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In spite of intense research on both chemical constituency and biological activity of Hypericum species, potential applications of their active components for pest control have been less well investigated. In the present study, Hypericum androsaemum (tutsan), Hypericum foliosum (malfurada), and Hypericum undulatum (wavy St. John's wort) aqueous and hexane extracts were studied for their molluscicidal and ovicidal activities against Radix peregra. The molluscicidal activity of the aqueous extracts was low, except for H. androsaemum infusion (median lethal concentration [LC50]adults = 317.1 ppm; LC50juveniles = 415 ppm), and less important compared with the toxicity of all three hexane extracts tested: H. androsaemum (LC50adults = 30.47 ppm; LC50juveniles = 73.25 ppm), H. undulatum (LC50adults = 30.55 ppm; LC50juveniles = 60.54 ppm), and H. foliosum (LC50adults = 48.61 ppm; LC50juveniles = 38.81 ppm). An ovicidal effect was observed only with H. androsaemum infusion (1.85% of hatching at 500 ppm) and H. foliosum hexane extract (0.0% of hatching at 100 ppm). A preliminary phytochemical investigation of the lipophylic extracts from these Hypericum sp. revealed a different chemical profile and confirmed the presence of ursolic acid only in H. undulatum as the main compound. The present study indicates that products from hexane extracts of the Hypericum sp. analyzed may be used as potential molluscicides to control snails responsible for transmitting fasciolosis. Environ. Toxicol. Chem. 2012;31:748-753. © 2011 SETAC [ABSTRACT FROM AUTHOR]

Abstract: The molluscicidal activity of essential oils from two endemic (Juniperus brevifolia; Laurus azorica) and three introduced (Hedychium gardnerianum; Pittosporum undulatum; Psidium cattleianum) Azorean plants against the snail Radix peregra was studied under laboratory conditions. Essential oils from leaves of H. gardnerianum, L. azorica and J. brevifolia presented promising molluscicidal activity on both adults and juveniles stages of R. peregra. The molluscicidal activity of these essential oils was found to be both time and concentration dependent. Lethal concentrations (LC50) varied between 15.4 (L. azorica) and 44.6ppm (H. gardnerianum) for juveniles and from 45.3 (H. gardnerianum) to 54.6ppm (J. brevifolia) for R. peregra adults. Ovicidal effect, calculated as percentage of egg hatching, at 100ppm concentration, was observed in essential oils from P. undulatum flowers (4.2% of hatching) and leaves of H. gardnerianum (4.9%), L. azorica (7.4%) and J. brevifolia (17.7%). The present study is the first attempt to assess the molluscicidal potential of some Azorean plants essential oils against a Lymnaeidae snail. In fact, the H. gardnerianum, L. azorica and J. brevifolia can offer natural alternative tools for the control of R. peregra population, but more research is needed in order to determine the mode of action of these oils and determine the side effects on the ecosystem where this freshwater snail occurs. [Copyright &y& Elsevier]