Testing the effect of invasive water hyacinth on predatory biocontrol of schistosome-transmitting snails Open Access

Oh, Sarah (Spring 2020)

Permanent URL: https://etd.library.emory.edu/concern/etds/pz50gx42n?locale=en
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Abstract

Human schistosomiasis is a globally impactful parasitic disease that is transmitted through freshwater snails. Efforts to reduce the density of these intermediate host snails have historically improved human health outcomes, but the use of toxic pesticides can harm ecosystems. As a consequence, there is strong interest in predatory biocontrol, which uses native predators, such as prawns or fish, to consume snails and disrupt transmission. By consuming prey that are intermediate hosts to parasites, predators can limit parasite transmission and human prevalence. In the schistosome-host system, prawns have been identified as a sustainable biocontrol for the intermediate hosts, Biomphalaria and Bulinus snails, but environmental changes occurring in endemic transmission sites, such as plant invasions, could affect prawn-based biocontrol of snails. Through a series of trials, predation rate of treatment groups with water hyacinths, invasive plants commonly found in endemic areas with schistosomiasis, and without the water hyacinth plant. The predation rates were measured as liters of snail habitat cleared by the 1 prawn per day. The rates were 10.7 (95% CI: 9.27, 12.3) for the experimental treatment with water hyacinths and 11.1 (95% CI: 9.66, 12.8) for without treatment, demonstrating no change due to the treatment group. The lack of statistically significant differences between experimental groups results in a finding that is deeply biologically significant: the presence of invasive water hyacinths would not impede the use of prawns as a means of biocontrol to control the population of schistosome-susceptible snails in the environmental context that the experiments were tested within. Although water hyacinth may be problematic due to it being an invasive plant, it is unlikely to disrupt efforts to promote prawn-based control of snails and schistosomes in areas that where schistosomiasis is endemic.  

Table of Contents

Table of Contents

Introduction……………………………………………………………………………………………………………………………….1

Predators….………………………………………………………………………………………………………….………..1

Environmental factors……………………………..….……………………………..………………………………….1

Schistosomes……………………………………………………………………………………….……………………..…2

Predators as Biocontrols………………………………………………..….……………………………..……….…..3

Water Hyacinths…………………………………..….……………………………..….…………………………….…..5

Methods……………………………………………………………………………………………………………………………………5

Results……………………………………………………………………………………………………………………………………….8

Conclusion…………………………………………………………………………………………………………………………………9

Future Directions…………………………………………………………………………………………..……………………………………11

References………………………………………………………………………………………………………………………………12

Figures and Tables

Figure 1……………………………..….……………………………..….……………………………..….………………………..……3

Figure 2……………………………..….……………………………..….……………………………..….………………………….….6

Figure 3………………………………..….……………………………..….……………………………..….…………………………..9

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