A light purple flower spike of water hyacinth

Water hyacinth is one of the world's worst water weeds clogging waterways and disrupting their use.

Biological control of water hyacinth

One of the world’s worst aquatic weeds, water hyacinth, has been controlled in many places around the world using biological control agents.

  • 30 January 2007 | Updated 14 October 2011

The weed

Water hyacinth, Eichhornia crassipes, a native of the upper Amazon catchment, is one of the world's worst aquatic weeds.

It was first noticed in Australia in Brisbane, Sydney and Grafton in the 1890s and was probably imported as an aquarium plant. Its ability to thrive in garden ponds ensured its rapid spread around the country until it was found in every mainland State and Territory.

Water hyacinth is an attractive, floating waterweed with a fibrous root system and dark green rounded leaves up to five centimetres in diameter. Flowers are light purple with a darker blue/purple and yellow centre and are carried in dense spikes projecting above the plant.

It can reproduce both vegetatively and through the production of vast quantities of seed. Once in rivers, dams and lakes, an infestation can double in size in a few weeks.

Water hyacinth forms dense mats that clog waterways and make them useless for navigation and other uses.

The problem

Water hyacinth forms dense mats that interfere with:

  • navigation
  • recreation
  • irrigation
  • power generation.

These mats also out-compete native aquatic plants.

Low oxygen conditions develop under water hyacinth mats and the dense floating mats impede water flow and create good breeding conditions for vectors of human and animal diseases.

The clogging of waterways may also interfere with the use of a water-body for cultural, social or commercial purposes causing substantial economic hardship and putting livelihoods at risk.

Biological control in Australia

Several biocontrol agents were released in Australia in the 1970s and 1980s, building on the initial research done in the USA. The tunnelling larvae of these insects achieved good control in sub tropical and tropical eastern Australia.

Two agents, a weevil, Neochetina eichhorniae, and a moth, Niphograpta albiguttalis, were released in the 1970s and another weevil, Neochetina bruchi, was introduced in 1990.

A moth, Xubida (Acigona) infusella, was released in Australia in 1981 but only limited establishment occurred in southern Queensland and impact is minimal.

Biological control overseas

It is overseas where CSIRO's expertise has had the most spectacular results. Most of this was due to the two weevils. The successful control of water hyacinth in many countries around the world has become one of the most spectacular examples of biological control.

Lake Victoria covered in water hyacinth at Kisuma in Kenya

Lake Victoria at Kisuma Yacht Club in Kenya before biological control agents cleared it of water hyacinth.

Lake Victoria at Kisuma clear of water hyacinth

Lake Victoria at Kisuma Yacht Club after biological control agents cleared it of water hyacinth.

CSIRO scientists assisted by:

  • providing biological control agents to other countries
  • surveying of the weed
  • satisfying pre-release requirements
  • establishing breeding colonies at key locations in each country
  • distributing agents
  • monitoring their effects.

Massive infestations in the Sepik River lagoons in Papua New Guinea, were cleared in less than five years.

Similarly, in collaboration with a range of organisations, huge infestations in Lake Victoria in Kenya, Uganda and Tanzania, were cleared of water hyacinth in less than three years.

The technology has also been used by others with dramatic effects in other countries such as Benin in West Africa, in South Africa and in Thailand.

The research by CSIRO was supported by the Australian Centre for International Agricultural Research (ACIAR) and AusAID.

Learn more about the Ecology and management of Australian weeds.