Compounds of formula (I) wherein the symbols have the meaning given in the specification, as well as processes for preparing the compounds (I), pesticidal compositions and synergistic mixtures comprising compounds (I), methods for the control of insects, acarids or nematodes by contacting the pests or their food supply, habitat or breeding grounds with a pesticidally effective amount of compounds formula (I), and a method for treating, controlling, preventing or protecting animals against infestation or infection by parasites which comprises orally, topically or parenterally administering or applying to the animals a parasiticidally effective amount of compounds of formula (I).