EFFECTIVENESS OF SOME NATIVE DIATOMACEOUS EARTH AGAINST MAIZE WEEVIL, SITOPHILUS ZEAMAIS (COLEOPTERA: CURCULIONIDAE), UNDER CONTROLLED CONDITIONS.

The Maize weevil, Sitophilus zeamais Motchulsky (Coleoptera: Curculionidae), is one of important pests of storage maize in Turkey. Laboratory experiments were carried out to investigate the effect of two local diatomaceous earth (Aydın and Ankara) and Silicosec® (Biofa, Germany) against S. zeamais adults at 25 and 30°C and 50-65% relative humidity. Maize grains (cultivar Decalp 6664) were treated with three doses of DEs (1000, 1500 and 2000 ppm) and untreated seeds were regarded as control. The dead adult counts were made 2, 3, 5, 7, 14 and 21 days after DEs. The progeny of S. zeamais was determined separately for each treatment after 60 days from end of the experiment. The highest mortality (100%) of the maize weevil was observed with 2000 ppm Ankara DE on 14th day after application at 25 °C, which was followed by Aydın and SilicoSec® DEs (99.0 and 90.1%). The insecticidal activity of native DEs increased with increasing application dose, exposure time and temperature. The highest insecticidal activity at 30 °C was determined for Ankara and Aydın DEs with 2000 ppm on 14th day (100%), followed by SilicoSec® (97.9%). All doses of Ankara DE had the highest insecticidal activity than rest of the DEs examined. New adult emergence (F1 offspring) was recorded in all DEs treatments; however, emergence was very low than control treatment. It is concluded that the native DEs (Ankara and Aydın) are very effective and promising against S. zeamais adults and might be used for its successful control in storage maize. [ABSTRACT FROM AUTHOR]