The invention relates to compounds of the formula (Ia) or (Ib), in which Aa, Ab, Ac, Ad, R1, R10 R11, R12, R13, R14, R15, R16, R17, Q, R4, R5, R6 and have the meanings indicated in the claims, and to agrochemical formulations containing the compounds according to formula (Ia) or (Ib) for use as acaricides and/or insecticides for combating animal pests, primarily arthropods and in particular insects and arachnids. 2-[3-(alkylsulfonyl)-2H-indazol-2-yl]-3H-imidazo[4,5-b]pyridine derivatives and similar compounds are particularly preferable.