Are insecticidal seed treatments effective on overwintered adults of Sunn pest, Eurygaster integriceps (Hemiptera: Scutelleridae)?

Application of insecticides against overwintered adults of Sunn pest has limitations. To find the new measurement against the insect, two insecticides imidacloprid, and thiamethoxam, were tested as seed treatments against overwintered adults of Sunn pest in semi-field and field conditions in Alborz province. This project was carried out in a split-plot design with planting dates at 3 levels (at the beginning of wheat cultivation in 2016, Nov. 7, mid- and late-dates in 2016, Nov. 20, and Dec. 4) as the main plots and seed treatments at 5 levels, including imidacloprid 700WS with two concentrations of 1 and 0.5 g/kg of wheat seed and thiamethoxam 350FS with two concentrations of 0.8 and 0.4 g/kg and control (without seed treatment) as the sub-plots. The comparison of the mean efficiency of treatments at different cultivation dates in the semi-field conditions showed that the lowest (9.1%) and the highest (71.66%) efficiencies were observed at the beginning and late cultivation dates, respectively. In seed treatments, thiamethoxam at high concentration had the maximum efficacy (84.4%) 48 days after the last planting date, and the minimum efficacy (5.55%) was related to thiamethoxam at low concentration 116 days after. The results of field conditions showed that the highest (15%) and lowest (1.25%) efficacies of seed treatments were 97 days after the last cultivation date. Thiamethoxam seed treatment at high concentration had the highest efficiency (21.6%) among the treatments at the first sampling date. On other sampling dates, the efficiency of all treatments was less than 10%. The seed treatment with imidacloprid and thiamethoxam did not have acceptable effectiveness against overwintered adults and nymphs of Sunn pest. Also, the change in the cultivation date of seed-treated wheat cannot be effective in reducing the overwintered adult population of Sunn pest.