A compound of formula (IV) wherein R 1 and R 2 are each independently selected from hydrogen, cyano, C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, C 2 -C 6 alkenyl and C 2 -C 6 alkynyl, in which the alkyl, cycloalkyl, alkenyl and alkynyl groups may be optionally substituted with 1 to 3 substituents independently selected from halogen, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; or R 1 and R 2 together with the carbon atom to which they are attached represent a C 3 -C 10 cycloalkyl group which may be optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; R 3 and R 4 are each independently selected from halogen, hydroxyl, C 1 -C 6 alkoxy, C 3 -C 7 cycloalkyl, C 2 -C 6 alkenyl and C 2 -C 6 alkynyl, in which the alkyl, alkoxy, cycloalkyl, alkenyl and alkynyl groups may be optionally substituted with 1 to 3 substituents independently selected from halogen, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; or each R 5 independently represents halogen, hydroxyl, mercapto, nitro, cyano, formyl, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, C 3 -C 6 alkenyloxy, C 3 -C 6 alkynyloxy, C 1 -C 6 alkylthio, -C(=NOR a )C 1 -C 6 alkyl, C 1 -C 6 alkylcarbonyl, aryl, heteroraryl, aryloxy or heteroraryloxy, in which the alkyl, cycloalkyl, alkenyl, alkynyl, alkoxy, alkenyloxy, alkynyloxy, aryl and heteroaryl groups may be optionally substituted with 1 to 5 substituents independently selected from halogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, cyano and C 1 -C 6 alkylthio; n is 0, 1, 2, 3 or 4; R a is selected from hydrogen, C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, C 3 -C 6 alkenyl and C 3 -C 6 alkynyl, in which the alkyl, cycloalkyl, alkenyl and alkynyl groups may be optionally substituted with 1 to 3 substituents independently selected from halogen, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; or a salt or N-oxide thereof. R 1 and R 2 are each independently selected from hydrogen, cyano, C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, C 2 -C 6 alkenyl and C 2 -C 6 alkynyl, in which the alkyl, cycloalkyl, alkenyl and alkynyl groups may be optionally substituted with 1 to 3 substituents independently selected from halogen, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; or R 1 and R 2 together with the carbon atom to which they are attached represent a C 3 -C 10 cycloalkyl group which may be optionally substituted with 1 to 3 substituents independently selected from the group consisting of halogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; R 3 and R 4 are each independently selected from halogen, hydroxyl, C 1 -C 6 alkoxy, C 3 -C 7 cycloalkyl, C 2 -C 6 alkenyl and C 2 -C 6 alkynyl, in which the alkyl, alkoxy, cycloalkyl, alkenyl and alkynyl groups may be optionally substituted with 1 to 3 substituents independently selected from halogen, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; or each R 5 independently represents halogen, hydroxyl, mercapto, nitro, cyano, formyl, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, C 3 -C 6 alkenyloxy, C 3 -C 6 alkynyloxy, C 1 -C 6 alkylthio, -C(=NOR a )C 1 -C 6 alkyl, C 1 -C 6 alkylcarbonyl, aryl, heteroraryl, aryloxy or heteroraryloxy, in which the alkyl, cycloalkyl, alkenyl, alkynyl, alkoxy, alkenyloxy, alkynyloxy, aryl and heteroaryl groups may be optionally substituted with 1 to 5 substituents independently selected from halogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, cyano and C 1 -C 6 alkylthio; n is 0, 1, 2, 3 or 4; R a is selected from hydrogen, C 1 -C 6 alkyl, C 3 -C 7 cycloalkyl, C 3 -C 6 alkenyl and C 3 -C 6 alkynyl, in which the alkyl, cycloalkyl, alkenyl and alkynyl groups may be optionally substituted with 1 to 3 substituents independently selected from halogen, C 1 -C 6 alkoxy and C 1 -C 6 alkylthio; or a salt or N-oxide thereof. <EOS>