The effect of diatomaceous earth treatment combined with 50 °C temperature on Sitophilus oryzae (L.) in wheat grain


Abstract: Diatomaceous earth (DE) and extreme temperatures (high or low) used in mutually independent treatments make effective alternatives to residual insecticides but many limiting factors prevent their wider use. To minimize such negative effects, we have examined the influence of a treatment with DE originating from Serbia in combination with 50 °C temperature on a laboratory and a field (Novi Pazar) population of S. oryzae. Wheat grain was treated with DE (0.25, 0.5 and 0.75 g/kg) before S. oryzae adults were added to grain in plastic cups and placed in a temperature chamber set to 50 °C for periods of 65 and 75 min. After each exposure period, the plastic cups were transferred to 24 °C in the laboratory, and lethal effects were checked after 1, 2, 7 and 14 days, while offspring insects were counted after 8 weeks. For comparison, the effects of DE on weevils at 24 °C, and effects of exposure to 50 °C temperature were recorded in separate bioassays. Adults of both populations in plastic cups not exposed to 50 °C temperature reached mortality of > 95% after 14 days in wheat grain treated with 0.5 and 0.75 g/kg DE. Regarding both weevil populations exposed to 50 °C temperature for 65 min, total mortality and 100% offspring reduction were found after 7 days of contact with 0.25-0.5 g/kg DE. The results of the present study reveal that a combination of DE and 50 °C temperature may be preferable to their independent use.

Cookie Consent with Real Cookie Banner