Deltamethrin emulsion activity in grain warehouses

Abstract: Spraying insecticides disinfest insect population on warehouses’ structure surface and prevent rapid infestation on new stored produce. However, insecticides efficacy varies on different sprayed surfaces.Deltamethrin is a synthetic pyrethroid, used in Israel with Keshet 2.5% EC (ADAMA Ltd.) product, for warehouse spraying. Keshet efficiency against stored product pests has been tested, by commercial spraying, in warehouse. Rice weevil (Sitophilus oryzae L.) adults were exposed to the treated surface, and their mortality was recorded after 24 hours’ exposure. On iron surface, the mortality was complete. On concrete surface, the mortality ranged between 20% to 100%, depending on the location in the warehouse. In a non-treated warehouse, which served as control, mortality was 0-20%. In laboratory conditions, by spraying Keshet with same dosage on a fresh concrete surface, no mortality was recorded. The results show that the efficiency of spraying on concrete varies between laboratory conditions and commercial spraying in warehouse.Furthermore, we have examined a number of factors that may affect the efficiency of Keshet on concrete in laboratory conditions: concrete age, grain dust stuck to concrete, and air temperature during the treatment. The results of this study indicate that Keshet activity is affected by a combination of all the factors together. Understanding the main factors that increase the success of insecticides is pivotal in grain storage management.