VIDEO: Nessie versus Mimosa. How tiny beetles are being deployed in the fight against invasive weeds

Territory Natural Resource Management created this video to showcase the weed management work it’s doing in partnership with the Bulgul Rangers and the Department of Land Resource Management’s weed management division.

It provides a 7-minute snapshot of one of the simplest and cost-effective methods being used in the Finniss River catchment area, south of Darwin, to manage widespread infestations of one of Australia's worst weeds, Mimosa pigra.

Mimosa can grow so quickly and extensively that it prevents access to waterways and chokes up floodplains, threatening cultural, recreational, pastoral and environmental activities.

To combat the massive problem of Mimosa tiny, golden brown beetles known as Nesaecrepida infuscata, or Nessie, have been introduced as biological control agents.

Nessie are not much bigger than a flea, but are very effective against Mimosa because they eat the weed, making it more susceptible to disease and reducing its ability to grow and produce seeds.

The video shows DLRM Weed Management Branch’s bio-control officer Bert Lukitsch and the Bulgul Rangers visiting bio-control sites where Nessie has been used to thin out the weeds and slow its growth.

One of the areas Nessie has been deployed is in paper bark swamps where it’s not possible to use chemicals as this could cause off-target damage to nearby, native flora species.

Managing weeds in the Finniss River catchment area is an ongoing process that Territory NRM has been involved in for several years.

Territory NRM continues to work with the Bulgul Rangers to distribute Nessie to areas that are difficult to access or that contain sensitive native species such as Melaleuca woodland.

Other methods being deployed to control Mimosa include ground foliar spraying, granular herbicide application, and aerial spraying using helicopters and fixed wing airplanes.

The Bulgul Rangers, Territory NRM and the DLRM weed management branch intend to establish several more bio-control sites within the Finniss River catchment area, in particular the lower floodplains.

It’s envisioned the populations of Nessie will spread over time and eventually reach all core mimosa infestations in the area, helping to thin the weed out and reduce its seed output.