TOXIC AND GROWTH INHIBITORY EFFECT OF DIATOMACEOUS EARTH AND THIAMETHOXAM ALONE AND IN COMBINATION AGAINST TRIBOLIUM CASTANEUM (HERBST) (COLEOPTERA: TENEBRIONIDAE)

Present study was conducted to investigate the effectiveness of thiamethoxam and three formulations of diatomaceous Earth (DE) (Concern®, Organics® and Food Grade®) against rust red flour beetle, Tribolium castaneum (Herbst). Three concentrations of thiamethoxam (0.25, 0.50 and 0.75 ppm) and DE (200, 400 and 600 ppm) were used. Best treatments of thiamethoxam and DEs were selected and their combined effects regarding mortality and progeny inhibition were evaluated. The experiment was performed on sterilized, crushed wheat grains at 30±2ºC and 65±5% R.H. The results showed that maximum mortality (90 %) was achieved in combination of Food Grade® with thiamethoxam and Concern® with thiamethoxam, while combination of organics® with thiamethoxam caused 82.22 % mortality after 21 days. In case of DE tested formulations, Food Grade® showed better results causing 67.77% mortality at the dose rate of 600 ppm after exposure period of 21 days followed by Concern® and Organics® which caused 59.98 % and 51.11 % mortality at dose rates of 600 and 400 ppm, respectively after 21 days exposure time. Similar trend of results were recorded for progeny production of T. castaneum, in combined treatments of D.E Food Grade® and D.E Concern® with thiamethoxam that was 0.00%. It can be concluded from these results that the use of diatomaceous Earth (DE) and thiamethoxam would be a better alternative for the protection of stored grains and their products.