Molluscicidal activity of Persea americana Mill. (Lauraceae) stem bark ethanolic extract against the snail Biomphalaria glabrata (Say, 1818): a novel plant-derived molluscicide?

Thiago L Rocha,José Clecildo B Bezerra,Joelma A.M De Paula,Yasmim R.R Silva,Vanessa C.S Amaral,Daniela B Dos Santos,Karine B Machado,Luciana D Silva

doi:10.1590/0001-3765202020200715

Thiago L Rocha, José Clecildo B Bezerra + Show 6 more

Open Access

https://doi.org/10.1590/0001-3765202020200715

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Abstract

Plant-derived molluscicides have been indicated as biodegradable and low-cost strategies for control of Biomphalaria spp., intermediate host for the Schistosoma. This study evaluated whether the crude ethanolic extract of the Persea americana stem bark has molluscicidal activity against embryos, newly-hatched and adults of Biomphalaria glabrata. The extract was obtained, characterized and its toxicity analyzed by snail embryotoxicity test (144 h) and acute toxicity test with newly-hatching and adult snails (96 h). Results showed the presence of flavonoids, anthraquinone heterosides, coumarins and tannins in the crude ethanolic extract, which showed molluscicidal activity against all life cycle stages of B. glabrata. The LC50 for embryos, newly-hatched and adults were 27.06, 30.60 and 55.55 ppm, respectively. Embryos exposed to the extract at 50 ppm showed hatching inhibition and at 6.2 and 25 ppm had the highest rates of morphological alterations, such as shell malformations and coagulation of the perivitelline substance. Adult snails exposed to the extract at 75 ppm showed a peak of behavioral changes, such as lethargy and shell reclusion, in addition to answers like hemolymph release in most concentrations. Further studies are required, prioritizing toxicity testing on non-target organisms and further elucidation of the active molecules.

Highlights

Schistosomiasis is a neglected parasitic disease, as it affects low-income populations in tropical and subtropical countries between Latin America, Africa and Asia, caused by trematodes of the genus Schistosoma (Weiland 1858), wherein the freshwater snails Biomphalaria spp. act as the intermediate host (WHO 2017)
The present study aimed to evaluate the molluscicide activity of the crude ethanolic extract from P. americana stem bark against different life cycle stages of the freshwater snail B. glabrata
The presence of phenolic compounds, such as flavonoids, anthraquinone heterosides, coumarins and tannins was detected in the extract

Summary

Introduction

Schistosomiasis is a neglected parasitic disease, as it affects low-income populations in tropical and subtropical countries between Latin America, Africa and Asia, caused by trematodes of the genus Schistosoma (Weiland 1858), wherein the freshwater snails Biomphalaria spp. act as the intermediate host (WHO 2017). The niclosamide (Bayluscide®), as it is active for adult and embryo snails, and is relatively safe during handling. The niclosamide has high toxicity to other aquatic animals and plants, high cost and difficulty of solubilization in organic solvents and water (WHO 2017). The toxicity of secondary plant metabolites against the snail Biomphalaria spp. have been related to different mechanisms of action (Singab et al 2006, Faria et al 2018, Mendes et al 2018).

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