the present invention provides a formulation characterised by the simultaneous presence in cyclodextrin based supramolecular complexes , of two components , one of which possesses insecticidal , acaricidal , fungicidal , snailcidal or vermicidal activity and the other possesses an activity synergistic with the first , enhancing its effectiveness . the biologically active substance is chosen from the following classes of chemical products : carbamates , organophosphates , thioureas , pentatomic or hexatomic heterocycles in which 1 , 2 or 3 nitrogen atoms are present . the synergistic substance can be chosen from components containing at least one aromatic or non aromatic carbocyclic ring , such as piperonyl butoxide , sesamol , verbutin or mgk 264 . for the same dose , the activity of the present formulations is greater than that of the mixture of the two active components alone or separately complexed with cyclodextrin . the process for preparing said formulation and its use for the activities herein indicated are further aspects of the present invention .