Comparing the efficacy of common insecticides against the apple armored scale, Lepidosaphes malicola (Hem: Diaspididae) in apple orchards of Semirom, Iran

The apple armored scale, Lepidosaphes malicola Borchsenius (Hem.: Diaspididae) an important pest of fruit trees. Control of this pest depends mostly on the use of chemical pesticides. To study the effect of several pesticides on the pest population, two separate experiments were conducted in a randomized complete block design with three replications in two orchards. The first factor was treatments [control (water), spirotetramat 0.5 and 0.75 ml/L, flupyradifurone, thiacloprid, and pyriproxyfen 0.5 ml/L]. The second factor was the sampling time (1 day before and 1, 3. 5, 7, 14, 21, 28 and 35 days after treatment). Spirotetramat and flupyradifurone (with more than 80 percent mortality) had the most effect on the nymphal mortality. The mortality in thiacloprid and pyriproxyfen was lower than that of spirotetramat and flupyradifurone. By considering the treatment time, the mortality rate of nymphs by flupyradifurone, a butenolide with knockdown effect reached its highest level one day after treatment. In 0.75 ml/L concentrations of spirotetramat the highest decrease in the nymphal population was observed one week after treatment. Spirotetramat with up and down bilateral movement ability is a very long-lasting systemic insecticide. Results indicated a negligible effect of the pesticides on adult mortality under female shields. The use of 1.5- 2 percent volck® oil in winter spraying had a significant effect on pest control. Overall, spirotetramat and flupyradifurone showed a significant effect on the nymph’s control and can be recommended.