The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp.

Wilson, John R.; Ajuonu, O.; Center, Ted D.; Hill, Martin; Julien, M. H.; Katagira, F.; Neuenschwander, Peter; Njoka, Stephen; Ogwang, J.; Reeder, Robert W.; Van, Thai K.

doi:10.1016/j.aquabot.2006.06.006

Cited by 79 publications

(48 citation statements)

References 8 publications

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“…But we clearly observed that the positive results occurred only due to biocontrol agents. The similar effects has been discussed in Lake Victoria and they concluded without biocontrol weevils water hyacinth would not have been controlled (Wilson et al, 2007) . The studies indicated the potential role of Neochetina spp.…”

Section: Resultssupporting

confidence: 55%

“…The biocontrol of water hyacinth in pond, river and dams has been a successful method employing weevils in various counties (Abjar and Bashir, 1984;Aguilar et al, 2003;Center et al, 1999a;Center and Dray Jr, 1992;Ochiel et al 2001;Wilson et al, 2007). The impact of Neochetina bruchi and Neochetina eichhorniae were monitored every month in the experimental site (Kadapokathi village) and control site (Vallukam parai) (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Impact of release of Neochetina spp. on growth and density of water hyacinth Eichhornia crassipes

Sivaraman

Murugesan

2017

JBC

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Water hyacinth (Eichhornia crassipes) is an invasive aquatic macrophyte which creates several problems in irrigation system of rivers. To control their rapid distribution in water bodies the biological control method was carried by employing weevils Neochetina bruchi and Neochetina eichhorniae on river based field trial. The study demonstrates effectiveness of biocontrol weevil open field release on experimental site (Chittar river). When compared to first release in field, the weevil intensity was increased in numbers. Active scraping was observed in the leaves and decay spots were seen in the stems of weed. Both N. bruchi and N. eichhorniae (250 No) were introduced biyearly at experimental site for one year. During these two years of observation period, stunted growth and reduced population were observed in the study site. The study highlights importance of Neochetina spp. on the management of E. crassipes.

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Section: Resultssupporting

confidence: 55%

Section: Resultsmentioning

confidence: 99%

Impact of release of Neochetina spp. on growth and density of water hyacinth Eichhornia crassipes

Sivaraman

Murugesan

2017

JBC

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“…The control of water hyacinth depends on the age of the plants, habitat, flooding, climatic conditions and nutrients especially nitrates and phosphates. "Biocontrol has been successful in tropical countries such as Papua New Guinea [200], Malawi [201], Lake Victoria [202,203], where only N. eichhorniae and N. bruchi were released" [15]. In Benin control by N. eichhorniae was substantial but not satisfactory [204,205].…”

Section: Biological Control Agentsmentioning

confidence: 99%

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

Kurugundla¹,

Mathangwane²,

Sakuringwa³

et al. 2016

TOPSJ

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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...

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“…The hyacinth invasion was in large part managed between 1997 and 1999 through manual removal and the introduction of a weevil (Neochetina eichhorniae). The effects of these management procedures were probably enhanced by an El Niño episode (1997)(1998), during which elevated water levels broke off large hyacinth stands, and where low light conditions (clouds) and rain reduced hyacinth growth (Njiru et al 2002, Williams et al 2005, Wilson et al 2007. Even though the hyacinth bloom was probably triggered by eutrophication, its decline is not a reaction to improved water quality: there are multiple pathways to any single phenomenon.…”

Section: Introduced Species Changed Ecosystemmentioning

confidence: 99%

Coupled human and natural system dynamics as key to the sustainability of Lake Victoria’s ecosystem services

Downing¹,

Nes²,

Balirwa³

et al. 2014

E&S

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ABSTRACT. East Africa's Lake Victoria provides resources and services to millions of people on the lake's shores and abroad. In particular, the lake's fisheries are an important source of protein, employment, and international economic connections for the whole region. Nonetheless, stock dynamics are poorly understood and currently unpredictable. Furthermore, fishery dynamics are intricately connected to other supporting services of the lake as well as to lakeshore societies and economies. Much research has been carried out piecemeal on different aspects of Lake Victoria's system; e.g., societies, biodiversity, fisheries, and eutrophication. However, to disentangle drivers and dynamics of change in this complex system, we need to put these pieces together and analyze the system as a whole. We did so by first building a qualitative model of the lake's social-ecological system. We then investigated the model system through a qualitative loop analysis, and finally examined effects of changes on the system state and structure. The model and its contextual analysis allowed us to investigate system-wide chain reactions resulting from disturbances. Importantly, we built a tool that can be used to analyze the cascading effects of management options and establish the requirements for their success. We found that high connectedness of the system at the exploitation level, through fisheries having multiple target stocks, can increase the stocks' vulnerability to exploitation but reduce society's vulnerability to variability in individual stocks. We describe how there are multiple pathways to any change in the system, which makes it difficult to identify the root cause of changes but also broadens the management toolkit. Also, we illustrate how nutrient enrichment is not a self-regulating process, and that explicit management is necessary to halt or reverse eutrophication. This model is simple and usable to assess system-wide effects of management policies, and can serve as a paving stone for future quantitative analyses of system dynamics at local scales.

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The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp.

Cited by 79 publications

References 8 publications

Impact of release of <i>Neochetina</i> spp. on growth and density of water hyacinth <i>Eichhornia crassipes</i>

Impact of release of <i>Neochetina</i> spp. on growth and density of water hyacinth <i>Eichhornia crassipes</i>

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

Coupled human and natural system dynamics as key to the sustainability of Lake Victoria’s ecosystem services

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The decline of water hyacinth on Lake Victoria was due to biological control by Neochetina spp.

Cited by 79 publications

References 8 publications

Impact of release of <i>Neochetina</i> spp. on growth and density of water hyacinth <i>Eichhornia crassipes</i>

Impact of release of <i>Neochetina</i> spp. on growth and density of water hyacinth <i>Eichhornia crassipes</i>

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

Coupled human and natural system dynamics as key to the sustainability of Lake Victoria&#8217;s ecosystem services

Contact Info

Product

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Coupled human and natural system dynamics as key to the sustainability of Lake Victoria’s ecosystem services