any cyclodextrin can be used for the purposes of the present invention . for example the cyclodextrin can be α , β , γ cyclodextrin as such or suitably derivatized to increase its hydrophilic or hydrophobic character . particularly preferred are β - cd , γ - cd and hp - β - cd . usable active principles in the present invention belong to one of the following classes of chemical products : carbamates , organophosphates , thioureas , pentatomic or hexatomic heterocyles where 1 , 2 or 3 nitrogen atoms are present , such as pyridine , pyrrole , imidazole , benzimidazole , thiazole , pyrazole , pyridazine , quinazoline , oxadiazine , triazine . particularly preferred are neonicotinoids , such as imidacloprid , acetamiprid , thiacloprid , thiamethoxam and akd1022 , carbamates such as pyrimicarb , aldicarb , thiodicarb , carbosulfan , carbofuran and propoxur ; organophosphates such as profenofos , dimethoate , omethoate , terbufos , azinphos - methyl , pyrimiphos - methyl , demeton - s - methyl , fenitrothion , trichlorfon and malathion ; mitochondrial electron transport inhibitors (“ meti ”) such as fenazaquin , tebufenpyrad , fenpyroximate , pyridaben and tolfenpyrad ; fungicides such as fludioxonil , clotrimazole , imazalil and pyrimethanil ; vermicides such as mebendazole , metronidazole , fenbendazole , thiabendazole and praziquantel ; nerve transmission inhibitors such as indoxacarb and fipronil and other active principles in which the mechanism of action against damaging species is still uncertain or which have miscellaneous mechanisms , such as pymetrozine , chlorfenapyr and pyridalyl . even more preferred are : imidacloprid , acetamiprid , thiacloprid , thiodicarb , carbosulfan , carbofuran , fenazaquin , pyridaben , fludioxonil , pyrimethanil , fenbendazole , clotrimazole , praziquantel , fipronil , pymetrozine and pyridalyl . the aforesaid preferred compounds can be subdivided on the basis of their activity as follows : insecticides : imidacloprid , acetamiprid , thiacloprid , thiamethoxam , akd 1022 , pyrimicarb , aldicarb , thiodicarb , carbosulfan , carbofuran , propoxur , profenofos , dimethoate , omethoate , azinphos - methyl , pyrimiphos - methyl , demeton s - methyl , pyrimiphos - methyl , demeton s - methyl , fenitrothion , trichlofon , malathion , pyridaben , tolfenpyrad , indoxacarb , fipronil , pymetrozine , chiorphenapyr , pyridalyl . acaricides : dimethoate , omethoate , pyrimiphos - methyl , demeton - 5 - methyl , fenithrothion , malathion , fenazaquin , tebufenpyrad , fenpyroximate , pyridaben . snailcides : propoxur , terbufos , pyrimiphos - methyl , fenitrothion , trichlorfon , malathion , tolfenpyrad , fipronil , chlorphenapyr , pyridalyl . vermicides : carbosulfan , carbofuran , terbufos , pyrimiphos - methyl , fenithrotion , trichlorfon , malathion , fipronil , mebendazole , metronidazole , fenbendazole , thiabendazole , clotrimazole , praziquantel . the quantity of active principle relative to cyclodextrin is preferably between 1 % and 50 % ( weight / weight ) and even more preferably between 2 % and 30 %. the components able to synergistically enhance active principle activity ( referred to herein in brief as “ synergistic compounds ”) are substances for se known and already in use . preferred examples of synergistic compounds are piperonyl butoxide and its analogues , sesamol , verbutin and mgk264 , piperonyl butoxide and verbutin being particularly preferred . piperonyl butoxide is most preferred . the synergistic compounds can be used as such or already pre - formulated with additives ; an example of a commercially available pre - formulation is marketed as pb80ec - nf , containing 88 % pbo and 12 % emulsifier ( dialkylsulfosuccinate also known as soitem ). the quantity of synergistic compound relative to cyclodextrin is between 0 . 1 % and 100 % ( weight / weight ), preferably between 10 % and 80 % and even more preferably between 20 % and 70 %. these percentages refer to the quantity of pure synergistic compound , therefore excluding any additives present in the pre - formulation . the quantity of active principle relative to the synergistic compound is between 0 . 5 % and 7000 % ( weight / weight ), preferably between 1 % and 1500 %, more preferably between 2 % and 100 % and even more preferably between 10 % and 70 %. emulsifiers , uv stabilizers , antioxidants and other additives can also be present in the aforesaid formulation . the quantity of said additives relative to cyclodextrin is preferably between 0 % and 30 % ( weight / weight ), more preferably between 1 % and 15 %. these percentages refer to all the additives present , also including those already present in the pre - formulations of the active principles utilized . usable emulsifiers are for example dodecylbenzenesulfonate , dialkylsulfosuccinate , lignin sulfonates , phospholipids , polyethylene glycols . usable uv stabilizers are for example 2 - hydroxy - 4 - methoxy - benzophenone , 2 - hydroxy - 4 - octoxy - benzophenone , 4 - hydroxy - 2 , 2 , 6 , 6 - tetramethylpiperidine sebacate . a microemulsified synergist can be optionally added to the formulations of the present invention , being the same as or different from that present in the supramolecular complex , in a quantity from 0 % to 300 % ( weight / weight ) relative to the cyclodextrin . the composition of the invention is preferably formulated as a solid or as a solid / oil composition ; said formulations can be utilised as such , or previously dissolved / emulsified in water or in aqueous solutions of water - miscible solvents , such as a c1 - 4 alcohol ; said aqueous solutions contain 0 %- 99 % by weight of organic solvent , preferably from 0 - 60 % by weight of organic solvent . the process for preparing the aforedescribed formulations is characterized by the formation of a supramolecular complex in cyclodextrins of the synergistic compound and the active principle having insecticidal , acaricidal , fungicidal , snailcidal or vermicidal activity . more specifically the preparation process can be performed in accordance with one of the following methods , indicated as procedure a and procedure b respectively . ( a ) preparing a solution or suspension , in a suitable solvent , of the synergistic compound and the active principle optionally in the presence of a suitable surfactant , the lafter being present in a quantity from 0 % to 12 %, preferable from 2 % to 4 % of the synergistic compound ; the solvent is preferably an alcoholic solvent , e . g . ethanol or isopropanol ; ( b ) preparing a solution of cyclodextrin in water or in water / water - miscible organic solvent mixtures ; the dissolution of the cd can conveniently be facilitated by heating ( e . g . between 50 ° and 90 ° c ., preferably between 70 ° c . and 80 ° c ., for 30 - 90 minutes ). ( c ) adding the solution / suspension obtained in ( a ) to the solution obtained in ( b ); preferably the solution / suspension of ( a ) is added slowly , e . g . over 2 - 10 hours ( more preferably over 4 - 8 hours ), pre - heated to a temperature between 500 and 90 ° c ., preferably between 500 and 75 ° c . ; ( d ) maintaining the mixture under agitation at a temperature between 40 ° and 90 ° c . ( preferably between 50 ° and 75 ° c .) for a time period generally between 12 and 36 hours ( preferably 18 - 24 hours ). the supramolecular complex of the synergistic compound and the active principle in cd is recovered from the reaction mixture by known methods , such as filtration , drying or lyophilization . ( a ) dissolving the active principle in the synergistic compound , heating to a temperature preferably between 700 and 140 ° c ., possibly in the presence of a suitable surfactant in a quantity up to 12 %, preferably from 2 % to 4 % relative to the synergistic compound ; ( b ) preparing a suspension of cyclodextrin in water preferably using a percentage ( weight / weight ) of cd between 30 % and 70 % and heating the suspension to a temperature between 60 ° and 80 ° c . ; ( c ) adding the hot solution obtained in ( a ) to the hot suspension obtained in ( b ) over a time period between 10 and 600 minutes ; ( d ) maintaining the mixture under stirring at a temperature between 50 ° and 90 ° c . ( preferably between 70 ° and 90 ° c .) for a time period generally comprised between 1 and 12 hours ( preferably between 1 and 4 hours ). the supramolecular complex of the synergistic compound and the active principle in cd is recovered from the reaction mixture by filtration and subsequent drying . the complex thus formed can be mixed with the previously indicated possible additional components of said formulations ; said optional components also include an additional quantity of synergistic compound in free form , being the same as or different from that present in the supramolecular complex ; said components can be mixed with the supramolecular complex as solids or as microemulsions , immediately prior to use . a further aspect of the invention is the use of the aforesaid formulations as insecticides , acaricides , fungicides , snailcides or vermicides in agriculture , for use in veterinary medicine , for eradicating household insects and for protecting manufactured articles . formation of said supramolecular complex of the active principle and synergistic compound in cd has surprisingly led to a significant increase in composition effectiveness compared to the mixture of the two components used as such or complexed individually with cyclodextrin . by means of the invention an enhanced interaction between the active principle and the synergistic compound is achieved ; in comparative trials undertaken by the inventors , said enhancement was always found to be greater than 50 %. enhancement of activity leads to various advantages of industrial significance : for example for the same active substance used , more active synergistic compositions can be obtained ; or compositions with an effectiveness equal to known compositions can be obtained but with lower amount of active substance ; the lesser amount of active substance in use leads to reduced product cost , reduced environmental impact of the manufacturing process , as well as reduced volume / weight of the final composition , with further practical advantages for the operator using these formulations . consequently with the present invention insecticide , acaricide , fungicide , snailcide or vermicide formulations are unexpectedly obtained , which are highly effective and less costly than known formulations . the following examples illustrate the invention without however in any way limiting it . the suitable cd in distilled water is introduced at 50 °- 90 ° c . into a 2 - neck flask equipped with cooler and nitrogen outlet . the cd aqueous solution , with concentration between 2 % and 15 % by weight , for example at 10 %, is left under stirring at the same temperature for 1 hour . after said period a solution in water soluble solvent containing the active principle and synergistic compound in the required proportions is added in portions over a 6 - hour period . the mixture is maintained under stirring at 40 °- 90 ° c . for a further 12 - 36 hours , then the mixture is left to cool to ambient temperature under stirring and finally left to decant for 3 - 5 hours . the mixture is evaporated to dryness under vacuum . the supramolecular complexes thus obtained prove to be stable in the solid phase for at least 30 days at 23 ° c . the βcd ( 2 g ) in distilled water ( 20 ml ) is introduced at 75 ° c . into a 2 - neck flask , equipped with cooler and nitrogen outlet . the solution is left under stirring for 1 hour at 75 ° c . after this period a solution of isopropanol ( 25 ml ) containing pbo / soitem ( 98 / 2 , 0 . 536 g equal to 0 . 525 g of pbo and 0 . 011 g of soitem in total ) and acetamiprid ( 0 . 115 g ) is added in portions over a 6 - hour period . the mixture is maintained under stirring at 75 ° c . for a further 18 hours , then left to cool to ambient temperature under stirring over a 2 - hour period and finally left to decant for 3 hours . the solution is evaporated under vacuum to a solid residue to provide 2 . 6 g of formulated product . the βcd ( 2 g ) in distilled water ( 20 ml ) is introduced at 75 ° c . into a 2 - neck flask , equipped with cooler and nitrogen outlet . the solution is left under stirring for 1 hour at 75 ° c . after said period a solution of isopropanol ( 25 ml ) containing pbo / soitem ( 98 / 2 , 0 . 536 g equal to 0 . 525 g of pbo and 0 . 011 g of soitem in total ) and imidacloprid ( 0 . 134 g ) is added in portions over a 6 - hour period . the mixture is maintained under stirring at 75 ° c . for a further 18 hours , then left to cool to ambient temperature under stirring over a 2 - hour period and finally left to decant for 3 hours . the solution is evaporated under vacuum to a solid residue to provide 2 . 4 g of formulated product . using the same method as described in example 2 , a solution of isopropanol ( 22 . 5 ml ) containing pbo / soitem ( 98 / 2 ) ( 0 . 0018 g equal to 0 . 0017 g of pbo and 0 . 0001 g of soitem ) and 0 . 103 g of acetamiprid is slowly added to a solution of 1 . 8 g βcd in 18 ml of distilled water . by following the aforegiven method , 1 . 9 g of formulated product are obtained . using the same method as described in example 2 , a solution of isopropanol ( 25 ml ) containing pbo / soitem ( 98 / 2 ) ( 0 . 01 g equal to 0 . 0098 g of pbo and 0 . 0002 g of soitem ) and 0 . 115 g of acetamiprid is slowly added to a solution of 2 . 0 g γcd in 20 ml of distilled water . by following the aforegiven method , 2 . 1 g of formulated product are obtained . using the same method as described in example 3 , a solution of isopropanol ( 22 . 5 ml ) containing pbo / soitem ( 98 / 2 ) ( 0 . 0018 g equal to 0 . 0017 g of pbo and 0 . 0001 g of soitem ) and 0 . 12 g of imidacloprid is slowly added to a solution of 1 . 8 g βcd in 20 ml of distilled water . by following the aforegiven method , 1 . 8 g of formulated product are obtained . using the same method as described in example 3 , a solution of isopropanol ( 45 ml ) containing pbo / soitem ( 98 / 2 ) ( 0 . 018 g equal to 0 . 017 g of pbo and 0 . 001 g of soitem ) and 0 . 241 g of imidacloprid is slowly added to a solution of 3 . 6 g βcd in 36 ml of distilled water . by following the aforegiven method 3 . 8 g of formulated product are obtained . using the same method as described in example 2 , a solution of isopropanol ( 120 ml ) containing pbo / soitem ( 98 / 2 , 2 . 92 g equal to 2 . 87 g of pbo and 0 . 050 g of soitem in total ) and thiabendazole ( 1 . 7 g ) is slowly added to a solution of β - cd ( 14 . 4 g ) in 120 ml of water . the mixture is maintained under stirring at 75 ° c . for a further 5 hours , then allowed to cool at about 40 ° c . and maintained at this temperature under stirring for 15 hours . cooling at ambient temperature is then performed and the solution is dried under vacuum yielding 19 . 1 g of formulated product . using the same method as described in example 2a solution of isopropanol ( 120 ml ) containing pbo / soitem ( 98 / 2 , 3 . 87 g equal to 3 . 79 g of pbo and 0 . 077 g of soitem in total ) and fipronil ( 1 . 6 g ) is slowly added to una solution of β - cd ( 14 . 4 g ) in 120 ml of water . the mixture is maintained under stirring at 75 ° c . for a further 5 hours , then it is allowed to cool at about 40 ° c . and maintained at this temperature under stirring for 15 hours . cooling at ambient temperature is then performed , and the solution is dried under vacuum , yielding 19 . 7 of formulated product . the suitable cd in distilled water is introduced at a temperature comprised between 20 ° and 30 ° c . into a 2 - neck flask equipped with cooler and nitrogen outlet in weight / weight proportions preferably between 30 % and 70 %. the suspension is then heated to a temperature comprised between 60 ° and 80 ° c . and left under stirring at the same temperature for a convenient time period e . g . 10 - 30 minutes . after said period a preheated mixture of the active principle and synergistic compound in the required proportions are added in portions . the mixture is maintained at a temperature comprised between 70 ° and 90 ° c . under stirring for a further 1 - 2 hours then left to cool to ambient temperature under stirring . a solid is obtained by filtration which is then dried under vacuum . the supramolecular complexes thus obtained prove to be stable in the solid phase for at least 30 days at 23 ° c . βcd ( 13 . 9 g ) in water ( 20 ml ) is introduced into a 2 - neck flask at 25 ° c . the mixture , consisting of a suspension , is left under stirring ( 300 rpm ) for 15 minutes at 25 ° c . after this time the temperature is brought to 70 ° c ., then a mixture of acetamiprid ( 0 . 802 g ), pbo ( 3 . 65 g ) and soitem ( 0 . 07 g ) is added over a 2 - hour period . the mixture is agitated for 1 hour at a temperature comprised between 70 ° and 80 ° c ., then left to cool to ambient temperature . by means of filtration a white solid is obtained which is dried for 3 hours under vacuum ( 25 ° c ./ 1 mbar ) to provide 14 . 4 g of formulated product . βcd ( 13 . 9 g ) in distilled water ( 20 ml ) is introduced into a 2 - neck flask at 25 ° c . the mixture , consisting of a suspension , is left under stirring ( 300 rpm ) for 15 minutes at 25 ° c . after this time the temperature is brought to 70 ° c ., then a mixture of imidacloprid ( 0 . 933 g ), pbo ( 3 . 65 g ) and soitem ( 0 . 07 g ) is added over a 2 - hour period . the mixture is agitated for 1 hour at 90 ° c ., then left to cool to ambient temperature . by means of filtration a white solid is obtained which is dried under vacuum ( 25 ° c ./ 1 mbar ) for 3 hours to provide 16 . 4 g of formulated product . using the same method as described in example 11 , a formulation was prepared starting from β - cd ( 50 g ) in distilled water ( 72 ml ), diazinon ( 4 g ) in a mixture with pbo ( 14 . 1 g ) and soitem ( 0 . 3 g ). by following the previously reported procedure , 64 g of formulated product are obtained . using the same method as described in example 11 , a formulation was prepared starting from of β - cd ( 25 g ) in of distilled water ( 36 ml ), imazalil ( 1 . 95 g ) in a mixture with pbo ( 7 g ) and soitem ( 0 . 15 g ). by following the previously reported procedure , 27 . 5 g of formulated product are obtained . using the same method as described in example 11 , a formulation was prepared starting from β - cd ( 50 g ) in distilled water ( 72 ml ), fenazaquin ( 4 . 0 g ) in a mixture with pbo ( 14 g ) and soitem ( 0 . 3 g ). by following the previously reported procedure 58 . 2 g of formulated product are obtained . using the same method as described in example 11 , a formulation was prepared starting from β - cd ( 50 g ) in distilled water ( 72 ml ), pyrimicarb ( 3 . 1 g ) in a mixture with pbo ( 13 . 2 g ) and soitem ( 0 . 27 g ). by following the previously reported procedure 60 . 5 g of formulated product are obtained . using the same method as described in example 11 , a formulation was prepared starting from β - cd ( 50 g ) in distilled water ( 72 ml ) pyridaben ( 4 . 8 g ) in a mixture with pbo ( 14 . 1 g ) and soitem ( 0 . 3 g ). by following the previously reported procedure 64 . 2 g of formulated product are obtained . using the same method as described in example 11 , a formulation was prepared starting from β - cd ( 50 g ) in distilled water ( 72 ml ), pyrimethanil ( 2 . 6 g ) in a mixture with pbo ( 14 . 1 g ) and soitem ( 0 . 3 g ). by following the previously reported procedure 57 . 3 g of formulated product are obtained . hydroxypropyl p - cyclodextrin ( 10 g ) in distilled water ( 250 ml ) is introduced at room temperature into a two - neck flask provided with cooler and nitrogen outlet . thereafter , a solution of pbo / soitem 98 / 2 p / p ( 4 . 4 g ) and imidacloprid ( 1 . 0 g ), in isopropanol ( 10 ml ) is added . the solution is heated to 75 ° c . and is allowed to react at this temperature for 3 h , then the mixture is allowed to cool at room temperature under stirring . the mixture is dried under vacuum , yielding 15 . 3 g of formulated product . the “ leaf dip bioassay ” used for testing the activity of insecticides against bemisia tabaci ( whitefly ) biotype b , was similar to that described by cahill , m et al , bull . entomol . res . 85 , 181 - 187 , 1995 . cotton plants ( gossypium hirsutum l .) were grown without any exposure to the insecticides . the leaves were cut up into disc shapes and immersed in an aqueous solution of insecticide containing 0 . 01 % of agral then left to dry at 25 ° c . control leaves were immersed in agral and distilled water only . about 20 adult insects were placed onto the small discs of treated cotton leaf . the insects were allowed to feed and maximum mortality was evaluated at 24 and 48 hours . by using the formulations prepared as in examples 2 and 3 the results given in table 1 were obtained . lc50 % a . i . and lc99 % a . i indicate the quantity of active ingredient ( i . e pure insecticide ) able to achieve mortality for 50 % and 99 % of the insects tested . as a comparison , both the data obtained with imidacloprid and acetamiprid in the absence of the synergistic compound ( pbo ) and the data obtained with imidacloprid and acetamiprid in a mixture with the same quantity of pbo present in the formulation products of examples 2 and 3 are given in the same table . the data demonstrate that the formulations of examples 2 and 3 are much more effective than both the corresponding pure insecticides and the mixture of insecticides and synergistic compound . the resistance factor to imidacloprid was equal to 2336 times that of non - resistant insects . the resistance factor to acetamiprid was equal to 21 times that of non - resistant insects .