Hyacinth mite developed
THE biological control unit at Namulonge Agricultural and Animal Research Institute will soon introduce local fungal pathogens to feed on water hyacinth in areas where the conditions do not support the survival of the weevils. One of such pathogens is the grazing mite (Orthogolumna terrebrantis).
By Timothy Muwonge and P. Nansubuga
THE biological control unit at Namulonge Agricultural and Animal Research Institute will soon introduce local fungal pathogens to feed on water hyacinth in areas where the conditions do not support the survival of the weevils. One of such pathogens is the grazing mite (Orthogolumna terrebrantis).
The two weevils, Neochetina Bruchi and Neochetina Encomia, which cleared the weed from the region’s major water bodies at the peak of its infestation in the 90s, cannot survive in cold weather, highly turbid and fast moving water conditions. However, these conditions favour the multiplication of the weed.
Dr Richard Mollo, the lead researcher on the fungal pathogens said they are host- specific, can survive in any weather feeds and breeds on only the green part of the hyacinth.
“The fungal pathogens have nothing to do with the roots and their performance will therefore, not be affected by poor aeration in the water unlike the weevils. In areas where the weevils are operating, they will very easily penetrate the spores made by the weevils on the hyacinth to damage it even faster. So, the combination will definitely contain the up coming problem†Dr Mollo said.
The Head, Biological Unit, Dr. James Ogwang, said the weevils’ biology is linked to the quality of water and weather where the plants are growing.
“The weevils failed to establish their colony on the thick mats of the hyacinth at the source of the Kagera River in the highlands of Rwanda because of very cold weather.
The other factor is the fast moving waters which sweeps the weevils downstream before causing the desired impact on the weed,†he said.
The other factor Dr Ogwang also noted was the turbid and heavily polluted waters, like where the Nakivubo channel enters L.Victoria. These, he said, greatly reduce on the circulation of oxygen in the water, which results in the death of the weevils at pupae stage.
He however, said the weevils had done a great job on resident mats of the hyacinth that had clogged the major water bodies and that the few mats that are resurging will be controlled in a natural cycle.
“No amount of effort will ever eradicate the water hyacinth from the water bodies, but rather to keep it within maintenance level where it is continually suppressed by the weevils as it regenerates in a natural cycle†Ogwang noted.
THE biological control unit at Namulonge Agricultural and Animal Research Institute will soon introduce local fungal pathogens to feed on water hyacinth in areas where the conditions do not support the survival of the weevils. One of such pathogens is the grazing mite (Orthogolumna terrebrantis).
The two weevils, Neochetina Bruchi and Neochetina Encomia, which cleared the weed from the region’s major water bodies at the peak of its infestation in the 90s, cannot survive in cold weather, highly turbid and fast moving water conditions. However, these conditions favour the multiplication of the weed.
Dr Richard Mollo, the lead researcher on the fungal pathogens said they are host- specific, can survive in any weather feeds and breeds on only the green part of the hyacinth.
“The fungal pathogens have nothing to do with the roots and their performance will therefore, not be affected by poor aeration in the water unlike the weevils. In areas where the weevils are operating, they will very easily penetrate the spores made by the weevils on the hyacinth to damage it even faster. So, the combination will definitely contain the up coming problem†Dr Mollo said.
The Head, Biological Unit, Dr. James Ogwang, said the weevils’ biology is linked to the quality of water and weather where the plants are growing.
“The weevils failed to establish their colony on the thick mats of the hyacinth at the source of the Kagera River in the highlands of Rwanda because of very cold weather.
The other factor is the fast moving waters which sweeps the weevils downstream before causing the desired impact on the weed,†he said.
The other factor Dr Ogwang also noted was the turbid and heavily polluted waters, like where the Nakivubo channel enters L.Victoria. These, he said, greatly reduce on the circulation of oxygen in the water, which results in the death of the weevils at pupae stage.
He however, said the weevils had done a great job on resident mats of the hyacinth that had clogged the major water bodies and that the few mats that are resurging will be controlled in a natural cycle.
“No amount of effort will ever eradicate the water hyacinth from the water bodies, but rather to keep it within maintenance level where it is continually suppressed by the weevils as it regenerates in a natural cycle†Ogwang noted.