Effects of Laurus nobilis (Lauraceae) on Biomphalaria glabrata (Say, 1818)

Area of Science:

• Pharmacology
• Ecotoxicology
• Malacology

Background:

• Biomphalaria glabrata is a key intermediate host for Schistosoma mansoni, the parasite causing schistosomiasis.
• Controlling snail populations is crucial for schistosomiasis transmission interruption.

Purpose of the Study:

• To evaluate the molluscicidal activity of aqueous extracts from Laurus nobilis (bay leaf) on Biomphalaria glabrata.
• To determine the toxicity of leaf and flower extracts on snail embryos and adult snails.

Main Methods:

• Aqueous extracts from Laurus nobilis leaves and flowers were tested.
• Embryos (blastula stage) and adult Biomphalaria glabrata snails were exposed to varying extract concentrations (20-300 ppm for embryos, 200-2500 ppm for adults) for 24 hours at 25°C.
• Embryos were observed for 20 days, and adult snails for 10 days post-treatment.

Main Results:

• Leaf extract showed toxicity on embryos at 125 ppm; flower extract was effective at 35 ppm.
• Flower extract exhibited higher toxicity against adult snails (LD90 at 340 ppm) compared to leaf extract (LD90 at 1900 ppm).
• Malformations observed were generally unspecific, but cephalic and shell abnormalities occurred in embryos exposed to concentrations above 50 ppm (leaf) and 25 ppm (flower).

Conclusions:

• Laurus nobilis aqueous extracts possess significant molluscicidal properties against Biomphalaria glabrata.
• Flower extract demonstrates greater efficacy and toxicity than leaf extract for both embryonic and adult stages.
• These findings suggest potential for Laurus nobilis as a natural agent for controlling snail vectors, warranting further investigation into its active compounds and mechanisms of action.