RESULTS OF INVESTIGATIONS OF THE PROPERTIES, ACTIVITY AND APPLICATION OF PHYSICAL INSECTICIDES - INERT DUSTS

Among recent tendencies to substitute the chemical method of plant protection, physical insecticides have also some importance. Physical insecticides include inert dusts, i.e. dusts without chemical action which breeks down the impermeability of the epicuticular wax monolayer causing death of insects by dehydration. A survey of the extensive investigations carried on in order to contribute to the better knowledge of different inert dusts is given in this paper and some possibilities of their use are mentioned. The topics of these investigations were as follows: the biological activity of 32 different dusts on ten different coleopteraus insects of stored products, the possibilities to activate some dusts, the influence of the water content of grain, of the relative air humidity and of the temperature on the activity of different dusts on varions test misects, the residnal activity of some dusts apter storing the treated in different conditions, the inflance of dust on the progeny of weevils, the application of dusts in from of water suspension, some investigation deposing inert dusts on the body of insects using a microapplicator, the dynamics of the water loss of insect bodies treated with dusts, the measuring of the sorptive capacity of dusts for linseed oil, rhodamine B, methylene blue and beeswax, the measuring of the dynamics of aceptance or of the loss of water from different dusts in various conditions etc, etc