Biocontrol for aquatic weeds
Council currently grow four species of weevil within the Biological Control facility in Durack. These weevils are grown to combat Salvinia (Salvinia molesta), Water Lettuce (Pistia stratiotes) and Water Hyacinth (Eichhornia crassipes). The four weevil species are:
- Cyrtobagous salviniae (Salvinia weevil)
- Neochetina bruchi and Neochetina eichorniae (Water Hyacinth weevils)
- Neohydromonus affinis (Water Lettuce weevil).
Council runs the facility which forms part of a cooperative effort with neighbouring Councils and SEQ Water. The facility provides biocontrol agents for the control of these aquatic weeds across south east Queensland.
Aquatic weed impacts
Aquatic weeds can have a devastating impact on water ways affecting environmental, social and economic values as they:
- restrict water flow
- block gaseous exchange (leads to de-oxygenated water)
- decrease value as habitat for aquatic fauna
- increase cost of water treatment
- can create a breeding ground for mosquitoes.
Benefits of biocontrol for invasive aquatic weeds
Aquatic weeds can be difficult to control due to issues with access and the sensitivity of their environment. Some advantages of using biological control include:
- species specific – they only impact target species
- tested and trialled – these weevils have been deployed across Queensland for decades, with widespread acknowledgement of the results. The program also won a Healthy Land and Waterways Award for Government Stewardship in 2017
- prevent thousands of tonnes of biomass from compromising the water quality in the Brisbane river
- minimise the damage to local infrastructure
- reduce the need to use chemicals in waterways
- reduce the financial burden on SEQ residents to manage aquatic weeds
- capable of establishing in places that are difficult or dangerous to access
- reduce the social impacts of managing common areas.
All Brisbane residents are eligible to apply for biocontrol to manage aquatic weed infestations on private land. Council staff can also access them for the management of weeds on public land. There is no cost associated with the program for people in the Brisbane Local Government Area (LGA).
Other program partners include:
- SEQ Water
- City of the Gold Coast
- Redlands City Council
- Moreton Bay Regional Council
- Scenic Rim Regional Council.
If you live in an area covered by a program partner, contact them directly to access the program free of charge. If you are outside the program area, you can still apply, however costs may apply and are based on the extent of the infestation.
Permits and application process
The distribution of aquatic biocontrol agents (weevils) is undertaken in accordance with a permit issued under the Biosecurity Act 2014. As a result, there is an administrative process that requires the collection of information and assessment of applications prior to accessing the facility.
If you would like to obtain weevils to manage an aquatic weed, complete the online form. Submit the form, including relevant photos of the waterway and the infestation you are seeking to manage. Council will conduct a desktop assessment and contact you to discuss the recommended treatment option.
Application for Biological Control agents
Weevil acquisition and the ongoing function of the weevil facility is facilitated through aquatic weed exchange. On collection day, you will be provided with the weevils in double-lined garbage bags, along with the aquatic weed that you are treating. This ensures that you will be receiving the full life cycle of weevils – including the adults, larvae and eggs. This is the most effective method of establishing a self-sustaining colony.
Weed material at the biocontrol facility is regularly removed and consumed by the breeding population of weevils and must be replenished frequently. This provides the weevils with fresh feed and ensures that the breeding program can continue. When collecting biological controls, you may be requested to provide some of your fresh aquatic weed in return for the material that contains the biocontrol agents. Further guidance on this will be provided as your application progresses.
The best time to introduce the weevils into your dam or pond is during the warmer months and when your water levels are at their highest and not receding. Council will provide information on the best techniques for deployment during your application process.
Recent releases in Brisbane
Two species of beetle have been released to assist with the management of Madeira Vine (Anredera cordifolia) and Cat’s Claw Creeper (Dolichandra unguis-cati). These beetles will not cause the plant to die, however will complement existing control measures in managing the invasive vines and can compromise the health of the plant, allowing native species to recover.
The cat’s claw creeper jewel beetle (Hylaeogena jureceki) has been released at a number of sites within south east Queensland since it was approved for Australian release in May 2012. The release of the jewel beetle, in addition to the release of the leaf sucking tinged (Carvalhotingis visenda) and leaf-tying moth (Hypocosmia pyrochroma), will prove valuable in helping to manage the challenging vine.
The leaf feeding madeira vine beetle (Plectonycha correntina) was first released in Queensland in 2011. Both the adult and larval stages of this beetle feed on madeira vine leaves.
For information regarding Council’s Biological Control Facility or other biological control strategy, contact Council on 07 3403 8888 or email the project team.