The role of eutrophication in the biological control of water hyacinth, Eichhornia crassipes, in South Africa

BioControl ◽  
2011 ◽  
Vol 57 (2) ◽  
pp. 247-261 ◽  
Author(s):  
Julie A. Coetzee ◽  
Martin P. Hill
Keyword(s):  
South Africa ◽  
Biological Control ◽  
Water Hyacinth ◽  
Eichhornia Crassipes

Removal of Chlorpyrifos by Water Hyacinth (Eichhornia crassipes) and the Role of a Plant-Associated Bacterium

2015 ◽  
Vol 17 (7) ◽  
pp. 678-685 ◽  
Author(s):  
Choochai Anudechakul ◽  
Alisa S. Vangnai ◽  
Naiyanan Ariyakanon
Keyword(s):  
Water Hyacinth ◽  
Eichhornia Crassipes

Interactions within pairs of biological control agents on water hyacinth, Eichhornia crassipes

2013 ◽  
Vol 67 (3) ◽  
pp. 483-490 ◽  
Author(s):  
Danica Marlin ◽  
Martin P. Hill ◽  
Marcus J. Byrne
Keyword(s):  
Biological Control ◽  
Water Hyacinth ◽  
Eichhornia Crassipes ◽  
Biological Control Agents

Alien Invasive Aquatic Plant Species in Botswana: Historical Perspective and Management

2016 ◽  
Vol 9 (1) ◽  
pp. 1-40 ◽  
Author(s):  
C. N. Kurugundla ◽  
B. Mathangwane ◽  
S. Sakuringwa ◽  
G. Katorah
Keyword(s):  
South Africa ◽  
Biological Control ◽  
Plant Species ◽  
Water Hyacinth ◽  
Water Bodies ◽  
Pistia Stratiotes ◽  
Okavango Delta ◽  
Aquatic Weeds ◽  
Water Lettuce ◽  
The Government

Aquatic ecosystems in Botswana have been under threat by the aquatic alien invasive plant species viz., salvinia Salvinia molesta Mitchell, water lettuce Pistia stratiotes L., and water hyacinth Eichhornia crassipes (Mart.) Solms-Laub. While salvinia has been termed the major threat to the Botswana wetlands, water lettuce and water hyacinth are considered to be of minor importance. This review presents the species biology, distribution, historical spread, negative impacts, control achieved right from their discovery in the country by referring to their control and management in the world. Having infested the Kwando-Linyanti-Chobe Rivers in the 1970s, salvinia was initially tried by the use of herbicides, paraquat and glyphosate, between 1972 and 1976. With the discovery of the host specific biological control weevil Cyrtobagous salviniae Calder and Sands in 1981, the weevil was introduced by Namibians on Kwando and Chobe Rivers in 1983 and by Botswana in 1986 in the Okavango Delta. While the control was slowly establishing in Kwando-Linyanti-Chobe Rivers, it became apparent that lakes and perennial swamps within and outside Moremi Game Reserve of the Okavango Delta were infested with salvinia from 1992 onwards. With continuous and sustained liberation of the weevil in the Kwando-Linyanti-Chobe Rivers and in the Okavango Delta between 1999 and 2000, salvinia control was achieved by 2003, and since then the weevil constantly keeps the weed at low levels. The success is mainly due to sustainable monitoring through the application of physical and biological control methods. However, salvinia is still threatening the Okavango Delta due to factors such as tourism activities, boat navigation fishing and transporttion by wild animals. The first occurrence of water lettuce was recorded on Kwando and Chobe Rivers in 1986. Its biocontrol weevil Neohydronomous affinis Hustache was released in the year 1987. The weevil became extinct in Selinda Canal and Zibadianja Lake on Kwando River due to dry and wet events for over 10 years and the weed had been under control biologically on Chobe River. Having surface covered the Selinda and a part of the Zibadianja in high flood and rainfall in 1999/2000 season, research was undertaken to contain water lettuce, which led to its eradication by 2005. Regular physical removal of the water lettuce prior to fruit maturity is an effective method of control or eradicating the weed in seasonal water bodies. The Limpopo Basin (shared by Botswana, South Africa, Zimbabwe and Mozambique) has become vulnerable to water hyacinth infestation. Water hyacinth infested the trans-boundary Limpopo River in 2010 sourced from Hartbeesport Dam on Crocodile River in South Africa. Botswana and South Africa have been consulting each other to implement integrated control of the weed jointly in the Limpopo River. Water hyacinth could be a continuous threat to the dams and the rivers in the Limpopo basin if its control is not taken seriously. These three species are found growing in Botswana in a range of pH between 4.5 and 10.3 and in the range of conductivities between 20 and 580 µS cm-1. Range of soluble nitrates, phosphates and potassium in the habitats of salvinia infestations were 0.02 to 1.5, 0.01 to 1.78 and 0.3 to 6.92 mg L-1 respectively. Water lettuce infestation in the seasonal Selinda Canal had a maximum of 4.7 mg L-1 nitrates, 2.8 mg L-1 phosphates and 7.9 mg L-1 potassium. Nevertheless, these three nutrients were in the range of 0.41 to 9.56 mg L-1, 0.2 to 2.9 mg L-1, and 7.7 to 11.53 mg L-1 respectively in the Limpopo River where water hyacinth infestations were observed. These nutrients were considerably high during decomposition phase of biological control of weeds. The Government of Botswana “regulates the movement and importation of boats and aquatic apparatus, to prevent the importation and spread of aquatic weeds both within and from the neighboring countries” by “Aquatic Weed (Control) Act” implemented in 1986. These measures, combined with communities, conservation groups, NGOs and public awareness campaigns, have highlighted the gravity of aquatic weeds spreading into wetlands, dams and other water bodies. In conclusion, the Government of Botswana is committed and supportive through the Department of Water Affairs in protecting the wetlands of the country efficiently and prudently.

Eichhornia crassipes (water hyacinth).

2021 ◽  
Author(s):  
Julissa Rojas-Sandoval ◽  
Pedro Acevedo-Rodríguez
Keyword(s):  
Biological Control ◽  
Water Hyacinth ◽  
Management Strategy ◽  
Eichhornia Crassipes ◽  
Aquatic Plant ◽  
Integrated Management ◽  
Rice Paddy ◽  
The World ◽  
Rice Paddy Fields

Abstract E. crassipes, a native of South America, is a major freshwater weed in most of the frost-free regions of the world and is generally regarded as the most troublesome aquatic plant (Holm et al., 1997). It has been widely planted as a water ornamental around the world because of its striking flowers. Wherever it has encountered suitable environmental conditions it has spread with phenomenal rapidity to form vast monotypic stands in lakes, rivers and rice paddy fields. Then it adversely affects human activities (fishing, water transport) and biodiversity. It is impossible to eradicate, and often only an integrated management strategy, inclusive of biological control, can provide a long-term solution to this pest.

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