Weevils Called In To Combat Against Aquatic Weed Invasion

Researchers backed by the Victorian Government are developing innovative ways to combat a weed that is damaging Victoria’s waterways.

Parliamentary Secretary for Regional Victoria Danielle Green visited Senior Research Scientist Dr Raelene Kwong and her team at the Tatura SmartFarm, where they’ve identified three species of weevil, a small beetle attracted to moisture, as an important natural enemy of the sagittaria weed.

Sagittaria has been invading waterways in southern-eastern Australia since the 1960s – when it was imported into Australia from the USA as an attractive ornamental pond plant. It has since been declared a problematic species.

Dr Kwong identified three different weevil species, also from the USA, that could help control the long grassy plant. The beetles were imported into the Government’s secure quarantine facilities at AgriBio in Bundoora.

Researchers have conducted stringent testing of the weevils over the last five years to demonstrate releasing them would not pose a threat to native species or other important plants in Australia.

More than $2 million is spent in Victoria by waterway managers in the Goulburn Murray Irrigation District to try and control this highly invasive weed each year. Sagittaria chokes native plants, hinders the movement of fish and impedes waterflows to farms and orchards.

The Tatura SmartFarm is the ideal location to produce and release weevils because it is close to some of the worst sagittaria infestations in the state.

Scientists from the SmartFarm will now collaborate with farmers, community groups and waterway authorities to release the weevils and closely monitor their impacts. When the adult weevils are released, they will attack the sagittaria by laying their eggs in the flowers and fruits of the plant. Both the larvae and adult weevils then feed on the weed.

According to Dr Kwong, it may take time for the weevil to have a measurable impact. However, the long-term benefits of biocontrol are both ecologically and economically significant with the weevil reducing the high quantities of sagittaria seed that spread rapidly downstream.

The Tatura SmartFarm is one of five SmartFarms in the state delivering on the Government’s commitment to modernise and protect the state’s farming industries through innovation, investment and future skills as outlined in its ten-year Strategy for Agriculture. For more information on SmartFarms, visit agriculture.vic.gov.au.

Source: Vic Government