The occurrence of thrips on grapevine and their control of insecticides and bio-insecticides

Abstract

The occurrence of thrips on grape cultivation var. Beauty Seedless and Flame Seedless and their control of insecticides and bio-insecticides were carried out at the Royal Agricultural Station Inthanon, Chiang Mai Province from February to July 2020. All specimens collected were mainly identified as chilli thrips, Scirtothrips dorsalis Hood, 1919. These thrips could appear during the budburst and shoot growth (immediate pre-bloom). Their population then gradually increased to its peak at the first stage of veraison. The efficiency of controlling thrips in laboratory conditions was evaluated using 11 methods, including four groups of insecticides (fipronil, carbaryl, imidacloprid, and carbosulfan), six bio-pesticides (herbal fermented water formula PP1-PP4, potassium soap, and Beauveria bassiana), and one control treatment, respectively. It was found that four insecticides were the most effective chemicals for thrips control and there was no statistically significant difference between treatments (p>0.05). Their mortalities increased to 73.33±21.68, 90.00±5.77 and 100.00±0.00% after one-, three-, and five-day(s) exposure. Furthermore, the potassium soap (K-soap) was efficient in controlling 83.67±6.67% of thrips after five days of exposure. Regarding mortality after six days of exposure, three formulations of herbal fermented water (PP1, PP2, PP4) and the entomopathogenic fungus, B. bassiana displayed about 70.00±0.00% mortality. In contrast, the herbal fermented water formula PP3 had the lowest efficiency, as it could control thrips only 36.67±8.82% after seven days of exposure. In addition, the mortality rate after spraying with B. bassiana on day 7 was 63.33±3.33%, with every treatment suggesting a steady death rate of thrips after spraying.