In 2016, we investigated the resistance of English grain aphid (Sitobion avenae [F.]) to four different insecticides (Actara 25 WG, Calypso SC 480, Fastac 100 EC in Bulldock EC 25) under laboratory conditions. The insecticides were used in three different concentrations (20, 100, 500 %). The resistance was tested with standard method IRAC no. 19. The aphids, which were used in the experiment, were collected in the winter wheat fields from three different locations: at the Laboratory Field of Biotechnical Faculty in Ljubljana, in Šentjernej, and in Zagorica near Kamnik. The leaves of wheat were treated with different concentractions of insectitides. Leaves of wheat in control treatment were only dipped to distilled water. The leaves were placed into Petri dishes with agar. Into each Petri dish we placed 20 aphids with fine brush. Each of 13 treatments (4 insecticides used in 3 concentrations, and a control treatment) have been repeated three times. We found out that with increasing concentration of insecticides, the mortality of the pest under investigation also increase. On all three locations the highest actual mortality (always above 90 %) of English grain aphid was caused by Bulldock EC 25, while the lowest (73–82 %) was caused by Actara 25 WG. With these results we confirm that in Slovenia English grain aphid is the most resistant to neonicotinoid Actara 25 WG, while the most efficient insecticide is pyrethroid Bulldock EC 25.
|
