A compound, or salt thereof, represented by the general formula (Ia), (Ib), (Ic) or (Id) :( where, R1 and R2 may be the same or different, and represent a C1-10 C6 alkyl group which may be substituted with 1 to 3 substituents, which may be the same odifferent, selected from the group consisting of a halogen atom, a C1-C6 alkoxy group, a C1-C6 alkylthio group and a phenoxy group； an aryl group that can be substituted with 1 to 6 substituents, which may be the same or different, selected from the group consisting of a halogen atom, a C1-C6 alkyl group which may be substituted with 1 to 3 identical or different halogen atoms, a group C1-C6 alkoxy, an amino group which may be substituted with 1 to 2 identical or different C1-C6 alkyl groups or acyl groups, a nitro group, a cyano group, a hydroxyl group, a mercapto group, and a C1-C6 alkylthio group ； a heteroaryl group that may be substituted with 1 to 6 substituents, which may be same or different, selected from the group consisting of a halogen atom, a C1-C6 alkyl group that may be substituted with 1 to 3 same or different halogen atoms, and a C1-C6 alkoxy group； an aralkyl group which may be substituted with 1 to 6 substituents, which may be the same or different, selected from the group consisting of a halogen atom, a C1-C6 alkyl group which may be substituted with 1 to 3 equal halogen atoms or different, a C1-C6 alkoxy group, an amino group which may be substituted with 1 to 2 equal or different alkyl groups or C1-C6 acyl groups, a nitro group, a cyano group, a hydroxyl group, a mercapto group and a group C1-C6 alkylthio； or R1 and R2 together represent a C3-C10 cycloalkyl group, which may be substituted with 1 to 3 substituents, which may be the same or different, selected from the group consisting of a halogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group and a phenoxy group； R3 and R4 may be the same or different, and represent a hydrogen atom； a C1-C6 alkyl group which may be substituted with 1 to 3 substitue
