The invention relates to substituted amidine compounds of formula (I), to the enantiomers, diastereomers and salts thereof and to compositions comprising such compounds. The invention also relates to the use of the substituted amidine compounds, of their salts or of compositions comprising them for combating animal pests. Furthermore the invention relates also to methods of applying such substituted amidine compounds.The substituted amidine compounds of the present invention are defined by the following formula I:wherein A1to A4, B1to B3, R1to R3, (R4)p, (R5)q, X and Y are defined as in the description.本發明係關於一種式(I)之經取代脒化合物、其對映異構體、非對映異構體及鹽,且係關於包含該等化合物之組合物。本發明亦係關於一種經取代脒化合物、其鹽或包含其之組合物用於對抗動物害蟲之用途。此外,本發明亦係關於一種施用該等經取代脒化合物之方法。本發明之經取代脒化合物係由下式I定義:其中A1至A4、B1至B3、R1至R3、(R4)p、(R5)q、X及Y係如說明書中所定義。