The Prawn Macrobrachium vollenhovenii in the Senegal River Basin: Towards Sustainable Restocking of All-Male Populations for Biological Control of Schistosomiasis

Abstract

Early malacological literature suggests that the outbreak of schistosomiasis, a parasitic disease transmitted by aquatic snails, in the Senegal River basin occurred due to ecological changes resulting from the construction of the Diama dam. The common treatment, the drug praziquantel, does not protect from the high risk of re-infection due to human contact with infested water on a daily basis. The construction of the dam interfered with the life cycle of the prawn Macrobrachium vollenhovenii by blocking its access to breeding grounds in the estuary. These prawns were demonstrated to be potential biological control agents, being effective predators of Schistosoma-susceptible snails. Here, we propose a responsible restocking strategy using all-male prawn populations which could provide sustainable disease control. Male prawns reach a larger size and have a lower tendency to migrate than females. We, therefore, expect that periodic restocking of all-male juveniles will decrease the prevalence of schistosomiasis and increase villagers' welfare. In this interdisciplinary study, we examined current prawn abundance along the river basin, complemented with a retrospective questionnaire completed by local fishermen. We revealed the current absence of prawns upriver and thus demonstrated the need for restocking. Since male prawns are suggested to be preferable for bio-control, we laid the molecular foundation for production of all-male M. vollenhovenii through a complete sequencing of the insulin-like androgenic gland-encoding gene (IAG), which is responsible for sexual differentiation in crustaceans. We also conducted bioinformatics and immunohistochemistry analyses to demonstrate the similarity of this sequence to the IAG of another Macrobrachium species in which neo-females are produced and their progeny are 100% males. At least 100 million people at risk of schistosomiasis are residents of areas that experienced water management manipulations. Our suggested non-breeding sustainable model of control—if proven successful—could prevent re-infections and thus prove useful throughout the world.

Perceptions about interventions to control schistosomiasis among the Lake Victoria island communities of Koome, Uganda

“…On the use of biological agents such as fresh water prawns [25, 26] or ducks [27] to feed on the host snails, the participants were concerned about the numbers required. They expressed the fear that the agents (especially ducks) may be poached.…”

The spatial spread of schistosomiasis: A multidimensional network model applied to Saint-Louis region, Senegal

“…At the same time, the dam created a suitable habitat for the snails hosting schistosomiasis and resulted in persistently high infection levels in the villages along the Senegal River and its tributaries (Talla et al., 1990). Moreover, the dam interfered with the life cycle of the prawn Macrobrachium vollenhovenii , an effective predator of the snails, whose key role as potential biological control agent has been the object of recent studies (Alkalay, Rosen, Sokolow, Faye, Faye, Aflalo, Jouanard, Zilberg, Huttinger, Sagi, 2014, Sokolow, Lafferty, Kuris, 2014, Sokolow, et al., 2015). …”

Breeding and larval rearing in hatchery of Macrobrachium vollenhovenii (Herklots, 1857) in a perspective of biological control against human Schistosomiasis in tropical area

“…The few studies carried out on this species have focused mainly on its biology and ecology (Savaya et al, 2014;Konan et al, 2010;Bello-Olusoji, 1997;Anetekhai, 1986;Marioghae, 1982) [8][9][10][11][12] . Specific breeding techniques for M. vollenhovenii are poorly studied around the world (Niass et al, 2015;Makombu et al, 2014;Willführ-Nast et al, 1993;Anetekhai et al, 1987) [13][14][15][16] .…”