Insecticidal Efficacy of Iranian Diatomaceous Earth s on Adults of Oryzaephilus surinamensis

Abstract

Diatomaceous Earth (DE) is a dust composed of fossi lized bodies of unicellular algae used as an insecticide. In this study, the insectic idal potential of four Iranian DE deposits was assessed in adults of Oryzaephilus surinamensis (L.) . Three of DE deposits were collected from Maragheh, Mamaghan, and Khorasan Jon oobi mines and Sayan ® formulation was obtained from Kimia Sabz Avar Compa ny. The insect adults were exposed on wheat, peeled barley, and rice treated w ith 300, 600, 1,000, 1,500, and 2,000 ppm of the DE deposits. Experiments were conducted at 27 ± 1°C and 55 ± 5% RH in continuous darkness. Mortality of the exposed indiv iduals was counted after 2, 5, 10, and 14 days of exposure on the treated substrate. Morta lity increased with increasing exposure intervals and concentration level. Satisfa ctory level of protection was observed on wheat grain; as 100% mortality was recorded on w heat treated with 600 ppm of all tested DE deposits after a 10-day exposure. However , for rice, even after 10 days of exposure to 2000 ppm mortality didn’t reach 100%. T he lowest LC 50 value (39 ppm) was obtained in wheat treated with Khorasan DE sample a nd the highest one (908 ppm) was achieved in rice treated with Sayan ® . The present study suggests that Iranian DEs may b e used as potential grain protectants in stored-produ ct pest management programs. Keywords: Barley storage, Pest management, Rice storage, Stor ed grain protectant, Wheat storage.