Management of aquatic vegetation in the lower Senegal River basin

Pieterse, A.H.; Hellsten, Seppo; Janauer, Georg A.; Dieme, Charles; Diouf, Sara; Exler, Norbert

doi:10.1080/03680770.2001.11901777

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…and Phragmites spp. can expand rapidly into littoral areas if left unchecked, and thereby limit the area of water contact sites and the availability of water to rural villages (42). Our work suggests (but does not prove) that clearing emergent vegetation could exacerbate the transmission of urogenital schistosomiasis by opening habitat for colonization by the nonemergent vegetation types that are associated with high snail density, including Ceratophyllum spp., Ludwigia spp., and Potamogeton spp., and increasing the size of water contact sites—all factors that our analyses suggest might increase the local abundance of snails and, therefore, the risk of urogenital schistosomiasis to humans.…”

Section: Discussionmentioning

confidence: 99%

Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission

Wood

Sokolow

Jones

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

108

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Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world’s largest recorded schistosomiasis epidemic—the Lower Senegal River Basin in Senegal—intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we identified several environmental proxies that were more effective than snail variables for predicting human infection: the area covered by suitable snail habitat (i.e., floating, nonemergent vegetation), the percent cover by suitable snail habitat, and size of the water contact area. Unlike snail surveys, which require hundreds of person-hours per site to conduct, habitat coverage and site area can be quickly estimated with drone or satellite imagery. This, in turn, makes possible large-scale, high-resolution estimation of human urogenital schistosomiasis risk to support targeting of both mass drug administration and snail control efforts.

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Section: Discussionmentioning

confidence: 99%

Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission

Wood

Sokolow

Jones

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

108

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“…Pistia stratiotes can survive when plants are rooted in mud, or as seeds and can even withstand highly saline soil (den Hollander et al 1999). The weed is common in many waters in West Africa (Pettet and Pettet 1970) where it has been reported in Benin, Côte d'Ivoire, Nigeria and Senegal (Ajuonu and Neuenschwander 2003, Pieterse et al 2002, den Hollander et al 1998. Pistia stratiotes develops dense mats and its noxious effects include the following: water loss through evapotranspiration with consequent negative impact on the water balance in entire regions; the clogging of rivers and canals; interference with the operation of hydroelectric power stations (Napompeth 1990); hampering of fishing activities (Howard andHarley 1998, Dray andCenter 2002); hampering of navigation; negatively affecting water control and use for agricultural purposes; displacement of native species because of modifications of environmental conditions due mainly to oxygen depletion in water and sediments; increased sedimentation caused by the roots, and excessive shading by the leaves (Labrada and Fornasari 2002).…”

Section: Introductionmentioning

confidence: 96%

“…Following its success as a biocontrol agent elsewhere, the weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) was imported into Senegal in 1994. Successful biological control of water lettuce was achieved at Lake Guiers and Djoudj National Park and no other severe infestations were subsequently reported around the country (Pieterse et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Quantitative post-release evaluation of biological control of Pistia stratiotes Linnaeus (Araceae) by the weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) in Senegal

Hill¹

2009

African Journal of Aquatic Science

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The South American floating aquatic plant Pistia stratiotes (Araceae) was introduced into Senegal in the early 1990s and by 1994 had covered some 2 034 ha on Lake Guiers. The biological control agent Neohydronomus affinis (Coleoptera: Curculionidae) was released in this area between September 1994 and April 1995. A quantitative post-release evaluation showed that the weed cover decreased by about 25% every two months, completely eliminating the water lettuce mats within eight months. The weevils dispersed some 150 km in 18 months and controlled water lettuce in several water bodies in the Djoudj National Park. A resurgence of the weed in the Senegal River Delta in 2005 prompted further releases of the weevil, once again resulting in effective control. The biological control programme against water lettuce in Senegal has been highly successful and the weed is no longer considered problematic.

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Effective Biological Control of Salvinia molesta in the Senegal River by Means of the Weevil Cyrtobagous salviniae

Pieterse¹,

Kettunen²,

Diouf³

et al. 2003

AMBIO: A Journal of the Human Environment

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The invasion of Salvinia molesta in the Lower Senegal River Delta in Mauritania and Senegal in 1999 posed a serious threat to the socioeconomic conditions of the local people as well as to wetland biodiversity. Eventually, an effective biological control of S. molesta was obtained by means of the weevil Cyrtobagous salviniae, which was introduced in the river in Senegal and Mauritania in May 2000 and in Senegal in April 2001. In October 2001, it became apparent that the weevils were doing a magnificent job. The color of the plants was turning from green to dark-brown or black, and subsequently the plants started to sink to the bottom. Detailed monitoring of the dispersal of C. salviniae in November-December 2001 confirmed the visual observations of the outcome of biological control. In April 2002, it could be concluded that S. molesta was no longer a problem in the Senegal River.

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Management of aquatic vegetation in the lower Senegal River basin

Cited by 4 publications

References 7 publications

Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission

Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission

Quantitative post-release evaluation of biological control of Pistia stratiotes Linnaeus (Araceae) by the weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) in Senegal

Effective Biological Control of Salvinia molesta in the Senegal River by Means of the Weevil Cyrtobagous salviniae

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