The Control Effect of Two Granular Insecticides on Biotype B of the Stone Leek Leafminer, <i>Liriomyza chinensis</i>（Kato）（Diptera: Agromyzidae）

In recent years, widespread damage caused by biotype B of the stone leek leafminer, Liriomyza chinensis（Kato）（Diptera: Agromyzidae）, has become an issue in Welsh onion fields throughout Ibaraki Prefecture. This study aims to evaluate the efficacy of granular insecticides in controlling L. chinensis in Welsh onion fields harvested in early autumn. Specifically, we applied either cyantraniliprole-thiamethoxam granules（6 kg/10 a）or dinotefuran granules（9 kg/10 a）to the base of the plants in late August, and compared their effectiveness to a non-granule control. Although all treatments showed an increase in the number of flies from mid to late September, the percentage of damaged leaves in the groups treated with granules was lower than that in the non-granule control. Furthermore, the effectiveness of dinotefuran was equal to or greater than that of cyantraniliprole-thiamethoxam. These results suggest that dinotefuran is a lower-cost alternative with saved times of usage of insecticide components, in late August on Welsh onions harvested in autumn.