Little did the 19th century royal ruler of Egypt, Muhammad Ali, imagine when he decided to use the pretty blue flower recently brought into Egypt to embellish his palace fountain, what a scourge it would spread to be
. The beautiful water hyacinth has proliferated along the Nile and its many canals to become a menace of unimaginable proportions affecting the livelihood of people who depend on river access, and costing the State millions of pounds in attempts to eliminate it. Scientists are pitting their wits against this invasive species as they try to find a solution.
In its native habitat of South America, the water hyacinth is part of a well-established ecosystem and poses no threat to the environment. Outside its natural habitat, however, the plant’s explosive growth is relentless. It destroys biodiversity, depletes oxygen, reduces water quality, and blocks waterways, thus hampering agriculture, fisheries, recreation and hydropower.
Scientific researcher Yehia Hussein Fayyad, head of Egypt’s plant care research centre and manager of the biological project for water hyacinth control, told Watani how the water hyacinth came to be such a pest in regions outside its native habitat and beyond the reach of its natural enemies.
• How did the water hyacinth arrive in Egypt?
For its beauty of colours, Muhammad Ali Pasha who ruled Egypt from 1805 to 1848 and goes down in history as the founder of modern Egypt, was the first to use the water hyacinth as decoration inside his palace gardens. Officials threw the surplus into the River Nile, and this began the infestation of this part of Africa. Before the Aswan High Dam was built in the 1960s the annual flood helped to dispel the plant by carrying it out to sea, where it was killed by the salinity. The plant was first registered in Egypt as a nuisance in 1932 by an English expert in pest control working at the Egyptian Ministry of Agriculture.
• What are the main methods used in Egypt to combat the water hyacinth?
Up to 1990, Egypt’s Ministry of Water Resources and Irrigation used manual, mechanical and chemical control methods, but these methods cost the State millions of Egyptian Pounds annually. Then, in 1990, a new decree was issued banning the use of chemicals pesticides on all water courses in Egypt.
In 1999, a project to combat water hyacinth biologically was approved. With a French fund for five years in the lakes of Mariout and Edku as the first phase, the project involved using specific insect species to eliminate the plant. In 2004, the second phase for Lake Burulllus and Lake Manzala was approved. This entailed the introduction of two species of weevil.
Biological control could provide a lasting, cost-effective, environmentally safe solution, and is theoretically the best method for solving the water hyacinth problem.
• How do these insects overcome the water hyacinth?
The two weevil species, Neochetina eichhorniae and Neochetina bruchi, and two moth species, Niphograpta albiguttalis (previously known as Sameodes albiguttalis) and Xubida infusella, are all present in Argentina and have evolved alongside the plant to create a natural and harmonious balance. Once the plant is no longer there, the weevil dies, so there is no fear of an upset in the ecological balance.
N. eichhorniae has been especially efficacious and has played a key role in removing large infestations of water hyacinth in tropical areas. The other weevil, N. bruchi, was tested in Australia and was found to be effective in battling water hyacinth. It is suggested the introduction of both weevils to an aquatic system is the best possible option, because their life cycles complement each other. However, both weevils are much less effective in sub-tropical and cooler areas.
• What real achievements have been realised in the project so far?
Biological combat has proved effective. The total area in Lake Edku covered by water hyacinth decreased by 39.6 per cent during the period from April 2000 to March 2001. This was repeated at the eastern end of Lake Mariout, where the plant decreased by 29 per cent over the same period. So far water hyacinth infestation has decreased by 95 per cent in Egypt as a whole.
• What do you think about the call to make use of water hyacinth in the production of animal feed or paper?
This is not recommended, since this plant absorbs heavy metal elements that cause serious disease in humans, such as kidney failure, hepatitis and cancer. And if the plant is used as animal feed, these elements would be transmitted to humans who consume dairy products or meat. Why would we create an industry from a plant that should be eliminated?
• Residents in some governorates are still registering complaints about the plant. Do you have a comment on this?
The water hyacinth grows from seed and through vegetative reproduction. Seeds are produced in capsules at the base of each flower. Daughter plants are produced by vegetative reproduction, and remain attached to the parent plant until they are broken off by wind or other physical damage. Flowering can begin as early as October and continue through the summer months. Each of the flowers on a stalk remains open for one to two days before beginning to whither. When all the flowers on a plant have withered the stalk gradually bends into the water, and after about 18 days seeds are released from capsules at the base of each dead flower.
Complaints are renewed at this time every year because it is the pollen season. But we are following up on the situation in the lakes, and have found that there is an adequate ecological balance as far as the hyacinth and the weevil are concerned.
The number of complaints has fallen sharply and is now only 5 per cent of the number before the current eradication programme began.
As long as the biological combat is on hand, there is no place for fears of the scourge of the water hyacinth.
4 May 2014
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