Molluscicidal agents

Use of a compound of the formula:

• wherein
• R1 denotes a hydrogen atom or a methyl group,
• A denotes an ethylene group which can be substituted by methyl, or a trimethyl goup which can be substituted by methyl,
• X denotes an oxygen or sulphur atom or the group
• wherein
• R2 denotes a hydrogen atom, a C1-C4-alkyl group which can be substituted by a substituent selected from amongst halogens, C1-C4-alkoxy groups, C1-C4-alkylthio groups and cyano, a C2-C4-alkenyl group, a C2-C4-alkinyl group, a pyridylmethyl group which can be substituted by halogen and/or methyl, a benzyl group which can be substituted by halogen and/or methyl, a formyl group, an alkylcarbonyl group having 1 or 2 carbon atoms in the alkyl structural unit which can be substituted by halogen, a phenylcarbonyl group which can be substituted by halogen and/or methyl, an alkoxy or alkylthiocarbonyl group having 1 to 4 carbon atoms in the alkyl structural unit, a phenoxycarbonyl group, a C1-C4-alkylsulphonyl group which can be substituted by halogen, or a phenylsulphonyl group which can be substituted by methyl, and
• R3 denotes a hydrogen atom, and
• Y denotes a 5- or 6-membered heterocyclic group which contains two or three hetero atoms selected from amongst oxygen, sulphur, and nitrogen atoms, at least one of these being a nitrogen atom, or denotes a 3-pyridyl group, the heterocyclic group and the 3-pyridyl group optionally being substituted by at least one substituent selected from amongst halogen atoms, alkyl groups having 1 to 4 carbon atoms, alkoxy groups having 1 to 4 carbon atoms, alkylthio groups having 1 to 4 carbon atoms, halogenoalkyl groups having 1 to 4 carbon atoms, halogenoalkoxy groups having 1 to 4 carbon atoms, alkylsulphonyl groups having 1 to 4 carbon atoms, the cyano group and the nitro group, and
• Z denotes the group
• as a molluscicidal agent.