-7 ISSN 1440-6845 Biological Control and Ecology of Cabomba and Alligator Weed Publication No. 11/029 Project No. AWRC08-53 The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication. The Commonwealth of Australia, the Rural Industries Research and Development Corporation and the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person arising directly or indirectly from any act or omission or for any consequences of any such act or omission made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors. The Commonwealth of Australia does not necessarily endorse the views in this publication. This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165. Researcher contact details Name: Shon Schooler Address: CSIRO Ecosystem Sciences, PO Box 2583, Brisbane QLD 4001 Phone: 07-3833-5662 Fax: 07-3833-5504 Email: [email protected] In submitting this report, the researchers have agreed to RIRDC publishing this material in its edited form. RIRDC contact details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6271 4100 Fax: 02 6271 4199 Email: [email protected]. Web: http://www.rirdc.gov.au Electronically published by RIRDC in May 2011 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 634 313 ii Foreword Alligator Weed (Alternanthera philoxeroides) and Cabomba (or Caroline fanwort, Cabomba caroliniana) are amongst the worst aquatic threats in Australia. Alligator weed was introduced to Newcastle (NSW) as a culinary herb in the 1940s, but it has now has spread to all States. Inundation allows Alligator Weed to outcompete other species and desirable forage grasses. Cabomba was most likely introduced to Australia as an aquarium plant, but it is now a serious aquatic weed throughout the country. Its dense infestations interfere with recreational and agricultural use of water bodies and crowd out native aquatic plants. Both Alligator Weed and Cabomba are very difficult to control after they invade water bodies. In view of the economic, social and environmental impacts and the difficulty of controlling both weeds by using conventional methods, biological control is recognised as an important research component in the national strategies for dealing with the weeds. This project extends the work of two previous projects, begun in 2003, aimed at finding safe and effective biological agents to control these weeds. In the earlier work, the researchers had identified, prioritised and started the host specificity testing of several potential invertebrate agents. The goal of this project was to provide safe and sustainable control of Alligator Weed and Cabomba through biological control and improvements in best-practice methodology. The researchers found the beetle Systena nientula is not a suitable biological control agent for Alligator Weed as it can complete its life cycle on several native species. The host specificity testing of the weevil Hydrotimetes natans was not completed due to insufficient numbers of the weevil being able to be reared in quarantine. However, several additional potential agents were identified for subsequent testing. In terms of non-biological controls, shading of Cabomba reduced the plant’s biomass, but it is not an effective eradication method because vegetative propagules remain in the sediment. This project was funded in Phase 1 of the National Weeds and Productivity Research Program, which was managed by the Australian Government Department of Agriculture, Fisheries and Forestry (DAFF) from 2008 to 2010. The Rural Industries Research and Development Corporation (RIRDC) is now publishing the final reports of these projects. Phase 2 of the Program, which is funded to 30 June 2012 by the Australian Government, is being managed by RIRDC. Further research will be funded on the ecology and dispersal of Cabomba and on the ecology and biological control of Alligator Weed. RIRDC is commissioning some 50 projects in Phase 2 that both extends on the research undertaken in Phase 1 and moves into new areas. Reports on these projects will be published in the second half of 2012. This report is an addition to RIRDC’s diverse range of over 2000 research publications which can be viewed and freely downloaded from our website www.rirdc.gov.au. Information on the Weeds Program is available online at www.rirdc.gov.au/weeds Most of RIRDC’s publications are available for viewing, free downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313. Craig Burns Managing Director Rural Industries Research and Development Corporation iii Acknowledgments In connection with the cabomba shading trial, thanks to Ms Henrika Sonne for the use of her property; Phil Moran (Noosa & District Landcare) managed the project and assisted with the construction, installation and removal of the shade fabric; Vanessa Moscato (Noosa & District Landcare and Noosa Water Watch) monitored water quality; Terry Stokes (Noosa Landcare volunteer) assisted with preparing and installing the shade fabric and propagating the native species for revegetation; and Andrew Petroeschevesky (National Aquatic Weeds Management Group) and Geoff Black (Sunshine Coast Regional Council) provided useful advice. iv Contents Foreword ............................................................................................................................................... iii Acknowledgments ................................................................................................................................. iv Executive Summary ............................................................................................................................. vii 1 Introduction ..................................................................................................................................... 1 2 Host specificity testing of Systena nitentula .................................................................................. 2 Methods............................................................................................................................................. 2 Origin of the colony ................................................................................................................... 2 Biology ....................................................................................................................................... 2 Host testing ................................................................................................................................. 3 Results ............................................................................................................................................... 4 Biology ....................................................................................................................................... 4 Host testing ................................................................................................................................. 4 Conclusions ....................................................................................................................................... 5 3 Host specificity testing of Hydrotimetes natans ............................................................................. 6 Methods............................................................................................................................................. 7 Origin of the colony ................................................................................................................... 7 Biology ....................................................................................................................................... 7 Host testing ................................................................................................................................. 7 Discussion ......................................................................................................................................... 9 4 Shade as an eradication strategy for Cabomba caroliniana ...................................................... 10 Methods..........................................................................................................................................