Biological activity of the Schinus molle L. (Anacardiaceae) essential oil on granary weevil, Sitophilus granarius (Linnaeus) (Coleoptera: Dryophthoridae)

Abstract

Granary weevils, Sitophilus granarius (Linnaeus, 1758) (Coleoptera: Dryophthoridae) are important pest of stored grain worldwide. Larvae and adults cause weight and quality losses by feeding on grains. The aim of the study was to assess potential of the essential oil isolated from Schinus molle L. (Anacardiaceae) against adults of S. granarius under laboratory conditions. In the contact toxicity assays, five different concentrations, i.e., 5, 7.5, 10, 12.5 and 15% (v/v) were used. The doses of plant essential oil were applied to test insects using a microapplicator (1 µl/adult). Pure acetone was used in the negative control group (1 µl/adult). K-Obiol® EC 25 (Bayer AG, Germany) containing 25 g/l deltamethrin and 250 g/l piperonyl butoxide was utilized as a positive control group in the dose suggested on the label. After exposure, mortality of the adults was determined at 24, 48, 72 and 96 h. According to the results of the study, mortality rates increased with increase in the dose. After 24 hours, mortality rates of over 70% were observed at doses of 10, 12.5 and 15 % (v/v) (74.96, 94.90, 93.01%, respectively). At the end of 96th hour, the effects of the same doses were determined as 82.55, 95.56 and 97.49%, respectively. These results indicated that essential oil of S. molle has significant potential in the control of S. granarius as contact insecticide.