Insecticidal combination to control mammal fleas, in particular fleas on cats and dogs

A synergistic spot-on composition for the long lasting protection against ectoparasites on mammals which comprises synergistic amounts

• (A) at least one compound of the formula:
• in which:
• R1 is CN or methyl or a halogen atom;
• R2 is S(O)nR3 or 4,5-dicyanoimidazol-2-yl or haloalkyl;
• R3 is alkyl or haloalkyl;
• R4 represents a hydrogen or halogen atom;
• or a radical NR5R6, S(O)mR7, C(O)R7, C(O)O—R7, alkyl, haloalkyl, or OR8 or a radical —N═C(R9)(R10);
• R5 and R6 independently represent a hydrogen atom or an alkyl, haloalkyl, C(O)alkyl, alkoxycarbonyl or S(O)r—CF3 radical;
• R5 and R6 may together form a divalent alkylene radical which may be interrupted by one or two divalent hereto atoms or;
• R7 represents an alkyl or haloalkyl radical;
• R8 represents an alkyl or haloalkyl radical or a hydrogen atom;
• R9 represents an alkyl radical or a hydrogen atom;
• R10 represents a phenyl or heteroaryl group optionally substituted with one or more halogen atoms or one or more substituents selected from the group consisting of OH, —O-alkyl, S-alkyl, cyano or alkyl;
• R11 and R12 represent, independently of each other, hydrogen, halogen, CN or NO2;
• R13 represents a halogen atom or a haloalkyl, haloalkoxy, S(O)qCF3 or SF5 group;
• m, n, q and r represent, independently of each other, an integer equal to 0, 1 or 2;
• X represents a trivalent nitrogen atom or a radical C—R12, the other three valency positions of the carbon atom forming part of the aromatic ring;
• with the proviso that when R1 is methyl, then R3 is haloalkyl, R4 is NH2, R11 is Cl, R13 is CF3 and X is N;
• or R2 is 4,5-dicyanoimidazol-2-yl, R4 is Cl, R11, is Cl, R13 is CF3 and X is ═C—Cl;
• (B) at least one insect growth regulator (IGR) that mimics juvinile hormones;
• (C) imidacloprid;
• and
• a fluid vehicle comprising at least one customary spot-on formulation adjuvant.