Effectiveness of binary combinations of abamectin and deltamethrin with two inert dusts for the management of Trogoderma granarium Everts on wheat grains

Abstract

The insecticidal efficacy of two insecticides, abamectin (AB) and deltamethrin (DL), alone or in combination with two inert dusts, diatomaceous earth (DE) and kaolin (KA), was assessed against larvae of Trogoderma granarium Everts (Coleoptera: Dermestidae) on wheat grains. The two insecticides (AB and DL) were evaluated at rates of 0.25, 0.5 and 1.0 mg/kg and two inert dusts (DE and KA) were tested at rates of 100, 500 and 1000 mg/kg. The larval mortality was recorded after 7, 14 and 21 days of treatment. The emerged adults (F1) from treated larvae were counted after 30 days of treatment, while F2 and grain weight loss were observed after 80 days of treatment. The binary combinations of two insecticides and two inert dusts showed higher insecticidal activity than individual treatments. The complete larval mortality of T. granarium was achieved in treatment with a mixture of KA (1000 mg/kg) and AB (1.0 mg/kg). While the highest larval mortality of T. granarium in the treatments with binary combinations of DL with DE or KA was 70%. Furthermore, the binary combinations of DE and KA with AB and DL at the highest application rate caused complete inhibition of F1 progeny. Similarly, significant inhibition of F2 progeny was observed after 80 days of treatment with these binary mixtures compared with control treatment. Moreover, full protection of wheat grains was attained in the combinations of two insecticides (AB and DL) at 1.0 mg/kg and two inert dusts (DE and KA) at1000 mg/kg. The findings of the present study indicate that the combinations of AB with DE or KA have high efficacy against T. granarium, and could be used for the control of this invasive insect species in stored wheat.