Evaluation of repellency effect of diatomaceous Earth formulation (Detech®) on three coleopteran stored grain insects

Abstract: In this study, repellent effect of diatomaceous earth formulation (Detech®) against Sitophilus oryzae (L.), Tribolium confusum du Val. and Rhyzopertha dominica (F.) adults were determined. For repellency tests, two-choice tests on single-layered wheat and in deep cups were carried out in a climate chamber at 25 ± 1 °C temperature, 65 ± 5% relative humidity and in completely dark condition. In repellency tests, 1000 ppm concentration of DE was used.In both two-choice tests carried out on single-layer wheat and in deep cups, there were significant differences among the insect numbers and percentages of the insects for S. oryzae and T. confusum in arenas with DE-treated and untreated wheat at almost all exposure periods at 1000 ppm concentration of diatomaceous earth formulation (Detech®). However, there were not significant differences among the insect numbers and percentages of the insects for R. dominica in arenas with DE-treated and untreated wheat at all exposure periods.The results of two-choice tests indicated that S. oryzae and T. confusum adults preferred mostly arenas with untreated wheat and thus, tested DE formulation had a high repellent effect on S. oryzae and T. confusum adults. Conversely, no repellent effect of DE formulation on R. dominica adults, which have low mobility in the grains was determined.