1,2,3-thiadiazol-5-yl-urea derivatives of the general formula (Ia), wherein R1a is selected from the group consisting of C 1 -C 6 alkyl, substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; C 2 -C 6 alkenyl, optionally substituted with moiety selected from hydroxy, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; C 2 -C 6 alkynyl, optionally substituted moiety selected from hydroxy, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; tetrahydro-furan-2-yl-methyl or tetrahydro-furan-3-yl-methyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; thiophen-2-yl-methyl or thiophen-3-yl-methyl optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; furan-2-yl-methyl or furan-3-yl-methyl, substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; 1,3-dioxolan-2-yl-methyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; tetrahydropyran-2-ylmethyl, tetrahydropyran-3-ylmethyl or tetrahydropyran-4-ylmethyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; (3,4-dihydro-2H-pyran-2-yl)methyl, (3,4-dihydro-2H-pyran-3-yl)methyl, (3,4-dihydro-2H-pyran-4-yl)methyl, (3,4-dihydro-2H-pyran-5-yl)methyl or (3,4-dihydro-2H-pyran-6-yl)methyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen. R1a is selected from the group consisting of C 1 -C 6 alkyl, substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; C 2 -C 6 alkenyl, optionally substituted with moiety selected from hydroxy, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; C 2 -C 6 alkynyl, optionally substituted moiety selected from hydroxy, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; tetrahydro-furan-2-yl-methyl or tetrahydro-furan-3-yl-methyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; thiophen-2-yl-methyl or thiophen-3-yl-methyl optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; furan-2-yl-methyl or furan-3-yl-methyl, substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; 1,3-dioxolan-2-yl-methyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; tetrahydropyran-2-ylmethyl, tetrahydropyran-3-ylmethyl or tetrahydropyran-4-ylmethyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen; (3,4-dihydro-2H-pyran-2-yl)methyl, (3,4-dihydro-2H-pyran-3-yl)methyl, (3,4-dihydro-2H-pyran-4-yl)methyl, (3,4-dihydro-2H-pyran-5-yl)methyl or (3,4-dihydro-2H-pyran-6-yl)methyl, optionally substituted with at least one moiety selected from hydroxy, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, thio, C 1 -C 4 alkylthio, cyano and halogen.