Insecticidal effect of Central Anatolian Region diatomaceous earths against rice weevil (Sitophilus oryzae L.) and confused flour beetle (Tribolium confusum Du Val.) on stored paddy and rice

In this study, insecticidal efficacy of four different local diatomaceous earth (DE) deposits obtained Central Anatolian Region in Turkey and commercial DE deposit (German origin), Silicosec® were evaluated against substantial pests on stored grain as Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Tribolium confusum du Val (Coleoptera: Tenebrionidae) at five different concentrations of 100, 300, 500, 900 and 1500 ppm on stored paddy and rice. Mortality of the exposed adults was assessed after 7, 14 and 21 days of exposure, and then progeny (F1) production on treated grains was recorded 65 days later. The tests were carried out at 25±1 oC temperature, 55±5% R.H. under dark laboratory conditions. The most effective DEs in a short time were assessed CBN-1 which caused 89% mortality of S. oryzae and AG2N-1 which caused 97% mortality of T. confusum adults at 1500 ppm concentration after 7 days of exposure in paddy. Similar high insecticidal efficacy was determined on Silicosec®, BHN-1 and CBN-1 exposed to 900 ppm for 14 days and 500 ppm for 21 days, and AG2N-1 exposed 900 ppm for 21 days with the 97 to 100% mortality level of S. oryzae adults in paddy. On the other hand, complete mortality of T. confusum adults was recorded on AG2N-1 at 900 ppm for 14 days and treatments of AG2N-1, BGN-1, CBN-1 for 21 days at 500, 900 and 1500 ppm respectively whereas 87% mortality rate was determined for 21 days exposure of Silicosec® at the highest concentrations on paddy. Overall DE and concentrations on rice treatments caused generally low efficacy on S. oryzae and T. confusum adults. The progeny (F1) production was not completely prevented in all DE treatments, although significantly reduced progeny production was determined in comparison with the untreated control groups depending on the increase of concentration. In conclusion, this study indicated that Turkish DE deposits, BGN-1, BHN-1, AG2N-1 and CBN-1 had high insecticidal efficacy in comparison with the commercial Silicosec® and would have potential to be used against insects in the pest management of stored paddy.